Stabilisation of groundnut oil with gallic acid and leaf extracts of Lonchocarpus sericeus and Lonchocarpus cyanescens

This study evaluated the antioxidant properties of two Lonchocarpus species leaf extracts. It also profiled the phenolic constituents of their active fractions using HPLC. Of the four solvent fractions obtained, ethyl acetate of Lonchocarpus cyanescens (LC) had the highest antioxidant activity (metal chelating ability [IC₅₀], 2,2-diphenyl-1-picrylhydrazyl hydrate [IC₅₀], ferric reducing antioxidant power, total antioxidant capacity, total flavonoid content, and total phenolic content with 0.673 ± 0.061 μg/ml, 0.245 ± 0.007 μg/ml, 177.6 ± 3.7 mg AAE/g, 202.5 ± 3.6 mg AAE/g, 1,323.1 ± 16.7 μg CE/g, and 1244.3 ± μg GAE/g values, respectively). Processing of the groundnut oil was observed to compromise its natural defence system. Gallic acid was the best of the three antioxidant agents used to stabilise groundnut oil followed by the ethyl acetate fraction of LC, and butylated hydroxyanisole (BHA) the least. It can be concluded that gallic acid and ethyl acetate fraction of LC could be used to replace BHA implicated in aetiology of cancer but safety and acceptability of their use in vegetable oil should be investigated.