เชื้อราเอนโดไฟท์ที่ผลิตสารต้านจุลินทรีย์จากพืชป่าชายเลนในภาคใต้ของประเทศไทย

Thesis (M.Sc., Microbiology)--Prince of Songkla University, 201

Quantitative analysis of povidone-iodine thin films by X-ray photoelectron spectroscopy and their physicochemical properties

In this study, povidone-iodine (PVP-I) has been formulated as a topical spray to produce a thin film for the controlled release of I2. By means of experimental design, 27 formulations containing glycerol, ethanol, PEG 400, copovidone and HFA 134a as a propellant were prepared. The pH values of all formulations were in the range of 6–7. The viscosity was within the range of 11.9–85.9 mPas. The surface tensions were 20.3 to 24.6 mN m–1 and the contact angles were between 19.3 and 38.7. The assays for the iodine contents were within acceptable range (80–120 %). X-ray photoelectron spectroscopy analysis revealed the ionized form of iodine was much higher than the unionized form. The MIC and MBC values of the PVP-I sprays against Staphylococcus aureus, S. epidermidis and Pseudomonas aeruginosa were higher than that of commercial PVP-I solution. The cytotoxicity study confirmed that the PVP-I spray had lower toxic effects on keratinocytes and fibroblasts compared to the commercial PVP-I solution. The formulation containing 59 % ethanol, 18 % copovidone and 12 % PEG 400 showed good antibacterial activity

Antimicrobial activity of endophytic fungi isolated from the mangrove plant Sonneratia apetala (Buch.-Ham) from the Sundarbans mangrove forest

Endophytic fungi reside in the intercellular space of plant nourished by the plant. In return, they provide bioactive molecules which can play critical roles on plant defense system. Fifty six endophytes were isolated from the leaves, root, bark and fruits of Sonneratia apetala, a pioneer mangrove plant in the Sundarbans, Bangladesh. A total of 56 isolates were obtained and 12 different species within 8 genera were identified using morphological and molecular characteristics. Antimicrobial activity of Ethyl Acetate (EtOAc) and Methanolic (MeOH) extracts of these 12 different species were analyzed by resazurin assay and the Minimum Inhibitory Concentrations (MICs) were determined. The fungal extracts showed antimicrobial activities against more than one tested bacterium or fungus among 5 human pathogenic microbes, i.e. Escherichia coli NCTC 12241, Staphylococcus aureus NCTC 12981, Micrococcus lutus NCTC 7508, Pseudomonas aeruginosa NCTC 7508 and Candida albicans ATCC 90028. Overall, Methanolic extracts showed greater activity than that of Ethyl Acetate extracts. Of the isolates identified, Colletotrichum gloeosporioides, Aspergillus niger and Fusarium equiseti were the most active isolates and showed activity against microorganisms under investigation. Methanolic extracts of C. gloeosporioides and A. niger showed the lowest MIC (0.0024 mg/mL) against Pseudomonas aeruginosa. The study indicates that endophytic fungi isolated from S. apetala species posses potential antimicrobial properties, which could be further investigated

Phlebotomine Sand Flies in Southern Thailand: Entomological Survey, Identification of Blood Meals and Molecular Detection of Trypanosoma spp.

An entomological survey at rural and cavernicolous localities in four provinces in southern Thailand provided 155 blood-fed females of sand flies (Diptera: Psychodidae) that were identified based on morphological characters as Idiophlebotomus asperulus (n = 19), Phlebotomus stantoni (n = 4), P. argentipes (n = 3), Sergentomyia anodontis (n = 20), S. barraudi (n = 9), S. hamidi (n = 23), S. hodgsoni (n = 4), S. hodgsoni hodgsoni (n = 32), S. indica (n = 5), S. iyengari (n = 2), S. khawi (n = 17), S. silvatica (n = 11) and Sergentomyia sp. (n = 6). The dominant species in this study was S. hodgsoni hodgsoni, which was collected specifically in a Buddha cave. Screening for DNA of parasitic protozoans revealed eight specimens (5.16%) of four species (S. barraudi, S. indica, S. khawi and Id. asperulus) positive for Trypanosoma sp., while no Leishmania spp. DNA was detected. Blood meals of engorged females were identified by PCR-Restriction Fragment Length Polymorphism (PCR-RFLP) assay on a fragment of cytochrome b (cyt b) gene with a success rate 36%, humans, dogs, and rats being determined as sources of blood. Bloodmeal analysis of two Trypanopsoma-positive females (S. barraudi and Sergentomyia sp.) identified blood from dogs and humans, respectively. Our findings indicate that S. barraudi, S. indica, S. khawi and Id. asperulus may be incriminated in circulation of detected Trypanosoma spp

Antifungal metabolites from marine-derived Streptomyces sp. AMA49 against Pyricularia oryzae

