Chemistry, Pharmacology, And Pharmacokinetics Property Of Cistanches Herba
Mar 25, 2022
ali.ma@wecistanche.com
Zhifei Fua,b , Xiang Fana,b , Xiaoying Wanga,c,⁎ , Xiumei Gaoa,b
Abstract:
Ethnopharmacological relevance: Cistanches Herba is an Orobanchaceae parasitic plant. As a commonly used traditional Chinese Medicine (TCM), its traditional functions include treating kidney deficiency, impotence, female infertility, and senile constipation. Chemical analysis of Cistanches Herba revealed that phenylethanoid glycosides, iridoids, lignans, oligosaccharides, and polysaccharides were the main constituents. Pharmacological studies demonstrated that Cistanches Herba exhibited neuroprotective, immunomodulatory, hormonal balancing, anti-fatigue, anti-inflammatory, hepatoprotection, anti-oxidative, anti-bacterial, anti-viral, and anti-tumor effects, etc. The aim of this review is to provide updated, comprehensive, and categorized information on the phytochemistry, pharmacological research, and pharmacokinetic studies of the major constituents of Cistanches Herba.
Materials and methods: The literature search was conducted by systematic searching multiple electronic databases including SciFinder, ISI Web of Science, PubMed, Google Scholar, and CNKI. Information was also collected from journals, local magazines, books, monographs.
Results: To date, more than 100 compounds have been isolated from this genus, including phenylethanoid glycosides, carbohydrates, lignans, iridoids, etc. The crude extracts and isolated compounds have exhibited a wide range of in vitro and in vivo pharmacologic effects, such as neuroprotective, immunomodulatory, anti-in-inflammatory, hepatoprotection, anti-oxidative, anti-bacterial, and anti-tumor effects. The phenylethanoid glycosides, echinacoside, and acteoside have attracted the most attention for their signifificantly neuropharmacology effects. Pharmacokinetic studies of echinacoside and acteoside also have also been summarized.
Conclusion: Phenylethanoid glycosides have demonstrated wide pharmacological actions and have great clinical value if challenges such as poor bioavailability, fast and extensive metabolism are addressed. Apart from phenylethanoid glycosides, other constituents of Cistanches Herba, their pharmacological activities, and underlying mechanisms are also needed to be studied further.
Keywords: Cistanches Herba, Phytoconstituents, Pharmacology, Echinacoside, Acteoside, Pharmacokinetics
1. Introduction
Cistanches Herba (Roucongrong in Chinese), is an Orobanchaceae parasitic plant. The genus Cistanche contains 27 species in the world , distribution mainly in arid and semi-arid habitats across Eurasia and North Africa, such as China, Iran, India, Mongolia (Piwowarczyk et al., 2016). It has been used for centuries in TCM as a yang-tonic herb. Eight species and one variation of Cistanches Herba have been recorded in China and only Cistanche deserticola Y. C. Ma and Cistanche tubulosa (Schenk) Wight are recorded in Chinese Pharmacopeia. Modern pharmacological studies have shown that Cistanches Herba has various activities such as anti-neurodegenerative disease (Wu et al., 2014a), immunoregulatory (Dong et al., 2007), anti-inflflammation (Nan et al., 2013), hepatoprotective (You et al., 2016).
The broad spectrum of biological activities reported in this genus has been attributed to the complex and varied phytochemical composition. This contribution reviews the information on the traditional use, chemical composition, and pharmacology properties of the extracts. The pharmacokinetics of echinacoside and acteoside were also included.
Previous reviews on Cistanches Herba have focused on extraction, isolation, and chemical analysis of constituents, neuropharmacological effects and have little information about pharmacokinetic studies (Z. Li et al., 2016c; Gu et al., 2016; Jiang and Tu, 2009). Being aware of all this previous reviewing work, we have aimed to update the available information about the traditional uses, lists all phytochemical constituents and pharmacological activities (from the 1950s to the beginning of 2017), especially pharmacokinetic studies of echinacoside and acteoside and clinical applications of Cistanches Herba to provide references for the further research and application of this genus.
2. Ethnobotany
2.1. Distribution
Cistanches Herba grows on desert and sand dunes， the primary areas of cultivation of Cistanches Herba are the Mediterranean region, Asia, and Africa (Shahi Shavvon and Saeidi Mehrvarz, 2010; Piwowarczyk et al., 2016). In China, eight species and one variation of Cistanches have been recorded, including C. deserticola Y. C. Ma, C. tubulosa (Schrenk) Wight, C. salsa (C.A. Mey) G. Beck, C. Sinensis G. Beck, C. lanzhouensis Z. Y. Zhang, C. ambigua (Bge.) G. Beck, C. fifissa (C. A. Mey) G. Beck, C. ningxiaensis D. Z. Ma et A. Duan and salsa var. albiflora P. F. Tu et Z. C. Lou, which mainly distributed in Inner Mongolia, Ningxia, Gansu, Qinghai, and Xinjiang (Liu, 2004; Ma and Duan, 1993). It is called “desert ginseng” in China because of its excellent medicinal functions and nourishing effects.
