The free radical scavenging capacity (RSC) of antioxidants from sesame cake extract was studied using the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH(*)()) on a kinetic model. Pure lignans and lignan glycosides isolated from methanolic extract by preparative HPLC were used in the study. To understand the kinetic behavior better and to determine the RSC of sesame antioxidants, the second-order rate constant (k(2)) was calculated for the quenching reaction with [DPPH(*)] radical. The k(2) values of the sesame antioxidants were compared with those of butylated hydroxytoluene and alpha-tocopherol. The k(2) values for sesamol, sesamol dimer, sesamin, sesamolin, sesaminol triglucoside, and sesaminol diglucoside were 4.00 x 10(-)(5), 0.50 x 10(-)(5), 0.36 x 10(-)(5), 0.13 x 10(-)(5), 0.33 x 10(-)(5), and 0.08 x 10(-)(5) microM(-)(1) s(-)(1), respectively.

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Syzygium cumini, widely known as Jamun, is a tropical tree that yields purple ovoid fleshy fruit. Its seed has traditionally been used in India for the treatment of diabetes. Based on the available ethno-pharmacological knowledge, further studies were extended to understand the chemical composition and antioxidant activities of three anatomically distinct parts of fruit: the pulp, kernel and seed coat. Fruit parts, their corresponding ethanol extracts and residues were evaluated for chemical composition. The alcoholic extract was evaluated for its antioxidant potential against DPPH(•), OH(•), O(2) (•-) and lipid peroxidation. The whole fruit consisted of 666.0 ± 111.0 g kg(-1) pulp, 290.0 ± 40.0 g kg(-1) kernel and 50.0 ± 15.0 g kg(-1) seed coat. Fresh pulp was rich in carbohydrates, protein and minerals. Total fatty matter was not significant in all three parts of fruit. Detailed mineral analysis showed calcium was abundant in all fruit parts and extracts. Total phenolics, anthocyanins and flavonoid contents of pulp were 3.9 ± 0.5, 1.34 ± 0.2 and 0.07 ± 0.04 g kg(-1), respectively. Kernel and seed coat contained 9.0 ± 0.7 and 8.1 ± 0.8 g kg(-1) total phenolics respectively. Jamun pulp ethanol extract (PEE), kernel ethanol extract (KEE) and seed coat ethanol extract (SCEE) showed a high degree of phenolic enrichment. DPPH radical scavenging activity of the samples and standards in descending order was: gallic acid> quercetin > Trolox > KEE > BHT > SCEE > PEE. Superoxide radical scavenging activity (IC(50)) of KEE was six times higher (85.0 ± 5.0 µg mL(-1)) compared to Trolox (540.0 ± 5.0 µg mL(-1)) and three times compared to catechin (296.0 ± 11.0 µg mL(-1)). Hydroxyl radical scavenging activity (IC(50)) of KEE was 151.0 ± 5.0 µg mL(-1) which was comparable with catechin (188.0 ± 6.0 µg mL(-1)). Inhibition of lipid peroxidation of the extracts was also studied and their activity against peroxide radicals were lower than that of standard compounds (BHT, 79.0 ± 4.0 µg mL(-1); quercetin, 166.0 ± 13.0 µg mL(-1); Trolox, 175.0 ± 4.0 µg mL(-1); PEE, 342.0 ± 17.0 µg mL(-1); KEE, 202.0 ± 13.0 µg mL(-1) and SCEE, 268.0 ± 13.0 µg mL(-1). Copyright © 2007 Society of Chemical Industry.

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Sea buckthorn berries from Hippophae rhamnoides, H. tibetana, and H. salicifolia were collected from the cold deserts of the Himalayas (Lahaul, Ladakh, and Spiti; India) and characterized in terms of the FA, carotenoid, tocopherol, and tocotrienol composition in their pulp oil. These varied from species to species. Total carotenoids ranged from 692 to 3420 mg/kg in pulp oils of fresh berries, and total tocols, from 666 to 1788 mg/kg. Hippophae salicifolia berries contained substantially lower amounts of pulp oil, with lower levels of carotenoids and tocopherols. There was little difference in the proportion of individual tocols in pulp among the three species. α-Tocopherol alone constituted 40-60% of total pulp tocols in berries. Pulp oils had palmitoleic acid (32-53%) as the most abundant FA followed by palmitic (25-35%), oleic (8-26%), linoleic (5-16%), and linolenic (0.6-2.6%) acids, with the highest deviation observed in the proportion of palmitoleic acid in these berries. Hippophae rhamnoides and H. tibetana contained the highest amount of the lipophilic carotenoids and tocols. Hippophae salicifolia berries had higher amounts of lipophobic constituents such as vitamin C and flavonols.

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