Cytotoxic triterpenes from the acid hydrolyzate of Gynostemma pentaphyllum saponins

Research progress of Chinese herbal medicine compounds and their bioactivities: Fruitful 2020

Traditional Chinese medicines (TCMs) have continued to be a treasure trove. The study of chemodiversity and versatility of bioactivities has always been an important content of pharmacophylogeny. There is amazing progress in the discovery and research of natural components with novel structures and significant bioactivities in 2020. In this paper we review 271 valuable natural products, including terpenoids, steroids, flavonoids, phenylpropanoids, phenolics, nitrogen containing compounds and essential oil, etc., isolated and identified from TCMs published in journals of Chinese Traditional and Herbal Drugs (Zhong Cao Yao) and Chinese Herbal Medicines (CHMs), and focus on their structures, source organisms, and relevant bioactivities, paying special attention to structural characteristics of novel compounds and newly revealed pharmacological properties of known compounds. It is worth noting that natural products with antitumor activity still constitute the primary object of research. Among the reported compounds, two new triterpenoids, i.e., ursolic acid 3-O-β-cis-caffeate and mollugoside E, display remarkable cytotoxicity against PC-9 and HL-60 cell lines, respectively. Three known phenolic compounds, i.e., pyoluteorin, 4-hydroxy-3-methoxy cinnamaldehyde and 3,7-dimethoxy-5-hydroxy-1,4-phenanthrenequinone, exhibit significant cytotoxicity against multiple cell lines. Numerous studies on the free radical scavenging activity of reported compounds are currently underway. In vitro, three known phenolic compounds, i.e., 3,4-O-dicaffeoylquinic acid methyl ester, 3,4,5-O-tricaffeoylquinic acid methyl ester and arbutin, had more considerable antioxidant activities than vitamin C. The anti-inflammatory, anti-diabetic, hypolipidemic, neuroprotective and antimicrobial activities of isolated compounds are also encouraging. The structural characteristics and bioactivities of TCM compounds highlighted here reflect the enormous progress of CHM research in 2020 and will play a positive role in the future drug discovery and development. According to pharmacophylogeny, the phylogenetic distribution of compounds with different natures and flavors can be explored, with view to better mining TCM resources.

Progress in the Medicinal Value, Bioactive Compounds, and Pharmacological Activities of Gynostemma pentaphyllum

Gynostemma pentaphyllum (Thunb.) Makino (GP), also named Jiaogulan in Chinese, was known to people for its function in both health care and disease treatment. Initially and traditionally, GP was a kind of tea consumed by people for its pleasant taste and weight loss efficacy. With the passing of the centuries, GP became well known as more than just a tea. Until now, numbers of bioactive compounds, including saponins (also named gypenosides, GPS), polysaccharides (GPP), flavonoids, and phytosterols were isolated and identified in GP, which implied the great medicinal worth of this unusual tea. Both in vivo and in vitro tests, ranging from different cell lines to animals, indicated that GP possessed various biological activities including anti-cancer, anti-atherogenic, anti-dementia, and anti-Parkinson's diseases, and it also had lipid-regulating effects as well as neuroprotection, hepatoprotective, and hypoglycemic properties. With the further development and utilization of GP, the research on the chemical constituents and pharmacological properties of GP were deepening day by day and had made great progress. In this review, the recent research progress in the bioactive compounds, especially gypenosides, and the pharmacological activities of GP were summarized, which will be quite useful for practical applications of GP in the treatment of human diseases.

Triterpenoids from the genus Gynostemma: Chemistry and pharmacological activities

ETHNOPHARMACOLOGICAL RELEVANCE

G. pentaphyllum, also known as Jiao-Gu-Lan, has been used traditionally as folk remedies for many diseases, including diabetes mellitus, metabolic syndrome, aging, and neurodegenerative diseases in China and some countries in East and Southeast Asia. It is considered as an "immortality herb" in Guizhou Province, because it was consumed regularly by the elderly native inhabitants. Other species of the same genus Gynostemma such as G. longipes and G. laxum have been used as alternatives to G. pentaphyllum in ethno-medicine in Vietnam and other Asian countries.

AIM OF THE REVIEW

The review aims to summarize up-to-date study results on Gynostemma species, including traditional usage, phytochemical profile, pharmacological activities, and toxicological studies, in order to suggest future research orientation and therapeutic applications on acute and chronic diseases.

MATERIALS AND METHODS

The relevant literature on the genus Gynostemma was gathered from secondary databases (Web of Science and PubMed), books, and official websites. The latest literature cited in this review was published in February 2020.

RESULTS

The genus Gynostemma has been widely used in traditional medicine, mainly for treatment of diabetes, hypertension, obesity, and hepatosteatosis. To date, 328 dammarane-type saponins were isolated and structurally elucidated from Gynostemma species. Crude extracts, saponin-rich fractions (gypenosides), and pure compounds were reported to show a wide range of pharmacological activities in both in vitro and in vivo experiments. The most notable pharmacological effects were anti-cancer, cardioprotective, hepatoprotective, neuroprotective, anti-diabetic, anti-obesity, and anti-inflammatory activities. Toxicological studies were conducted only on G. pentaphyllum, showing that the plant extracts were relatively safe in both acute and long-term toxicity experiments at the given dosage while no toxicological studies were reported for the other species.

CONCLUSIONS

The review summarizes current studies on traditional uses, phytochemistry, biological properties, and toxicology of medicinal Gynostemma species. Till now, the majority of publications still focused only on G. pentaphyllum. However, the promising preliminary data of other Gynostemma species indicated the research potential of this genus, both in phytochemical and pharmacological aspects. Furthermore, clinical data are required to evaluate the efficacy and undesired effects of crude extracts, standard saponin fractions, and pure compounds prepared from Gynostemma medicinal plants.

Medicinal Value and Potential Therapeutic Mechanisms of Gynostemma pentaphyllum (Thunb.) Makino and Its Derivatives: An Overview

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Gynostemma pentaphyllum (Thunb.) Makino (GpM) and its derivatives, especially gypenosides (Gyps), are widely used as safe and convenient natural herbal drugs for the treatment of many diseases for a long time, and Gyps have different oral bioavailability (OB) values and low ability to cross the blood-brain barrier (BBB). The effects of GpM and isolates on fibrosis, inflammation, oxidation, proliferation and migration are proved. GpM shows bidirectional regulation effect on proliferation, oxidation and apoptosis in tumor and non-tumor cells. GpM and its extractions can resist proliferation, activate oxidation and apoptosis in tumor cells and have opposite effects on non-tumor cells. We succinctly present some current views of medicinal value and potential therapeutic mechanisms of GpM and its derivatives.