Unraveling the chemical composition, antibacterial, antioxidant and cytotoxic potential of Citrus reticulata Blanco dropped fruit extracts

Fruit wastes are one of the major contributors of the biomass wastes. Citrus reticulata Blanco shows substantial fruit drop due to diverse environmental factors leading to huge agricultural waste which can be utilized as source of valuable products of nutraceutical and pharmacological importance. The present study aimed to evaluate the antioxidant, antibacterial and cytotoxic potential of citrus fruits biomass dropped in the month of June. The dropped citrus fruits extracts were prepared by soxhlet extraction technique using hexane, ethyl acetate and methanol as solvents. The GC-MS analysis of fruit extracts revealed the presence of numerous bioactive compounds as nobiletin (35.08%), 3,3′,4′,5,5′,7-hexamethoxyflavone (28.33%) and ethyl oleate (15.17%) as major components in methanol, ethyl acetate and hexane extracts respectively. The extracts were further evaluated for their antibacterial potential against Escherichia coli, Yersinia enterocolitica, Staphylococcus aureus and Bacillus spp. The methanol extract showed maximum antibacterial potential against all the tested bacteria having MIC as 75–125 μg/mL and significant reduction in biofilm formation. The extract also showed synergistic interaction with standard antibiotic i.e., streptomycin against E. coli, Bacillus spp. and S. aureus and also showed the highest cytotoxic activity against HT-29 and Ln-Cap cell lines having IC50 values; 360 and 400 μg/mL respectively. The antioxidant potential of methanol and ethyl acetate extracts was nearly same having IC50 values; 75.5 and 76.0 μg/mL in the DPPH and NO radical scavenging assays respectively. Hence, the dropped citrus fruits which are generally regarded as waste can be utilized as source of antibacterial, antioxidant and cytotoxic agents.