Optimization of extraction and quantification of Flavonoids from Averrhoa bilimbi fruits using RP-HPLC and its correlation between total flavonoids content against antimicrobial activity

The present study was conducted to evaluate Averrhoa bilimbi fruits flavonoids extraction and quantification analysis through RP-HPLC and its comparison study on total flavonoids concentration versus antimicrobial activity analysis based on minimum inhibitory concentrations. Optimization of extraction was carried out using three different methods; among all methods the ultrasonic conventional assistant extraction (UCAE) showed an excellent recovery of flavonoids with solid phase elution. UCAE was performed with ethanol using different solvents ratio, the total flavonoid content was quantified through spectrophotometrically (850 ± 25 mg/kg) and flavonoids (myricetin and luteolin) were quantified by RP-HPLC. Optimized yield of myricetin and luteolin were presented in A. bilimbi fruits 336 ± 15 and 231 ± 18 mg/kg, respectively. Antimicrobial activity examined against E. coli, S. aureus and B. subtilis species using spectroscopically. The extracted sample with known quantity of total flavonoids content (10–200 µg/mL) used against E. coli, S. aureus and B. subtilis, MIC results shows 55.6 ± 6, 31 ± 3 and 28 ± 2 µg/mL respectively. Higher flavonoid content plays major role on antioxidant activities, which were evaluated and compared with commercial antioxidant butylated hydroxytoluene (BHT) employing superoxide anion scavenging activity and total reducing power IC50 value results shows 100 and 175 µg/mL, respectively. The maximum yield of flavonoid content results shows method suitability of flavonoids extraction and quantification.