Reactive oxygen species causes harm to cell membranes and biomolecules, wherefore chronic diseases develop. Antioxidants scavenge such free radicals combating oxidative stress. This research aimed to determine the antioxidant potential of the aqueous stem bark, root and leaf extracts of Rhaphiolepis bibas against standards. DPPH radical scavenging activity was high from th stem bark extract at 72.33% with root extract at 65.85% and leaf extract at 55.91%, while ascorbic acid scavenged 89.53% of DPPH radicals. The leaf extract had the highest H2O2 scavenging activity of 91.92% with stem bark at 91.17% and the root extracts at 89.12%. The aqueous root extract of R. bibas had a significantly higher FRAP capacity in comparison to the leaf extracts and the stem bark. The abilities to chelate iron by the leaf extract were statistically higher compared to the root and stem bark extracts. Stem bark extracts had the highest phenol content of about 149.44 followed by the root extract at 141.14 and the least amount of phenol was found in the aqueous leaf extract having 73.012 Gallic acid equivalent/g. The root extracts had the highest total flavonoid 377.66-milligram quercetin equivalent/gram dry weight followed by stem bark extract at 255.72 and the least amount was found in aqueous leaf extract having 164.52 mgQE/g of sample dry weight. The existence of secondary metabolites linked to antioxidant action was shown by the qualitative phytochemical screening.
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Biological profiles of Q. cerris, Q. dalechampii, and Q. robur bark extracts: A characterization study
Objective: The main objective of the present study was to characterize the extracts obtained from the bark of three oak species in order to assess their use in potential cosmetic products.
Methods: The extracts were obtained from the oak barks (periderm and rhytidome) using ultrasound-assisted extraction. The total polyphenolic content was assessed afterward, using the Folin–Ciocâlteu method, while the antioxidant capacity was determined using methods based on the neutralization of the 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and 2,2-diphenyl-1-picrylhydrazyl radicals. To assess the tyrosinase inhibitory effect, a protocol using L–DOPA as the substrate of the enzyme was employed.
Results: The extracts presented high levels of polyphenolic compounds, with Q. cerris having the highest content. Because of the high concentration of the extracts in polyphenolic compounds, they revealed a great reducing capacity against both DPPH and ABTS radicals, but unfortunately the tyrosinase inhibitory activity of the tested extracts was very weak compared to the positive control.
Conclusions: The extracts may have beneficial effects when used in cosmetic products because of the antioxidant effects, but more studies must be conducted for the determination of the main phytochemical compounds comprised in the extracts and their correlation to the biological effects.