Chemical constituents, antimicrobial and antioxidant activity of essential oil of Citrus limetta var. Mitha (sweet lime) peel in Pakistan

The essential peel oil of Citrus limetta var. Mitha (Sweet lime) extracted by hydro-distillation was assessed for chemical constituents, antimicrobial and antioxidant activity. Gas chromatographic analysis identified 17 constituents among which limonene (95.98 %) was found as major component followed by camphene (1.79 %), while the remaining terpenes were less than 1%. The results of antimicrobial activity of essential oil tested by disc diffusion method, against different against bacteria and fungi showed that it exhibited maximum zone of inhibition against Bacillus cereus ATCC 14579 (28 mm) and Bacillus subtilis ATCC 6633 (26 mm) followed by Staphylococcus aureus ATCC 25923 (21 mm), where as the minimum zone of inhibition was shown by Fusarium oxysporum ATCC 48122 (11 mm) after 48 h of incubation at their respective temperature (37°C for bacteria and 25°C for fungi). The inhibition zones, measured after 48 and 96 h, showed that it was active against all tested bacteria and fungi. The results of its antioxidant activity showed that it was able to reduce the stable radical 1-diphenyl-2-picrylhydrazyl (DPPH) to yellow-colored DPPH-H reaching 87.77% of DPPH scavenging effect at its 100% concentration comparative to ascorbic acid as reference standard being a strong antioxidant reagent. The results of our study showed that essential oil of C. limetta var. Mitha peel can be an effective medicine against different pathogenic microbes.   Key words: Citrus limetta var. Mitha, essential oil, antimicrobial activity, antioxidant, pathogenic microbes.