Tetrahydroxanthene-1,3(2H)-diones and Oxidized Hexadiene Derivatives from Uvaria leptopoda and Their Biological Activities.

The first phytochemical investigation of the twig extract of Uvaria leptopoda resulted in the isolation and identification of three new tetrahydroxanthene-1,3(2H)-diones, uvarialeptones A-C, two new oxidized hexadiene derivatives, uvarialeptols A and B, together with ten known compounds. Their structures were elucidated by spectroscopic techniques and mass spectrometry. Uvarialeptones A and B were unprecedented tetrahydroxanthene-1,3(2H)-dione dimers which exhibited a cyclobutane ring via [2 + 2] cycloaddition from uvarialeptone C and 9a-O-methyloxymitrone, respectively. The structure of uvarialeptone A was confirmed by X-ray diffraction analysis using Mo Kα radiation. Compound 3 inhibited NO production at an IC50 value of 6.7 ± 0.1 µM.

Styryl lactone derivatives and aristolactam alkaloids from Goniothalamus tapis Miq. and their α-glucosidase inhibitory activity.

Two new styryl lactone derivatives, goniothapic acids A (1) and B (2), and 18 known compounds, were isolated from the twig and leaf extracts of Goniothalamus tapis Miq. The structures of new compounds were characterised by spectroscopic methods and HRESITOFMS. Their absolute configuration was established by comparing the experimental and calculated ECD spectra. Eleven compounds were evaluated for their α-glucosidase inhibitory activity. Of these, (-)-goniothalamin (5) and oldhamactam (16) showed the best α-glucosidase inhibitory activity with IC50 values of 54.8 and 57.9 µM, respectively.

In Vitro Anti-Inflammatory, Anti-Oxidant, and Cytotoxic Activities of Four Curcuma Species and the Isolation of Compounds from Curcuma aromatica Rhizome.

The genus Curcuma is part of the Zingiberaceae family, and many Curcuma species have been used as traditional medicine and cosmetics in Thailand. To find new cosmeceutical ingredients, the in vitro anti-inflammatory, anti-oxidant, and cytotoxic activities of four Curcuma species as well as the isolation of compounds from the most active crude extract (C. aromatica) were investigated. The crude extract of C. aromatica showed 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity with an IC50 value of 102.3 µg/mL. The cytotoxicity effect of C. aeruginosa, C. comosa, C. aromatica, and C. longa extracts assessed with the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay at 200 µg/mL were 12.1 2.9, 14.4 4.1, 28.6 4.1, and 46.9 8.6, respectively. C. aeruginosa and C. comosa presented apoptosis cells (57.7 3.1% and 32.6 2.2%, respectively) using the CytoTox-ONE™ assay. Different crude extracts or phytochemicals purified from C. aromatica were evaluated for their anti-inflammatory properties. The crude extract of C. aromatica showed the highest potential to inhibit NF-κB activity, followed by C. aeruginosa, C. comosa, and C. longa, respectively. Among the various purified phytochemicals curcumin, germacrone, curdione, zederone, and curcumenol significantly inhibited NF-κB activation in tumor necrosis factor (TNF) stimulated HaCaT keratinocytes. Of all compounds, curcumin was the most potent anti-inflammatory.

α-Glucosidase inhibitory and nitric oxide production inhibitory activities of alkaloids isolated from a twig extract of Polyalthia cinnamomea.

The first phytochemical investigation of Polyalthia cinnamomea led to the isolation and identification of two new oxoprotoberberine alkaloids, (-)-(13aS)-polyalthiacinnamines A and B, together with eleven known compounds. The structures of the new compounds were elucidated by extensive spectroscopic methods. The absolute configuration of miliusacunine E and consanguine B was established by X-ray diffraction analysis using Cu Kα radiation and ECD spectra, whereas the absolute configurations of polyalthiacinnamines A and B were established by comparison of their ECD spectra and specific rotations with those of miliusacunine E and consanguine B. Compounds 1-4, 6, and 8 exhibited α-glucosidase inhibitory activities (IC50 values ranging from 11.3 to 57.9 µM) better than a positive control (acarbose, IC50 83.5 µM). Compound 2 also exhibited NO production inhibitory activity with an IC50 value of 24.4 µM (indomethacin, a positive control, IC50 = 32.2 µM).

