Assessment of extraction techniques for total phenolics and flavonoids from Annona muricata seeds

The study describes the assessment of extraction techniques for total. phenolics (TP) and flavonoids (TF) from the seeds. of Annona muricata, Which is commonly. a neglected part of the fruit. Conventional extraction techniques like heat reflux, Soxhlet extraction, maceration with stirring and complementary extraction techniques like microwave assisted extraction. (MAE) and ultrasound assisted extraction (UAE) were attempted. The TP and TF were determined spectrophotometrically using Folin-Ciocalteu reagent and aluminium chloride, respectively. Among all, extraction techniques, MAE accounted for higher extraction yield (16.2% w/w) followed by Soxhlet (9.68% w/w), maceration with stirring (8.12% w/w), heat reflux (6.76% w/w) and UAE (5.2% w/w). MAE method was optimised for various parameters like microwave power, irradiation time, solvent type, solvent concentration, preleaching time, solvent to material ratio and extraction cycle. Sonication time for UAE was also optimised. Higher TP content equivalent to gallic acid was obtained using heat reflux (0.147 +/- 0.057 mg GAE/g) and Soxhlet methods (0.146 +/- 0.012 mg GAE/g), followed by UAE, maceration with stirring and MAE techniques. TF content equivalent to quercetin Was achieved higher (0.679 +/- 0.288 mg QE/g) through MAE technique, which is almost double than the quantity obtained using UAE and maceration with stirring methods. The study clearly explicated the higher extraction yield and TF content but not TP, by MAE method compared to other techniques. Hence MAE under the optimised conditions is suitable for the targeted extraction of quercetin like flavonoids and conventional methods are appropriate for total phenolics extraction.