2.2. Traditional uses
Cistanches Herba is a very important TCM that was first recorded in Shen Nong Ben Cao Jing, in approximately 100 AC, written in the HouHan Dynasty. Among all the tonics, Cistanches Herba is widely accepted as a “top-tier” one. ‘kidney-yang defificiency syndrome’ is one of the elementary syndrome patterns in TCM, which is characterized by weakness, fatigue, soreness of waist and knees, aversion to cold and in particular sexual dysfunction (Shen, 1999). Medical application of Cistanches Herba cures yang defificiency, erection dysfunction, and females with irregular menstruation, infertility, and morbid leucorrhea as noted in Compendium of Materia Medica. In Chinese Pharmacopeia (2015 edition) only C. deserticola and C. tubulosa were listed, however, C. sala and C. Sinensis were also used as Roucongrong in folk (Tian, 2002; Jiangsu New Medical College, 1986). Cistanches Herba is sweet and salty in taste, warm in nature, acts on kidney and large intestine channels, and has effects of invigorating the kidney and supplementing essence, moisturizing the intestine, and relaxing bowels. As a commonly used TCM, its traditional functions include treating kidney defificiency, impotence, female infertility, profuse metrorrhagia, and senile constipation (Jiangsu New Medical College, 1986). Chinese Pharmacopeia Committee Editing (2005) advocated the Cistanche at a daily dose of 6–10 g, boiled in water for oral use. In China, there are several formulas containing Cistanches Herba used in traditional uses, such as ①Roucongrong Wan, to treat kidney defificiency and impotence: Cistanches Herba, Rehmanniae Radix preparator, Cuscutae Semen, and Schisandrae Chinensis Fructus (Zhang, 1959a) ②Jingang Wan, to treat soreness of loins and knees: Cistanches Herba, Morinda Officinalis Radix, Eucommiae Cortex, and Dioscoreae spongiosis Rhizoma (Liu, 1959) ③Jichuan Jian, to relieve constipation: Cistanches Herba, Angelicae Sinensis Radix, Achyranthis bidentatae Radix, Alismatis Rhizoma, Cimicifugae Rhizoma, and Aurantii Fructus (Zhang, 1959b). Chemical analysis reveals that phenylethanoid glycosides, iridoids, lignans, oligosaccharides, and polysaccharides are the main constituents. Pharmacological studies demonstrate that Cistanches Herbaexhibits endocrine regulation, neuroprotective, immunomodulatory,anti-tumor, anti-inflflammatory, hepatoprotection activities, etc. This review presents and analyzes recent developments in the chemistry, pharmacology, and pharmacokinetics property of Cistanches Herba and provides a reference for further study and clinical application.
2.3. Economic importance
Cistanches Herba is a natural resource, with edible and pharmaceutics value. With the development of TCM and dietary cures, the demand for it has been increasing year by year. Artificial planting of Cistanches Herba is necessary and advocated in China in order to protect the wild resources, such as C. deserticola, C. tubulosa, and C. salsa. Professor Pengfei Tu has made a great contribution to this field (Tu and Guo, 2015a, 2015b). C. deserticola lives parasitically on the roots of psammophyte Haloxylon ammodendron (Chenopodiaceae) and C. tubulosa is parasitized on the roots of Tamarix, which are best for precautions sand species. C. salsa, is a plant parasite found on the roots of shrub plants, such as Chenopodiaceae, Tamaricaceae, Zygophyllaceae, which are used for improving saline land. Artificial planting has a stronger positive for the climate, soil, and environment, which could produce good economic, social, and ecological benefits.
3. Chemical constituents
The chemical components of Cistanches Herba are variable which might be related to species, plant origins, and location. More than 100 compounds from this genus have been identifified, including phenylethanoid glycosides (PhGs), carbohydrates, lignans, iridoids, essential oils, and amino acids, etc. PhGs as the main constituents, up to 4%, 3%, and 0.3% in C. tubulosa, C. salsa, C. deserticola, respectively (Wang et al., 2017). The content of total sugar content was determined to be from 26% to 46% with phenol–sulfuric method in different locations of C. deserticola (Xue and Zhang, 1994).
3.1. Phenylethanoid glycosides
PhGs are a class of polyphenolic compounds distributed in many plants. To date, a total of 69 PhGs have been found by HPLC-LTQOrbitrap-MS in Cistanches Herba (J. Zhang et al., 2015), however, as far as we know, just over fifty PhGs have been isolated, including 2 monosaccharide glycosides, 33 disaccharide glycosides, and 18 trisaccharide glycosides(1–53, Table 1). PhGs have been reported to have various pharmacological activities, such as neuroprotective, immunomodulatory, anti-inflflammatory, hepatoprotective, anti-oxidative, etc.
3.2. Carbohydrates
Carbohydrates are another main constituent of Cistanches Herba. As important natural products, carbohydrates have drawn a lot of attention, however, the studies on their chemical composition of them are relatively less compared to PhGs. In the past few years, several saccharides structures have been found and are still in progress. Galactitol, the main active component of monosaccharide, possess laxative property (Y. Gao et al., 2015b). Most studies on polysaccharides have been focused on extraction, isolation, purification, and structural analysis. Structural analysis of polysaccharides is difficult because many factors such as geographical location, environmental conditions, and extraction method can affect the monosaccharide composition, fine structure, and size. Despite all that, researchers have elucidated several polysaccharides' composition or their structural backbones (Table 2). The monosaccharide composition of Cistanches Herba polysaccharides consisted of mainly mannose, galactose, glucose, xylose, uronic acids, etc.
3.3. Other compounds
Other compounds have been isolated from Cistanches Herba, including 15 lignans (54–68, Table 3), 27 iridoids (69–94, Tables 3, 4) Benzyl glycosides (Lei et al., 2007), serval monoterpenes(Yoshizawa et al., 1990; Yamaguchi et al., 1999; Morikawa et al., 2010), besides β- sitosterol, D-mannitol, succinic acid, β-sitosterol β-D-glucoside, kankanose and so on, have also been reported. HPLC-MS or GC-MS had detected the alkaloids, betaine N, N-dimethyl glycine methyl ester, and essential oils in Cistanches Herba (Qin, 2012; Du et al., 1988).
4. Pharmacological properties
Cistanches Herba, as an important TCM, has a wide range of applications. Echinacoside and acteoside as the main active constituents of PhGs were studied extensively, which are used as index components in quality identification. Here, we also summarized the echinacoside and acteoside activities of other plants.
