Souwalak Phongpaichit

Phylogenetic diversity of endophyte assemblages associated with the tropical seagrass Enhalus acoroides in Thailand

Seagrasses are flowering plants inhabiting coastal and marine environments, with a worldwide distribution. They serve as feeding, breeding and nursery grounds for economically important marine organisms including endangered species. The tropical seagrass Enhalus acoroides was collected from Had Khanom-Mu Ko Thale Tai National Park, southern Thailand. The objectives of this study were to investigate for the presence of endophyte assemblages in E. acoroides, as well as to describe the diversity of endophytes based on LSU, ITS1, 2, 5.8S rDNA sequence analyses. Forty-two fungal assemblages were isolated and identified through molecular data. This resulted in a diversity of fungal groups of Ascomycota (98%) and Basidiomycota (2%). Three major Ascomycota classes including the Sordariomycetes (36%), Eurotiomycetes (33%) and Dothideomycetes (24%) were determined. The predominant ascomycete orders were the Hypocreales, followed by the Eurotiales and the Capnodiales, respectively. Additionally one taxon belonged to the Russulales, Basidiomycota and was possibly mycorrhiza. This study confirms that E. acoroides harbors a wide diversity of fungal endophytes, and provides a baseline for further studies on fungal-host plant interactions.

Anthraquinone, cyclopentanone, and naphthoquinone derivatives from the sea fan-derived fungi Fusarium spp. PSU-F14 and PSU-F135.

Five new metabolites, fusaranthraquinone (1), fusarnaphthoquinones A-C (2-4), and fusarone (5), were isolated from the sea fan-derived fungi Fusarium spp. PSU-F14 and PSU-F135 along with 18 known compounds. The structures were elucidated on the basis of spectroscopic evidence. Their antibacterial, antifungal, antimycobacterial, antimalarial, and cytotoxic activities were examined.

Antifungal activities of extracts from Thai medicinal plants against opportunistic fungal pathogens associated with AIDS patients

In this study, 36 extracts derived from 10 plant species were selected to screen for their antifungal activity against clinical isolates of Candida albicans, Cryptococcus neoformans and Microsporum gypseum. Selection was based on their use by traditional Thai healers or their reported antimicrobial activities in an attempt to find bioactive medicines for use in the treatment of opportunistic fungal infections in AIDS patients. The disc diffusion and hyphal extension–inhibition assays were primarily used to test for inhibition of growth. Minimum inhibitory concentration was determined by dilution methods. The chloroform extracts of Alpinia galanga and Boesenbergia pandurata had pronounced antifungal activity against C. neoformans and M. gypseum, but exhibited weak activity against C. albicans. Alpinia galanga and B. pandurata are excellent candidates for the development of a remedy for opportunistic fungal infections in AIDS patients.

Phthalide and isocoumarin derivatives produced by an Acremonium sp. isolated from a mangrove Rhizophora apiculata.

Nine new fungal metabolites, one phthalide derivative, acremonide (1), and eight isocoumarin derivatives, acremonones A-H (2-9), were isolated from the mangrove-derived fungus Acremonium sp. PSU-MA70 together with 10 known compounds. Their structures were determined by NMR analysis. The known 8-deoxytrichothecin and trichodermol exhibited moderate antifungal activity against Candida albicans and Cryptococcus neoformanns, respectively.

Metabolites from the endophytic fungus Xylaria sp. PSU-D14

Glucoside derivatives, xylarosides A (1) and B (2), were isolated from the broth extract of the endophytic fungus Xylaria sp. PSU-D14 along with two known compounds, sordaricin (3) and 2,3-dihydro-5-hydroxy-2-methyl-4H-1-benzopyran-4-one (4). The structures were assigned by spectroscopic methods. Sordaricin (3), one of the known metabolites, exhibited moderate antifungal activity against Candida albicans ATCC90028 with a MIC value of 32 microg/ml.

