Anti-Infective Agents - Volume 12, Issue 2, 2014

With the everincreasing problem of multidrug resistance worldwide, concerns are growing regarding use of alternative compounds to supplement or modify the actions of antibiotics. Along with drug resistance, antibiotics also provide a number of side effects, diarrhea being a very prominent one. Antibiotic associated diarrhea (AAD) is difficult to manage and therefore concepts like ‘probiotics’ have gained importance. In this respect, ‘prebiotics’, which are ‘food’ to ‘feed’ the healthy colonic flora, is an upcoming concept. Because antibiotics alter the normal intestinal flora, controlling the composition of the flora could be truly beneficial. Prebiotics are short chain carbohydrates that can alter the intestinal microbial flora to one rich in bifidobacteria and lactobacilli, the organisms that constitute ‘balanced healthy flora’ and resist gut colonizations by pathogenic flora and infections. The approach seems reasonable. Moreover, prebiotic compounds can be easily incorporated into foodstuffs unlike probiotics. Despite the availability of many natural compounds with prebiotic activity, only inulin and fructo-oligosaccharides have successfully met the criteria to be labeled as prebiotics with substantial evidence. Therefore, it is much early to suppose that prebiotics will markedly change the fate of AADs, even though their potential to restore gut microbial balance is definite. Continuous research studying the effects of more such compounds is required to substantiate the several physiological benefits of prebiotics.

Lymph node tuberculosis (TB) represents the most common form of extrapulmonary TB that affects most often laterocervical lymph nodes. The disease, favored by states of immunosuppression, manifests itself by usually unilateral swelling, which may be associated with skin changes (hyperaemia, infiltration or fistula) and poor systemic symptoms. Our study included 75 patients arrived at the hospital “V. Monaldi” of Naples from 2008 to 2012, in order to evaluate some aspects of clinical, diagnostic and therapeutic characteristics of tuberculous lymphadenopathy. All patients were subjected to clinical, microbiological and radiological findings, surgical biopsy (alternatively, fine needle aspiration cytology, FNAC) of lymph nodes affected by pathology, antituberculosis chemotherapy for six months and subsequent followup. 49% patients were female and 51% male (mean age 44.5 years). 50.7% of patients were immunocompromised (6.7% of HIV-positive cases, 4% with type II diabetes mellitus, 16% of drug users, 6.7% treated with immunosuppressive drugs, 4% affected by malnutrition, 12% homeless). The laterocervical lymphadenopathy was unilateral in 70.7% of cases, smaller than 2 cm in 66.7%, single in 62.7%, with normal overlying skin in 72%. 9.3% of cases showed pulmonary involvement. 68% of cases excisional biopsy was performed for microbiological and histopathological examination and in 32% patients FNAC (integrated with excisional biopsy in more than half of the cases). Lymph node tuberculosis is still a problem of high clinical significance. Diagnosis requires excisional biopsy for differential diagnosis from other forms of adenopathy; treatment utilises a multi-agent chemotherapy scheme that allows a good cure rate, with few side effects.

Tuberculosis (TB) is of increasing concern due to the recent emergence and spread of MDR-TB, XDR-TB, TDR-TB and HIV/AIDS pandemic. There is urgent need for novel antitubercular agents which can shorten the treatment duration. Based on isosteric replacement and 3D structural similarity between Linezolid, an oxazolidine antimycobacterial agent, we have designed novel 4-amino-3,5-di(substituted)thiazolin-2(3H)thione/ones, synthesized and evaluated for their antimycobacterial activity on Mycobacterium tuberculosis H37Rv strain. Some of the compounds exhibited potent antimycobacterial activity with MIC values in the range of 1-2 µg/mL. Active compounds were further screened against MDR-TB and XDR-TB strain and found to exhibit promising in vitro activity.

