Biological antimicrobial activity

Ivermectin is the catalytic reduction product of avermectin, a macroHde containing a spiroketal ring system. Two other related antibiotics having significantly different stmctural features and biological properties, moxidectin and milbemycin oxime, were more recentiy introduced into the market. Although these compounds have no antimicrobial activity, they are sometimes referred to as antibiotics because they are derived from fermentation products and have very selective toxicities. They have potent activity against worms or helminths and certain ectoparasites such as mites and ticks. 

Cold-pressed essential oils from the peel are some of the most important by-products recovered during the processing of Citrus fruits. The presence of limonene in the aqueous discharges, with its antimicrobial activity [1], decreases the effectiveness of the waste treatment system and increases the time necessary for the biological breakdown of the organic matter produced in the peel oil recovery system [2,3]. Additional recovery of essential oils from waste water would increase industry s returns and reduce the pollution problems associated with the disposal of waste water [4,5]. Several methods for reducing the levels of residual essential oils in the aqueous effluent have been developed over the years [6-11]. 

Biological Activity of Catechins and Proanthocyanidins Other than Antimicrobial Activity... 

Stadler M etal., Lachnumon and lachnumol A, new metabolites with nematicidal and antimicrobial activities from the ascomycete Lachnum papyraceum (Karst.) Karst. I. Producing organism, fermentation, isolation and biological activities,... 

A diversity of biological effects are possessed by benzofused six-membered heterocycles. These range from antimicrobial activity to cardiovascular, CNS, and inflammation-influencing agents. It can be inferred that the ring system itself is primarily a molecular scaffold upon which to assemble the characteristic pharmacophore for the various receptors involved. It is interesting also to note that the range of bioactivities involved differ substantially from those seen with the benzofused five-membered heterocycles described in Chapter 10. 

They also show a wide range of biological activities (13-15). These include antitumor properties (16), antimicrobial activity (17),... 

Quinoline alkaloids from the Rutaceae family (a = L-anthranilic acid) show antimicrobial activity. Moreover, quinoline alkaloids of the Haplophyllum species are known for their powerful biological properties. For example, skim-mianine has sedative, hypothermic and antidiuretic uses. Haplophyllidine is a strong depressant of the CNS. 

Key words alkaloids, antimicrobial activity, anti-parasitic activity, biology, cytotoxicity, DNA, endogenous security mechanism, estrogenic effect, evolution, genes, haemoglobinization, immune system, inhibitor, locoism, narcotics, regulation, stimulator... 

Although all tetracyclines have a similar mechanism of action, they have different chemical structures and are produced by different species of Streptomyces. In addition, structural analogues of these compounds have been synthesized to improve pharmacokinetic properties and antimicrobial activity. While several biological processes in the bacterial cells are modified by the tetracyclines, their primary mode of action is inhibition of protein synthesis. Tetracyclines bind to the SOS ribosome and thereby prevent the binding of aminoacyl transfer RNA (tRNA) to the A site (acceptor site) on the 50S ri-bosomal unit. The tetracyclines affect both eukaryotic and prokaryotic cells but are selectively toxic for bacteria, because they readily penetrate microbial membranes and accumulate in the cytoplasm through an energy-dependent tetracycline transport system that is absent from mammalian cells. 

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