Chemical Compositions and Tyrosinase Activity of the Essential Oils of Alpinia aquatica

The essential oils obtained from the fresh rhizome, leaf, and pseudostem of Alpinia aquatica Roscoe. were hydrodistillated and analyzed using capillary gas chromatography (GC) and gas chromatography-mass spectroscopy (GC-MS). β-Pinene (11.7%), α-humulene (8.9%), aromadendrene (8.7%), and sabinene (7.7%) were the major components in the rhizome oil. The most abundant components of the leaf oil were germacrene D (21.3%), β-pinene (15.6%) and sabinene (12.1%), while α-humulene (19.8%), germacrene D (15.2%) and β-caryophyllene (8.7%) were the main constituents in the pseudostem oil. Antityrosinase assay revealed that all the three essential oils exhibited weak tyrosinase inhibition activities. The rhizome oil showed the highest inhibition activity with the value of 9.5% for the L-DOPA oxidation.

Systematic comparison of sets of (13)C NMR spectra that are potentially identical. Confirmation of the configuration of a cuticular hydrocarbon from the cane beetle Antitrogus parvulus

A systematic process is introduced to compare (13)C NMR spectra of two (or more) candidate samples of known structure to a natural product sample of unknown structure. The process is designed for the case where the spectra involved can reasonably be expected to be very similar, perhaps even identical. It is first validated by using published (13)C NMR data sets for the natural product 4,6,8,10,16,18-hexamethyldocosane. Then the stereoselective total syntheses of two candidate isomers of the related 4,6,8,10,16-pentamethyldocosane natural product are described, and the process is applied to confidently assign the configuration of the natural product as (4S,6R,8R,10S,16S). This is accomplished even though the chemical shift differences between this isomer and its (16R)-epimer are only ±5-10 ppb (±0.005-0.01 ppm).

Flavonoids and triterpenes from the leaves of Artocarpus fulvicortex

Five flavonoids, 5-hydroxy-(6:7,3':4')-di(2,2-dimethylpyrano)flavone 1, carpachromene 2, cycloartocarpesin 3, norartocarpetin 4 and 2'-hydroxy-4,4',6'-trimethoxychalcone 5, along with three triterpenes, friedelin 6, lupeol 7 and 13-sitosterol 8 were isolated for the first time from the leaves of Artocarpus fulvicortex F.M. Jarrett. The structures of these compounds were established by analysis of their spectroscopic (1D and 2D NMR) and spectrometric (MS) data, as well as by comparison of these with those reported in the literature.

Flavonoids and Triterpenes from the Leaves of Artocarpus Fulvicortex

Five flavonoids, 5-hydroxy-(6:7,3′:4′)-di(2,2-dimethylpyrano)flavone 1, carpachromene 2, cycloartocarpesin 3, norartocarpetin 4 and 2′-hydroxy-4,4′,6′- trimethoxychalcone 5, along with three triterpenes, friedelin 6, lupeol 7 and β-sitosterol 8 were isolated for the first time from the leaves of Artocarpus fulvicortex F.M. Jarrett. The structures of these compounds were established by analysis of their spectroscopic (1D and 2D NMR) and spectrometric (MS) data, as well as by comparison of these with those reported in the literature.

Chemical compositions of the rhizome oils of two Alpinia species of Malaysia

The essential oils obtained by hydrodistillation of the rhizomes of Alpinia aquatica Rosc. syn. Alpinia melanocarpa and Alpinia malaccensis Roscoe were analysed by capillary gas chromatography and gas chromatography-mass spectrometry. Eighteen compounds, representing 98.4% of the essential oil were identified in A. aquatica rhizome oil, with β-sesquiphellandrene in 36.5% being the major constituent, while 20 compounds representing 99.7% of the rhizome oil of A. malaccensis were identified, among which methyl (E)-cinnamate (78.2%) was the major constituent.

Isolation and identification of radical scavenging and tyrosinase inhibition of polyphenols from Tibouchina semidecandra L

Phytochemical and bioactivity studies of the leaves and stem barks of Tibouchina semidecandra L. have been carried out. The ethyl acetate extract of the leaves yielded four flavonoid compounds, identified as quercetin, quercetin 3-O-α-l-(2''-O-acetyl) arabinofuranoside, avicularin, and quercitrin, while the stem barks gave one ellagitannin, identified as 3,3'-O-dimethyl ellagic acid 4-O-α-l-rhamnopyranoside. Evaluation of the antioxidative activity on the crude extracts and pure compounds by electron spin resonance (ESR) and ultraviolet-visible (UV-vis) spectrophotometric assays showed that the pure isolated polyphenols and the EtOAc extract possessed strong antioxidative capabilities. Quercetin was found to be the most active radical scavenger in DPPH-UV and ESR methods with SC(50) values of 0.7 μM ± 1.4 and 0.7 μM ± 0.6 μM, respectively, in the antioxidant assay. A combination of quercetin and quercitrin was tested for synergistic antioxidative capacity;, however, there was no significant improvement observed. Quercetin also exhibited strong antityrosinase activity with a percent inhibition of 95.0% equivalent to the positive control, kojic acid, in the tyrosinase inhibition assay.