Marine-derived actinobacteria are considered as potential sources of bioactive metabolites including antifungal substances. Fifteen out of 155 marine-derived actinobacteria exhibited strong antifungal activity against the rice blast fungus Pyricularia oryzae. Their extracts were further determined for minimum inhibitory concentrations (MIC) and minimum fungicidal concentrations (MFC). Ethyl acetate extract from the strain AMA49 and its subfraction AMA49F1 strongly inhibited hyphal growth of various P. oryzae strains with MICs (8 to 16µg/ml) and MFCs (16 to 128µg/ml) comparable to propiconazole. Both extracts destroyed fungal membrane and organelles, completely inhibited conidial germination, appressorium formation, and were non-toxic to Galleria mellonella. High performance liquid chromatography/mass spectrometry identified oligomycin A and its derivatives as the active components of AMA49F1 besides several diketopiperazines. AMA49 was identified as a Streptomyces sp. based on morphological characteristics and 16S rDNA sequence analysis. The results suggest that the Streptomyces sp. strain AMA49 is a potential biocontrol agent against rice blast pathogen P. oryzae. This is the first report on the inhibitory effect of the marine-derived Streptomyces extract containing oligomycin A and its derivatives on mycelial growth, conidial germination and appressorium formation of P. oryzae

Ethanolic cashew leaf extract: Antioxidant potential and impact on quality changes of dried fermented catfish during storage

Ethanolic cashew (Anacardium occidentale, L.) leaf extract (ECLE) rich in phenolic compounds was prepared with the aid of ultrasonication. Impacts of light, heat, and pH on stability of antioxidant activity of ECLE were investigated. Exposure to light at an intensity of 1000 lx for 24 h showed no effect on activity of ECLE (p > 0.05). When being exposed to light for an extended periods (48 h), total phenolic content (TPC) became lower (p < 0.05). Light intensities at 2400–4000 lx for 24 h significantly decreased TPC and reduced antioxidant activities (p < 0.05). Thermal treatment at 60–100 ̊C for 1 h plausibly induced decomposition and simultaneously released low-molecular-weight phenolic compounds, leading to an increase in activity (p < 0.05). ECLE showed the augmented antioxidant activity in pH range of 3–5. When ECLE was added to dried fermented catfish (DFC) at 200–600 mg/kg and stored for 21 days at 30 ̊C, ECLE at 600 mg/kg effectively retarded lipid oxidation and inhibited the growth of microorganisms of DFC during storages, thereby extending the shelf life of DFC. ECLE could therefore be utilized as natural food additive or preservative in DFC

Bactericidal Action of Shrimp Shell Chitooligosaccharide Conjugated with Epigallocatechin Gallate (COS-EGCG) against Listeria monocytogenes

The antibacterial effect of chitooligosaccharide conjugated with five different polyphenols, including catechin (COS-CAT), epigallocatechin gallate (COS-EGCG), gallic acid (COS-GAL), caffeic acid (COS-CAF), and ferulic acid (COS-FER), against Listeria monocytogenes was investigated. Among all the conjugates tested, COS-EGCG showed the highest inhibition toward Listeria monocytogenes, with a minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 1024 and 1024 &micro;g/mL, respectively. The COS-EGCG conjugate also had a bactericidal effect on the environmental and clinical strains of L. monocytogenes. The low concentration of COS-EGCG conjugate augmented the formation of biofilm and the growth of L. monocytogenes. Nevertheless, the inhibition of biofilm formation and bacterial growth was achieved when treated with the COS-EGCG conjugate at 2 &times; MIC for 48 h. In addition, the COS-EGCG conjugate at 2 &times; MIC had the potential to inactivate the pre-biofilm, and it reduced the production of the extracellular polysaccharides of L. monocytogenes. The COS-EGCG conjugate at the MIC/4 effectively impeded the motility (the swimming and swarming) of L. monocytogenes, with an 85.7&ndash;94.3% inhibition, while 100% inhibition was achieved with the MIC. Based on scanning electron microscopic (SEM) images, cell wall damage with numerous pores on the cell surface was observed. Such cell distortion resulted in protein leakage. As a result, COS-EGCG could penetrate into the cell and bind with the DNA backbone. Therefore, the COS-EGCG conjugate could be further developed as a natural antimicrobial agent for inhibiting or controlling L. monocytogenes

RELEASE AND PERMEATION OF INDOMETHACIN FROM PHOSPHOLIPID COMPLEX FILM GENERATED FROM SPRAY FORMULATIONS

An indomethacin topical spray was prepared using lecithin and a cholesterol derivative as a phospholipid complex in a film. Polyvinylpyrrolidone (PVP) was used as a film-forming agent. Drug penetration through keratinocytes was evaluated as well as cytotoxicity to the keratinocytes and fibroblast cells. The results reveal that the PVP concentration provided fine droplets under a microscope with a low contact angle (12.07°-22.53°). Incorporating PVP in the formulation reduced the hydrodynamic radius or size by 20 times. The SEM and TEM results showed smoother surfaces of the thin film for larger quantities of the PVP film-forming agent in the formulations. It also gave the highest drug penetration when the PVP was 0.5%. However, the film-forming agent can also act as a control release barrier. The percent viabilities of the human keratinocytes and fibroblasts were higher in the indomethacin spray phospholipid complex thin film formulation than the pure drug