Isolation and HPLC Quantitative Determination of 5α-Reductase Inhibitors from L.f. Leaf Extract.

Steroid 5α-reductase plays a crucial role in catalyzing the conversion of testosterone to dihydrotestosterone, which is involved in many androgen-dependent disorders. Leaf-hexane extract from L.f.

Cytotoxic and antibacterial depsidones from the endophytic fungus isolated from Thai rice.

Four new depsidones, mollicellins V-Y (-), together with eight known depsidones (-) were isolated from the endophytic fungus, detached from stems of Thai rice. Their structures were determined by extensive spectroscopic methods. Mollicellins X, H, and F (, and ) showed potent cytotoxicity against the human oral epidermoid carcinoma (KB) cell line, and mollicellin F () also showed a potent cytotoxicity against the human hepatocellular carcinoma (HepG2) cell line.

Spirosteroids and α-glucosidase inhibitory norlignans from Asparagus racemosus Willd. roots.

Three undescribed spirosteroids, asparacemosones A-C, an undescribed spiro-21-norsteroid, asparacemosone D, along with seven known compounds were isolated from Thai herbal plant Asparagus racemosus Willd. roots. Their structures were elucidated by spectroscopic analysis including NMR, UV, IR and mass spectrometry.

Bioactive secondary metabolites from roots of planch.

Two new aromadendrin rhamnosides, cissusfoliate A () and 3--cissusfoliate A () together with seven known compounds (-) were isolated from the roots of Planch. Their structures were determined by extensive spectroscopic methods. The absolute configurations of compounds were assigned by combination of the coupling constant values of H-2 and H-3 and the comparison of their experimental ECD spectra with those reported in literature.

A new antibacterial tirucallane from roots.

Phytochemical investigation of the roots of a Thai medicinal plant, provided a new tirucallane, 3-epimesendanin S 12-acetate (), together with four known compounds, 3-epimesendanin S (), meliasenin G (), -sitosterol () and -sitosterol glucoside (). Their structures were characterized by intensive spectroscopy including 1 D and 2 D NMR, UV, IR and MS spectrometric analysis. The isolated compounds were evaluated for antibacterial and acetylcholinesterase inhibitory activities.

Bioactive homogentisic acid derivatives from fruits and flowers of Miliusa velutina.

Chromatographic separation of fruits and flowers of the Thai medicinal plant, Miliusa velutina, resulted in the isolation of five new rare homogentisic acid derivatives, miliusanal (1) and miliusanones A-D (2-5), together with fifteen known secondary metabolites (6-20). Their structures were determined through the use of extensive spectroscopic data. The absolute configurations of homogentisic acid derivatives 2-7 were identified using NOESY data and a comparison of experimental and calculated ECD spectral data.

Bioactive xanthoquinodins and epipolythiodioxopiperazines from 7s-1, an endophytic fungus isolated from (Lour.) Mart.

A new xanthoquinodin B9 (), together with two known xanthoquinodins, xanthoquinodin A1 () and xanthoquinodin A3 (), three epipolythiodioxopiperazines, chetomin (), chaetocochin C () and dethio-tetra(methylthio)chetomin (), and four other compounds, chrysophanol (), emodin (), alatinone (), and ergosterol () were isolated from the endophytic fungus 7s-1, isolated from (Lour.) Mart. All isolated structures were established based on their spectroscopic data analyses.

Antibacterial dihydrobenzopyran and xanthone derivatives from Garcinia cowa stem barks.

Two new compounds, garciniacowol (1) and garciniacowone (2) along with 15 knowncompounds were isolated from the stem barks of Garcinia cowa. Their structures weredetermined by intensive spectroscopic methods. The structure of 1 was a symmetrical dimericdihydrobenzopyran derivative, whereas the framework of 2 was a triprenyl caged-xanthoneprecursor.

Antibacterial carbazole alkaloids from Clausena harmandiana twigs.

Three new carbazole alkaloids, harmandianamines A-C (1-3), together with fifteen known compounds (4-18) were isolated from the twigs of Clausena harmandiana. The structures were elucidated by spectroscopic methods, including UV, IR, NMR, and MS. The antibacterial activity against Escherichia coli TISTR 780, Salmonella typhimurium TISTR 292, Staphylococcus aureus TISTR 1466 and methicillin-resistant S.

Bioactive carbazole alkaloids from Clausena wallichii roots.

Four new carbazole alkaloids, clausenawallines C-F (1-4), along with 18 known compounds (5-22) were isolated from the roots of Clausena wallichii. Compounds 3, 9, and 22 exhibited significant antibacterial activity against methicillin-resistant Staphylococcus aureus SK1 (MRSA SK1) and Staph. aureus TISTR 1466 with MIC values in the range 4-16 μg/mL, whereas compound 4 showed the highest cytotoxicity against oral cavity cancer (KB) and small-cell lung cancer (NCI-H187) with IC(50) values of 10.