4.1. Endocrine regulation activities
Cistanches Herba was commonly used as a tonic for kidneys. According to TCM, C. deserticola decoction (1.5 g/kg, 3.0 g/kg, 6.0 g/ kg, i.g.) was reported to be able to raise the weight of seminal vesicle and prostate gland of the male rat, alleviate the testicular toxicity induced by hydroxyurea and modulate the serum sex hormones at some level (Gu et al., 2013). C. deserticola decoction (10 g/kg, i.g.) also could ameliorate the mice reproductive toxicity induced by Leigongteng glycoside (J. Li et al., 2014), besides, the 70% ethanol extract of C. tubulosa (echinacoside 4.2%, acteoside 2.3%, 0.2 g/kg, i.g.) reversed bisphenol A-induced testicular and sperm damage in SD rats through gonad axis up-regulated steroidogenesis enzymes, and echinacoside was one of the active compounds (Jiang et al., 2016). T. Wang et al. (2015) reported that the 70% ethanol extract of C. tubulosa (0.4 and 0.8 g/kg for 20days, i.g.) improved SD rat's sperm count, motility, as well as progesterone and testosterone level. Immunohistochemistry and western blot results showed that the cholesterol side-chain cleavage enzymes expression (CYP11A1, CYP17A1, and CYP3A4) was enhanced by the extraction. Not only in the rat but also in the mice model of perimenopause, Cistanches Herba showed hormone regulation activity (Wei, 2014). Limited information suggested that water extraction of C. deserticola induced cytotoxicity in the male ICR mice reproductive system at three different doses (250, 500, 1000 mg/kg, p.o.) for 35 days, through the suppression of spermatogenesis and hormonal secretion, induced testicular damage (Kim et al., 2012). However, Gao et al. (2016) demonstrated that C. deserticola powder (polysaccharides content 13.6%) had no side effects administered at 7.8 g/kg for males and 8.0 g/kg (p.o.) for female SD rats for 90 days in viscera index and histopathology. Different samples, animal models, evaluation indexes, and administration intervals may play an important role in the results obtained. The toxicity is important and the mechanism worthy of further investigation.
4.2. Anti-neurodegenerative diseases activities
Alzheimer's disease (AD) is the most common type of neurodegenerative disease, accompanied by cognitive and memory impairment. In the past and present, many research groups focused their research on neuroprotective effects. Cistanches Herba water and alcohol extract all showed an anti-AD effect. Aqueous extracts of C. tubulosa contained three phenylethanoid glycosides (100 and 200 mg/kg for 15days, i.g.), echinacoside (25.4%), acteoside (3.8%), and isoacteoside (4.1%), which repaired the rat's cognitive dysfunction caused by Aβ 1–42 via decreasing amyloid deposition, inhibiting cholinergic and hippocampal dopaminergic neuronal damage (Wu et al., 2014b). C. deserticola 95% ethanol extract (250 μg/mL) induced nerve growth factor (NGF) secretion in rat glioma C6 cells and led to neurite extension in rat pheochromocytoma PC12 cells. In vivo, the extract stimulated NGF production in the cortex and hippocampus, promoted neuronal cell differentiation, neurite outgrowth, and synapse formation in the hippocampus at 5 and 20 mg/kg (3 days, p.o.) (Choi et al., 2011). In the vascular dementia rat model, the PhGs (10 mg/kg for 14days, i.p.) have shown the protection of hippocampal neurons through decreasing tau phosphorylation and increasing the collapsin response mediator protein-2 expression level (Chen et al., 2015). Add C. deserticola (15 mg/ kg) into the control diet for 2 months, the learning abilities of senescence-accelerated OXYS rats were elevated in the morris water maze, and anxiety was reduced in the plus-maze, cataract, and retinopathy with aging were improved, however, there was no effect on open Fifield (Stefanova et al., 2011). An open-label, the non-placebo-controlled study was conducted to investigate the neuroprotective clinical evidence of C. tubulosa Glycoside Capsules (Memoregain®). The total 48 weeks’ study in 18 patients, administered two 300 mg capsules 3 times per day. The result showed that Memoregain® had the potential to treat mild and moderate AD patients (Guo et al., 2013). It has been showing that PhGs (100 mg/d for 40days) can improve senescence-accelerated mouse (SAMP8) mice spatial learning and memory, decrease malondialdehyde (MDA), increase superoxide dismutase (SOD) level, glutathione peroxidase (GSH-Px) activities in mice brain and survival rate of intact pyramidal cells of the hippocampal region (Jia et al., 2014a, 2014b). Kuang used the mouse model induced by D-gal and sodium nitrite also gave the conclusion that PhGs could improve learning and memory, and the mechanism related to increasing Na+-K+ ATPase, GSH-Px, and SOD activity and decrease nitric oxide (NO) content (Kuang, 2009).
Amyloid fibrils accumulation in the cerebral can easily lead to neurodegenerative disorders. Acteoside (30 μM) has been reported to inhibit Aβ42 aggregation by activating nuclear translocation of the transcription factor NF-E2-related factor 2 (Nrf2), increasing heme oxygenase-1 (HO-1) expression in PC12 cells and in SD rat model (Wang et al., 2012). It has been shown that acteoside (30, 60, and 120 mg/kg for 60days, i.g.) could decrease mouse nitric oxide synthase (NOS) activity and caspase-3 expression (L. Gao et al., 2015; Peng et al., 2015). Echinacoside (100, 300, and 500 μM) also showed activity against amyloid fibril-induced PC12cell death (D. Zhang et al., 2015).
