Evaluation of antibacterial activity of vitamin C against human bacterial pathogens / Avaliação da atividade antibacteriana da vitamina C contra patógenos bacterianos humanos

Now a day’s multidrug resistance phenomenon has become the main cause for concern and there has been an inadequate achievement in the development of novel antibiotics to treat the bacterial infections. Therefore, there is an unmet need to search for novel adjuvant. Vitamin C is one such promising adjuvant. The present study was aimed to elucidate the antibacterial effect of vitamin C at various temperatures (4°C, 37°C and 50°C) and pH (3, 8, and 11), against Gram-positive and Gram-negative bacteria at various concentrations (5-20 mg/ml) through agar well diffusion method. Growth inhibition of all bacterial strains by vitamin C was concentration-dependent. Vitamin C significantly inhibited the growth of Gram-positive bacteria: Bacillus licheniformis (25.3 ± 0.9 mm), Staphylococcus aureus (22.0 ± 0.6 mm), Bacillus subtilis (19.3 ± 0.3 mm) and Gram-negative bacteria: Proteus mirabilis (27.67 ± 0.882 mm), Klebsiella pneumoniae (21.33±0.9 mm), Pseudomonas aeruginosa (18.0 ± 1.5 mm) and Escherichia coli (18.3 ± 0.3 mm). The stability of vitamin C was observed at various pH values and various temperatures. Vitamin C showed significant antibacterial activity at acidic pH against all bacterial strains. Vitamin C remained the stable at different temperatures. It was concluded that vitamin C is an effective and safe antibacterial agent that can be used in the future as an adjunct treatment option to combat infections in humans.

Agora, a resistência antimicrobiana de um dia em patógenos aos antibióticos tornou-se a principal causa de preocupação e houve uma realização inadequada no desenvolvimento de novos antibióticos para tratar infecções bacterianas. Portanto, há uma necessidade de pesquisar um novo adjuvante, e a vitamina C é um desses adjuvantes promissores. O objetivo do presente estudo foi elucidar o efeito antibacteriano da vitamina C em diferentes temperaturas (4 °C, 37 °C e 50 °C) e pH (3, 8 e 11), contra Gram-positivos e Gram-cepas bacterianas negativas em várias concentrações (5-20 mg / ml) através do método de difusão em ágar bem. A inibição do crescimento de todas as cepas bacterianas pela vitamina C era dependente da concentração. A vitamina C inibiu significativamente o crescimento de bactérias Gram-positivas: Bacillus licheniformis (25,3 ± 0,9 mm), Staphylococcus aureus (22,0 ± 0,6 mm), Bacillus subtilis (19,3 ± 0,3 mm) e bactérias Gram- negativas: Proteus mirabilis (27,7 ± 0,9 mm), Klebsiella pneumoniae (21,3 ± 0,9 mm), Pseudomonas aeruginosa (18,0 ± 1,5 mm) e Escherichia coli (18,3 ± 0,3 mm). A estabilidade da vitamina C foi observada em vários valores de pH e várias temperaturas. A vitamina C mostrou atividade antibacteriana significativa em pH ácido contra todas as cepas bacterianas. A estabilidade da vitamina C permaneceu nas mesmas diferentes temperaturas (4 °C, 37 °C e 50 °C). Concluímos que a vitamina C é um agente antibacteriano eficaz e seguro que pode ser usado no futuro como uma opção de tratamento auxiliar para combater infecções em humanos, pois pode apoiar o sistema imunológico diretamente.

Evaluation of antibacterial activity of vitamin C against human bacterial pathogens

