Synthesis and antibacterial activity of some ester, amides, and hydrazides of 3-carboxyrifamycin S. Relationship between structure and activity of ansamycins.
Esters, amides, and hydrazides of 3-carboxyrifamycin S were synthesized by oxidizing the cyanohydrin of 3-formylrifamycin SV to 3-(cyanocarbonyl)rifamycin S, followed by treatment with alcohols, amines and hydrazines. The in vitro microbiological activity of the derivatives was quite low, especially toward Gram-negative bacteria. This poor activity was not shown to be due to the inadequate inhibiting action on the bacterial DNA-dependent RNA polymerase but to the poor penetration of the compounds through the bacterial cell wall. The microbiological activity was correlated to the chemical properties of the substituent on C3.
Objective: This study aims to compare the physicochemical quality of honey Ziziphus sp (Sider) and Acacia sp (Samar).Material and Methods: physicochemical analyzes were carried out of pH, acidity, electrical conductivity, and humidity of 46 samples of honey of Ziziphus sp and 24 type of Acacia sp consumed in the United Arab Emirates (UAE).Results: The physicochemical analysis confirmed the similar pH values (Ziziphus sp = 4.18