Antimicrobial

Antimicrobial’s efficiency is critically compromised by the emergence and spread of antimicrobial resistance, yet they are valuable therapeutics. Investigations were carried to test and analyze the antimicrobial susceptibility of E. coli isolates from Ajmer poultry farm. 24 tissue samples containing 6 liver, 12 small intestine, and 6 large intestine samples were processed for isolation and identification and characterization of pathogenic E. coli from 12 fowls of 4 selected poultry farms of Ajmer suspected for colibacillosis and subjected to detailed bacteriological and biochemical examination. 24 E. coli isolates were isolated following standard procedures. E. coli isolates found to be highly resistant to some of the classical drugs like tetracycline, amoxy clav, carbenicillin, cotrimoxazole and cefopodoxime and found to be highly sensitive (100%) to the remaining drugs, which is disclosed by antibiogram study. The most ineffective antibiotic drug was found to be tetracycline for all the E. coli isolates, as all these microbes were found 100% resistant to it. Multiple resistance to at least 2 to 4 antibiotics were observed in all the 24 isolates. 50% of the isolates were resistant to at least 4 antibiotics and 75% to at least 3 antibiotics and 25% to at least 2 antibiotics. Results from this study revealed the high prevalence rate of multidrug resistant E. coli isolates. It may suggest that the high resistance of E. coli to antibiotics constitutes a threat not only to poultry industry of Ajmer but also possesses a serious threat to public and animal health with adverse economic implications.

In the last two decades, antibiotic resistance has become a severe problem worldwide. This has lead to the search for new, safe and effective antimicrobial agents from alternative natural resources like plant products. Different parts of Lawsonia inermis L. (Family: Lythraceae) like roots, bark, leaves, flowers and seeds are traditionally used for the treatment of various ailments.  Alkaloids, tannin, phenolics, saponin and anthraquinone are present in both types of extracts of leaves of Lawsonia inermis. Glycosides are present in ethanolic extract of leaves and seeds. Terpenoids and flavonoids are not found in leaves but present in seeds. The disc diffusion assay showed that the leaves and seeds of Henna plant have different degrees of bacterial and fungal growth inhibition, depending on the strains.  The aqueous extracts showed broadest antimicrobial activity by inhibiting more or less most of the microbial strains involved. Aqueous extract was more effective than their ethanolic extracts. Klebsiella pneumonie and Serratia  marcescens were the most resistant strains tested. It could be concluded that seeds and leaves of Lawsonia inermis have potential antimicrobial efficacy. All extracts (aqueous or ethanolic) have shown better antimicrobial efficacy against Staphylococcus aureus, Escherichia coli and Aspergillus niger. Differential antimicrobial activity of plant parts against different bacteria might be due to concentration of different active phyto-compounds in different parts. Among those antimicrobial compounds, phenolic compounds, terpenoids, and alkaloids are very important compounds in antimicrobial or antioxidant action.

In this study, the crude methanol extract of whole plant of Vernonia cinerea Less. has been investigated for anti-diarrheal, anxiolytic, antimicrobial and membrane stabilizing activities. Test for anti-diarrheal activity was carried out by castor oil-induced diarrhea in mice. The anxiolytic activity was examined in mice by using the hole-cross test and open field-tests (OFT). The preliminary antimicrobial activity was determined at 500 μg/disc by the disc diffusion method against a number of Gram positive and Gram negative bacteria and fungi. RBC membrane stabilization method was used for the evaluation of in-vitro anti-inflammatory activity. The crude methanol extract of V. cinerea showed significant and dose-dependent anti-diarrheal activity in castor oil-induced diarrhea in mice. The results showed that the crude extract significantly increased the number of hole crossing as compared to control in hole cross tests. In open field test, the extract showed significant increase in number of square crossed. The efficacy of the extract (200-400 mg/kg b.w.) was compared with standard anxiolytic drug diazepam (1 mg/kg). Furthermore, the plant extract, at 500 µg/disc exhibited moderate antimicrobial activity against Blastomyces dermatitidis (zone of inhibition = 17.7 mm) and Shigella dysenteriae (zone of inhibition = 14.0 mm). In red blood cell stability test,  the sample at 0.5 and 1 mg/ml  inhibited the heat-induced haemolysis of RBCs by 15.45% and 27.73%, respectively whereas standard acetyl salicylic acid (ASA) demonstrated 71.36% inhibition of haemolysis. The obtained results provide supports for the use of this plant in traditional medicine but further pharmacologic studies are required to isolate and identify the bioactive molecules.

The structural and therapeutic diversity coupled with commercial viability of small heterocyclic molecules has fascinated organic and medicinal chemist. So, a great deal of research was carried out in the field of heterocyclic containing sulphur and nitrogen, because of their immense biological importance. The thiadiazole derivatives posses’ different pharmacological and biological activity. Hence, the search for never effective antimicrobial agents is imperative. It focuses on the problems of cross resistance and better activity against variety of infections. The majority of 1, 3, 4-thiadiazoles are based on the cyclisation of thiaosemicarbazide derivative incorporating this basic structural unit. The structure of new compounds prepared during present investigation has been authentically established by their IR, 1H NMR and Mass spectral studies. The antimicrobial activity of thiadiazole derivatives also reported some of these derivatives exhibit significant and broad spectrum antimicrobial activity. All the synthesized compounds were screened for antibacterial activity against Bacillus subtilis, Bacillus pumilus, E coli and Pseudomonas aureginosa by Disc diffusion method using ciprofloxacin as a standard against Gram positive and Gram negative bacteria. Key Words: Thiadiazole, Thiosemicarbazide, Antimicrobial, Cyclization, Screening 

An aqueous extract of the leaves of Eclipta alba (Astraceae) was obtained by cold maceration process and tested for it antimicrobial activity against Fusarium species to ascertain preservative potential in food products. The screening was performed against Fusarium oxysporum and Fusarium subglutinans by agar plate disc diffusion method at 50 µg/ml and 100 µg/ml concentrations. The results were interpreted by Kirby-Bauer standard and indicated that the extract showed significant antimicrobial property against Fusarium species, however, predominant activity was found against Fusarium oxysporum.

  Isatin is an important class of heterocyclic compounds. Recently, heterocyclic compounds analogues and their derivatives have attracted strong interest in medicinal chemistry due to their biological and pharmacological properties. The small and simple isatin nucleus possesses numerous biological properties like -antitumor, antimicrobial, anti-inflammatory, anticonvulsant, antiviral, anti HIV, antioxidant, CNS depressant activities. These activities are also possessed by its substituted derivatives as well. The present review outlines some commonly used procedures to synthesize the isatin moiety and its derivatives, with different biological activities.