Rathish Nair

In-vitro antimicrobial activity of Psidium guajava l. leaf extracts against clinically important pathogenic microbial strains

The methanol, acetone and N, N-dimethylformamide (DMF) fractions of leaves of Psidium guajava L. were evaluated for antibacterial and antifungal activity. Piperacillin and gentamicin were used as standards for antibacterial assay, while nystatin and flucanazole were used as standards for antifungal assay. 91 clinically important strains were used for the study which were both clinical isolates as well as identified strains. The antibacterial activity was more pronounced against gram-positive bacterial and fungal strains. Moderate activity was shown against the gram-negative bacterial strains studied.

Antimicrobial Activity of Terminalia catappa, Manilkara zapota and Piper betel Leaf Extract.

Aqueous and methanol extract of the leaves of Terminalia catappa L., Manilkara zapota L. and Piper betel L. were evaluated for antibacterial activity against 10 Gram positive, 12 Gram negative bacteria and one fungal strain, Candida tropicalis. Piperacillin and gentamicin were used as standards for antibacterial assay, while fluconazole was used as standard for antifungal assay. The three plants showed different degree of activity against the microorganisms investigated. The methanolic extract was considerably more effective than aqueous extract in inhibiting the investigated microbial strains. The most active antimicrobial plant was Piper betel.

Anticandidal Activity of Punica granatum. Exhibited in Different Solvents

Abstract Anticandidal activity of Punica granatum L.. extracts in ethanol, methanol, propanol, acetone, benzyl alcohol, 1,4-dioxan, and N,N.-dimethyl formamide (DMF) is reported. The selection of solvents was on the basis of their polarity. Growth inhibition using the agar ditch diffusion assay was determined on four different strains of Candida. species isolated from HIV-positive patients. Ethanolic extract showed activity against three Candida. species, whereas it was ineffective against Candida albicans. 1. The methanol, acetone, and propanol extracts were effective against all four Candida. species. The DMF extract was effective against Candida albicans. 1 and 2 and showed moderate activity against Candida albicans. 3, whereas it was ineffective against “Candida species. 1.” The 1,4-dioxan extract was effective against Candida albicans. 1, Candida albicans. 2, and Candida species. 1 and was ineffective against Candida albicans. 3. The benzyl alcoholic extract was ineffective in showing any kind of activity against any of the four candidal strains. These different extracts of P. granatum. were also compared with commercially available antibiotics such as nystatin, clotrimazole, and amphotericin B, and the natural plant extract proved to be better against some candidal species.

Marine Algae: Screening for a Potent Antibacterial Agent

This study was done to investigate the antimicrobial potentiality of the marine algae collected from different coastal regions of Gujarat and screened for the same. Twenty-six marine algae belonging to Rhodophyceae, Chlorophyceae and Phaeophyceae were screened for their potential antibacterial activity against five clinically important bacterial strains, namely Bacillus cereus, Micrococcus flavus, Citro-bacter freundii, Klebsiella pneumoniae and Pseudomonas testosteroni. Acetone and methanol were used for extraction; and the extracted yield was more when the solvent used was methanol. The antibacterial activity was done by both Agar disc diffusion method and Agar ditch method. The five bacterial strains showed varied response towards marine algal extracts. The most susceptible bacteria was B. cereus followed by K. pneumoniae and C. freundii while the most resistant bacteria were M. flavus and P. testosteroni. Among the 26 algae screened, E. intestinalis was the most potent alga and thus, this alga was selected for further studies. E. intestinalis was extracted in petroleum ether, 1,4-dioxan, acetone, methanol and DMF, and their antibacterial activity was studied against the above-stated five bacterial strains using agar disc method. Maximum extractive value of E. intestinalis was in methanol (2.05%) and minimum was in acetone (0.38%). The most susceptible bacteria was K. pneumoniae and maximum antibacterial activity was shown by petroleum ether extract and minimum was shown by 1,4-dioxan extract. The most resistant bacteria were M. flavus and C. freundii. The MIC values of E. intestinalis extracts ranged from 2500-9.765 µg/0.5 ml against B. cereus and K. pneumoniae. From these results it is concluded that the acetone extract of E. intestinalis is the most potent extract and can be used as a lead molecule in drug discovery in inhibiting some of the bacterial strains. E. intestinalis can be used as a promising novel marine antimicrobial agent in the coming years.