Aim: Plant extracts or plant-derived compounds are likely to provide a valuable source of new medicinal agents. In the present work anti-leishmanial activity of methanolic extracts of Gossypium hirsutum, Ferula assa-foetida and Artemisia aucheri, was studied on Leishmania major promastigotes by colorimetric assay in comparison to a trivalent antimony compound (tartar emetic). Methods: L. major promastigotes were cultured at 24±1°C to stationary phase in RPMI 1640 medium, supplemented with 10% heat inactivated fetal calf serum (FCS) and antibiotics. The biological activity of three plant extracts was studied against L. major promastigotes in comparison to tartar emetic. The optical density (OD) due to cleavage of the tetrazolium salt MTT [3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] into a colored product formazan by the parasite was measured using an ELISA reader, to determine IC50 values (50% inhibitory concentrations). All experiments were repeated in triplicate. Results: All three plant extracts and tartar emetic inhibited the growth of promastigote stage of L.major after 72 hours of incubation. Tartar emetic as positive control gave a 50% inhibitory concentration (IC50) of 4.7µg/ml, while the IC50 values of G. hirsutum, F. assa-foetida and A. aucheri, were determined as 3.6, 5.9 and 7.5µg/ml, respectively. Although G. hirsutum was more active than the others, but all extracts had profound effects on promastigotes of L. major. Conclusion: This study provides valuable data on potent activity of three plant extracts. Further works are required to evaluate the leishmanicidal effect of these plant extracts on animal models or human volunteers.

The present study was intended to reveal the antibacterial activity of various cold organic solvent extracts of Abrus precatorius L. (Fabaceae) and Asystasia gangetica (L.) T. Anderson (Acanthaceae) against the selected pathogens. Powders of whole plant parts of A. precatorius and A. gangetica were extracted with petroleum ether, benzene, chloroform and ethanol at ambient temperature. The dried extracts were tested for antibacterial activity by agar disc diffusion method. Among the different extracts of A. precatorius, ethanolic extracts showed maximum zone of inhibition (21 mm) against Bacillus subtilis followed by 13 mm against Staphylococcus aureus. Broadest spectrum of activity was exhibited in petroleum ether extracts of A. precatorius against different bacterial pathogens (5/7 pathogens). In A. gangetica, benzene extracts exhibited broadest spectrum of activity with the maximum level of inhibition (12 mm) against B. subtilis followed by 11 mm in ethanolic extracts against Salmonella typhi. Petroleum ether extracts of A. gangetica did not show any activity against the selected pathogens. The present study results clearly show that the extracts of A. precatorius and A. gangetica had significant and considerable antibacterial activity against various pathogens and further evaluation is necessary to find out the active principle compound responsible for bioactivity.

The biological properties of medicinal plants have been documented worldwide for many centuries. However, the top priority for the biomedical field is the search for safe and effective antibacterial agents against the wide variety of bacterial infections. Therefore, the present study aimed to evaluate various phytoconstituents and in-vitro antibacterial activity of crude extracts from Aegle marmelos, Capparis aphylla, Callistemon lanceolatus, Commelina bengalensis, Justicia adhatoda, Argemona mexicana, Achyranthes aspera, Catharanthus roseus and Syzygium cumini. The antibacterial activity of different solvent (Petroleum ether, Chloroform, Acetone, Methanol and water) extracts prepared from nine plants were screened against some reference strain of bacteria (Escherichia coli, Vibrio cholerae, Klebsiella pneumoniae, Proteus vulgaris, Bacillus subtilis, Salmonella typhi) by using resazurin based microtitre dilution assay and disc diffusion assay. The presence of phenols, tannins, flavanoids, terpenoid, steroids, alkaloids and saponins in the different extracts were established. A minimum inhibitory concentration of these bioactive extracts ranges from 6.00 to 0.37 mg/ml. In disc diffusion assay, at concentration of 25.0 µg/disc of some crude extracts showed significant activity against six bacterial strains. Gas chromatography-mass spectrometry (GCMS) studies were performed for the most bioactive plant leaves’ extracts which resulted in the identification of several bioactive compounds. Moreover, the most of bioactive extracts were found to be safe and non-toxic by acute toxicity study. This data indicate that these naturally occurring medicinal plants have antibacterial potential and could be active as new potential antibacterial drugs with least toxic effects.

