ANTIMICROBIAL SCREENING OF SOME NOVEL SUBSTITUTED BENZIMIDAZOLE DERIVATIVES

About Author
Ramesh Dhani 
Department of Pharmaceutical Chemistry
JNTUA-OTRI, Anantapur, India.
*E-mail: [email protected]

ABSTRACT:
Heterocyclic chemistry comprises at least half of all organic chemistry research worldwide. In particular, heterocyclic structures form the basis of many pharmaceutical, agrochemical and veterinary products. The benzimidazole contains a phenyl ring fused to an imidazole ring, as indicated in the structure of benzimidazole. Diversity of biological response profile has attracted considerable interest of several researchers across the globe to explore this skeleton for its assorted therapeutic significance. By using novel synthetic methods new benzimidazole derivatives were synthesized and further Melting points were determined by using Precision melting point apparatus in open capillaries and are uncorrected. The purity of the compounds was checked by TLC on silica gel G plates using n-Hexane, ethyl acetate (1:3) and methanol: chloroform (1:9) solvent system. The synthesized benzimidazole derivatives were characterized by IR, ¹H NMR spectral analysis. Benzimidazole is a lead nucleus for future developments to get effective compounds.
Key words: Benzimidazole, Acetohydrazide, Imidazole, n-Hexane, Ethyl acetate, Chloroform, Methanol
Introduction:
Substituted benzimidazole have received considerable attention during last few decades as they are endowed with variety of biological activities and have wide range of therapeutic  properties. A literature survey indicates that benzimidazole derivatives possess different pharmacological and biological activities, of which the most potent is, anti-microbial activity, anti-ulcer. We thought to synthesize some novel benzimidazole moiety incorporating with different aromatic and hetero cyclic aldehyde moiety. The conventional methodology was adopted to synthesize the titled compounds.
Heterocyclic chemistry comprises at least half of all organic chemistry research worldwide. In particular, heterocyclic structures form the basis of many pharmaceutical, agrochemical and veterinary products. The benzimidazole contains a phenyl ring fused to an imidazole ring, as indicated in the structure of benzimidazole. The important group of substances has found practical application in a number of fields. Recently in benzimidazole chemistry has been revived somewhat by the discovery that the 5,6-dimethyl benzimidazole moiety is a part of the chemical structure of vitamin B12.
Materials and Methods:
Biological Evaluation:
During the ninethteeth century, the French scientist Louis Paster and German  thiysiciaan demonstrated the roll of bacteria as pathogens the discovery of compound produce by bacteria and fungi have shown their the lethal effect to other bacteria led to development of antibioticsaterials and Methods
Type of Bacteria
Scientist use various system for classifying bacteria based on different, shapes, dependence on oxygen and by staining techniques
1. Aerobic and anaerobic Bacteria
Bacteria can be classified according to need of the oxygen to survive. As aerobic bacteria require oxygen and anaerobic do not requires oxygen to survive
eg. Bacillus Anthrax aerobics, Clostridium titani anarobics⁵.
2. Autotrophic and Heterotrophic Bacteria
All bacteria require carbon for growth and reproduction bacteria called autotrophes get their carbon from carbondioxide and heterotrophes from organic nutrient⁶.
3. Gram Positive and Gram Negative
Bacteria can be classify by the Gram staining techniques which is identified as Gram positive and Gram Negative after staining they stains purple and pink respectively⁷.
Eg. S. Aureus(Gram + ve), E.coli(gram -ve).
Fungi
Fungi are heterotropic organism, they don’t form embryos. Fungi are eukaryotic chemoorganiotropic organism that has no chlorophyll. fungi posses rigid cell wall containing chitin, manoproteins, glucans, and polysaccharides.They divide asexually and sexually or  by both  process. they may be uni or multi cellular, fungi are generally aerobic.
Anti Fungal Agents
Fungi cause a range of illnesses (mycoses) ranging from the chronic to the serious. These mycoses can manifest themselves in a variety of ways. Infections can be superficial, that is situated at or close to the surface of the skin or systemic which means they can affect the body as a whole, rather than individual parts or organs. Diseases such as athlete’s foot (Tinea pedis), ‘jock’ itch (Tinea cruris), Tinea manus (infection of the hand), thrush (oral and vaginal), and onchomycosis (affecting the nails)are examples of superficial infections caused by the dermatophytes from the Trichyphyton microsporum, C. albicans and Epidermophyton species. ‘Ringworm’ (Tinea corporis) is used as a general term for a fungal infection of the skin, in particular those of the scalp and feet. These infections are contagious, and cause intense itching. One or more of these organisms causes them. An important aspect to consider when developing treatments for mycoses is that fungi are eukaryotic. That is to say they have a nucleus within the cell containing the all-important nucleic acids. In very simplistic terms this means that some of the biochemistry regulating fungi turns out to be very similar to animal cells. They are therefore unlike the prokaryotic bacteria, which do not have a cell nucleus. This can in turn pose potential problems with toxicity. For many enzymes in a fungus there are related enzymes performing the same transformations in the human cell. If we want to target one of these enzymes with drug then absolute potency may not be as important as the difference in potency of our drug towards the different forms of the enzyme.
Results & Discussions:
Benzimidazoles have been reported for number of pharmacological activities and some molecules have shown significant activities and some compounds shows moderate and good activities.Here we have synthesized novel benzimidazole analogues and screened them for their anti-bacterial activities and the results are as follows. The synthesized all benzimidazole derivatives were screened for anti bacterial activity using DMF as a solvent against the organisms, S.aureus and E.coli. Antifungal activity using Candida albicans. By disc diffusion method on nutrient agar media. The standard drug used was Ampicillin for antibacterial and Ketoconazole as standard for antifungal activity.The antimicrobial screening results presented on above table reveals that compounds COM-3, COM -5, exhibited poor activity at 50 μg/ml, but at 100 μg/ml they have shown moderate activity against S.aureus, and moderate activity against E.coli. The compounds COM -1, COM -2, COM -4, have shown the poor activity against E. Coli and S.Aureus at 50mg. but the same compounds at 100 μg/ml against same organism have shown moderate activity. COM-5 have shown the very good activity against S.aureus at 100 μg/ml when compared with the standard drug Ampicillin. The Compounds were screened for the anti-fungal activity against Candida albicans the compounds COM -2, COM -3, COM -5, Showed highest degree of inhibition at 250 µg/ml and 500 µg/ml against C.albicans when compared with the standard drug Ketoconazole. However the activities shown by all the compounds tested were less than that of the standard. The compounds COM -1, COM -3, COM -5, have shown good anti bacterial activity due to the presence of electron donating group OCH3, N(CH3)2 , CH3 group which is attached at 4 fourth position of the phenyl ring system.The anti fungal activity shown that HC-2, HC-3, HC-5, have shown good antifungal activity it also may be due to the presence of electron donating group OCH3, N(CH3)2 , CH3 group which is attached at 4 fourth position of the phenyl ring system. However the activities shown by all the compounds tested were less than that of the standard.