Sesquiterpene and Xanthone Derivatives from the Sea Fan-Derived Fungus Aspergillus sydowii PSU-F154

Three new sesquiterpenes, named aspergillusenes A and B and (+)-(7S)-7-O-methylsydonic acid, and two new hydrogenated xanthone derivatives, named aspergillusones A and B, were isolated from the sea fan-derived fungus Aspergillus sydowii PSU-F154 together with 10 known compounds. Their structures were identified on the basis of spectroscopic data. The isolated compounds were evaluated for their antioxidant activity.

Epoxydons and a Pyrone from the Marine-Derived Fungus Nigrospora sp. PSU-F5

Nigrospoxydons A-C (1- 3) and nigrosporapyrone (4), four new metabolites, were isolated from the marine-derived fungus Nigrospora sp. PSU-F5 together with nine known compounds. Their structures were elucidated by spectroscopic methods, mainly 1D and 2D NMR spectroscopic techniques. The antibacterial activity against the standard Staphylococcus aureus ATCC 25923 and methicillin-resistant S. aureus was evaluated.

Pyrone derivatives from the marine-derived fungus Nigrospora sp. PSU-F18.

Pyrones, named nigrosporapyrones A-D (1-4), and five known compounds were isolated from the marine-derived fungus Nigrospora PSU-F18. Their structures were elucidated on the basis of spectroscopic evidence. The antibacterial activity against the standard Staphylococcus aureus ATCC 25923 and methicillin-resistant S. aureus was evaluated.

Evaluation of Antibacterial Activities of Medicinal Plants Widely Used Among AIDS Patients in Thailand

Abstract Antibacterial activity of 12 selected Thai medicinal plants used as self-medication by HIV/AIDS patients in Thailand was studied. Thirty-nine chloroform, methanol, and aqueous extracts from these plants were investigated for their antibacterial activity against important pathogenic bacteria commonly associated with AIDS infection. These included Staphylococcus aureus., methicillin-resistant Staphylococcus aureus. (MRSA), Streptococcus mutans., and Salmonella typhi.. Inhibition of growth was tested using paper disk agar diffusion method. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by agar microdilution method and agar dilution method in Petri dishes with millipore filters. The Gram-positive bacteria were proved to be susceptible to the chloroform extracts of Alpinia galanga. (L.) Willd., Boesenbergia rotunda. Mansf. (L.), Piper betle. (L.), Spilanthes acmella. (L.) Murray, and Zingiber zerumbet. (L.) Roscoe ex Sm. and the methanol extract of Boesenbergia rotunda.. Chloroform extract of Alpinia galanga. demonstrated the greatest inhibition zones of 29.1 and 23.7 mm against Staphylococcus aureus. and MRSA, respectively. The MIC values of this extract against Staphylococcus aureus. and MRSA were 128 and 256 µg/ml and the MBC values were 256 and 256 µg/ml, respectively. An active compound, 1′-acetoxy-chavicol acetate, was identified with MIC values against MRSA and Staphylococcus aureus. of 64 and 128 µg/ml, respectively.

Cyclohexene, diketopiperazine, lactone and phenol derivatives from the sea fan-derived fungi Nigrospora sp. PSU-F11 and PSU-F12

Nigrosporanenes A (1) and B (2), two new cylohexene derivatives, and tyrosol (3) were isolated from the sea fan-derived fungus Nigrospora sp. PSU-F11, whereas five known compounds: 4-hydroxybenzoic acid (4), aplysiopsene D (5), 3-isochromanone (6), (−)-drimenin (7) and diketopiperazine derivative (8), were obtained from the fungus Nigrospora sp. PSU-F12. Their structures were established by spectroscopic evidence. We also tested their cytotoxic (on African green monkey kidney fibroblast and breast cancer cells), antioxidant (in the DPPH assay), and antibacterial (against the standard Staphylococcus aureus ATCC 25923 and methicillinresistant S. aureus) activities.