Phytochemical Constituents and Antioxidant Activities of Dichloromethane-Methanol Leaf Extract and Fractions of Sabicea Brasiliensis (Rubiaceae)

Abstract

The objectives of this study were to determine the phytochemical components included in the dichloromethane-methanol (DCM-MeOH) extract of Sabicea brasiliensis and to assess the extract's impact on various antioxidant models. Fresh leaves of S. brasiliensis were processed to a fine powder using a milling machine. A 1000 g of the powdered leaves was extracted with 5 L of a 1:1 dichloromethane-methanol (DCM-MeOH) mixture for 72 h using cold maceration with intermittent vigorous shaking every 6 h. The extract was further fractionated using solvent-solvent partitioning method into n-hexane (SB-HF), ethyl acetate (SB-EF) and n-butanol (SB-BF) with SB-BF exhibiting the highest percentage yield of 62%. The leaf extract of S. brasiliensis was screened for the presence of phytochemicals and the in-vitro antioxidant assays were determined using standard methods. Phenols, tannins, glycosides, saponins, terpenoids, steroids and flavonoids were detected except alkaloids. The DCM-MeOH extract exhibited the most significant amount of phenolics (120.78 ± 1.06 mg), total flavonoids content (318.40 ± 4.03 mg), total tannin content (102.22 ± 7.58 mg) while n-hexane fraction had the least total phenolics content (38.73 ± 4.53 mg), total flavonoids content (149.73 ± 4.53 mg), and total tannin content (30.73 ± 1.53 mg). The IC₅₀ of the anti-radical powers of the extract ranged from 0.943 ± 0.01 µg/mL, 1.060 ± 0.01; to 1.127 ± 0.01 µg/mL, 0.887 ± 0.01 in the methanol and butanol subfractions respectively compared to the ascorbic acid standard (1.164 ± 0.01 µg/mL), the subfractions were more potent. This study provided a scientific validation for the folkloric claims regarding S. brasiliensis with novel anti-oxidative potentials.