A review of the phytochemistry and pharmacology of Kadsura heteroclita, an important plant in Tujia ethnomedicine

Ethnopharmacological relevance: Kadsura heteroclita (Roxb.) Craib (traditionally known as "Xue Tong") is an important member of the economically and medicinally important plant family Schisandraceae. "Xue Tong" is an imperative ingredient of the Tujia ethnomedicine, traditionally used for the treatment of rheumatoid arthritis (RA), hepatitis, and muscles and joint spasm. The plant is known to be a rich source of lignans and triterpenoids. These classes of natural products have been known to possess various pharmacological activities.

Aim of review: This review was motivated by the importance of K. heteroclita in traditional Chinese medicine (TCM). It aims to compile the available information on its botanical distribution and description, traditional uses, phytochemistry, pharmacological activities, toxicity, and quality control to provide a solid base for further research and development.

Materials and methods: Relevant literature was collected by several scientific databases including PubMed, CNKI, Scifinder, The Plant List, Google Scholar, Baidu Scholar, Books (Tujia pharmaceutical records, Guangxi Chinese herbal medicine, Hunan pharmaceutical records and Field identification manual of Chinese herbal medicine) and other literature sources (Flora of China, Pharmacopoeia of the People's Republic of China) which helped in collecting maximum data about the studied species.

Results: Traditional uses of K. heteroclita have proven its medicinal importance, providing a rationale for scientific research. Phytochemical studies on the stem of K. heteroclita resulted in the identification of 187 chemical constituents, among which lignans and triterpenoids are the predominant groups. The isolates and crude extracts have been found to exhibit a wide spectrum of in vivo and in vitro pharmacological activities such as anti-RA, anti-inflammatory and analgesic, hepatoprotection, anti-HIV, anti-cancer and anti-HBV. Schisanlactone E (xuetongsu), a triterpenoid, is one of the major components of K. heteroclita exhibiting anti-cancer, neuroprotective and anti-neuroinflammation activities. Interestingly and luckily, this plant has been found to be safe and non-toxic within the therapeutic dose range.

Conclusion: Pharmacological investigations have validated the use of K. heteroclita in traditional Chinese medicine (TCM). Literature review has demonstrated that lignans and triterpenoids are possibly responsible for most of the biological activities exhibited by this plant. To conclude, this plant shows immense potential for the discovery of more potent bioactive secondary metabolites and therefore further phytochemical and biological studies on other parts of K. heteroclita need to be conducted and more compounds need to be tested regarding their biological activities to completely explore its value as a tremendously important medicinal plant species.

Keywords: Kadsura heteroclita; Schisanlactone E; Tujia ethnomedicine; lignans; pharmacological activities; triterpenoids.