Antimicrobial and Antioxidant Activities of Chrysopogon zizanioides Root Extract against Some Human Pathogenic strains

Abstract

Chrysopogon zizanioides, vetiver or Khush, is a perennial bunchgrass of the family Poaceae. C. zizanioides is found to be effective against many infections from bacteria, fungi and protozoa. The aim of this study was to determine the antimicrobial and antioxidant activities of C. zizanioides root extract against selected human pathogenic microbial strains and to analyze its chemical composition. The root of C. zizanioides was washed, air dried, powdered and extracted by using petroleum ether, chloroform, and methanol. The chloroform extract was subjected to column chromatography over silica gel (60-200 mesh). The silica gel column chromatographic separation of the chloroform extract from fraction 27 afforded compound 1. The structures of the isolated compound were characterized using infra-red (IR) spectrum and NMR spectroscopic techniques ( 1H NMR, 13C NMR, DEPT-135). The C. zizanioides root was hydro distilled by using a Clevenger apparatus. The crude extract and isolated compound 1 of the plant were tested against Escherichia coli (ATCC 25923), Pseudomonas aeruginosa (ATCC 27823), Staphylococcus aureus (ATCC 25923), Streptococcus pyogenes (ATCC 11778) and Candida albicans (ATCC 10231). The crude extract and essential oil of C. zizanioides root were assessed for radical scavenging activity using DPPH assay. Antibacterial activities of the plant extracts were assessed using the agar disk diffusion method. The isolated compound was terpenoid.Gas chromatography and mass spectrometry analysis revealed the presence of a total of 19 chemical components. The petroleum ether extract at 200 mg/ml exhibited the maximum inhibition zone of 18.33±2.08 mm against S. pyogenes, while the chloroform and methanol extract at 200 mg/ml showed maximum inhibition zones of 19±1 mm against C. albicans. The isolated compound 1 exhibited maximum inhibition against S. aureus 12±0mm at a concentration of 10 mg/ml and C. albicans 17. 66±0mm. Among the studied crude samples chloroform extract at 500µg/mL showed the best radical scavenging activity with a % inhibition of 93.32 and an IC50 of 5.603. In the case of essential oil of C. zizanioides root radical scavenging activity % inhibition was 30.56 and its IC50 value was 255.88.The finding of this study showed that C. zizanioides root has considerable antimicrobial, and antioxidant properties, which should be further examined with particular attention to the mechanisms of antimicrobial activity.