Abstract Now a days multidrug resistance phenomenon has become the main cause for concern and there has been an inadequate achievement in the development of novel antibiotics to treat the bacterial infections. Therefore, there is an unmet need to search for novel adjuvant. Vitamin C is one such promising adjuvant. The present study was aimed to elucidate the antibacterial effect of vitamin C at various temperatures (4°C, 37°C and 50°C) and pH (3, 8, and 11), against Gram-positive and Gram-negative bacteria at various concentrations (5-20 mg/ml) through agar well diffusion method. Growth inhibition of all bacterial strains by vitamin C was concentration-dependent. Vitamin C significantly inhibited the growth of Gram-positive bacteria: Bacillus licheniformis (25.3 ± 0.9 mm), Staphylococcus aureus (22.0 ± 0.6 mm), Bacillus subtilis (19.3 ± 0.3 mm) and Gram-negative bacteria: Proteus mirabilis (27.67 ± 0.882 mm), Klebsiella pneumoniae (21.33±0.9 mm), Pseudomonas aeruginosa (18.0 ± 1.5 mm) and Escherichia coli (18.3 ± 0.3 mm). The stability of vitamin C was observed at various pH values and various temperatures. Vitamin C showed significant antibacterial activity at acidic pH against all bacterial strains. Vitamin C remained the stable at different temperatures. It was concluded that vitamin C is an effective and safe antibacterial agent that can be used in the future as an adjunct treatment option to combat infections in humans.

Resumo Agora, a resistência antimicrobiana de um dia em patógenos aos antibióticos tornou-se a principal causa de preocupação e houve uma realização inadequada no desenvolvimento de novos antibióticos para tratar infecções bacterianas. Portanto, há uma necessidade de pesquisar um novo adjuvante, e a vitamina C é um desses adjuvantes promissores. O objetivo do presente estudo foi elucidar o efeito antibacteriano da vitamina C em diferentes temperaturas (4 °C, 37 °C e 50 °C) e pH (3, 8 e 11), contra Gram-positivos e Gram-cepas bacterianas negativas em várias concentrações (5-20 mg / ml) através do método de difusão em ágar bem. A inibição do crescimento de todas as cepas bacterianas pela vitamina C era dependente da concentração. A vitamina C inibiu significativamente o crescimento de bactérias Gram-positivas: Bacillus licheniformis (25,3 ± 0,9 mm), Staphylococcus aureus (22,0 ± 0,6 mm), Bacillus subtilis (19,3 ± 0,3 mm) e bactérias Gram- negativas: Proteus mirabilis (27,7 ± 0,9 mm), Klebsiella pneumoniae (21,3 ± 0,9 mm), Pseudomonas aeruginosa (18,0 ± 1,5 mm) e Escherichia coli (18,3 ± 0,3 mm). A estabilidade da vitamina C foi observada em vários valores de pH e várias temperaturas. A vitamina C mostrou atividade antibacteriana significativa em pH ácido contra todas as cepas bacterianas. A estabilidade da vitamina C permaneceu nas mesmas diferentes temperaturas (4 °C, 37 °C e 50 °C). Concluímos que a vitamina C é um agente antibacteriano eficaz e seguro que pode ser usado no futuro como uma opção de tratamento auxiliar para combater infecções em humanos, pois pode apoiar o sistema imunológico diretamente.

Phytochemical Profiles Of Three Traditional Medicinal Plants And Its Antimicrobial Activities

Objective: The objective of the current study was to compare the phytochemical composition and to evaluate the antibacterial properties of Cissus qudrangularis, Cinnamomum zeylanicum and Trigonella foenum-graecum against the bacterial strains Escherichia coli and Bacillus circulans. Methods: Qualitative analysis and quantitative estimation of various phytochemical components were done using standard protocols. Antibacterial activity against gram-negative Escherichia coli and gram-positive Bacillus circulans was evaluated using standard protocol of agar well diffusion and disc diffusion assay. The zone of inhibition was calculated. Results: Preliminary phytochemical analysis showed the presence of alkaloids, saponins and tannins in all three plant extracts. In quantitative estimation, Cinnamomum zeylanicum showed high alkaloid content (22%), Cissus qudrangularis showed high saponin content (6%) Trigonella foenum-graecum showed a high concentration (4.65 mg/g) of tannin. All the three plants showed moderate antimicrobial activity. The water extract of Cinnamomum zeylanicum showed the highest zone of inhibition (13 mm) against Escherichia coli and the water extract of Trigonella foenum-graecum showed the highest zone of inhibition (11 mm) against Bacillus circulans. Conclusion: The result of this study supports the use of all the selected three medicinal plants as a source of antibacterial substance for the possible treatment of human pathogenic organisms. These plants can be further subjected to isolation of the therapeutic phytochemicals and further pharmacological evaluation.

