FTIR Spectroscopic Analysis and Antioxidant Activity of Extracts and Fractions from Impatiens balsamina L. Leaves

Abstract

Secondary metabolites in Impatiens balsamina L. leaves notably flavonoids, phenolics, naphthoquinones, and glycosides, exhibited high structural diversity, supporting both its traditional medicinal applications and potential as a natural antioxidant source. This study investigated the FTIR fingerprint profiles and antioxidant activity of water extract, methanol extract, and n-hexane, ethyl acetate, and methanol-water fractions from methanol extract. FTIR fingerprints identified core functional groups (O−H, aromatic C=C, aliphatic C−H, and C−O) across all samples. Exceptions included the carbonyl (C=O) band was absent in the methanol-water fraction, while hydroxyl (O-H) was undetected in the water extract. The antioxidant capacity was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, and ascorbic acid was used as positive control. The ethyl acetate fraction showed the strongest potency in all samples (IC50 = 157.04 ± 3.670 µg/mL), followed by the methanol extract (214.66 ± 6.281 µg/mL), both categorized as weak 
antioxidants. In contrast, the water extract, methanol-water fraction, and n-hexane fraction proved to be inactive (IC50 > 250 µg/mL). Ascorbic acid showed strong activity comparatively (10.42 ± 0.182 µg/mL). It was shown that the profile of extracted chemical constituents is determined by solvent polarity in fractionation, thereby influencing the observed functional activities.