Antioxidant activity, total phenolic and total flavonoid contents of the peel and seed of  Spondias dulcis (Amberalla) fruit

Purpose: Reactive oxygen species and the free radicals are implicated in many medical disorders as well as in the process of aging. Due to the toxicity of synthetic drugs there is much interest in natural products that could combat diseases. Furthermore side effects and resistance to antibiotics are well documented and as such there is much interest in herbal remedies that have antimicrobial activity. The objective of this research is to investigate the antioxidant and antibacterial potential of the extracts of the seed and peel of Spondias dulcis (Amberalla) fruit.

Method: The percentage radical scavenging activity was determined using 2,2-diphenyl-1-picrylhydrazyl(DPPH) radical scavenging assay. The reducing potential of the extracts were determined using Ferric ion reducing assay. The total phenol and total flavonoid contents were obtained from calibrations plots of Gallic acid and Quercetine respectively. The antibacterial assays against Staphylococcus aureus, Escherichia coli and Bacillus subtilis. were carried out using Agar well method.

Results: The antioxidant activity, total flavonoid and phenolic contents of the ethyl acetate, hexane and dichloromethane extracts of the Sri Lankan variety of Spondias dulcis was investigated. Of all extracts the highest activity was shown by the peel extracts of the S.dulcis fruit. The dichloromethane extract of the peel of the fruit showed the maximum activity in DPPH radical scavenging assay (93.40±0.02%) followed by the hexane extract of the peel (91.10±0.01%) compared to butylated hydroxy toluene (BHT) (74.26±0.01%) at the same concentration(127.5 μg ml-1). In the Fe3+ reducing power assay the dichloromethane and ethyl acetate extracts of the peel gave values of 0.35±0.12% and 0.30±0.05% respectively compared to BHT (0.71±0.04%) at the same concentration(3.33 μg ml-1).The highest phenolic content was found in the ethyl acetate extracts of peel (463.68±0.02 mg (GAE/g). The maximum flavonoid content was seen in the hexane extract of the peel (1133.77±0.01mg (QE/g). However, the antibacterial assay of the peel and the seed extracts did not show a significant activity against the bacterial species; Staphylococcus aureus, Escherichia coli and Bacillus subtilis.

Conclusion: Our results show that the non-utilized parts of the S. dulcis fruit contains high amount of antioxidant properties and may have the ability to reduce the risk of oxidative stress and defense against degenerative diseases.