Comparison of the antimicrobial effects of six different intracanal medicaments on Enterococcus Faecalis

Aim: to investigate the antimicrobial effects of six different intracanal medicaments on Enterococcus faecalis. Material & Methods: An agar well diffusion test was used to determine the efficacy of the experimental medicaments in removing E. faecalis (ATCC 29212). Medicaments were divided into 7 groups; calcium hydroxide (Ca(OH)2) with saline, Ca(OH)2 with anaesthetic solution, Ca(OH)2 with propylene glycol, commercially available premixed Ca(OH)2 paste, chlorhexidine gluconate gel, triple antibiotic paste (metronidazole, ciprofloxacin, doxicycline) with propylen glycol and talk powder with saline as negative control group. The diameters of the growth inhibition zones for each group were measured after 24 and 48 hours. Differences between groups were analysed using Kruskal-Wallis and Mann-Whitney U tests, and intragroup differences were analysed using Wilcoxon sign test. Results: Diameter of the inhibition zone observed for the triple antibiotic paste was significantly larger (p<0.01) and the diameter of the inhibition zone observed for the chlorhexidine gluconate gel was significantly smaller in comparison to the other tested medicaments (p<0.05). Conclusion: All of the tested medicaments were found to be effective on E. faecalis. However the results suggest that the triple antibiotic paste would be the preferred medicament against E. faecalis as it has the greatest antibacterial effect among the tested medicaments.

Importance of the agar-media in the evaluation of bacteriocin activity against the same test-microorganisms

Abstract Bacteriocins are peptides produced by various species of bacteria, especially lactic acid bacteria, which exhibit a large spectrum of action against spoilage bacteria and foodborne pathogens. Successful application of techniques for quantitative or qualitative bacteriocin determination relies not only on the sensitivity of the test-microorganisms, but also on the agar-medium employed. Cell free supernatants are routinely used to preliminary screen for antimicrobial activity of bacteria by means of the agar well diffusion method, but the supernatant may also include other molecules (such as medium components and/or intracellular compounds) accidentally released during cell free supernatant preparation, which may interfere with the assay. Reproducibility of bacteriocin activity against the same test-microorganisms is an important factor to be considered. Unfortunately, no specific information about bioassays standardization to determine bacteriocin activity is available in the literature. In this work, growth inhibition by means of the agar well diffusion assays were carried out on different agar-media showing a strong dependence on the agar-medium used, indicating that the inhibitory effects could also depend on the diffusion of exudates that are included in the cell-free supernatant. The results presented in this communication show that selection of the agar-medium is crucial for the bioassay response.

In vitro antimicrobial and antioxidant activities of bioactive compounds (secondary metabolites) extracted from Streptomyces lydicus A2.

In the present study, we report antibacterial and antioxidant activities of bioactive compounds extracts (ethyl acetate extract, methanolic extract, n-hexane extract) of Streptomyces lydicus A2 isolated from air in Sciencetific and Technological Equipments Building, Walailak University, Thailand. The S. lydicus A2 is potential to produce bioactive compounds showed various biological activities. In previous research, its culture broth or extract shows antimicrobial activity. In this study, extract prepared from S. lydicus A2 stored at -80 oC was reevaluated the antimicrobial activity when grew in various medium and incubation time to find out storage effect towards the antimicrobial activity. The extract (fractions) from S. lydicus A2 still inhibit test bacteria even though it decreases 50% than the extract prepared from S. lydicus A2 without -80 oC storage. Antimicrobial activity against Staphylococcus aureus and Bacillus cereus was only exhibited by the methanolic fraction S. lydicus A2. Only, the ethyl acetate extract was found to possess dose dependent DPPH free radical scavenging. The isolate A2 could be a potential candidate for the development of novel therapeutic agents active against pathogens and free radicals. Further studies on genomic characterization of isolate and structure determination of the bioactive compounds are under progress.

Antimicrobial studies of rhizome of Swertia petiolata.

