Activity-guided isolation and identification of anti-staphylococcal components from Senecio tenuifolius Burm. F. leaf extracts

ABSTRACT

Objective: To investigate activity-guided isolation and identification of anti-Staphylococcus aures components from Senecio tenuifolius Burm. F. (S. tenuifolius). Methods: Hexane, chloroform, ethyl acetate, methanol and aqueous extracts of S. tenuifolius were prepared by soxilation for antimicrobial activity against one registered Staphylococcus aureus (S. aureus) (ATCC No 25923) and two clinical isolates, methicillin resistant and methicillin sensitive S. aureus. NCCL standard methods were followed for antibacterial activity. GC-MS was performed to identify the chemical composition of bio active fraction. Results:Among all solvent extracts, methanol extract significantly reduced the growth of S. aureus (ATCC No 25923), methicillin resistant and methicillin sensitive S. aureus with the best zone of inhibition at 16.23, 14.06 and 15.23 mm and minimum inhibition concentration (MIC) values at 426.16, 683.22 and 512.12 μg/mL, respectively. In order to detect the active component in methanol extract, it was further purified by column chromatography, which yielded four fractions (St1, St2, St3, and St4). Among these four fractions, St3 was effective against the tested strains of S. aures, with the best zone of inhibition at 15.09, 13.25 and 14.12 mm and with best MIC values at 88.16, 128.11 and 116.12 μg/mL, respectively. Effective fraction partially purified from S. tenuifolius (St3) yielded MIC’s that were at least 20 fold less when compared to crude extract. GC-MS analysis of St3 revealed the presence of 3-[methyl-6,7-dihydro benzofuran-4 (5H)-one], 1,2-benzenedicarboxylic acid, hydroquinone, methyl ester and 3 unknown compounds. Conclusions:The study provides scientific evidence for traditional and folklore medicinal use of S. tenuifolius in skin infections treatment.