Discovery of bioactive metabolites from the leaves of Vitex pinnata using high-throughput flash chromatography

In our study we report the chemical investigation and various biological activities of secondary metabolites isolated from the leaves of Vitex pinnata L. In Malaysia, leaves of V. pinnata were traditionally used to treat cuts and wounds while the bark decoction is used for stomach ache and post-childbirth medicine [1,2]. High-throughput flash chromatography proved to be fast, robust, efficient and reproducible in the isolation and purification of the biologically active natural products. Ten compounds were isolated and chemical investigation revealed that retusin, kaemferol trimetyl ether, pheophytin a, β-sitosterol, and a new diterpene are the major compounds found in this leaves. The structures of all isolated compounds were determined by using 1D and 2D-NMR and also LC-MS. Antioxidant and antibacterial activities were tested on isolated compounds and fractions. In the qualitative antioxidant TLC assay, new diterpene and pheophytin a bleached the DPPH (0.2% in MeOH) purple colour indicating antioxidant activity. Retusin and β-sitosterol isolated from hexane extract showed to have antibacterial activity against Microbacterium marinum. Other bioassays such as antitrypanosomal and cytotoxicity studies are still under investigation. Consequently, this plant is a promising source for various biological activities