Antibacterial Activity of Some Plant Extracts Used in Folk Medicine

In the present work, selected plants were screened for their potential antibacterial activity. For evaluating antibacterial activity, both aqueous and organic solvent methanol was used. The plants screened were Ocimum sanctum, Jatropha gossypifolia, Boerhavia diffusa, Azadirachta indica, Solidago virgaurea, and Commelina benghalensis. The antibacterial activity was assessed against six bacterial strains—Pseudomonas testosteroni, Staphylococcus epidermidis, Klebsiella pneumoniae, Bacillus subtilis, Proteus morganii, Micrococcus flavus. Agar disc diffusion method and Agar ditch diffusion method were used to study the antibacterial activity of all these plants. Ps. testosteroni and K. pneumoniae were the most resistant bacterial strains. A. indica showed strong activity against tested bacterial strains. Therefore, we conclude that A. indica may prove to be a promising agent, and further exploration into this compound should be performed to determine its full therapeutic potential. In addition, its leaf extract can also be used as a lead molecule in combating the diseases caused by the studied bacterial strains.

Antibacterial and preliminary phytochemical and physico-chemical analysis of Eucalyptus citriodora Hk leaf.

The present communication deals with some studies on the antibacterial, physico-chemical and phytochemical parameters of different extracts of Eucalyptus citriodora leaf. The antibacterial study was performed using the agar ditch method on some clinically important bacteria, namely Pseudomonas pseudoalcaligenes, Proteus vulgaris, Citrobacter freundii, Staphylococcus subflava, Bacillus megaterium, and Enterobacter aerogenes. Physico-chemical parameters namely water, methanol, 1,4-dioxane, DMF, acetone soluble extractives, total ash, melting point, and pH were determined according to pharmacopoeial procedures. Methanol gave the maximum extract while it was minimum in water. Phytochemical parameters were screened for alkaloids, tannins, cardiac glycosides, saponins, steroids and flavonoids. Tannins and flavonoids gave positive results, while steroids and glycosides were absent. The most susceptible bacteria was C. freundii, while the most resistant was P. vulgaris.

Antimicrobial Activity of Terminalia catappa L. Leaf Extracts against Some Clinically Important Pathogenic Microbial Strains

Objective: The present study was undertaken to evaluate in-vitro antimicrobial activity of methanol, acetone and N, N-dimethylformamide extracts from leaf of Terminalia catappa L. (Combretaceae). Methods: In vitro antimicrobial activity of all the extracts was done by agar disc diffusion assay. 91 clinically important strains were used for the study, which were both clinical isolates as well as identified strains. Piperacillin and gentamicin were used as standards for antibacterial assay, while nystatin and flucanazole were used as standards for antifungal assay. Antimicrobial activity was determined by measurement of inhibition zone around each paper disc. For each extract three replicate trials were conducted against each organism. Results: The antibacterial activity was more pronounced against bacteria than fungal strains. The Gram positive bacteria were more susceptible than Gram negative bacteria. The methanol extract showed best antibacterial activity. T. catappa leaf extracts showed better antibacterial activity than commercially used antibiotics. Conclusion: Demonstration of antimicrobial activity of T. catappa provides the scientific basis for the use of this plant in the traditional treatment of diseases and may help to discover new chemical classes of antibiotic substances that could serve as selective agents for infectious disease chemotherapy and control. This investigation has opened up the possibility of the use of this plant in drug development for human consumption possibly for the treatment of various infections caused by microbes.