Swertia petiolata is used as folkore medicine in the treatment of skin diseases and mental disorders, ulcers, liver disorder and as bitter tonic, febrifuge, anthelmintic, antimalarial and antidiarrheal. Extracts of Swertia petiolata were prepared by soxhlet method. Dilutions were made in DMSO and subjected to antimicrobial activity by using agar well diffusion method, plate count agar (PCA) plates were inoculated with 100μl of each pathogenic microorganism adjusted to standardized inoculum (1.5 × 108 CFU/ml) in triplicates and spread with sterile swabs. After incubation for 24 hrs at 37 °C, the plates were observed. The zone of inhibition was measured and expressed in millimeters. Whereas the standard antibiotics; cefutaxim and amoxicillin showed antimicrobial activity with zones of inhibition ranging from > 15 mm to 10-15 mm. The hydro methanol extract showed excellent activity against Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis = 10-15mm), Gram-negative bacteria (Escherichia coli = 10-15 mm). However chloroform and petroleum ether extracts did not show significant antibacterial activity reflected by >4mm (gram +ve) and 5-10 mm (Gram-ve) and >4 mm (Petroleum ether extract). Phytochemical analysis of the extract showed the presence of steroids, tannins, phenolics, saponins, alkaloids, flavonoids and glycosides. From the study, it can be concluded that Swertia petiolata possesses significant antimicrobial activity which might be due to the presence of any/all these active constituents.

Antimicrobial Studies of Aqueous and Ethanolic Extracts of Enantia chlorantha Leaves and Stem Bark and Their Combined Effect on Selected Bacteria and Fungi.

Aim: To revalidate the antimicrobial effects of aqueous and ethanolic extracts of Enantia chlorantha leaves and stem bark against Enterococcus faecalis, Escherichia coli, Salmonella Typhi, Shigella sonnei, Staphylococcus aureus, Proteus vulgaris and Candida albicans; and to check the effects on the isolates when the stem bark and leave extracts are combined. Place and Duration of Study: Department of Biotechnology, School of Science, Federal University of Technology Owerri, Nigeria, between January 2013 and May 2013. Methodology: Agar well diffusion method was used for the susceptibility studies while the Minimum Inhibitory Concentrations were determined using the broth dilution method. The Minimum bactericidal/fungicidal concentration was determined by plating on nutrient agar. Results: The ethanolic extract of E. chlorantha stem bark showed antimicrobial activity on all 7 isolates tested with zones of inhibition in the range of 5mm to 33mm, while its aqueous extracts showed activity on only 3 of the 7 isolates with diameter zones of inhibition ranging between 5mm to 20mm. The aqueous leaf extracts showed activity against 3 of the 7 isolates while the ethanolic extracts had activity on 6. The minimum inhibitory concentration (MIC) of the ethanolic extract of both stem bark and leaves was between 1.56 and 12.5mg/ml, while that of aqueous extracts ranged from 6.25 to 12.5mg/ml. There was no obvious difference in the activity of the extracts when combined. Conclusion: This study validates potent antimicrobial activity of ethanol and aqueous extracts of Enantia chlorantha leaves and stem bark in line with similar studies. Further work is however needed to determine the toxicity of the plant extracts and also identify active components of the plant.

Radical scavenging and antibacterial activity of three Parmotrema species from Western Ghats of Karnataka, India.

Western Ghats are one of the biodiversity hotspots in the world. The present study was conducted to determine antibacterial and radical scavenging potential of three Parmotrema species viz., P. tinctorum, P. grayanum and P. praesorediosum from Maragalale and Guliguli Shankara, Western Ghats of Karnataka, India. The powdered lichen materials were extracted using methanol. Antibacterial activity of lichen extracts was tested against three Gram positive and five Gram negative bacteria by Agar well diffusion assay. Radical scavenging activity of lichen extracts was determined by DPPH free radical scavenging assay. Total phenolic content of lichen extracts was estimated by Folin-Ciocalteau reagent method. The lichen extracts showed dose dependent antibacterial activity. Overall, the lichen extracts were more inhibitory to Gram positive bacteria than Gram negative bacteria. P. grayanum displayed high inhibitory activity against test bacteria. Scavenging of DPPH radicals by lichen extracts was concentration dependent. Among the lichen species, P. grayanum showed higher scavenging potential as indicated by lower IC50 value. Total phenolic content was also high in P. grayanum. Thin layer chromatogram revealed the presence of Lecanoric acid, Orsellinic acid, Protolichesterinic acid, Chloroatranorin, Protopraesorediosic acid and Praesorediosic acid in lichen samples. The observed bioactivities of lichens could be ascribed to the presence of secondary metabolites. These lichens can be considered as suitable candidates for development of bioactive agents active against pathogenic microbes and oxidative damage.

