No abstract

The effect of tobamovirus (TMV and ToMV) infection on changes in antioxidant enzymes, endogenous salicylic acid, endogenous hydrogen peroxide, lipid peroxidation and protein oxidation was studied in compatible (tomato and bell pepper) and incompatible hosts (Nicotiana glutinosa and Nicotiana tabacum cv. xanthi). A time course study of antioxidant enzymes such as peroxidase and catalase was studied in both interactions. Along with these studies, a time course change of endogenous hydrogen peroxide in both compatible and incompatible hosts against tobamoviruses was carried out spectrophotometrically. Histochemical changes in hydrogen peroxide were studied by using Starch-potassium iodide (KI) method. The endogenous levels of salicylic acid were quantified at 24 hours post inoculation (hpi). The effect of tobamoviruses on the lipid peroxidation levels along with protein oxidation was also studied at 24 hpi. The results showed increased peroxidase, salicylic acid, lipid peroxidation, protein oxidation, hydrogen peroxide and decreased catalase in incompatible host-tobamovirus interaction in comparison to compatible hosts. In incompatible hosts, more numbers of cells showed hydrogen peroxide accumulation at 24 hpi. These results suggested the involvement of antioxidant enzymes, salicylic acid, hydrogen peroxide and oxidative stress in incompatible host defense against tobamoviruses. As a consequence of tobamovirus infection, an oxidative stress, indicated by the increase in lipid peroxidation was observed in incompatible interaction. Slight changes in enzymes, lipid peroxidation and hydrogen peroxide in incompatible hosts indicate that these changes have roles in susceptible hosts.

Effect of isolated astaxanthin (ASX) and astaxanthin esters (ASXEs) from green microalga-Haematococcus pluvialis on hepatotoxicity and antioxidant activity against carbon tetrachloride (CCl4) induced toxicity in rats was compared with synthetic astaxanthin (SASX). ASX, ASXEs, and SASX, all dissolved in olive oil, fed to rats with 100 and 250 μg/kg b.w for 14 days. They were evaluated for their hepatoprotective and antioxidant activity by measuring appropriate enzymes. Among the treated groups, the SGPT, SGOT and ALP levels were decreased by 2, 2.4, and 1.5 fold in ASXEs treated group at 250 μg/Kg b.w. when compared to toxin group. Further, antioxidant enzymes catalase, glutathione, superoxide dismutase and lipid peroxidase levels were estimated in treated groups, their levels were reduced by 30-50 % in the toxin group, however these levels restored by 136.95 and 238.48 % in ASXEs treated group at 250 μg/kg. The lipid peroxidation was restored by 5.2 and 2.8 fold in ASXEs and ASX treated groups at 250 μg/kg. The total protein, albumin and bilirubin contents were decreased in toxin group, whereas normalized in ASXEs treated group. These results indicates that ASX and ASXEs have better hepatoprotection and antioxidant activity, therefore can be used in pharmaceutical and nutraceutical applications and also extended to use as food colorant.