Integrated Chromatographic, FTIR and in vitro Antioxidant Explorations of Carica papaya Leaves Reveal Novel Phytocompounds of Ethnomedicinal Benefits

Abstract

Background: Carica papaya leaves are used in traditional medicine and contain diverse secondary metabolites with potential antioxidant activity. Aim: This study characterised the phytochemical constituents of an ethanolic C. papaya leaf extract using complementary analytical techniques and evaluated its in vitro antioxidant activity. Methods: Fresh leaves were air-dried, pulverised and extracted with ethanol by Soxhlet extraction. The extract was analysed by gas chromatography–flame ionisation detection (GC-FID), high-performance liquid chromatography (HPLC) and Fourier transform infrared spectroscopy (FTIR). Antioxidant activity was assessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and ferric-reducing assays. Results: GC-FID analysis detected multiple phytoconstituents, with limonene (25.504 ppm) and myricetin (15.250 ppm) among the most abundant reported compounds. HPLC analysis detected seven compounds, including rutin (3.25 ppm), quercetin (3.14 ppm), catechin (2.54 ppm) and sabinene (2.63 ppm). FTIR analysis showed absorption bands attributable to hydroxyl, carbonyl, amine, alkene, alkane, ether and aromatic functional groups. DPPH scavenging activity increased from 49.50 ± 0.25 % at 10 mg/mL to 85.63 ± 0.31 % at 80 mg/mL. The reported reducing activity similarly increased from 40.33 ± 0.89 µmole Fe(II)/g to 78.99 ± 0.35 µmole Fe(II)/g across the same concentration range. Conclusion: The ethanolic leaf extract contained diverse phytochemicals and demonstrated concentration-dependent in vitro antioxidant activity. Further analytical validation, isolation studies and biological investigations are required to establish the activities and potential applications of individual constituents.