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Abstract
The leaves of Gynura procumbens (Merr.) Compositae, commonly called “sambung nyawa” in Malaysia, are often eaten raw with rice. The methanol extract was prepared from the dried leaves using a Soxhlet apparatus. The methanol extract was then fractionated into chloroform, ethyl acetate, n-butanol, and aqueous fractions using a separating funnel. In the current study, the antioxidant potency of G. procumbens extract and fractions were investigated, employing various established in vitro systems, such as trolox equivalent antioxidant capacity, β -carotene–linoleic acid model system, 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging, reducing power, and xanthine oxidase inhibitory activity. Based on the results obtained, the extract and fractions showed different antioxidant potential. Among the fractions, the ethyl acetate fraction displayed higher antioxidant properties. The contents of the potential antioxidant component of the extract and fractions were also determined using HPTLC densitometric and spectrophotometric (using Folin-Ciocalteu reagent) methods. HPTLC study revealed that the methanol extract and the ethyl acetate and n-butanol fractions contain 0.74% and 2.9%, 7.76% and 12.75%, and 4.52% and 0.33% of kaempferol-3-O-rutinoside and astragalin, respectively. The total phenolic content of the extract and fractions varied from 4.37% to 23.43% of dry weight, expressed as gallic acid equivalents (GAE). With further data analysis, it was found there was a significant correlation (p < 0.05) between the total phenolic content of the sample and its DPPH scavenging activity and reducing power with correlation coefficients (r) of 0.891 and 0.926, respectively. These results suggest that phenolics in these plants provide substantial antioxidant activity.