Effects of Time on Phenolics and in vitro Bioactivity in Autoclave Extraction of Graviola (Annona muricata) Leaf

We investigated the effects of different autoclave extraction times (1-6 h) on the antioxidant, antidiabetic, and anti-inflammatory activities of phenolic compounds isolated from graviola (Annona muricata) leaves. In terms of yield and content of total polyphenols, total flavonoids, rutin, and kaempferol-3-O-rutinoside, the optimal extraction time was 4 h. At this time point, water extracts from graviola leaves (WEG) exhibited the highest DPPH radical scavenging activity, ferric reducing antioxidant power, and α-glucosidase inhibitory activity. The α-glucosidase inhibitory activity of WEG was significantly stronger than that of acarbose. Furthermore, WEG significantly suppressed lipopolysaccharide-induced nitric oxide production in RAW 264.7 cells and inhibited UVB-induced activator protein-1 (AP-1)-dependent transcription in human keratinocytes. In conclusion, WEG can be used as functional food ingredients in the food industry.