Screening of Chonemorpha fragrans Bioactive Extracts for Cytotoxicity Potential and Inhibition Studies of Key Enzymes Involved in Replication

BACKGROUND: Chonemorpha fragrans (Moon) Alston, a liana belonging to family Apocynaceae, is used in traditional medicinal systems for the treatment of various ailments. It is an unexplored medicinal plant with respect to its anticancer potential. OBJECTIVE: Cytotoxicity of sequential as well as crude extracts of in vivo plant parts (leaves, bark, and roots), in vitro cultures, and callus were compared. MATERIALS AND METHODS: 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell proliferation assay was used to compare the extracts of various in vivo plant parts (leaves, bark, and roots) along with in vitro culture systems (in vitro plantlets, callus). Furthermore, the extracts were used to evaluate inhibition of key enzymes involved in replication, i.e. topoisomerase (Topo) I and II, DNA polymerase, to check the probable mechanism of action for this cytotoxicity. RESULTS: MTT assay showed that the chloroform extract of callus has potent anticancer potential. The plant has a promising anticancer activity against human colon epithelium, lung carcinoma, and epidermoidal carcinoma cell lines. It was found to possess Topo as well as DNA polymerase inhibitory activity. CONCLUSION: The results have pointed toward pharmaceutical importance of this plant. This study is the first report of exploring the antiproliferative potential as well as inhibition studies of key enzymes involved in replication, which was useful to point out probable mechanism of action for extracts of C. fragrans. SUMMARY: It's a first report of cytotoxicity studies and inhibition of enzyme involved in the replication process by Chonemorpha fragrans plant extracts. The results reveal the pharmaceutical importance of this plant. From various assays performed here, a potent anticancer potential of chloroform extract of callus was revealed showing Topo I (E. coli and human) inhibitory activity, DNA pol inhibitory activity. Considering the importance of these activities, plant further needs to be explored in detail for in vivo cancer studies as well as for its metabolite content. Abbreviations used: CPT: Camptothecin, EDTA: Ethylenediaminetetraacetic acid, MTT: 3-4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide, Pol: Polymerase, Topo - Topoisomerase.