Parkinson's disease (PD) is a neurodegenerative disease characterized by a progressive loss of substantia nigra neurons and depletion of the transmitter dopamine (DA), with a series of pathological features, such as bradykinesia, resting tremor, and rigidity. Numerous studies have demonstrated that the extraction of Cistanches Herba, echinacoside, and acteoside signifificantly reduced caspase-3 and caspase-8 activation in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced apoptosis of cerebellar granule neurons (CGNs), protected dopaminergic neurons against dopamine neurotoxicity in C57BL/6 mice (Geng et al., 2004, 2007; Pu et al., 2003; Tian and Pu, 2005). Echinacoside (3.5 and 7.0 mg/kg for 7 days, i.g.) showed protective activity against 6-hydroxydopamine (6-OHDA)-induced rat striatal dopaminergic neurons injury, increasing the levels of DA, 3,4-dihydroxy phenylacetic acid (DOPAC) and homovanillic acid on the striatal extracellular (H. Chen et al., 2007). It was reported to be able to protect PC-12 cells from 6-OHDA or H2O2 induced apoptosis, decrease the generation of reactive oxygen species (ROS) and NO, as well as the level of Ca2+(Y. Wang et al., 2015; Kuang et al., 2009, 2010). In the tumor necrosis factor α (TNF-α) induced SH-SY5Y neuronal cells model, echinacoside also exhibited anti-apoptotic activity. Its mechanism of it was partly dependent on antioxidant activity, regulation of mitochondria function, inhibition of caspase-3 activation, and upregulation of the anti-apoptotic protein Bcl-2 expression (Deng et al., 2004a). Echinacoside inhibited rotenone-induced SH-SY5Y cells apoptosis via activating TrkA/TrkB receptors and their downstream signaling events (Zhu et al., 2013).
Besides echinacoside and acteoside, tubuloside B also has drawn lots of attention in PD disease. It showed anti-apoptosis activity in SH-SY5Y and PC12 neuronal cells. The mechanism was partially dependent on anti-oxidative stress effects, through maintaining mitochondria function, inhibiting caspase-3 activity, and decreasing free intracellular calcium concentration (Deng et al., 2004b; Sheng et al., 2002).
4.3. Immunoregulatory activities
Polysaccharides always exhibited remarkable immune-enhancing activity. Cistanches Herba contains about 26–46% of polysaccharides, meaning that the immunomodulation activities of Cistanches Herba might be mostly due to the immunoregulatory effects of polysaccharides. Pharmacological studies have shown that the crude polysaccharide fraction CDA-3B from Cistanches Herba exhibited immunoregulatory activity, promoted concanavalin A (ConA)-induced Tand LPS-induced B-cell proliferation of mice splenocytes in vitro, and CDA-1A only showed positivity on B-cell proliferation (Dong et al., 2007). Pectic polysaccharide is a common polysaccharide in Cistanches Herba. It has been reported that the ramified regions of the galacturonan core and the neutral side chains consisting of 3,6-β-D-galactan and 3,5-α-L-arabinan, which played an important role in biological activities expression. Ebringerova et al. (1997, 2002) isolated several pectic polysaccharides from C. deserticola, one of which exhibited remarkable immunomodulatory activities exceeding those of the commercial immunomodulator zymosan in vitro mitogenic and comedogenic rat thymocyte test. Maruyama's team had done a lot of research on C. salsa's immunoregulatory activity. First, the extract of C. salsa was reported to be able to stimulate IgM and IgG production in human lymph node lymphocytes with the dose of 0.1%, 1%, and 10% (Maruyama et al., 2008a). Secondly, the water extract of C. salsa was removed from low molecular weight constituents (PhGs and monoterpene) with a 3500 Da dialysis membrane (100 μg/mL), which showed the activity of stimulating IgM production in human B cell line Ball-1 and inducing slight cell proliferation. It also promoted IgG production (50 μg/mL) in the plasma B cell line HMy-2 (Maruyama et al., 2007, 2008c). However, the water extract showed different activities on the different cell lines. It inhibited the human Burkitt's lymphoma cell line Namalwa proliferation at more than 1 μg/mL (Maruyama et al., 2008b, 2008c). These authors speculated that the active constitutes in the water extract were polysaccharides, the high Mw active constituent that enhanced IgM production, and a middle Mw active constituent that inhibited cell proliferation (Maruyama et al., 2008d). The immunoregulatory mechanism of polysaccharides is not clear and needs to be further studied. Most studies have focused on polysaccharide activities, however, reports on oligosaccharides are limited. Ying Bai et al. (2013) found that C. deserticola oligosaccharides CDOS (100 mg/kg) can signifificantly enhance splenocytes cell proliferation and macrophages phagocytosis in mice.
PhGs also shows immunomodulatory and antitumor activities and the benefit is largely on the basis of their anti-oxidant activity. Acteoside induced macrophage-like line J774. A1 secret IL-1, IL-6, and TNF-α at 1–100 ng/mL, however, it showed cytotoxic activity at 50 μg/ mL (Inoue et al., 1998a). SAMP8 was treated with 70% ethanol extract of C. deserticolav (echinacoside and acteoside as the most prominent), oral administrations for 4 weeks, both naive T and natural killer cells in blood and spleen cell populations were signifificantly increased (Zhang et al., 2014). C. tubulosa PhGs (echinacoside 26.64%, acteoside 10.19%, and isoacteoside 1.71%) inhibited melanoma B16-F10 cells growth in vitro and in vivo (200 and 400 mg/kg), the mechanism associated with mitochondrion-dependent signaling pathway and immunoregulatory possibly played an important role (Li et al., 2016a).
4.4. Anti-tumor activities
Acteoside is a natural antioxidant product, unlike other anti-tumor compounds. According to a report, acteoside is a potent inhibitor of protein kinase C, with an IC50 value of 25 μM (Herbert et al., 1991). Li et al. (1997) found that it (10 and 20μmol/L) could improve MGc80-3 cells morphology towards normalization rather than by killing tumor cells with high cytotoxicity or other side effects. It could induce promyelocytic leukemia HL-60 DNA degradation with an IC50 value of 26.7 μM (Inoue et al., 1998b). Colorectal cancer is one of the most common malignancies in the world. Acteoside (25–100 μM) promoted apoptosis by regulating HIPK2-p53 signaling in the human colorectal cancer cell line. In addition, further in vivo study also found that it inhibited the growth of mice tumors and the inhibition rate up to 60.99% on the concentration of 80 mg/kg (Zhou et al., 2014). MTH1 is the most important enzyme for the sanitization of nucleotide pools, previous study revealed that echinacoside had the ability to inhibit MTH1 (IC50 = 7.01 μM) (Dong et al., 2015). It (20, 50, 100 μM) repressed SW1990 pancreatic adenocarcinoma cell growth by promoting ROS generation, disturbing mitochondrial membrane potential, and the mitogen-activated protein kinase (MAPK) pathway (Wang et al., 2016).
