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Antibiotics: The Battle with the Microbes
Published in Richard J. Sundberg, The Chemical Century, 2017
The structures of isoniazid and PAS are remarkably simple. There are two other active compounds, pyrazinamide and ethionamide, that resemble isoniazid in structure. Their mechanism of action gives us a glimpse into the relationship between structure and biological activity. All three compounds are “pro-drugs,” that is they are metabolically transformed by the target organism. The case of isoniazid is best understood. It is oxidized by a mycobacterial catalase-peroxidase to the isonicotinoyl radical.16 The radical then forms a series of adducts with NAD+ and NADP+. Some of the adducts are powerful inhibitors of one of the key enzymes in the formation of the protective coat of the tuberculosis bacilli.17 Ethionamide is metabolized to 2-ethyl-4-hydroxymethylpyridine and a second, as yet unidentified metabolite. Only the latter material is found inside the bacterial cell. Ethionamide and pyrazineamide are also activated by metabolism, but their precise mechanism of action remains uncertain. Cycloserine interferes with cell wall formation by M. tuberculosis. Scheme 12.3 gives the structures of these drugs.
Production of Amino Acids by Fermentation
Published in Nduka Okafor, Benedict C. Okeke, Modern Industrial Microbiology and Biotechnology, 2017
Nduka Okafor, Benedict C. Okeke
A derivative of serine, cycloserine, is an antibiotic produced by a streptomycete and used for the treatment of tuberculosis.Use as industrial synthetic raw materials:Surface-active agents: A surface-active agent has a water soluble (hydrophilic) as well as a water-repellent (hydrophobic) end. The hydrophilic end is dissolved in the water and consequently, the surface tension of the water is lowered. Surface active agents can be prepared from amino acids by introducing long-chain lipophilic groups to one of the two hydrophilic groups (–COOH, or –NH2) of amino acids. The resulting surface-active agents are either cationic (positive charge) or anionic (negative charge). As they lower the surface tension like soap, they foam just like soap. Some are even more effective than soap as cleansing agents, and some also have a strong bacteriostatic action. Thus, sodium lauryl sarcosinate is used in toothpaste and shampoo because it has a bacteriocidal as well as foaming action. These derivatives are also used as fungicides and pesticides.Production of polymers from amino acids: Polymers derived from amino acids are used in making synthetic leather, fire-resistant fabrics and anti-static materials.Use as cosmetics: Amino acids exhibit a buffering action that help maintain normal skin function by regulating pH and a protective action against bacteria. Detergents (surface active agents) derived from amino acids are less irritating than soaps because the pH of 5.5–6.0 is closer to that of the skin, whereas soap is slightly alkaline. Examples for the addition of amino acids to shampoos are anti-dandruff shampoos containing cysteine and the employment of thioglycolic as a reducing agent for the cold waving of hair.
Approaches for designing and delivering solid lipid nanoparticles of distinct antitubercular drugs
Published in Journal of Biomaterials Science, Polymer Edition, 2023
Mallikarjun Vasam, Rama Krishna Goulikar
Conventional therapeutic systems came into existence for the treatment of TB with anti-tubercular drugs. The five main types of drugs used in chemotherapy for tuberculosis are: First-line anti-tubercular drugs (Isoniazid, Rifampicin, Rifabutin, Ethambutol, and Pyrazinamide) work effectively against tuberculosis, while second-line anti-tubercular drugs (Ethionamide, Cycloserine) work well when first-line drugs fail due to drug resistance [4, 9]. In tuberculosis treatment, patients need to take four oral antibiotics every day for six to nine months. Generally, TB is treated in two steps: during the initial phase, most of the live bacilli are killed by treatment with four first-line antibiotics for two months. The second phase is called the continuation phase, in which rifampicin and isoniazid are used daily or three times a week for 4–6 months to kill the bacteria that survived the initiation phase [10], which has complicated long-term conventional treatment has lethal side effects of anti-tubercular drugs may cause poor patients’ compliance, which can lead to the growth of drug-resistant strains.