Investigation of the biosynthetic potential of endophytes in traditional Chinese anticancer herbs.

Kristin I Miller,Brett A Neilan,Daniel Man Yuen Sze,Chen Qing,William C S Cho

doi:10.1371/journal.pone.0035953

Abstract

Traditional Chinese medicine encompasses a rich empirical knowledge of the use of plants for the treatment of disease. In addition, the microorganisms associated with medicinal plants are also of interest as the producers of the compounds responsible for the observed plant bioactivity. The present study has pioneered the use of genetic screening to assess the potential of endophytes to synthesize bioactive compounds, as indicated by the presence of non-ribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) genes. The total DNA extracts of 30 traditional Chinese herbs, were screened for functional genes involved in the biosynthesis of bioactive compounds. The four PCR screens were successful in targeting four bacterial PKS, six bacterial NRPS, ten fungal PKS and three fungal NRPS gene fragments. Analysis of the detected endophyte gene fragments afforded consideration of the possible bioactivity of the natural products produced by endophytes in medicinal herbs. This investigation describes a rapid method for the initial screening of medicinal herbs and has highlighted a subset of those plants that host endophytes with biosynthetic potential. These selected plants can be the focus of more comprehensive endophyte isolation and natural product studies.

Highlights

There is an ongoing need for novel drugs that are highly effective in the treatment of cancer, drug resistant bacteria, fungal infections, emerging viruses and parasitic protozoan infections
This study has identified a subset of Traditional Chinese Medicine (TCM) herbs found to harbor endophytes with bioactive potential, and these plants can be targeted in future investigations
Some of the amplified polyketide synthase (PKS) and non-ribosomal peptide synthetase (NRPS) PCR products could be directly sequenced, many contained a mixture of amplicons that needed to be cloned into a TOPO cloning vector

Summary

Introduction

There is an ongoing need for novel drugs that are highly effective in the treatment of cancer, drug resistant bacteria, fungal infections, emerging viruses and parasitic protozoan infections. TCM theory is based on experiences of the effects of the medicines through documented trials to establish knowledge of the use of plants (approximately 5000 species) for the treatment of many diseases [2]. This TCM background has provided the basis for the discovery of several therapeutic agents, including the anticancer agents indirubin [3], camptothecin [4] and harringtonine [5]; aretemisinin (antimalarial) [6] and ephedra (central nervous system stimulant) [7]

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Conclusion