A method to determine the absolute configuration of 2,3-epoxy-2-methylbutanoate ester residues in natural products is presented, based on (i) the reduction of the ester function to yield a 2-methyl-1,2-butanediol, (ii) esterification of the obtained primary alcohol with either (R)-(+)- or (S)-(-)-Mosher's acid to afford the corresponding Mosher's ester, and (iii) 1H-NMR spectral comparison of t...

The essential oils of the aerial parts of Ocimum basilicum Linn.var. pilosum (Willd.) Benth., an endemic medicinal plant growing in China, was obtained by hydrodistillation and analysed by GC-MS. Fifteen compounds, representing 74.19% of the total oil were identified. The main components were as follows: linalool (29.68%), (Z)-cinnamic acid methyl ester (21.49%), cyclohexene (4.41%), alpha- cad...

This study analyzed the fatty acids composition and their profile qualitatively quantitatively of nine abundant macroalgal specimens collecting from Egyptian coasts. GC mass analysis identified 23 types, including 13 saturated (SFA) 10 monounsaturated (MUSFA). SFA dominated with 78%, while MUFAs had 22%, UFAs were negligible at 0.01%. MUSFA oleic acid (omega-9) was present in all species except...

We have performed a series of first-principles electronic structure calculations to examine the reaction pathways and the corresponding free energy barriers for the ester hydrolysis of protonated cocaine in its chair and boat conformations. The calculated free energy barriers for the benzoyl ester hydrolysis of protonated chair cocaine are close to the corresponding barriers calculated for the ...

The effect of nitric oxide synthase (NOS) inhibitors on the brain production of endogenous glutamate receptor antagonist, kynurenic acid, was estimated in vitro. Under standard incubation conditions N(G)-nitro-L-arginine, but not N(G)-nitro-L-arginine methyl ester, up to 5 mM, or 7-nitroindazole, up to 100 microM, inhibited de novo synthesis of kynurenic acid in cortical slices. However, during...

Vegetable oils and fats in comparison with diesel fuel have high viscosity, by transesterification method the viscosity of oil can be decreased. Transesterification of triglyceride with alcohol is one of the methods for production of biodiesel. In this study sunflower oil, methanol and ethanol, with molar ratio of (1:3, 1:4, 1:6, 1:8) and temperature (40, 50, 60 º C) were dependent parameters e...