Identification, evaluation the source of natural bioactive compounds from Calotropis gigantea l. flowers and their anticancer potential

Background: In the intensified search to derive biologically active compounds from natural products for various health care issues, attention is focused on non-edible plant sources. Among the wild plants, Calotropis [milk weeds] of the family Apocynaceae, are the repository of pharmaceutically active phytoconstituents. The flowers of C. gigantea are expected to be rich in bioactive compounds.Methods: The bioactive compounds and in vitro anticancer activity of C. gigantea flower extract were investigated. The compounds in the extract were separated using GC-MS and confirmed their structures with NIST (National Institute of Standard and Technology) database. The cytotoxicity of flower extracts against A-549 lung cancer cell lines was evaluated by MTT assay. Among the six identified compounds, three biologically active compounds with short retention time and abundance were chosen for molecular docking for anticancer activities. Molecular docking using the software GLIDE version 6.5 was used to trace their interactions with the anti-lung cancer protein, IT69.Results: The phytochemical screening indicated the rich presence of anticancer flavonoid and phenolic com-pounds in the flower extract. Inhibition of cell viability and growth and morphological alterations in cells were observed when A-549 cells were exposed to different concentrations of flower extract. The highest percentage of cell death (70 %) was observed in cells exposed to 100 mu g/ml concentration. Molecular docking of three identified compounds with lung anticancer protein complex, IT69 proved that Butanoic acid, 3-[(phenyl methoxy) imino] trimethylsilyl ester is a good anti-lung cancer agent. Hence for pulmonary cancer, the identified com-pound can intensively be tested further.