4.5. Anti-inflflammation activities
Inflflammatory responses include NO production, phospholipase A2 activation, ROS generation, histamine release in neutrophils, macrophages, and mast cells. NO plays an important role in lipopolysaccharide (LPS), TNF-α or IL-1 mediated inflflammatory process. On one hand, it is essential for maintaining cellular function, on the other hand, it was able to induce inflflammation injury as a reactive radical. The nuclear factor κB (NFκB) and activator protein-1 (AP-1) are recognized modulators of inflflammation. Several PhGs (Compound 1, 2, 24, 27, 46, 47, 52) (100 and 200 μM) from C. deserticola showed NO radical-scavenging activity, they inhibited LPS-induced NO production in cell line J774.1. Cistanoside K and tubuloside B inhibited LPS-induced NO production in mouse microglial cells (BV-2 cells) with IC50 14.94 and 14.32 μM (Xiong et al., 2000; Nan et al., 2013).
Macrophages are key players in inflflammation. Acteoside (50, 100 μM) was reported to have a suppressing ability on the activity of cyclooxygenase COX-2 and inhibit prostaglandin E2 (PGE2), TNF-α, and NO formation in LPS-stimulated mouse peritoneal macrophages (Dıaź et al., 2004). Lee et al. (2005) found that acteoside (100 μM) inhibited the LPS induced NO synthase expression via block AP-1 in the RAW264.7 macrophage cell line. Several studies reported that acteoside (10, 30, 100 μM) showed a dose-dependently inhibiting β-hexosaminidase release activity, arachidonic acid, and histamine release in RBL-2H3 cells stimulated by melittin. The molecular mechanisms are related to the competitive inhibition of Ca2+-dependent phospholipase A2 and down-regulation of Ca/nuclear factor of activated T cells and JNK MAPK signaling pathways (Sim et al., 2006; Song et al., 2012; Yamada et al., 2010). As an inhibitor of NFκB, acteoside (30 and 60 mg/ kg, i.p.) decreased lung inflflammatory responses in the LPS induced acute lung injury mice model (J. Wang et al., 2015). It (30 mg/kg for 15days, p.o.) down-regulated the expression of intercellular adhesion molecule-1 in glomeruli and suppressed leukocytes accumulation in crescentic-type anti-glomerular basement membrane nephritis of the rats (Hayashi et al., 1994, 1996). Acteoside (200 mg/kg, i.p.) possesses anti-nociceptive activity in rats subjected to chronic constriction injury for 14 days through suppressing microglial activation, anti-apoptotic and antioxidant (Amin et al., 2016).
50% ethanol of C. deserticola (0.1, 0.3, 1.0 g/kg) showed an anti-inflammatory effect, the butanoic layers (0.1, 0.3 g/kg) with higher activity in carrageenan-induced paw edema in the SD rats. The authors speculated that the kinin system but not opioid receptors and immune system were related to this process (Lin et al., 2002). When the extract of C. tubulosa (54 mg/kg) was used combined with fucoidan (18 mg/ kg), a synergistic effect was observed. NO, and PGE2 production was inhibited in the carrageenan-induced air pouch inflflammation mice model in vivo (Kyung et al., 2015). The mix was considered a proving candidate for promoting hair growth and treating dandruff and scalp inflflammation (Shin et al., 2015; Seok et al., 2015). C. salsa 50% ethanol extract showed an anti-proliferative effect on benign prostatic hyperplasia rats, through regulating inflflammatory cytokine and depressing Bcl-2/ Bax ratio and activation of caspase-3 (Chung et al., 2016).
4.6. Hepatoprotective activities
In recent years, it is reported that PhGs, such as acteoside, echinacoside, 2′-acetylacteosid, isoacteoside, cistanoside A, and tubuloside B exerted positively hepatoprotective effects through multiple mechanisms, including scavenging free radicals, blocking cytochrome P450 biotransformation, and strengthening antioxidant defense system, etc. (Xiong et al., 1998). PhGs (echinacoside 42.71% ± 0.42%, acteoside 14.27% ± 0.18%, IC50 = 119.125 μg/mL), acteoside (IC50 = 6.999 μg/ mL) and echinacoside (IC50 = 520.345 μg/mL) inhibited TGF-β1/Smad signaling pathway in hepatic stellate cell, which showed hepatoprotective activity in vitro(You et al., 2016). Acteoside (30, 100 mg/kg, s.c.) showed hepatoprotective activity against CCl4-induced live damage in rats (Xiong et al., 1998), this effect may be associated with the reduced P450 2E1 level and antioxidation (Lee et al., 2004). In this model, echinacoside (50 mg/kg, i.p.) also showed hepatoprotective effects through anti-oxidant and free radical scavenging activity (Wu et al., 2007). Echinacoside signifificantly reduced alanine aminotransferase levels in D-galactosamine plus LPS-injected mice when administered i.p. at 60 mg/kg (X. Li et al., 2014). Cistanoside A alleviated alcohol-induced hepatotoxicity in mice by increasing the activities of mitochondrial antioxidant enzymes (GST, SOD, and CAT) and energy metabolism enzymes (total ATPase, Na+-K+-ATPase, Ca2+-Mg2+-ATPase), as well as an antioxidant defense system, besides, it inhibited apoptosis and necrosis of the primary cultured hepatocytes through upregulating Bcl-2 and downregulating c-fos expression (Luo et al., 2014, 2016). Besides PhGs, C. deserticola polysaccharide (0.11, 0.33, 1.00, 3.00 mg/mL, Mw = 1300 kDa), which contained a higher proportion of galacturonic acid, can inhibit the growth and proliferation of HepG2 cell line, furthermore, it (200, 600, 1800 mg/kg) showed hepatoprotective activity against liver injury induced by alcohol in ICR mice (Guo et al., 2016).
