Antioxidant and anti-inflammatory potential, and chemical composition of fractions of ethanol extract of Annona muricata leaf

Serious health challenges have been associated with inflammation which is a major cause of mortality in the world. This study evaluated the antioxidant, anti-inflammatory potential, and chemical compositions of fractions of ethanol extract of Annona muricata leaf. The leaves were dried at room temperature, blended and extracted in sequential with solvents of varying degree of polarities, i.e., n-hexane, ethyl acetate and ethanol. Ethanol extract was fractionated via solvent-solvent partitioning into five fractions, i.e., n-hexane fraction (F1), dichloromethane fraction (F2), dichloromethane/ methanol (1:1) fraction (F3), methanol fraction (F4), and ethanol fraction (F5). These fractions were examined for their in-vitro antioxidant activities on DPPH, ABTS and H2O2 while the anti-inflammatory activities were investigated using lipoxygenase inhibition, proteinase inhibition and membrane stabilization assays. The F4 being the most active fraction was further analyzed with GCMS to determine its chemical compositions. The results showed that F4 had the highest H2O2 scavenging activity at 10–100 µg/mL. The activity of F4 at 50 µg/mL was significantly higher (P<0.05) than that of other treatments including the standard (Vitamin C). Activity of F4 also showed significantly higher (P<0.05) membrane stabilization than other fractions at 50-100 µg/mL. F4 exhibited higher antioxidant and anti-inflammatory activities than the other fractions. The activity of this fraction could be attributed to the synergetic effect of various antioxidant compounds present in the fraction. Some of the bioactive compounds identified in the GC-MS of F4 were coumaran, tyrosol, phytol, tetracosanol, elaidic acid methyl ester and β-sitosterol. Keywords: Bioactivity, concentration, inhibition, radical scavenging