Cytotoxic, Antimicrobial and Antioxidant Properties of <i>Commelina diffusa</i>Burm. F.

Commelina diffusa Burm. F. is a herbaceous tropical plant with different traditional medicinal uses. Present study is aimed to isolate the bioactive compounds from DCM-Methanol extract of the powdered whole plant of Commelina diffusa and to investigate the cytotoxic, antimicrobial and antioxidant activities of the crude extract and its twelve vacuum liquid chromatographic fraction (CD1-12). Vacuum Liquid Chromatography (VLC) was employed to isolate bioactive metabolites. The physicochemical properties of the isolated compound were examined and the molecular structure was elucidated by NMR spectroscopy.?Cytotoxic, antibacterial, antioxidant activities were evaluated following brine shrimp lethality bioassay, disc diffusion method and DPPH free radical scavenging assay respectively. The isolated compound was identified as steroid (stigmasterol) which had significant cytotoxic effect on vero cell line. The crude extract and its fractions (CD8-CD12) exhibited strong cytotoxicity in brine shrimp lethality bioassay having LC50 values 3.79, 9.19, 29.49, 16.60, 19.36, 44.58 μg/mL respectively. The crude extract showed mild to strong antibacterial activity. Fractions (CD5-CD12) showed mild to strong antibacterial activity against Escherichia coli in comparison with Kanamycin (standard). Strong antioxidant activities were found in crude extract (IC50 value 30.52 μg/ml), CD11 (IC50 value 39.27 μg/ml) and CD12 (IC50 value 19.50 μg/ml). The study suggests Commelina diffusa plant extract to have strong antioxidant and cytotoxic activity which is indicative of presence of compounds with broad spectrum of curative applications. One compound namely stigmasterol has been isolated from the plant.

Antimicrobial potential of Actinomycetes species isolated from marine environment

Objective:To evaluate the antimicrobial activity of Actinomycetes species isolated from marine environment.Methods:Twenty one strains of Actinomyceteswere isolated from samples of Royapuram, Muttukadu, Mahabalipuram sea shores and Adyar estuary. Preliminary screening was done using cross-streak method against two gram-positive and eight gram-negative bacteria.The most potent strains C11 and C12 were selected from which antibacterial substances were extracted. The antibacterial activities of the extracts were performed using Kirby-Bauer disc diffusion method. Molecular identification of those isolates was done.Results:All those twenty one isolates were active against at least one of the test organisms. Morphological characters were recorded. C11 showed activity againstStaphylococcusspecies(13.0暲0.5 mm),Vibrio harveyi(11.0暲0.2 mm),Pseudomonas species(12.0暲0.3 mm). C12 showed activity against Staphylococcus species(16.0暲0.4 mm),Bacillus subtilis(11.0暲0.2 mm),Vibrio harveyi(9.0暲0.1 mm),Pseudomonas species(10.0暲0.2 mm). 16S rRNA pattern strongly suggested that C11 and C12 strains were Streptomyces species.Conclusions:The results of the present investigation reveal that the marineActinomycetesfrom coastal environment are the potent source of novel antibiotics.Isolation, characterization and study of Actinom ycetescan be useful in discovery of novel species of Actinomy cetes.

Determination of Malaysian Herbs and Spices as Biopreservative Agents in Food Products

Preservatives are usually added to food products to ensure longer shelf life and prevent decomposition process and microbial growth. However, synthetic food preservatives can also give negative side effect to health and are harmful to human and animal physiology. Based on the potential of herbs and spices as antimicrobial agent, the purpose of this study is to identify antibacterial activity from extracts of some local herbs and spices: Phaeomeria speciosa (P. speciosa), Aquilaria subintegra (A. subintegra), Polygonum minus (P. minus), Syzygium aromaticum (S. aromaticum), Cinnamomum verum (C. verum) and Piper nigrum (P. nigrum) against food bacteria using disc diffusion method. Results revealed that dichloromethane extracts of C. verum, hexane extracts of S. aromaticum and P. minus showed the most active antibacterial against tested bacteria. The Minimal Inhibitory Concentrations (MIC) ranged from 25 to 75 mg/ml for dichloromethane extract of C. verum, hexane extract of S. aromaticum and P. minus. Therefore further research should be pursued to identify the chemical structure of antibacterial agents from the active extracts as an alternative source of natural preservatives.

Assessment of Antifungal Activity of Some Himalayan Foliose Lichens Against Plant Pathogenic Fungi

In vitro antifungal activity of the acetone, methanol and chloroform extracts of four lichen species viz, Bulbothirx setschwanensis, Everniastrum nepalense, Heterodermia diademata, Parmelaria thomsonii were investigated against seven plant pathogenic fungi (Aspergillus flavus, A. fumigatus, Alternaria alternata, Fusarium oxysporum, F. solani, F. roseum and Penicillium citrinum) with reference to commercially available synthetic antifungal drug Ketoconazole (positive control). Lichen secondary metabolites were extracted using Soxhlet extractor and were further recovered through gentle evaporation of solvents in rotatory evaporator. Antifungal activity was analysed employing BauerKirby disc diffusion assay. Acetone and methanol extracts of lichenized fungi were found more effective against tested plant pathogenic fungi. Principal component analysis concluded that though, Ketoconazole was effective against four of the tested plant pathogenic fungi, acetone and methanol extracts of lichens were comparatively more effective against some broad spectrum plant pathogenic fungi (Fusarium oxysporum, F. solani, F. roseum).

Anti-enteric bacterial activity of the traditional medicinal plants of Kanyakumari coast,Tamilnadu,India

Objective:To evaluate the antimicrobial potentials of 6 traditionally used medicinal plants to treat gastrointestinal infection against pathogenic bacteria,as most of the pathogens develop drug resistance against commonly used antibiotics.Methods:Crude extracts from different parts of different plants were tested against bacterial strains of clinical significance.Extraction of bioactive principles was done with water and ethanol.Evaluation of antibacterial activity was done by disc diffusion assay against selected bacterial stains.Results:Of the 6 different plant materials tested,extracts prepared from Psidium guajava leaves showed significantly higher efficacy.Extracts prepared using alcohol exhibited higher antibacterial activity when compared to their corresponding aqueous extracts.Conclusions:The findings of the present study suggested that phytochemical extracts of the presently studied plant materials possess significant anti-enteric bacterial activity,and thus lend pharmacological credibility to the suggested traditional use of the plant as a natural remedy for the treatment,management and/or control of gastrointestinal diseases in the coastal tracts of Kanyakumari district,Tamilnadu,India.