Camptothecin (CPT), a quinoline indole alkaloid, is one of the important inhibitors of eukaryotic DNA topoisomerase I. The highest concentration of this alkaloid has been reported from the fruits of Pyrenacantha volubilis Hook. Here we report the spatial and temporal distribution pattern of CPT in seeds and fruits of P. volubilis. Temporally, CPT content was highest in mature but unripe fruits compared to ripened fruits. Spatially, cotyledonary tissues of the seed had the highest amount of CPT followed by seed coat and fruit coat. This pattern is best explained by selection to deter fruit predators during fruit development, but attracting the fruit dispersers when fruits are mature and ripe.

Pradeep Thalappil

Department Of Chemistry

Vadlapudi R.Rajeev Kumar

Patel Mohana Kumara

Amitava Srimany

Fulltext

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Current Science

Background Camptothecin (CPT), a quinoline alkaloid, is a potent inhibitor of eukaryotic topoisomerase I. Because of this property, several derivatives of CPT are used as chemotherapeutic agents. CPT is produced by several plant species belonging to the Asterid clade as well as by a number of endophytic fungal associates of these plants. In this study, we report the production of CPT by four bacterial endophytes and show the possible role of a plasmid in the biosynthesis of CPT. Methods Endophytic bacteria were isolated from leaves, stems and fruits of Pyrenacantha volubilis Hook. (Icacinanceae). The bacterial isolates were purified and analyzed for production of CPT by ESI-MS/MS and NMR analysis. Bacterial identity was established based on the morphology and 16s rRNA sequence analysis. Crude extracts of the bacterial endophytes were evaluated for their cytotoxicity using colon cancer cell lines. The role of plasmid in the production of CPT was studied by purging the plasmid, using acriflavine, as well as reconstituting the bacteria with the plasmid. Results Four bacterial isolates, Bacillus sp. (KP125955 and KP125956), Bacillus subtilis (KY741853) and Bacillus amyloliquefaciens (KY741854) were found to produce CPT in culture. Both based on ESI-MS/MS and NMR analysis, the identity of CPT was found to be similar to that produced by the host plant. The CPT was biologically active as evident by its cytotoxicity against colon cancer cell line. The production of CPT by the endophyte (Bacillus subtilis, KY741853) attenuated with sub-culture. A likely role of a plasmid in the production of CPT was established. A 5 kbp plasmid was recovered from the bacteria. Bacterial isolate cured of plasmid failed to produce CPT. Conclusion Our study implies a possible role of a plasmid in the production of CPT by the endophytic bacteria and opens up further work to unravel the exact mechanisms that might be involved. © 2017 Elsevier GmbH

Phytomedicine

Camptothecin-producing endophytic bacteria from Pyrenacantha volubilis Hook. (Icacinaceae): A possible role of a plasmid in the production of camptothecin

Spatial and temporal distribution pattern of camptothecin in seeds and fruits of Pyrenacantha volubilis Hook. (Icacinaceae) during different fruit developmental stages

Journal	Current Science
Publisher	Indian Academy of Sciences
ISSN	00113891
Open Access	No