Title : Response surface optimization of microwave-assisted extraction of Parkia speciosa leaves and assessment of their multifunctional biological properties
Abstract:
Medicinal plants are recognized as valuable natural sources of bioactive compounds with diverse pharmacological applications. Parkia speciosa, commonly known as stink bean, is widely consumed in Southeast Asia and traditionally used for the management of diabetes, inflammation, hypertension, and microbial infections. The present study aimed to optimize the extraction of polyphenolic compounds from P. speciosa leaves using microwave-assisted extraction (MAE) combined with Box–Behnken Design (BBD) under response surface methodology. Three extraction parameters, including ethanol concentration, microwave power, and extraction time, were optimized to maximize phenolic recovery and antioxidant potential. The optimized leaves extract (OLPS) demonstrated a high total phenolic content of 115.62 ± 0.35 mg GAE g⁻¹. Antioxidant analysis revealed strong free radical scavenging activity with DPPH IC₅₀ of 25.39 ± 0.46 µg/mL and ABTS IC₅₀ of 13.32 ± 0.28 µg/mL, together with significant reducing capacity in FRAP and CUPRAC assays. Phytochemical profiling by UPLC-Q-TOF-MS identified a diverse range of secondary metabolites, particularly flavonoids, phenolic acids, glycosides, lignans, and fatty acid derivatives. Major compounds identified included quercetin, rutin, kaempferol, gallic acid, quercetagitrin, cynarotrioside, and baicalein. The extract also demonstrated significant antidiabetic activity, showing inhibition against α-amylase (IC₅₀ 112.66 ± 1.23 µg/mL) and α-glucosidase (IC₅₀ 75.54 ± 0.64 µg/mL) enzymes, while enhancing glucose uptake in 3T3-L1 adipocytes by 75.65% at 200 µg/mL. Strong antibacterial activity was observed against Staphylococcus aureus infection and Staphylococcus epidermidis, alongside antifungal activity against Candida albicans. Cytotoxic evaluation revealed moderate anticancer potential against MCF-7, MDA-MB-231, and HT-29 cancer cell lines. Molecular docking studies showed strong binding affinities for Cynarotrioside (-9.6 kcal/mol) and Quercetagitrin (-9.0 kcal/mol) against target enzymes, while ADME analysis confirmed favorable drug-likeness properties. The findings demonstrate that optimized P. speciosa leaf extract is a rich source of multifunctional phytochemicals with significant antioxidant, antidiabetic, antimicrobial, and anticancer potential. The study highlights the effectiveness of MAE optimization and supports the future development of P. speciosa as a promising natural candidate for pharmaceutical and nutraceutical applications.
Keywords: Parkia speciosa; Microwave-Assisted Extraction; Box–Behnken Design; Antioxidant Activity; Antidiabetic Activity; Antimicrobial Activity; Cytotoxicity; Molecular Docking.