Leaf Extracts of Vernonia amygdalina Del. from Northern Ghana Contain Bioactive Agents that Inhibit the Growth of Some Beta-lactamase Producing Bacteria in vitro.

Aims: The current study was aimed at evaluating the phytochemical profile and in vitro bacteria growth inhibitory potential of different solvent leaf extracts of V. amygdalina from northern Ghana. Study Design: Different solvent extracts of the plant were quantitatively and qualitatively evaluated for phytochemicals. In vitro bacteria sensitivity assay of the extracts was evaluated using some beta-lactamase producing bacteria as test microbes. Methodology: Ethanolic, methanolic, petroleum ether and aqueous leaf extracts of Vernonia amygdalina were studied in vitro for growth inhibition against beta-lactamase producing bacteria such as Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa using agar well diffusion method. Saponins, flavonoids, glycosides, alkaloids, tannins, phenolics, reducing sugars, anthracenosides, terpenes and phytosteroids were determined qualitatively and quantified. Results: All the phytochemicals tested were found to be present in both the methanolic and ethanolic leaf extracts. The aqueous extract showed the presence of saponins, reducing sugars and anthracenosides. Glycosides, flavonoids, saponins and alkaloids were the only groups of phytochemicals found in the petroleum ether extract. The methanolic extract showed the greatest amount of saponins (14.23%), flavonoids (2.15%), alkaloids (7.49%), tannins (5.4%), terpenes (10.20%) and phenolics (8.24%). The methanolic extract at concentration of 4 mg/ml showed growth inhibitory activities against all the test organisms with zone of inhibitions ranging from 16.00±0.50 (against E. coli) to 20.50±0.03 mm (against S. aureus). The ethanolic extract showed activity against only two of the test organisms viz. 23.00±0.33 mm against P. aeruginosa and 12.00±0.00 mm against S. aureus at similar concentration. All test organisms were resistant to both aqueous and pet ether extracts. Conclusion: The antibacterial activities of the methanolic and ethanolic extracts were significant (P < 0.05) and may be mediated by the presence of saponins, flavonoids, tannins, terpenes and alkaloids. Results from present study corroborate previous findings and also presents methanolic leaf extract of the plant as a credible candidate for the discovery of new phytotherapeutic agents against the beta-lactamase producing bacteria tested.

Antibacterial efficacy of Pimenta dioica (Linn.) Merill and Anacardium occidentale L. against drug resistant urinary tract pathogens.

The aim of the present study was to determine antibacterial effect of leaf and bark extracts of Pimenta dioica (Linn.) Merill (Myrtaceae) and Anacardium occidentale L. (Anacardiaceae) against drug resistant clinical isolates of urinary tract infection viz., Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus and Enterococcus faecalis. Agar well diffusion method was employed to assess inhibitory activity of leaf and bark extracts. Among extracts, bark extract of P. dioica and leaf extract of A. occidentale exhibited high inhibitory activity. The bark extract of P. dioica showed high inhibition of clinical isolates than other extracts. Among bacteria, E. faecalis and K. pneumoniae were inhibited to high and least extent respectively. The inhibitory potential of extracts could be attributed to the presence of bioactive secondary metabolites. Isolation of inhibitory principles from crude extracts and their inhibitory activity against UTI pathogens are to be carried out.

Protective effect of Lannea coromandelica Houtt. Merrill. against three common pathogens.