Rearranged benzophenones and prenylated xanthones from Garcinia propinqua twigs.

The first phytochemical investigation of Garcinia propinqua has led to the isolation and identification of three new compounds, including two rearranged benzophenones, doitunggarcinones A (1) and B (2), and a xanthone, doitunggarcinone C (3), together with seven known compounds (4-10). The structures of 1-3 were elucidated on the basis of spectroscopic methods, including UV, IR, NMR, and MS. The antibacterial activity of the 10 isolates was evaluated against Escherichia coli TISTR 780, Salmonella typhimurium TISTR 292, Staphylococcus aureus TISTR 1466, and methicillin-resistant Staphylococcus aureus (MRSA) SK1.

Antibacterial compounds from Zanthoxylum rhetsa.

A new amide, zanthorhetsamide (1), along with nine known compounds (2-10) was isolated from the roots and stem barks of Zanthoxylum rhetsa. The structure was characterized by spectroscopic methods. In addition, the antibacterial activity of the isolates was evaluated. Dihydrochelerythrine (4) exhibited strong activity against methicillin-resistant Staphylococcus aureus SK1 and moderate activity against Escherichia coli TISTR 780 with MIC values of 8 and 16 µg/mL, respectively.

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. aureus (MRSA) SK1 of some isolated compounds was also evaluated. Compound 6 exhibited significant antibacterial activity against MRSA SK1 with an MIC value of 0.25 µg/mL which higher than that of standard drug, vancomycin (MIC value=1 µg/mL) whereas compounds 14 and 5 showed strong activity with MIC values of 4 and 8 µg/mL, respectively. Only compound 14 showed strong antibacterial activity against S. aureus TISTR 1466 with an MIC value of 4 µg/mL.

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 10.2 and 4.5 µM, respectively.

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. The antibacterial activities against Escherichia coli TISTR 780, Salmonellatyphimurium TISTR 292, Staphylococcus aureus TISTR 1466, and methicillin-resistant S. aureus(MRSA) SK1 of the isolated compounds were also evaluated. Compounds 2 and 9 exhibitedgood antibacterial activity against MRSA SK1 with the same minimum inhibitory concentration(MIC) value of 2 µg/mL. Moreover, compound 2 also showed good antibacterial activityagainst S. aureus with an MIC value of 2 µg/mL.

Rapid antioxidant capacity screening in herbal extracts using a simple flow injection-spectrophotometric system.

A simple flow injection (FI)-spectrophotometric system for the screening of antioxidant capacity in herbal extracts was developed. The analysis was based on the color disappearance due to the scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical by antioxidant compounds. DPPH and ascorbic acid were used as reagent and antioxidant standard, respectively. Effects of the DPPH concentration, DPPH flow rate, and reaction coil length on sensitivity were studied. The optimized condition provided the linear range of 0.010-0.300mM ascorbic acid with less than 5%RSD(n=10). Detection limit and quantitation limit were 0.004 and 0.013mM, respectively. Comparison of antioxidant capacity in some herbal extracts determined by the FI system and a standard method was carried out and no significant difference was obtained.

Phenolic compounds from the seeds of Garcinia dulcis.

Dulcisxanthone G, 1,3,6-trihydroxy-2-(2,3-dihydroxy-3-methylbutyl)-7-methoxy-8-(3-methyl-2-butenyl)xanthone, together with 13 known compounds were isolated from the seeds of Garcinia dulcis. Their structures were determined by analysis of 1D and 2D NMR spectroscopic data. The activities on antibacterial and antioxidation of the isolated compounds were examined.