Antioxidant potential of silk protein sericin against hydrogen peroxide-induced oxidative stress in skin fibroblasts.

The antioxidant potential of silk protein sericin from the non-mulberry tropical tasar silkworm Antheraea mylitta cocoon has been assessed and compared with that of the mulberry silkworm, Bombyx mori. Skin fibroblast cell line (AH927) challenged with hydrogen peroxide served as the positive control for the experiment. Our results showed that the sericin obtained from tasar cocoons offers protection against oxidative stress and cell viability is restored to that of control on pre-incubation with the sericin. Fibroblasts pre-incubated with non-mulberry sericin had significantly lower levels of catalase; lactate dehydrogenase and malondialdehyde activity when compared to untreated ones. This report indicates that the silk protein sericin from the non-mulberry tropical tasar silkworm, A. mylitta can serve as a valuable antioxidant.

Lysosomal stability in Oreochromis mossambicus (Peters) on exposure to surfactants.

The three commonly used surfactants viz. anionic sodium dodecyl sulfate (SDS), cationic cetyl tri methyl ammonium bromide (CTAB) and non-ionic triton X-100 were toxic even at sub lethal levels (1 ppm for 30 days) to 0. mossambicus. Lysosomal stability index (LSI) was lowest in triton-exposed animals in vitro. In vivo, CTAB was the most toxic. SDS, the anionic surfactant was the least toxic. The possible role of surfactant structure, critical micellar concentration (CMC) and metabolism in influencing the toxicity is discussed and mechanism of action via membrane lipid peroxidation is suggested.

Surfactant-induced lipid peroxidation in a tropical euryhaline teleost Oreochromis mossambicus (Tilapia) adapted to fresh water.

Exposure to anionic (sodium dodecyl sulfate, SDS), cationic (cetyl trimethyl ammonium bromide CTAB) and non ionic (Triton X-100) surfactants at a sub lethal concentration of 1 ppm resulted in severe oxidative stress in the hepatic, renal and cardiac tissues of fresh water adapted Oreochromis mossambicus. Hepatic catalase showed significant increase (P<0.001) in all the surfactant exposed fish, but the renal enzyme was significantly increased only in CTAB dosed fish (P<0.001) and the cardiac enzyme showed significant increase in Triton (P<0.05) and CTAB dosed fish (P<0.001). SOD levels were significantly increased (P<0.001) in hepatic, renal and cardiac tissues of all the surfactant-treated fish. Glutathione reductase also was significantly increased (P<0.001) in the hepatic and renal tissues of surfactant dosed fish except cardiac tissues of CTAB exposed animals. Glutathione levels in the tissues studied were significantly higher in the surfactant treated animals (P<0.001) whereas malondialdehyde levels were significantly elevated only in the hepatic tissues of animals exposed to Triton (P<0.001). The surfactants based on their charge, antioxidant profile and in vivo metabolism may be arranged in the order of decreasing toxicity as CTAB > Triton > SDS. Thus it may be inferred from the present study that the antioxidant defenses and the in vivo metabolism of the surfactants are key factors in deciding the surfactant toxicity.