Background: Ayurvedic text reports suggested Lannea coromandelica is used in various microbial origin disorders like dysentery, sore eyes and leprosy, genital wounds. Objective: The present study was designed to investigate the antimicrobial effect of L. coromandelica Houtt. Merrill. (Anacardiaceae) on microbes which cause female reproductive tract infection. Materials and Methods: Ethanolic and aqueous bark extract (Ext.) of L. coromandelica were screened against strains of Streptococcus pyogens, Staphylococcus aureus, and Candida albicans. Antimicrobial assay had been done with agar well diffusion method. Results: Ethanolic extracts [100% (16 mg), 75% (12 mg) and 50% (8 mg)] of L. coromandelica exhibited zone of inhibition (ZI) 19.21 mm, 18.45 mm, 16.41 mm and 18.12 mm, 17.35 mm, 16.35 mm against S. aureus and S. pyogens, respectively. However, only 100% and 75% ethanolic extract showed (ZI-19.18 mm, 16.29 mm) activity against C. albicans. Nevertheless, aqueous extract (100%) showed higher antifungal activity (ZI-16.97 mm). Ciprofl oxacin and amphotericin B were used as a standard drugs in the present study. Conclusion: The results demonstrated that L. coromandelica Houtt. Merrill. have antibacterial activity against S. pyogens, S. aureus and antifungal property against C. albicans. Our fi ndings corroborate the ethnobotanical use of L. coromandelica in traditional medicine system (Ayurveda) of India.

Antimicrobial and antioxidant activities of a macrolichen Usnea pictoides G. Awasthi (Parmeliaceae).

Lichens are self-sufficient symbioses between an alga and a fungus. In the present study, we have determined total phenolic content, antimicrobial and antioxidant efficacy of a macrolichen Usnea pictoides G.Awasthi (Parmeliaceae) collected at Mullayanagiri, Western Ghats of Chikmagalur, Karnataka, India. The lichen was powdered and extracted sequentially using solvents of increasing polarity viz., petroleum ether, chloroform, ethyl acetate and methanol. Total phenolic content of solvent extracts was estimated by Folin-Ciocalteau reagent method. Antimicrobial activity of solvent extracts was tested against two bacteria viz., Staphylococcus aureus and Pseudomonas aerugionsa and two fungi viz., Candida albicans and Cryptococcus neoformans by Agar well diffusion assay. Antioxidant activity of solvent extracts was determined by DPPH free radical scavenging assay and Ferric reducing assay. Thin layer chromatogram showed the presence of usnic acid. The total phenolic content was highest in methanol extract followed by ethyl acetate, chloroform and petroleum ether extracts. S. aureus and C. neoformans showed high susceptibility to solvent extracts among bacteria and fungi. A dose dependent scavenging of DPPH radicals by solvent extracts was observed. The scavenging potential of methanol extract was higher than other extracts. In ferric reducing assay, methanol extract showed stronger reducing power than other extracts. Overall, extracts containing high phenolic contents exhibited stronger antioxidant activity. The inhibitory potential of the lichen extracts might be attributed to the presence of usnic acid. The radical scavenging and ferric reducing potential of solvent extracts could be attributed to the phenolic compounds. A positive correlation was observed between total phenolic content and the antioxidant activity of lichen extracts. The lichen U. pictoides can be a potential candidate for the development of bioactive agents.

Comparison of antifungal activity of medicinal plant Tylophora indica Merr. with its in vitro raised plant and callus.

The antifungal potential of medicinal plant Tylophora indica Merr. was evaluated by agar well diffusion method and it was compared with the activity of its in vitro raised plant and callus . The extracts of in vitro raised plant and callus showed better antifungal activity against the tested fungal species as compared to parent plant. Minimum inhibitory concentrations (MIC) of the extracts were determined by broth microdilution method. The MIC of the alcoholic leaf extracts of parent plant against tested fungi ranged from 12.0 to 98.0 μg/ml, whereas, the MIC of extract of in vitro raised plant and callus ranged from 1.53 to 49.0 μg/ml and 3.05 to 24.0 μg/ml respectively. The present study leads to conclusion that extracts of Tylophora indica contain good antifungal activity which could be used in the treatment of various fungal infections showing resistance to treatment by currently used antifungal agents. As the in vitro raised plant and callus gave good results, in vitro cultivation of the explants may be used to obtain novel antifungal compounds. This is the first report on antifungal activity of Tylophora indica through in vitro raised plant and its callus.

