1997a) show maximum activity towards p-NP butyrate, good activity towards p-NP caproate (C6 acyl group
) and p-NP caprylate (C8 acyl group
) and poor activity towards p-NP esters composed of long carbon chain fatty acids (C12 - C18).
In the same time, it was noticed the importance of the presence of a hydroxyl group at C-8, as in penicillosides F and G, which are still active inspite of their less lipophilicity than pencillosides D and E with only one acyl group
(benzoyl) which may be compensated with the prsence of a hydroxyl group at C-8.
Due to substitution of acyl group
instead of OH group in 1, 10 dihydoxyanthracen-2-O-acetate (1) and Anthracen-1, 2-10-tri-O acetate (2), the affinity of compound decreases to scavenge the free radicals generated by DPPH.
The "family" of acylcarnitines analyzed by MS/MS include fatty acyl groups
for saturated and unsaturated species ranging from the 2-carbon acetylcarnitine (C2) through the 20-carbon aliphatic groups (27).
Disubstituted compounds were obtained from the reactions of 4 with methyl iodide, benzyl chloride, acetyl chloride, benzoyl chloride, 4-methoxybenzoyl chloride, 2-chlorobenzoyl chloride and propanoyl chloride in acetone in the presence of K2CO3 via replacement of all the oxime protons with alkyl and acyl groups
. Pure and defined products could not be obtained from the reaction of 4 with chloroacetyl chloride and 2-bromoethanol.
L-carnitine transports fatty acids into the mitochondria for oxidation and removes excess acyl groups
. It also increases the rate of mitochondrial oxidative phosphorylation, which tends to decline with age.
Fatty acid ester are hydrolyzed by esterases and lipases, but esterases hydrolyze the ester bonds of the water's soluble fatty acid ester with short-chain acyl groups
([less than or equal to] [C.sub.8]), whereas lipases hydrolyze long-chain acyl groups
([greater than or equal to] [C.sub.10]) (WINKLER; STUCKMANN, 1979).The same authors did not detect any activity with p-nitrophenyl caprylate ([C.sub.8]), p-nitrophenyl laurate ([C.sub.12]) and p-nitrophenyl palmitate as substrate of esterase.
One possible explanation for this phenomenon is that the HA gellan needs higher temperature for the conformational order than LA gellan (Morris et al., 1996), this is probably due to the presence of the acyl groups
present in the HA gellan, preventing the association between the biopolymer chains (Chandrasekaran and Thailambal, 1990).
Carnitine prevents accumulation of acetyl and acyl groups
which inhibit the [beta]-oxidation.
Similarly as in the very low-esterified MERO-CMC derivative (23), only the carbon peak substituted by acyl groups
(C6e) at 65.26 ppm was distinguished from the noise.