Yodhathai Thebtaranonth

Antiviral isoflavonoid sulfate and steroidal glycosides from the fruits of Solanum torvum.

The C-4 sulfated isoflavonoid, torvanol A (1), and the steroidal glycoside, torvoside H (3), together with the known glycoside, torvoside A (2), were isolated from a MeOH extract of Solanum torvum fruits. Upon enzymatic hydrolysis with beta-glucosidase, torvoside A (2) and torvoside H (3) yielded the corresponding acetal derivatives 4 and 5, respectively. Torvanol A (1), torvoside H (3) and compound 5 exhibited antiviral activity (herpes simplex virus type 1) with IC(50) values of 9.6, 23.2 and 17.4 microg/ml, respectively. Compounds 1-5 showed no cytotoxicity (at 50 microg/ml) against BC, KB and Vero cell lines.

Antimalarial sesquiterpenes from tubers of Cyperus rotundus: structure of 10,12-peroxycalamenene, a sesquiterpene endoperoxide.

Activity-guided investigation of Cyperus rotundus tubers led to the isolation of patchoulenone, caryophyllene alpha-oxide, 10,12-peroxycalamenene and 4,7-dimethyl-1-tetralone. The antimalarial activities of these compounds are in the range of EC50 10(-4)-10(-6) M, with the novel endoperoxide sesquiterpene, 10,12-peroxycalamenene, exhibiting the strongest effect at EC50 2.33 x 10(-6) M.

Potent In Vitro Antimalarial Activity of Metacycloprodigiosin Isolated from Streptomyces spectabilis BCC 4785

ABSTRACT Bioassay-guided fractionation of the extract from the fermentation broth of Streptomycesspectabilis BCC 4785 led to the isolation of three principle antimalarial agents, metacycloprodigiosin, bafilomycin A1, and spectinabilin. Metacycloprodigiosin exhibited potent in vitro activity against Plasmodiumfalciparum K1, with a 50% inhibitory concentration of 0.0050 ± 0.0010 μg/ml, while its cytotoxicity was much weaker.

Unusual enniatins produced by the insect pathogenic fungus Verticillium hemipterigenum: isolation and studies on precursor-directed biosynthesis

Abstract Two new enniatins H ( 3 ) and I ( 4 ), whose substituents on 2-hydroxycarboxylic acid moieties were different from those of known compounds, were isolated, together with known enniatins B ( 1 ) and B 4 ( 2 ), from the insect pathogenic fungus Verticillium hemipterigenum BCC 1449. Structures of these compounds were elucidated by spectroscopic means. Studies on precursor-directed biosynthesis with strain BCC 1449 led to the production and identification of three analogs, enniatins G ( 5 ), C ( 6 ) and MK1688 ( 7 ), as well as the stereochemical elucidation of 3 and 4 . Enniatins 1 – 7 were evaluated for their antiplasmodial and antimycobacterial activities.

Antimalarial halorosellinic acid from the marine fungus Halorosellinia oceanica

Three known compounds, 2-hexylidene-3-methylsuccinic acid (1), cytochalasin Q (2), and 5-carboxymellein (3), together with two new derivatives, 2-hexylidene-3-methylsuccinic acid 4-methyl ester (4) and an ophiobolane sesterterpene named halorosellinic acid (5), were isolated from culture broth of the marine fungus Halorosellinia oceanica BCC 5149. Compounds 1-3 exhibited moderate cytotoxicity against KB and BC-1 cell lines with IC(50) values of 1-13 microg/mL, while compounds 2, 3, 5, and 6 showed antimalarial activity with respective IC(50) values of 17, 4, 13, and 19 microg/mL. Halorosellinic acid (5) possessed only weak antimycobacterial activity with the minimum inhibitory concentration of 200 microg/mL.

Developments in cyclisation reactions

Cyclisations cationiques, radicalaires et anioniques. Cyclisations catalysees par des metaux

Precursor-directed biosynthesis of beauvericin analogs by the insect pathogenic fungus Paecilomyces tenuipes BCC 1614

Abstract Precursor-directed biosynthesis of beauvericin analogs, cyclohexadepsipeptide antibiotics, was investigated using the insect pathogenic fungus Paecilomyces tenuipes BCC 1614. Feeding l -isoleucine or d -alloisoleucine in liquid medium led to the enhanced production of beauvericin A and beauvericin B together with beauvericin and a missing analog, beauvericin C. Feeding experiments with d -isoleucine or l -alloisoleucine resulted in the production of diastereomers of beauvericins A, B and C, named allobeauvericins A, B and C, respectively.

Isolation and structure determination of four novel diterpenes from jatropha curcus

Abstract Four novel diterpenes have been isolated from Jatropha curcus and the structures have been determined by NMR spectroscopy and x-ray diffraction. All four compounds are structurally related and belong to the crotophorbolane class of compounds.

Hirsutellide a, a new antimycobacterial cyclohexadepsipeptide from the entomopathogenic fungus Hirsutella kobayasii

A new cyclohexadepsipeptide, named hirsutellide A (1), was isolated from a cell extract of the entomopathogenic fungus Hirsutella kobayasii BCC 1660. The structure of 1 was elucidated by analyses of spectroscopic data, and its absolute stereochemistry was addressed by the use of Marfeys method. Hirsutellide A (1) exhibited antimycobacterial and antimalarial activities, but was inactive toward the Vero cell line (at 50 microg/mL).

An antimalarial peroxide from Amomum krervanh Pierre

Several terpenes, including the novel diterpene peroxide (5) with potent activity against Plasmodium falciparum, have been isolated from Amomum krervanh (“cardamom”).