Biological activities of Sarcanthus pauciflorus.

Sarcanthus pauciflorus is a pendulous epiphytic orchid belonging to the family Orchidaceae. The present study was conducted to determine antimicrobial, antioxidant, anthelmintic and insecticidal efficacy of methanol extract of S. pauciflorus. Antimicrobial activity of methanol extract was determined against four bacteria and two fungi by Agar well diffusion method. Antioxidant activity was performed by DPPH free radical scavenging and Ferric reducing assay. Anthelmintic activity was studied on the basis of time taken for paralysis and death of adult Indian earthworms by the extract. Insecticidal activity, in terms of larvicidal effect, was evaluated using II instar larvae of Aedes aegypti. Total phenolic content of extract was estimated by Folin-Ciocalteau reagent assay. Phytoconstituents viz., tannins, saponins and glycosides were detected in methanol extract. Content of total phenolics was found to be 258.65 mg GAE/g of extract. All test bacteria and fungi were susceptible to extract of orchid. Bacillus subtilis and Cryptococcus neoformans were susceptible to high extent among bacteria and fungi respectively. Gram positive bacteria have shown greater susceptibility than Gram negative bacteria to extract. The extract exhibited marked dose dependent scavenging of DPPH free radicals. An increase in absorbance at 700nm revealed reducing power of the extract. The extract caused paralysis and death of adult Indian earthworms in a dose dependent manner. The lethal effect of extract on II instar larvae of Aedes aegypti was found to be dose dependent. The results of the present study shows that the methanol extract of S. pauciflorus is found to possess antimicrobial, antioxidant, anthelmintic and insecticidal activities which might be attributed to the presence of secondary metabolites. Further experimentations concerned with isolation of the bioactive components present in the orchid and determination of their biological activities are under progress.

Antioxidant and antimicrobial activity of flowers of Wendlandia thyrsoidea, Olea dioica, Lagerstroemia speciosa and Bombax malabaricum.

Flowers of higher plants have been used for centuries for several purposes such as medicine, food and garnishing food in many parts of the world. In the present study, we have determined the antioxidant and antimicrobial activity of methanol extract of flowers of Wendlandia thyrsoidea (Roemer & Schultes) Steudel (Rubiaceae), Olea dioica Roxb. (Oleaceae), Lagerstroemia speciosa L. (Lythraceae) and Bombax malabaricum DC. (Bombacaceae). Antioxidant efficacy of various concentrations of flower extracts was evaluated by DPPH free radical scavenging assay and Ferric reducing assay. Antimicrobial activity was determined against four bacteria and two fungi by agar well diffusion method. Total phenolic and flavonoid contents were determined by Folin-Ciocalteau reagent and Aluminium chloride colorimetric estimation methods respectively. The DPPH free radical scavenging effect of flower extracts was concentration dependent and was higher in case of extract of L. speciosa followed by W. thyrsoidea, B. malabaricum and O. dioica. In ferric reducing assay, it was shown that the absorbance of reaction mixture at 700nm increased on increasing the concentrations of flower extracts indicating reducing power of extracts. The reducing ability was also highest in L. speciosa extract. Extract of L. speciosa displayed marked inhibitory activity against bacteria and fungi than other flower extracts. Gram positive bacteria have shown more susceptibility than Gram negative bacteria. Among fungi, C. neoformans was more inhibited than C. albicans. Extracts of B. malabaricum and O. dioica were not effective against C. albicans. The phenolic and flavonoid contents were higher in L. speciosa and O. dioica respectively. A positive correlation has been observed between total phenolic content of flower extracts and antioxidant and antimicrobial activity. The flowers can be employed as a remedy for treatment of infectious diseases and oxidative damage. Further, isolation of active components from flower extracts and their biological activity determinations are under progress.

