Study of Phyto- and Physicochemical Analysis, Antimicrobial and Antioxidant Activities of Essential Oil Extract of Callistemon citrinus (Curtis) Skeels Leaves

The essential oil was extracted from the leaves of Callistemon citrinus (Bottlebrush)by hydro-distillation using a Clevenger apparatus. The component analysis of the oil was carried out by GC-MS technique, which showed eucalyptol (56.47%), α-pinene (18.80%), and D-limonene (9.91%), as the major compounds in C. citrinus oil. The physicochemical parameters such as yield percentage, specific gravity, refractive index, optical rotation, acid value, saponification value, and ester value were determined. The antioxidant activities of extracting oils were determined by DPPH assay and the radical scavenging activity (IC50) value was calculated. The remarkable free radical scavenging effect was observed in bottlebrush oil with IC50 = 390.73 µg/mL. Bottlebrush oil (50% and 100%) exhibited antimicrobial activity against all the four selected strains of bacteria (E. coli, S. aureus, B. subtilis, S. dysenteriae) as well as fungi (Candida albicans).