Sieving fractionation, phenolics profile and in vivo antioxidant activities of Dichrostachys glomerata Forssk. powder

Powder fractions of Dichrostachys glomerata were produced by drying the fruits to 10% moisture, grinding followed by sieving to differentiate powders of sizes <180, 180-212, 212-315 and ≥315 µm, respectively. The obtained powders were analysed for their phenolics profile and in vivo antioxidant activities in rats were evaluated. Lyophilized ethanolic extract and crude powder were used for comparison. The phenolic compounds (mg/100 g): epicatechin (19-30), caffeic acid (313-468), protocatechuic acid (338-799) and quercetin (369-639) were significantly correlated (r>0.65; p<0.05). For in vivo antioxidant properties, the rats fed with fine powders reduced their malondialdehyde in all organs from 19 to 64% (180-212 µm) and 29 to 38% (<180 µm), while increase in catalase (250-1310% and 249-1121%) and superoxide dismutase (72-251 and 5-404%) were observed, respectively in the 180-212 µm fraction and ethanolic extract powder. The 180 to 212 µm fraction with high phenolic contents protected rats from oxidation by modulating malondialdehyde, superoxide dismutase and catalase levels similar to ethanolic extract powder, although still lower than vitamin C. Thus, sieving fractionation has a huge potential as substitute to ethanol extraction of phenolic compounds from D. glomerata to obtain powder fractions usable as natural bio-functional ingredients.