Isolation and characterization of potential antibiotic producing actinomycetes from water and sediments of Lake Tana, Ethiopia

To isolate, evaluate and characterize potential antibiotic producing actinomycetes from water and sediments of Lake Tana, Ethiopia. Methods: A total of 31 strains of actinomycetes were isolated and tested against Gram positive and Gram negative bacterial strains by primary screening. In the primary screening, 11 promising isolates were identified and subjected to solid state and submerged state fermentation methods to produce crude extracts. The fermented biomass was extracted by organic solvent extraction method and tested against bacterial strains by disc and agar well diffusion methods. The isolates were characterized by using morphological, physiological and biochemical methods. Results: The result obtained from agar well diffusion method was better than disc diffusion method. The crude extract showed higher inhibition zone against Gram positive bacteria than Gram negative bacteria. One-way analysis of variance confirmed most of the crude extracts were statistically significant at 95% confidence interval. The minimum inhibitory concentration and minimum bactericidal concentration of crude extracts were 1.65 mg/mL and 3.30 mg/mL against Staphylococcus aureus, and 1.84 mg/mL and 3.80 mg/mL against Escherichia coli respectively. The growth of aerial and substrate mycelium varied in different culture media used. Most of the isolates were able to hydrolysis starch and urea; able to survive at 5% concentration of sodium chloride; optimum temperature for their growth was 30 °C. Conclusions: The results of the present study revealed that freshwater actinomycetes of Lake Tana appear to have immense potential as a source of antibacterial compounds.

Evaluation of Malawian Vernonia glabra (Steetz)Vatke leaf and Securidaca longepedunculata (Fresen) root extracts for antimicrobial activities.

The aqueous, ethanol and acetone crude extracts and dichloromethane, hexane, ethyl acetate and nbutanol fractions of the Securidaca longepedunculata roots and Vernonia glabra leaves were studied for their antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans using agar well diffusion method. The phytochemical presents, as well as the minimum inhibitory concentration (MIC) and minimum bacteriacidal/fungicidal concentration (MBC/MFC) of the extracts were also determined using standard methods. Results obtained indicated that Vernonia glabra leaves acetone extracts had excellent antimicrobial activity against E. coli, P. aeruginosa and ethanol extracts against S. aureus. The n-butanol fractions had the best activity against E. coli and S. aureus, dichloromethane fraction against P. aeruginosa and ethyl acetate fraction against C. albicans. For S. longepedunculate root ethanol extracts showed best activity against E. coli, acetone extract against P. aeruginosa and aqueous extract against C. albicans. The n-butanol fractions had best activity against E. coli, P. aeruginosa and C. albicans. These results verified the claims by traditional healers in Malawi that the plants extracts treats bacteria related ailments such as diarrhoea and could be a potential source for development of phytomedicine.

In vitro antibacterial activity of Terminalia chebula leaf gall extracts against some human pathogenic strains.

The leaf galls of Terminalia chebula is used widely as Karkatasringi in south Indian markets. Karkatashringi is an important crude drug employed in various indigenous systems of medicine against several diseases and the drug has diverse medicinal properties. The present study was carried out to understand the antimicrobial activity of various extracts. The antibacterial activity of T. chebula (leaf gall) was evaluated against ten bacterial strains including Gram-positive and Gram-negative bacteria using the agar-well diffusion method. Among the two extracts tested, the ethanol extract presented the best results against all the bacteria while aqueous extract showed moderate inhibition of the microbial growth. Each extract is unique against different microorganisms; Staphylococcus aureus was more susceptible to both extract among the tested organisms, whereas Serratia marcescens and Proteus mirabilis were less susceptible for ethanol and aqueous extract respectively. The inhibitory effect of the extracts was compared with standard antibiotic Ciprofloxacin.

In vitro assessment of antimicrobial activity of the selected essential oils.

The present study evaluates the antimicrobial activity of three essential oils of Eucalyptus globulus, Eugenia caryophyllata and Psoralea corylifolia. The agar well diffusion method was used to assess the antimicrobial activity against five selected microorganisms S. aureus and B. subtilis (Gram-positive bacteria); E. coli and P. aeruginosa (Gram-negative bacteria) and P. chrysogenum (Fungus). The results revealed that the E. globulus was found to be most significant in comparison to the other oils. All the three oils have revealed higher antimicrobial activity against S. aureus.