Mycobacterial infections (particularly, tuberculosis caused by Mycobacterium tuberculosis) represent a significant threat to public health, especially south of the Sahara. The problem has been compounded by poor patient compliance due to long periods of treatment, thus resulting in the development of multi-drug resistant (MDR) and extremely drugresistant (XDR) forms the of bacterium. It has, therefore, become imperative to seek new drugs from unexplored sources against these infections. Natural products, from ancient times, have often been used as drugs for the treatment of various ailments. They have also served as templates for the design and synthesis of new drugs. In sub-Saharan Africa particularly, ethnobotanical and ethnomedical knowledge of plants has been exploited to manage several different ailments, including tuberculosis. Thus research efforts have often been concentrated on plants as a source of treatment of diseases as well as drug leads. In this mini review, we report the biological activities of compounds derived from African medicinal plants with the potential for the treatment of anti-mycobacterial infections. Seventy nine (79) antimycobacterial compounds have been identified in sub-Sahara Africa covering the period from 1995 to 2013.

The effect of sulfonamide drugs on the electrophysical properties of Escherichia coli strains B-878 and K-12 was investigated by the example of sulfacetamide sodium (sulfacyl sodium). Substantial changes in the orientational spectra of cell suspensions incubated with various concentrations of sulfacetamide sodium occurred only at the first five frequencies of the orienting electric field (740–2800 kHz). Sulfacetamide sodium at 0.08 µg/ml changed the magnitude of the electro-optical signal of the suspensions. A study of the time course of sulfacetamide sodium effect on the cells showed that the signal magnitude decreased by 57% of the no-drug control after 5 min of exposure to the drug and that on subsequent exposure, the signal magnitude remained almost unchanged (changes no greater than 5% of the no-drug control). The spectral changes differed significantly for the sensitive and resistant strains. The orientational spectral changes induced by sulfonamides may be useful for testing the resistance of bacteria to this family of drugs.

The conjugation of different substituted styryl (-CH=CH-Aryl) moieties with the biologically relevant heteroaromatic scaffolds such as 4-benzylidene-2-methyloxazol-5-one, 3-methyl-1-phenylpyrazol-5-one, 2-methylbenzimidazole, 6-methyluracil afforded the newer series (four different series, 1A-3C, 2A-C, 3A-C & 4A-C) of styrene derivatives. Newer styrene derivatives were synthesized and characterized by IR, NMR (1H & 13C), Mass spectroscopic/spectrometric methods and elemental analysis. Results of the antibacterial activity study reveal that the synthesized compounds possess in-vitro activity against the tested bacterial strains, which, however, was comparatively very less than that of the standard drug, amikacin sulphate. From the structure-activity relationship study, it could be attributed that the overall antibacterial efficacy of the conjugated series of styrene derivatives is the sum of bio-effectiveness of styryl moieties and heterocyclic scaffolds.

The aim of the study was to evaluate antibacterial and antioxidant potential of the actinomycete isolate Streptomyces cinnamonensis VITNS1 isolated from paddy field, Vellore, Tamil Nadu. The antibacterial activity of crude extract was tested against bacterial pathogens. The free radical scavenging potential of the crude extract was determined by DPPH assay. The morphological, physiological and the biochemical properties of the strain VITNS1 was confirmed by conventional methods and genotypic characterization was carried out using 16S rDNA partial gene sequencing. The authenticity of the crude chemical constitutes were determined by (GC-MS). The strain VITNS1 was identified as Streptomyces sp on biochemical and morphological characterization. Phylogenetic tree was constructed and the 16S rRNA gene sequence showed 99% similarity to Streptomyces cinnamonensis strain N56-1. The antibacterial activity studied against Staphylococcus aureus (26mm) was found to exhibit the best spectra of activity, followed by Pseudomonas aeruginosa (25mm), Salmonella typhi (25mm) Escherichia coli (24mm) at 30mg/mL concentration. The ethyl acetate extract possessed DPPH free radical scavenging activity at 5mg/mL with 70% inhibition. The (GC-MS) Gas Chromatography revealed the presence of six volatile compounds. Hence the results of antibacterial and antioxidant activity of the extract clearly indicated that the terrestrial environment are the major sources for the isolation of bioactive compounds from actinomycetes and a promising tool for drug discovery.