Host-mimetic metabolomics of endophytes: Looking back into the future

Abstract

Endophytic research is now gaining pace together with the technological advancement and refinements. The phenomenal potential of endophytes as prolific producer of a wide range of bioactive compounds occupies a complimentary domain of natural product research. The discovery of paclitaxel (Taxol) as bioactive natural product of endophytic origin seems to draw indisputable attention not only for their antitumor activity but as potential microbial alternative for this high in-demand drug. Plenty of opinion is given by the enthusiasts on microbial production of paclitaxel as phylogenetic process and driving paradigm of evolution; however, skeptics described it as phylogenetic anomalies. But despite being highly controversial, the horizontal gene transfer (HGT) theory still seems quite justifiable. Let's have another example: maytansinoid, a potent cytotoxic agent, was isolated and characterized from microbial endophyte of the same plant; however in both cases, further investigations recorded their occurrence not only in same host but also from deferent distant hosts and even from different endophytes. So the report of taxane and related taxoids from a taxonomically distant host raises several questions. One may assume that this might be due to evolutionary invention; however, it is very unlikely to accept that all modules of gene responsible for biosynthesis of these molecules invented in microbial systems during long evolutionary symbiosis. With this chapter we are trying to get into the mechanistic aspects of host-specific chemicals synthesized by endophytic microbes together with our experience with isolation and characterization of host-specific compounds like piperine and azadirachtin. Nevertheless, the significance of this potential of endophytes cannot be ignored, as it provides not only alternative source to existing pharmaceuticals but also on the other hand save the valuable biodiversity of highly medicinal plants.