Amphotericin B (AmB) has been shown to have both immunosuppressive and -enhancing effects, making its precise nature of action enigmatic. In the present study, we found that AmB inhibited concanavalin A (Con A)-induced T cell proliferation if added within first 30 min of stimulation, after which inhibition began to diminish rapidly. However, AmB did not inhibit T-cell proliferation induced by a combination of PMA and ionomycin. AmB inhibition of Con A-induced proliferation was completely overcome by cyclooxygenase inhibitor ibuprofen ([alpha-methyl-4-(isobutyl)phenylacetic acid]) and H(2)O(2) scavenger catalase. In fact, in the presence of ibuprofen and catalase, AmB enhanced, instead of suppressing, Con A-induced proliferation in a dose-dependent way. The effect of catalase was limited to the removal of extracellular H(2)O(2) only, as the enzyme did not enter the cells. AmB stimulated H(2)O(2) production by macrophages, but not by a lymphocyte population, which was inhibited by ibuprofen. Our T-cell preparation contained about 3% macrophages, and AmB inhibition of proliferation was further pronounced by increasing the macrophage number by as little as 1%. Finally, AmB inhibition of Con A-induced T-cell proliferation was completely overcome by 2-mercaptoethanol. On the basis of these results, we suggest that AmB stimulates H(2)O(2) production by macrophages through the activation of the cyclooxygenase pathway of arachidonate metabolism. H(2)O(2) then inhibits Con A-induced T-cell proliferation by interfering with an early step of the T-cell receptor signaling pathway through the oxidative modification of some signaling proteins. Our results also show that AmB enhances T-cell proliferation, which can be seen only after blocking its inhibitory effect.
Medicinal and healing proper- ties of herbs are closely related to their chemical components which are classified into some major groups like alkaloids, phenols, terpenoids, steroids, saponins, tannins etc. and getting these chemicals out into the herbal remedy depends upon the solubility of these compounds in various solvents. In the present study aqueous ethanol diethyl ether acetone and methanol extracts of Barleria prionitis leaves were investigated for phyto-chemical and anti-microbial activity. The micro-organisms employed were Staphylococcus aureus Escherichia coli,and Pseudomonas, aeruginosa and Bacillus subtilis. The susceptibility of bacterial strains against the all extracts was determined using the disk diffusion method. The findings showed that potential antibacterial properties of the extracts against the organisms tested. The most susceptible microorganisms were S. aureus, while the least susceptible was E. coli. Aqueous extracts had no activity against the test bacteria the leaves of plant were found abundant with biologically active phytochemicals.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.