In vitro evaluation of antioxidant properties of Cocos nucifera Linn. water

Tender Cocos nucifera L. (Palmacea) water (CW), variety Chandrasankara, was tested for its ability to scavenge free radicals, inhibit lipid peroxidation and protect hemoglobin from nitrite-induced oxidation. Fresh sample of CW scavenged 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azino-bis(3-ethylbenz-thiazoline-6-sulfonic acid) (ABTS) and superoxide radicals but promoted the production of hydroxyl radicals and increased lipid peroxidation. The activity was most significant for fresh samples of CW and diminished significantly upon heat, acid or alkali treatment or dialysis. Maturity of coconut drastically decreased the scavenging ability of CW against DPPH, ABTS and superoxide radicals. CW protected hemoglobin from nitrite-induced oxidation to methemoglobin when added before the autocatalytic stage of the oxidation. Acid, alkali or heat treated or dialyzed CW showed a decreased ability in protecting hemoglobin from oxidation. The scavenging ability and protection of hemoglobin from oxidation may be partly attributed to the ascorbic acid, which is an important constituent of CW. As CW is a rich source of vitamins, amino acids and enzymes, etc., more than one active principle maybe involved.