4.7. Cardiovascular protection
The compounds (1, 7, 24, 31, and kankanose) were obtained from the C. tubulosa methanol extraction showed vasorelaxant activity in isolated rat aortic strips (Yoshikawa et al., 2006). Ko K. M. group have found that the methanol/ethanol extract from C. deserticola could stimulate ATP generation capacity by enhancing the oxidative phosphorylation in H9c2 cells and the rat's heart, thereby protecting against myocardial ischemia/reperfusion (I/R) injury (Leung and Ko, 2008; Wong and Ko, 2013). C. deserticola PhGs (content 71.7%) were considered to be an effective constituent treatment for IR-induced injury in rats. They not only signifificantly reduced oxidative stress in myocardial tissue, such as MDA levels, and elevated the activities of GSH-Px, SOD, but also upregulated apoptosis-related proteins Bcl-2/Bax and down-regulated cleaved caspase-3 (Qian et al., 2016). Besides, Cistanches Herba methanol extract (0.5 g/kg, 1.0 g/kg for 3days, i.g.) enhanced heart ventricular tissue mitochondrial glutathione status, decreased mitochondrial Ca2+ content, and increased mitochondrial membrane potential after I/R injury in SD rats (Siu and Ko, 2010). Statins are the common drugs used to correct dyslipidemia, which induced myotoxicity. The water extract of Cistanches Herba (0–2000 μg/mL) exerted a dose-dependent protective effect by improving ATP production and via the caspase-3 pathway in simvastatin treated L6 skeletal muscle cells, however, acteoside (0–160 μM) only showed a weak protective effect on cells (Wat et al., 2016).
Acteoside (3–50 µmol/L) enhanced phenylephrine-induced contraction without affecting the maximum response in endothelium-intact rings, mainly through inhibition of endothelial NO synthase/release and NO-mediated tetraethylammonium-sensitive activation of K+ channels (Tam et al., 2002). Besides, long-term intake of 100 mg of acteoside per day in patients with cardiovascular risk signifificantly inhibited platelet aggregation (Campo et al., 2012, 2015).
Echinacoside (30–300 μM) improved endothelium-dependent relaxation via the NO-cGMP signal pathway in rat aortic rings (He et al., 2009). In this concentration, it also had a positive effect in hypoxic pulmonary hypertension rats and the mechanism of it was close to the NO-cGMP-PKG-BKCa channels opening and intracellular Ca2+ levels decline (Gai et al., 2015).
4.8. Gastrointestinal tract protection activities
Cistanches Herba was used for treating irritable bowel syndrome and constipation. Oligosaccharides and galactitol were reported as the main active component with laxative activity in the ICR mice model (Gao et al., 2015b). Jia found that oral administration of C. deserticola water extract (0.4 g/kg/day, 2–3% PhGs, 65–70% polysaccharides, 0.6–1% protein) reduced intestinal mucosal hyperplasia and helicobacter infection in Tgfb1 Rag2 mice and the mechanism of action likely depends on immune activity (Jia et al., 2012a). After feeding C. deserticola water extraction (3.3 g/kg), the peristalsis of the gastrointestinal tract was increased and defecation time was shortened in the mice model (Zhang et al., 2009).
Acteoside (i.p., 120, 600 μg/day) showing ameliorate activity in dextran sulfate sodium (DSS)-induced acute and chronic colitis mice model was shown to have a relationship with anti-inflflammatory and antioxidant activity (Hausmann et al., 2007). Acteoside (600 μg/day, i.g.) inhibited methotrexate-induced mice mucosal layer damage, by reducing crypt depth and increasing villus height in duodenum, jejunum, and ileum, and may exert its effect through anti-inflflammatory activity (Reinke et al., 2015). In farm animals, disease pressure, feed transitions, and environmental factors all can possibly disturb the gut. Giancamillo et al. (2013) added acteoside (5 mg/kg) to the piglet's diet, after 166 days of trial, the oxidative and nitrosative stress in the mucosal was decreased, which showed that acteoside may be useful in animal feed additive. Acteoside (40 mg/kg, i.g.) showed a protective effect on ulcers induced by pyloric ligation in rats and inhibited H+-K+-ATPase activity in vitro (IC50 = 60.98 μg/mL, omeprazole as a positive control with IC50 = 30.24 μg/mL) (Singh et al., 2010).
Echinacoside (25–100 μg/mL) upregulated TGF-β1 expression, resulting in stimulating cell proliferation and preventing cell apoptosis in intestinal epithelial MODE-K cells. In the DSS-induced colitis mice model, oral administration of echinacoside (20 mg/kg) extracts signifificantly suppressed acute colitis development (Jia et al., 2014a, 2014b, 2012b).
4.9. Anti-diabetic activities
Quite a number of studies confirmed the anti-diabetic effect of Cistanches Herba. Echinacoside and acteoside (125 and 250 mg/kg, i.g.) suppressed the increase of postprandial blood glucose levels and improved glucose tolerance in starch-loaded mice, inhibited rat intestinal a-glucosidases, lens aldose reductase, and human intestinal Maltas activity in vitro (Morikawa et al., 2014). Male db/db mice were administered C. tubulosa extract (acteoside 2.66%, echinacoside 11.59%, total phenolic 66.29 ± 0.44 mg gallic acid/g and polysaccharide 10.15 ± 0.26%, 4.55, 2.73, 0.91 g/kg, i.g.), the results showed that the fasting blood glucose and postprandial blood glucose levels were decreased signifificantly, the insulin resistance and dyslipidemia were improved, but there was no significant effect on serum insulin levels or hepatic and muscle glycogen levels (Xiong et al., 2013). The ethanol extract of C. tubulosa (echinacoside 25%, acteoside 9%, 400 mg/kg for 14days, i.g.) signifificantly decreased serum cholesterol levels, enhanced mRNA expressions of low-density lipoprotein receptor and cytochrome P450 side-chain cleave in high cholesterol diet-fed mice. Acteoside was considered to be a major effective compound (Shimoda et al., 2009). Wong et al. (2014) showed that the ethanol extract of Cistanches Herba (1.5, 15, 45 mg/kg, i.g.) signifificantly decreased the body weight and improved insulin sensitivity of diabetic mice, possibly through mitochondrial uncoupling and increasing energy consumption.
