Phytochemical Analysis and Bioactivity of Nepalese Medicinal Plants, with Compound Isolation from <i>Dischidia bengalensis</i> Colebr.

Abstract

Numerous medicinal plants have been used traditionally to treat, relieve, and prevent various diseases since ancient time, yet many of them are to be scientifically investigated. The present study was carried out with the aim of phytochemical screening, determination of 1,1–diphenyl–2–picrylhydrazyl (DPPH) free radical scavenging activity and antibacterial activity of 70% methanolic extracts of six medicinal plants of Nepal used by different ethnic tribes, and to isolate chemical compounds from one of them. Agar well diffusion method was used to assess the in vitro antibacterial activity, whereas the chemical isolation was carried out using different chromatographic techniques. Then, the structure of the isolated compounds was determined by using NMR (Nuclear Magnetic Resonance) spectroscopic method, followed by spectral analysis in comparison with published data. Of the six extracts, the extracts of <i>Angiopteris helferiana</i> and <i>Drynaria coronans</i> showed moderate antibacterial activities. Moreover, the extract of <i>Dischidia bengalensis</i> showed the most potent antioxidant activity and was thus subjected to chromatographic separations utilizing different chromatographic principles to isolate 2"-<i>O</i>- rhamnosylvitexin (<b>1</b>) and isovitexin (<b>2</b>). These secondary metabolites are reported for the first time from this plant whilst, their pharmacological activity is yet to be screened.