ADVERTISEMENTS:
This article throws light upon the seven commonly used chemicals in Chemotherapy.
1. Arsenic compounds such as arsphenamine, neoarsphenamine etc. against (syphilis) caused by Treponema and sleeping sickness caused by Trypanosome, a protozoal etc.
2. Bismuth compounds such as sodium bismuth thioglycollate, bismuth salicylate etc. in treatment of syphilis.
ADVERTISEMENTS:
3. Antimony compounds such as tartar emetic (antimony potassium tartrate) against Kala-azar (Leishmania), sleeping sickness etc.
4. Sulphonilamides which resemble in structure very much the building blocks of cellular materials act as competitive inhibitors that upset the normal processes of biosynthesis. Many bacteria synthesize their folic acid (coenzyme component) from p-amino benzoic acid whereas mammals and several other organisms used already formed folic acid.
Therefore, when sulphonilamide, structurally similar to p-amino- benzoic acid, is administered to a host suffering from disease caused by a microorganism requiring p-amino benzoic acid for synthesis of folic acid, the organism suffers from de-angement of biosynthetic process as it uses the drug, sulphonilamide in place of p-amino-benzoic acid.
ADVERTISEMENTS:
The host, however, does not use this drug. Sulphonilamides, therefore, have selective toxicity for many bacteria.
5. Quinine from cinchona bark an alkaloid against malaria, emetine from ipecac against amoebic dysentery, malaria, is plant products used in therapy.
6. Dyes such as gentian violet, acid fuchsin etc. can be used as sound disinfectants without causing harm.
7. Antibiotics are products of metabolism of micro-organisms which interfere with metabolism of other micro-organisms causing gradually their death. Some of the more commonly used antibiotics are penicillin from Penicillium, terramycin, streptomycin Chloromycetin etc. from Streptomyces, bacitracin from Bacillus etc.
ADVERTISEMENTS:
The mode of action of antibiotics is varied. Polymyxin from Bacillus polymyxa causes dis-organisation of the cell membrane like any surface-active synthetic chemical mentioned elsewhere. Some act as structural analogues of special metabolites or catalysts and thereby interfere with biosynthesis of cellular components.
For example antimycin from Streptomyces is said to interfere with electron transport at the level of cytochrome b. Chloramphenicol also from Streptomyces is said to inhibit protein synthesis whereas mitomycin C yet another product of Streptomyces is reported to interfere with synthesis of D.N.A.
Penicillin which is more effective on many Gram-positive bacteria is said to act only on growing cells. It interferes with the synthesis of mucocomplex (cell wall component) as a result the cells fail to form cell wall and thus undergo osmotic lysis.
Comments are closed.