4.10. Anti-osteoporosis activities
Osteoporosis is a disease of aging characterized by low bone mass, which is most commonly seen in the postmenopausal stage. Estrogen deficiency is considered the major cause of bone loss in postmenopausal women. A study has reported that Cistanches Herba water extract (i.g.,100 and 200 mg/kg) reversed bone loss and prevented female rats osteoporosis, which is associated with enhancing bone mineral density, bone mineral content, maximum load, displacement at maximum load, stress at maximum load (Liang et al., 2011). Extensive studies have been carried out to elucidate the mechanisms, including upregulation of alkaline phosphatase, bone morphogenetic proteins-2, and osteopontin mRNA expression as well as some bone metabolism-related genes, e.g. Smad1, Smad5, TGF-β1, and TIEG1 (T. Li et al., 2012; Liang et al., 2013). Yang's research group showed that echinacoside concentration from 0.01 to 10 nmol/L can signifificantly stimulate bone regeneration through increasing osteoprotegerin/receptor activator of NFκB ligand (OPG/RANKL) ratio in MC3T3-E1 cells (F. Li et al., 2012). Authors concluded that echinacoside (30, 90, 270 mg/kg for 12 weeks, i.g.) can effectively prevent osteoporosis induced by estrogen defificiency in an ovariectomized rat model (Li et al., 2013). Fang et al. (2015) found that echinacoside (0.1, 1.0, and 10 nmol/L) promoted rat osteoblast cell proliferation through extracellular regulated protein kinase (ERK)/bone morphogenetic protein-2 (BMP-2) signal pathway activation.
Chen et al. (2007b) have reported that Cistanches Herba polysaccharides (50 and 100 mg/kg, i.p.) could promote the bone marrow cell-cycle transition and hematopoietic function recovery in bone marrow-depressed anemic mice, accelerate hematogenesis in rubrum strain and macronucleus strain.
4.11. Antioxidant activities
The PhGs from Cistanches Herba is considered effective ingredients for anti-oxidative activity. Due to their phenolic hydroxy structure, PhGs can act as antioxidants via direct combination with free radicals and activate the antioxidant defense systems. These compounds' antioxidant effect increases with the number of phenolic hydroxyl groups (Xiong et al., 1996). Oxidative damage is critically involved in various pathogeneses such as inflflammation, senescence, cancer, and so on. The free radicals may cause tissue injury and echinacoside (2, 10, 50, 125 mg/kg, i.p.) can protect against acute lung injury caused by oleic acid through scavenging free radicals in rats (Zhang et al., 2007). Free radical as a promoter of the aging process in humans, echinacoside (1, 20, 50, 100 μM) showed anti-oxidant activity by triggering cells from the G1 phase to enter the S and G2 phase, effectively decreasing ROS levels and protecting cells from DNA damage in human embryo lung fibroblastic MRC-5 cells model (Xie et al., 2009).
4.12. Other biological activities
C. deserticola extraction (acteoside 5.6%, echinacoside 33.3%, 0.25, 0.50, 1.00 g/kg) showed anti-fatigue effects, increased swimming time forced of ICR mice, signifificantly decreased serum creatine kinase, lactate dehydrogenase and lactic acid levels, contrarily, signifificantly increased hemoglobin and glucose levels (Cai et al., 2010). The fatty acids, elaidic acid, and palmitic acid from C. sala showed a suppressing effect on SOS-induced mutagenesis activity (Shimamura et al., 1997). C. deserticola ethanol extract, ethyl acetate, butanol, and water fraction were reported to have a sedative effect and the water fraction showed the greatest activity (Lu, 1998). Butanoic fraction of C. tubulosa showed an anti-microbial effect on Escherichia coli (Adnan et al., 2014). The study reported that Cistanches Herba had obesity-suppressing activity through increasing energy consumption (Wong et al., 2015).
Acteoside can alleviate hyperuricemia in the potassium oxonate-induced hyperuricemic mice model by inhibiting xanthine dehydrogenase and xanthine oxidase activity (Huang et al., 2008).S. Wang et al. (2015) investigated the effects of echinacoside on hematopoietic function in 5- FU-induced bone marrow depression mice, data suggested that echinacoside may promote the recovery of hematopoietic function of the bone marrow by activation of GM-CSF/PI3K pathway. Echinacoside was reported to possess anti-senescence activity, the mechanism is associated with down-regulation of p53 expression (Zhu and Wang, 2011). The primary pharmacological actions of Cistanches Herba are summarized in Table 5.
5. Pharmacokinetics studies
Although Cistanches Herba contained many chemical constituents, pharmacokinetic studies of these compounds focused on echinacoside and acteoside due to their high content and clear pharmacological activity. PhGs are usually administered orally. Poor oral absorption was observed in the Caco-2 cell monolayer model (Y. Gao et al., 2015a). There exist different opinions on PhGs absorption. Shen reported that echinacoside was the substrate of P-glycoprotein (P-GP), verapamil and clove oil could improve echinacoside absorption. The mechanisms of which the enhancing effect could be exocytosis of P-GP inhibition and altering of the intestinal mucous membrane of the lipid phase (Shen et al., 2015). Tanino et al. (2015) gave the opposite conclusion that echinacoside and acteoside transport were irrelevant to P-GP. Glucose trans-porter-dependent played an important role in this progress. Cistanche polysaccharides were also poorly absorbed by Caco-2 cells (Qi et al., 2010). It is important that more studies be carried out to elucidate the absorption mechanism of Cistanches Herba.
