Antioxidant Activities and Phenolics Contents of Avocado (Persea americana Mill.) Peel in vitro

Abstract

Background: Synthetic-based antioxidants are suspected to cause toxic or mutagenic effects toward human health, therefore, the demand for natural antioxidants increased. One of the natural antioxidant sources is Avocado Peel (AP). Objective: The objective of this study is to determine antioxidant activities of the extract, fractions and isolates from AP using in of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS+ vitro method ) radical scavenging, reducing power of iron (III) as well as total phenolic and flavonoid contents. Materials and Methods: Ethyl acetate fraction of AP is fractionated using vacuum liquid chromatography and gravitation column chromatography methods. To identify the chemical structure of the active compound of antioxidants in AP, FTIR spectroscopy and gas chromatography-mass spectrometry (GC-MS) are used. Results: Among extracts evaluated, methanol extract has the strongest antioxidant activity. Further fractionation of methanolic extract showed that fraction 8 is the most active fraction with IC50 values of 4.221±0.137 mg mLG1 (DPPH assay) and 0.855±0.013 mg mLG1 (ABTS assay), with reducing power of iron (III) of 723.067±18.849 mg ascorbic acid gG1 fraction. Phenolics contents contributed 37, 40.78 and 47.45%, compared with the contribution of flavonoids compounds of 26.71, 19.25 and 34.62% for DPPH radical scavenging, ABTS radical scavenging and reducing power of iron (III) to iron (II), respectively. Isolation of the fraction 8 of methanol extract indicated the presence of 1,2,4-trihidroksiheptadek-12,16-diyne and isolation of the ethyl acetate extract indicated the presence of 1,2,4-trihidroksiheptadek-16-yne-18-ene. Conclusion: The AP is potential to be used as food supplement due to its antioxidant activities