నైరూప్య

Phenolic and flavonoid rich bioactive leaf fractions of Eucalyptus camaldulensis ameliorates listeriolysin O activity and H2O2 induced oxidative stress in Caco-2 cells

Ozioma Forstinus

Eucalyptus camaldulensis is a rich source of bioactive essential oil with extensive application in folk medicine. Leaves of the plant are rich in phenolic and flavonoid content with antimicrobial and antioxidant activities. In this study, leaves of E. camaldulensis were extracted and the aqueous and ethanol fractions were obtained. The antimicrobial activities of the ethanol and aqueous fractions showed minimum inhibitory concentrations range of 16–64 and 158–316 µg/ml, respectively. Antioxidant assay indicated better activity for the aqueous fraction with IC50 of 7.07 and 17.96 µg/ml for DPPH and ABTS assays, respectively. Folin–Ciocalteu and AlCl3 assays revealed a total phenolic content of 9.04±0.26 and 3.58±0.04 mg GAE/mg fraction and total flavonoid content of 2.07 ± 0.02 and 3.37±0.05 mg QE/mg fraction for aqueous and ethanol fractions, respectively. At sub-inhibitory concentrations Listeriolysin O induced RBC haemolysis was reduced by 63–98% and 6–92% after treatment with aqueous and ethanol fractions, respective. Cell studies on Caco-2 human colon cells revealed that at sub-toxic concentrations, H2O2 induced toxicity was ameliorated by 8–23% and 15–83% by aqueous and ethanol fractions, respectively. In addition, H2O2 induced oxidative stress measured using Griess assay showed a reduction in nitrite production of 4–17 and 3–14 µM for aqueous and ethanol fractions, respectively. The study reveals that phytochemical fractions of E. camaldulensis possess multiple bioactivity and can be explored as preservative, or functional additive in food.