Evaluation of the Free Radical Scavenging Activities of Ethanol Extracts of Annona muricata (Soursop) Leaves and Bark for Cosmetic Emulsions

Abstract

Plant extracts offering skin health benefits such as antioxidant and photoprotective properties are increasingly used in cosmetic formulations. The antioxidant properties of ethanol extracts of Annona muricata (soursop) leaves and bark were assessed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay. The leaf extract yielded 448 µg GAE/mL (micrograms of gallic acid equivalent per milliliter) total phenolic content, 119 µg QE/mL (micrograms of quercetin equivalent per milliliter) total flavonoid content and 101 µg TAE/mL (micrograms of tannic acid equivalent per milliliter) total tannin content, while the bark extract yielded 575 µg GAE/mL total phenolic content, 24.2 µg QE/mL total flavonoid content and 126 µg TAE/mL total tannin content. The 50% inhibitory concentration (IC₅₀) values reveal the free radical scavenging properties of the samples as follows: ascorbic acid (104 µg/mL) > bark extract (128 µg/mL) > leaf extract (198 µg/mL), showing that ascorbic acid, a commercial antioxidant, exhibited the most effective free radical scavenging property. The free radical scavenging abilities of these extracts may be attributed to their rich phytochemical contents. Cosmetic emulsions formulated with the plant extracts were oil-in-water emulsions stable for 60 days at room temperature (30 °C), in an incubator (40 °C) and in a refrigerator (7 °C). The results showed that A. muricata leaf and bark extracts could potentially be applied as natural free radical scavenging ingredients in antioxidant and anti-aging cosmetic formulations for photoprotective skincare through ultraviolet (UV) radiation shielding.