Chemical constituents from tiger's betel, Piper porphyrophyllum N.E.Br. (Fam. Piperaceae)

Seven flavonoid compounds have been isolated from the aerial parts of tiger's betel (Piper porphyrophyllum), which were identified as 5,7-dimethoxyflavone, 4',5,7-trimethoxy-flavone, 3',4',5,7-tetramethoxyflavone, 4'-hydroxy-3',5,7-trimethoxyflavone, 5-hydroxy-3',4',7-trimethoxyflavone, 4',5-dihydroxy-3',7-dimethoxyflavone and 5-hydroxy-7-methoxyflavanone. The identification of all compounds was achieved by physical properties and spectroscopically. These data were also confirmed by comparison with previously reported spectral data. Flavonoid compounds with high content in P. porphyrophyllum can probably be used as a chemical marker for this Piper species.

Sesquiterpenes from the Rhizomes of Curcuma ochrorhiza

From the rhizomes of Curcuma ochrorhiza, four sesquiterpenes, isofuranodiene, germacrene, furanogermenone and zederone, have been isolated, the structures of which have been elucidated by spectroscopic methods.

Sesquiterpenes from the rhizomes of Curcuma ochrorhiza

From the rhizomes of Curcuma ochrorhiza, four sesquiterpenes, isofuranodiene, germacrene, furanogermenone and zederone, have been isolated, the structures of which have been elucidated by spectroscopic methods.

Combined xanthorrhizol-curcumin exhibits synergistic growth inhibitory activity via apoptosis induction in human breast cancer cells MDA-MB-231

Background

It has been suggested that combined effect of natural products may improve the treatment effectiveness in combating proliferation of cancer cells. The present study was undertaken to evaluate the possibility that the combination of xanthorrhizol and curcumin might show synergistic growth inhibitory effect towards MDA-MB-231 human breast cancer cells via apoptosis induction. The effective dose that produced 50% growth inhibition (GI₅₀) was calculated from the log dose-response curve of fixed-combinations of xanthorrhizol and curcumin generated from the sulforhodamine B (SRB) assay. The experimental GI₅₀ value was used to determine the synergistic activity of the combination treatment by isobolographic analysis and combination-index method. Further investigation of mode of cell death induced by the combination treatment was conducted in the present study.

Results

Isobole analysis revealed that substances interaction was synergistic when xanthorrhizol and curcumin were added concurrently to the cultures but merely additive when they were added sequentially. The synergistic combination treatment was then applied to the cultures to investigate the mode of cell death induced by the treatment. Immunofluorescence staining using antibody MitoCapture™ revealed the possibility of altered mitochondrial transmembrane potential, which is one of the hallmark of apoptosis. Hoechst 33258 nuclear staining assay showed the rate of apoptosis of MDA-MB-231 cells to increase in response to the treatment. Apoptotic cell death was further confirmed by DNA fragmentation assay, where internucleosomal excision of DNA was induced upon treatment with xanthorrhizol-curcumin.

Conclusion

This is the first time the combined cytotoxic effect of xanthorrhizol and curcumin on MDA-MB-231 cells has been documented and our findings provide experimental support to the hypothesis that combined xanthorrhizol-curcumin showed synergistic growth inhibitory activity on MDA-MB-231 cells via apoptosis induction.

Anti-inflammatory Activity of Piper Magnibaccum (Piperaceae)

Anti-inflammatory activity of a crude extract of Piper magnibaccum (Piperaceae) and of compounds isolated from it was established using the TPA-induced mouse ear edema model and an in vitro quantitative lipoxygenase inhibition assay. Five compounds were isolated from P. magnibaccum [β-sitosterol, N-isobutyl-(2 E,4 E)-tetradecadienamide, linoleic acid, 13-(4′, 5′-dimethoxytridecanoyl)piperidine, and piperine]. The light petroleum extract of the plant exhibited significant anti-inflammatory activity in both models. N-isobutyl-(2 E,4 E)-tetradecadienamide showed significant activity, with an IE % value of 70.2 + 5.4 in the TPA-induced mouse ear edema model and 87.2 + 0.11 in the in vitro quantitative lipoxygenase inhibition assay.

Inhibitory effect of compounds from Zingiberaceae species on human platelet aggregation

Twelve compounds isolated from Alpinia mutica Roxb., Kaempferia rotunda Linn., Curcuma xanthorhiza Roxb., Curcuma aromatica Valeton and Zingiber zerumbet Smith (Family: Zingiberaceae) and three synthesized derivatives of xanthorrhizol were evaluated for their ability to inhibit arachidonic acid- (AA), collagen- and ADP-induced platelet aggregation in human whole blood. Antiplatelet activity of the compounds was measured in vitro by the Chrono Log whole blood aggregometer using an electrical impedance method. Among the compounds tested, curcumin from C. aromatica, cardamonin, pinocembrine and 5,6-dehydrokawain from A. mutica and 3-deacetylcrotepoxide from K. rotunda showed strong inhibition on platelet aggregation induced by AA with IC(50) values of less than 84 microM. Curcumin was the most effective antiplatelet compound as it inhibited AA-, collagen- and ADP-induced platelet aggregation with IC(50) values of 37.5, 60.9 and 45.7 microM, respectively.