Response surface methodology-based optimised ultrasound-assisted extraction of phenolics from Solanum lasiocarpum Dunal (terung asam) fruit: Anti-diabetic evaluation and ADMET study

Abstract

Solanum lasiocarpum Dunal, known as ‘terung asam,’ is an indigenous fruit-vegetable widely cultivated on Borneo Island, particularly in Sarawak (Malaysia) and Kalimantan (Indonesia). This study optimised the ultrasound-assisted extraction of S. lasiocarpum fruit extract (SLFE) using response surface methodology (RSM) and evaluated its anti-diabetic activity. Initial screening with a one-factor-at-a-time (OFAT) approach assessed solvent extraction, extraction time, ultrasonic amplitude, and solid-to-solvent ratio. These parameters were further refined using RSM with a central composite design to optimise crude extract yield (CEY), total phenolic content (TPC), and chlorogenic acid (CGA). Anti-diabetic activity was assessed via in silico molecular docking and in vitro α-glucosidase inhibition. Optimal conditions were an extraction time of 8.93 min, ultrasonic amplitude of 57.00 %, and a solid-to-solvent ratio of 1:29.68 g/mL, resulting in CEY (45.32 ± 0.67 %), TPC (28.22 ± 0.86 mg GAE/g), and CGA (1.78 ± 0.12 mg/g). In silico, CGA demonstrated a higher molecular docking vina score (−7.1 kcal/mol) than acarbose (−6.5 kcal/mol), while in vitro, SLFE exhibited an IC₅₀ of 54.82 ± 0.08 μg/mL, compared to acarbose (9.47 ± 0.13 μg/mL) and CGA (8.15 ± 0.22 μg/mL). These findings establish SLFE as a valuable source of phenolic compounds with significant anti-diabetic activity, suggesting its potential as a food ingredient and dietary supplement.