Bioactive extract recovery from hyptis suaveolens leaves using solid-liquid extraction technique: Experimental data modelling and biological activities

Abstract

This study investigated the recovery of phenolic phytochemicals from Hyptis suaveolens leaves (HSL), a widely available weed in Nigeria, using heat-assisted solid–liquid extraction. The effects of extraction time (50–70 min), temperature (60–80 °C), and solid–liquid ratio (0.2–1.0 g/100 mL) on total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity (DPPH) were evaluated. Extracts were characterized by HPLC, and experimental data were modeled using artificial neural networks (ANN). The optimally prepared extract was subjected to in vivo acute and sub-acute toxicity studies in Swiss albino rats. While antimicrobial activity was assessed in vitro against Salmonella paratyphi, Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Streptococcus spp., and Proteus vulgaris using the disk diffusion method. Optimized extraction conditions - 61.28 min, 62.74 °C, and 0.58 g/100 mL - yielded TPC of 33.055, TFC of 7.171, and DPPH scavenging activity of 9.528. The ANN model demonstrated high predictive accuracy (R² = 0.94 - 0.99) for TPC, TFC, and DPPH responses. HPLC analysis confirmed the presence of gallic acid, chlorogenic acid, caffeic acid, rutin, and ferulic acid. Acute toxicity test demonstrated extract safety at 5000 mg/kg body weight, while sub-acute studies revealed no deleterious effects on liver or kidney function. The extract exhibited notable antibacterial activity, with inhibition zones ranging from 6.43 to 10.48 mm. Overall, the antioxidant, antimicrobial, and toxicological profiles of H. suaveolens leaf extract underscore its potential for pharmaco-medicinal, food, and allied industrial applications.