Bioactive small-molecule constituents of Lao plants.

Ren Yulin,M Henkin Joshua,D Soejarto Djaja,Sydara Kongmany,Douglas Kinghorn A,G Elkington Bethany

doi:10.5897/jmpr2021.7137

Abstract

Laos has a rich plant diversity, and medicinal plants are used extensively in Lao traditional medicine for the treatment of a variety of human diseases. However, only a relatively small number of these plants have been investigated for their major components with potential antitumor, anti-infective, and other types of bioactivities. These species include Asparagus cochinchinensis, Diospyros quaesita, Gongronema napalense, Marsypopetalum modestum, Nauclea orientalis, Rourea minor, Stemona pierrei, and Stemona tuberosa. Thus far, the bioactive compounds isolated from these Lao plants include alkaloids, glycerol esters, phenolic compounds such as lignans and stilbenoids, steroids, and triterpenoids. Of these, the norlignan, nyasol (1b), the triterpenes, pyracrenic acid [3β-O-trans-caffeoylbetulinic acid (3)] and betulinic acid (3b), and the dimeric thiopyridine, dipyrithione (5), were found to show both cancer cell cytotoxicity and anti-infective activity. The present review focuses on examples of promising lead compounds isolated from Lao plants, with their possible development as potential therapeutic agents being discussed. It is hoped that this contribution will provide useful information on higher plants growing in Laos to help stimulate future discoveries of potential agents for the treatment of cancer, infections, and other diseases.

Highlights

The Lao People’s Democratic Republic, a landlocked country known widely as Laos, is a small country located in the east-central section of the Indo-Chinese peninsula, flanked by Thailand in the west, Myanmar and the Chinese province of Yunnan in the north, Vietnam in the east, and Cambodia in the south
These include a 9'-norlignan, 3-hydroxy-4methoxy-4-dehydroxynyasol (1), and its analogues, 3methoxynyasol (1a), nyasol (1b), and 1,3-bis-di-phydroxyphenyl-4-penten-1-one (1c) (Figure 1), along with a new spirostanol saponin, asparacoside (2), and its analogues asparacosins A (2a) and B (2b) (Figure 1). These compounds were evaluated for cytotoxicity against Col-2 colon, KB oral epidermoid, LNCaP prostate, and Lu-1 lung human cancer cells, and 1, 1a, and 2 were deemed active, but 1b, 1c, 2a, and 2b were not (Zhang et al, 2004). These results demonstrated that the 3,4ortho-hydroxy and -methoxy groups are important for the mediation of cancer cell line cytotoxicity by 1, but neither transposing the substituents between the C-3 and C-4 positions nor introducing a carbonyl group at the C-9' position seems to contribute to the resultant cytotoxic potency
Only limited phytochemical investigations have been conducted far on eight of these plants, namely, A. cochinchinensis, D. quaesita, G. napalense, M. modestum, N. orientalis, R. minor, S. pierrei, and S. tuberosa, of which none is endemic to the country

Summary

Introduction

The Lao People’s Democratic Republic, a landlocked country known widely as Laos, is a small country located in the east-central section of the Indo-Chinese peninsula, flanked by Thailand in the west, Myanmar and the Chinese province of Yunnan in the north, Vietnam in the east, and Cambodia in the south. With the aid of field interviews with healers in Laos, several plant-derived lead compounds showing activities related to cancer, acquired immunodeficiency syndrome (AIDS) caused by infection from human immunodeficiency viruses (HIV), malaria, and/or tuberculosis (TB) infectious diseases have been identified (Soejarto et al, 2012).

Results

Conclusion