Oral administration of acteoside at 40 mg/kg produced the following pharmacokinetic parameters: Cmax, 312.54 ± 44.43 ng/mL; Tmax, 17.4 ± 10.2 min; T1/2, 63 ± 13.8 min; AUC0–5 h, 364.67 ± 76.05 ng/(mL*h), respectively. The absolute bioavailability of acteoside was about 1% and the rat plasma protein binding ratio was about 60% with the equilibrium dialysis method (Wen et al., 2016). The low blood drug concentration and relatively rapid metabolism were observed. Acteoside was rapidly absorbed and widely distributed in various tissues, including the intestine, stomach, lung, brain, etc. The highest concentration was detected in the intestine and lung, followed by the stomach, muscle, and other tissues. It is worth noting that acteoside is widely distributed in all parts of the brain tissues, however, its mechanism for crossing the blood-brain barrier is unknown (Wen et al., 2016). Lei first reported that the metabolism of PhGs mainly occurred in the colon but not in the stomach and intestinal. PhGs are always administered as oral formulations and unavoidably interact with gut microbiota in the intestinal. Acteoside consists of four chemical moieties: caffffeic acid, hydroxytyrosol, glucose, and rhamnose group. Under gut microbiota, acteoside is metabolized to other active components via hydrolyzation, isomerization, hydrogenation, dehydroxylation, methylation, acetylation, hydroxylation, and methoxylation. 14 metabolites were identifified, among which caffffeic acid and hydroxytyrosol were reported to possess biological activity, even more than acteoside (Cui et al., 2016). Qi et al. (2013) reported that 35 metabolites of acteoside in rats’ urine were detected by UPLC/ESI-QTOF-MS and metabolic pathways of acteoside were proposed. Methylation occurred more easily in the metabolic process in vivo. A little amount of acteoside was found in urine, bile, or feces, suggesting the extensive metabolism in rats (Wen et al., 2016).
Echinacoside absorption is similar to acteoside. The oral bioavailability of echinacoside was detected by HPLC-UV, a single oral administration of 100 mg/kg of echinacoside got Cmax, 612.2 ± 320.4 ng/mL; Tmax, 15.0 min; T1/2, 74.4 min; AUC0–6 h, 60704.9 ng min /mL and the absolute bioavailability of echinacoside was 0.83% (Jia et al., 2006). Li et al. (2015) found that echinacoside was stable in simulated gastric juice and intestinal juice. Under human intestinal bacteria, echinacoside produced a variety of secondary metabolites, such as acteoside, HT, 3-hydroxyphenylpropionic acid, etc. It could transform into acteoside by the deglycosylation reaction in β-Glucosidase (Lei et al., 2001; Zhao et al., 2011). Fast and extensive metabolic may contribute to the low bioavailability.
6. Discussion and future perspectives
Cistanches Herba as a tonic herb, it been one of the most widely used ‘kidney-yang’ tonic herbs in China for thousands of years. They have attracted growing interest in recent years owing to their significant biological activity, immunomodulatory, anti-cancer, anti-oxidant, anti-in- inflammatory and hepatoprotective therapeutic effect, etc., especially neuroprotective effects. Modern studies showed that damage and functional disorders of the hypothalamic-pituitary-target gland axis, including the adrenal gland, thyroid, and gonad, are the main pathological mechanisms of ‘kidney-yang defificiency syndrome’. The hypothalamus is considered to be the pivot to link neuroendocrine with immune systems (Shen, 1999). Cistanches Herba as a ‘kidney-yang’ tonic herb takes part in neuroendocrine-immune networks, which is related to neuroprotective and immunomodulation effects; cures yang deficiency, erection dysfunction, and females with irregular menstruation, which is related to endocrine regulation activities; cures soreness of waist and knees, which is related to anti-osteoporosis and anti-fatigue activity; moisturizes the intestine and relaxing bowels, which is related to gastrointestinal tract protection activity.
In clinical applications, Cistanches Herba showed several activities. In part 4.2, C. tubulosa glycoside capsules (Memoregain®) have the efficacy of treating mild and moderate AD patients (Guo et al., 2013); In part 4.5, echinacoside glycosides combined with fucoidan can prevent hair loss and scalp inflflammation (Seok et al., 2015). Besides single herb, the compounds containing Cistanches Herba also be used in clinical. Bushen Huoxue Granule, Cistanches Herba as an important active composition brings improvement in people with Parkinson's disease (M. Li et al., 2016).
PhGs exhibit strong neuroprotective effects, based on their anti-oxidant activity, anti-apoptosis activity, anti-inflflammation activity. PhGs may be a potential candidate for treating several diseases. However, its clear pharmacological characteristics such as the poor permeability, fast and extensive metabolism in the gut, is a riddle yet to be resolved by scientists. The exact mode of action of parent and metabolites are still elusive and deserved special attention in the future. Polysaccharides as another active constituent are difficult to be digested by the human body. Recently, lots of reports indicate that dietary polysaccharides can be fermented into short-chain fatty acids to produce benefits for gut microbiota. There is not enough evidence to show the mechanism of action of Cistanches polysaccharides (Fig. 1).
In conclusion, Cistanches Herba is a nutraceutical and functional food, as well as potentially representing a valuable source for bioactive compounds and pharmaceutical applications. The information presented in this review may form the basis of providing adequate knowledge for future studies and developments as well as commercial exploitation of Cistanches Herba. Despite that, there are still many challenges that need resolution in order to ease herbal medicine development before approval and marketed as a safe pharmaceutical product.
Acknowledgments
This work was supported by the National Natural science foundation of China (Grant no. 81630106) and the Program for ChangjiangScholars and Innovative Research Team in University (NO. IRT_14R41).
Conflict of interest
The authors declare that there is no conflict of interest regarding the publication of this paper.
From: ' Cistanches Herba: An overview of its chemistry, pharmacology, and pharmacokinetics property' by Zhifei Fua,b, et al
---Journal of Ethnopharmacology 219 (2018) 233–247
