Kapila N. Seneviratne

Antioxidant activities of the phenolic extracts of seed oils and seed hulls of five plant species.

Antioxidant activities of the phenolic extracts of seed oils and seed hulls of five plant species were compared with those of butylated hydroxyl toluene (BHT) solutions at comparable phenolic concentrations in order to understand the phenolic dependence of the antioxidant activity and to evaluate the potentials of these phenolic extracts as alternatives for synthetic antioxidants. For this purpose, colorimetrically determined total phenol contents of the plant extracts were adjusted to known concentrations by suitable dilutions and the solutions of BHT with comparable concentrations were prepared by diluting a stock solution. The correlations of the total phenol contents and o-diphenol contents with the antioxidant activities of the phenolic extracts were also tested. Antioxidant activities of the phenolic extracts from different plants varied even at equal total phenol concentrations. o-Diphenol contents showed better correlations with the antioxidant activities than total phenol contents. A clear idea about the antioxidant potentials and the dependence of antioxidant activities on the quality and the quantity of phenolic substances can be obtained by comparison of the antioxidant activities of different phenolic extracts at equal total phenol concentrations.

Effect of three edible oils on the intestinal absorption of caffeic acid: An in vivo and in vitro study

Polyphenolic antioxidants are mainly absorbed through passive paracellular permeation regulated by tight junctions. Some fatty acids are known to modulate tight junctions. Fatty acids resulting from the digestion of edible oils may improve the absorption of polyphenolic antioxidants. Therefore, we explored the effect of three edible oils on the intestinal absorption of caffeic acid. Rats were fed with soybean oil and caffeic acid dissolved in distilled water. Caffeic acid contents in the plasma collected up to 1 hr were quantified. The experiment was repeated with coconut oil and olive oil. Component fatty acids of the oils were individually tested in vitro for their effect on permeability of caffeic acid using Caco-2 cell monolayers. Highest absorption of caffeic acid was observed in animals fed with coconut oil. In vitro transport percentages of caffeic acid in 2.5 mmol/L solutions of fatty acids were 22.01±0.12 (lauric), 15.30 ± 0.25 (myristic acid), 13.59 ± 0.35 (linoleic acid), 3.70 ± 0.09 (oleic acid) and 0.10–2.0 (all other fatty acids). Lauric acid and myristic acid are the two major fatty acids present in coconut oil. Therefore, these fatty acids may contribute to the higher absorption of caffeic acid in the presence of coconut oil.

Comparison of the basic nutritional characteristics of the first extract and second extract of coconut milk

Coconut milk is the aqueous extract of grated coconut kernel. In traditional cooking in the South Asian region, grated coconut kernel is hand-pressed with water to obtain a viscous white coconut milk known as first extract (FE). The coconut kernel remaining after the first extraction is further extracted with a fresh portion of water to obtain second extract (SE), which is less viscous. In the present study, the nutritional composition and the effect of FE and SE on the serum lipid profiles was evaluated. The results indicate that the lipid and protein contents of SE is equivalent to a 3 fold diluted solution of FE. However, the levels of sugars and phenolic contents of the SE cannot be achieved by the same fold ofdilution of FE. There is no significant difference (p < 0.05)in the lipid profiles of the rats fed with SE after 21 days.