Enzymatic and Synthetic Routes of Castor Oil Epoxidation.

Epoxidation of castor oil in synthetic and enzymatic routes was carried out in order to promote a system with less environmental impact. The epoxidation reactions of castor oil compounds upon addition of lipase enzyme with and without acrylic immobilization and with reaction times of 24 and 6 h, as well as the synthetic compounds upon addition of Amberlite resin and formic acid, were investigated using Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance in hydrogen molecules (1H-NMR). The analysis indicated that the enzymatic reactions (6 h) and synthetic reactions provided a conversion from 50 to 96% and epoxidation from 25 to 48%, resulting from peak stretching and signal disintegration in the hydroxyl region due to the appearance of H2O in the interaction of peracid with catalyst. In systems without toluene, a dehydration event with a peak absorbance of 0.02 AU, indicating a possible vinyl group at 2355 cm-1 in enzymatic reactions without acrylic immobilization, was observed and resulted in a selectivity of 2%. In the absence of a solid catalyst, an unsaturation conversion of castor oil above 90% was achieved; however, this catalyst is necessary for the epoxidation to take place, whereas the lipase enzyme becomes able of epoxidizing and dehydrating the castor oil upon changing the time or reaction system. The conversation from 28 to 48% of solid catalysts (Amberlite and lipase enzyme) displays their importance to the instauration conversion of castor oil into oxirane rings.

Antioxidant activity of co-products from guava, mango and barbados cherry produced in the Brazilian northeast.

Co-products from the juice processing of guava (CG), mango (CM) and barbados cherry (CB) were investigated with a view to their exploitation as a potential source of natural antioxidants. The ethanolic extracts were analyzed for total extractable phenolic content (TEP), DPPH radical scavenging activity (RSA-DPPH), ferric reducing antioxidant power (FRAP) and antioxidant activity in relation to the ß-carotene/ linoleic acid system. The TEP levels in the CG, CM and CB extracts were (24.15 ± 1.59), (44.18 ± 1.73) and (49.21 ± 3.70) mg GAE/g extract, respectively. The CM extract showed higher DPPH, FRAP and antioxidant activity in the ß-carotene/linoleic acid system. The data revealed a positive linear correlation between TEP, RSA-DPPH and FRAP (r² = 0.85-0.98); however, the ß-carotene/linoleic acid system (r² = 0.01-0.26) shows low correlation with the TEP levels and other assessment systems. The results suggest that co-products generated from the juice processing of the studied fruit have promising use as a natural source of antioxidants.

Gastroprotective effect of lupeol on ethanol-induced gastric damage and the underlying mechanism.

The effect of lupeol, a natural pentacyclic triterpene on ethanol-induced gastric damage in mice was evaluated. The gastroprotection was assessed by determination of changes in mean gastric lesion area, quantification of mucosal non-protein sulfhydryls (NP-SH), and characterized using drugs that influence the endogenous prostaglandins, alpha(2)-adrenoceptors, nitric oxide, K(ATP)-channels, and intracellular calcium. Orally administered lupeol (3, 10, and 30 mg/kg) significantly and dose-dependently attenuated the ethanol-induced gastric damage by 39-69%, whereas the positive control N-acetylcysteine (NAC, 300 mg/kg, i.p.) afforded 32% protection. Both lupeol and NAC restored the NP-SH depleted by ethanol but the lupeol effect was only marginal. Lupeol gastroprotection was attenuated by indomethacin and L-NAME, the respective COX and NO-synthase inhibitors and was weakly sensitive to alpha(2)-adrenergic antagonist yohimbine and K(ATP)-channel blocker glibenclamide, but more profoundly to calcium blocker verapamil. These pharmacological effects of lupeol may synergistically contribute to alleviating the ethanol-associated gastric damage, which is multifactorial.

Gastroprotective effect of mangiferin, a xanthonoid from Mangifera indica, against gastric injury induced by ethanol and indomethacin in rodents.

In search of novel gastroprotective agents, mangiferin, a naturally occurring glucosylxanthone from Mangifera indica L. (Anacardiaceae), was evaluated in mice on gastric injury induced by ethanol and indomethacin. The effects of mangiferin on gastric mucosal damage were assessed by determination of changes in mean gastric lesion area or ulcer score in mice and on gastric secretory volume and total acidity in 4-h pylorus-ligated rats. Mangiferin (3, 10 and 30 mg/kg, P. O.) significantly attenuated the gastric damage induced by ethanol by 30, 35, and 63 %, and of indomethacin by 22, 23 and 57 %, respectively. N-Acetylcysteine (750 mg/kg, I. P.) and lansoprazole (30 mg/kg, P. O.) used as positive controls in these ulcerogenic models resulted in 50 % and 76 % suppression of gastric injury, respectively. In 4-h pylorus-ligated rats, intraduodenally applied mangiferin (30 mg/kg) caused significant diminutions in gastric secretory volume and total acidity. In addition, like N-acetylcysteine, a donor of sulfhydryls, mangiferin effectively prevented the ethanol-associated depletion of gastric mucosal non-protein sulfhydryl content in mice, suggesting an antioxidant action. These findings provide evidence that mangiferin affords gastroprotection against gastric injury induced by ethanol and indomethacin most possibly through the antisecretory and antioxidant mechanisms of action.