Subcellular Localization and Quantification of Camptothecin in Different Plant Parts of Chonemorpha Fragrans

Abstract

Chonemorpha fragrans (C. fragrans), a liana belonging to family Apocynaceae, shows presence of widely used anticancer compound Camptothecin (CPT). CPT is a modified monoterpene indole alkaloid produced by very few species belonging to unrelated orders of angiosperms, especially plants belonging to the families Apocynaceae and Icacenaceae. In this work a sensitive high performance thin layer chromatography method (HPTLC) was used for detection and quantification of CPT. HPTLC analysis showed that highest amount of CPT was present in root methanolic extract (0.023% of dry weight) followed by stem bark methanolic extract (0.013% of dry weight). Also, the subcellular localization of an anticancer drug has been studied using autofluroscence property of CPT under Ultra violet (UV) light. Localization study revealed that out of all the organs studied roots accumulated highest levels of CPT followed by stem bark. Xylem tissues showed a major accumulation site for CPT. Presence of CPT in in vitro culture is an important finding as in vitro systems can be used for further experiments to reduce overexploitation of natural population. This is the first report rearding subcellular localization and quantification of CPT in sequential extracts of different plant parts in C. fragrans. Anti-cancer activity of CPT is due to its ability to inhibit the eukaryotic DNA topoisomerase I (2). Naturally occurring CPT is important source of chemotherapeutic agents for clinical treatment of cancer. It also inhibits retroviruses such as the human immunodeficiency virus (HIV) (3). Chemical synthesis of camptothecin is reported but extraction from plant sources is cost effective method. This fact makes the plants more valuable as a source of CPT as there are limited sources available for CPT extraction. The literature survey reveals that the presence of any valuable product from plant becomes the reason for its overexploitation and so for its threatened status. It is essential to find out new sources as well as attempts have to be made in order to boost the CPT production in the available sources. The present study illustrates first time the presence of CPT in the in vitro cultures of C. fragrans established in our lab. Localization and quantification of anti-cancer alkaloid Camptothecin (CPT) in vivo and in vitro in the sequential plant extracts of C. fragrans has been investigated in this communication. These results have important implications for harnessing the high yielding individuals for clonal multiplication. Presence of such drug in the cultures will help to prevent the overexploitation as well as could prove an alternative source.