Variations in the composition, cytoprotective and anti-inflammatory effects of natural polyphenols of edible oils extracted from fresh and dried coconut testa

Abstract

Coconut is a commonly consumed palm variety in various south Asian countries including India and Sri Lanka. The important products obtained from the coconut palm are tender water, edible oils from coconut kernel and milk. The coconut kernel-derived edible oils are widely recognized as functional foods and are reported to be beneficial in various non-communicable diseases. However, the coconut testa oil (CTO) extracted from the testa of coconut is a less explored product and has significant nutritional and pharmacological importance. In this study, the phenolic component characterization, anti-radical potentials and subsequent alleviating effect of polyphenols isolated from CTO prepared from fresh (CTOF) and dried (CTOD) coconut testa against free radical-induced cell death were analyzed. The total polyphenols and flavonoids content of CTOD was found to be higher than the CTOF (p < 0.05); further, the phenolic profiling indicated the possible flavonoids present in the CTOD. In cultured normal intestinal epithelial cells (IEC-6), the CTOD had a significantly higher protective effect against hydrogen peroxide-induced damages than the CTOF at their similar doses. The pre-treatment increased the intra-cellular antioxidant levels, enzyme activities and subsequently reducing cellular oxidized lipid content. Further, the anti-inflammatory effect of CTOD and CTOF was evaluated against lipopolysaccharide-stimulated macrophages; the CTOD was efficient in reducing the cytokine release induced by the LPS and nitric oxide radical production inhibition compared to the CTOF. Overall, the present study identifies that the CTO prepared from dried coconut testa contain higher polyphenols and also have significantly higher antioxidant and anti-inflammatory effects.