Phytochemical Analysis, Antibacterial and Radical Scavenging Activities of Root Extracts of Cucumis Prophetarum L.

Abstract

Cucumis prophetarum is among plants traditionally used by Borena people for the treatment of wide array of diseases including lung disorders, heart failure, back pain, gonorrhea, intestinal problems and abnormal menstrual cycle. Considering the absence of prior scientific report that supports ethno-medicinal uses of the roots of the plant, this study focused on isolation of chemical constituents, evaluation of the anti-bacterial and radical scavenging activities of the roots of C. prophetarum. In view of this, the roots were successively extracted on maceration with hexane, CHCl3 and MeOH to furnish 4 g (1% w/w), 15 g (3.75% w/w), and 23 g (5.75% w/w) yield respectively. The hexane extract, after silica gel column chromatography, afforded two new compound namely compound 32 and 33 along with three known compounds such as myristic acid (29), 24-ethyl-3-hydroxylcholesta-5,25-diene (30) and α-spinasterol (31).The extracts and isolated compounds were evaluated for their antibacterial activity using Agar disc diffusion against four strains of bacterial pathogens including E. coli, S. thyphimurium, S. aureus and B. subtilis. Results showed that all extracts and isolated compounds showed inhibition diameter beyond 9 mm. The hexane extract, methanol extract, compound 31 and compound 32 exhibited inhibition diameter of 15±1.41, 14.6±1.7, 13±0 and 13.6±0.94, respectively, against E. coli. Whereas compound 32 and 33 showed inhibition diameter 13±1.41 against S. thyphimurium. Both the crude extracts and isolated compounds investigated herein were in inhibition diameter range (9-12 mm) against S. aureus and compound 33 also exhibited inhibition diameter of 13.3±0.54 against B. subtilis. Molecular docking of isolated compounds was done using Autodock vina software. Among the investigated ligands compound 32 exhibited better docking efficiency with DNA gyrase with binding affinity -7.3. The extracts and isolated compounds were also assessed for their radical scavenging activity using DPPH assay. The methanol extract displayed promising radical scavenging activity of 70.57% (IC 50 = 28.87). The antibacterial activity presented herein supports the traditional use of this plant against bacteria.