[show abstract][hide abstract] ABSTRACT: A chemical study of the Vietnamese plant species Trigonostemon howii led to the isolation of a new tigliane-type diterpenoid, trigowiin A (1), along with several known coumarins and phenylpropanoids. The planar structure and the relative configuration of compound 1 were elucidated based on spectroscopic analysis, including 1D- and 2D-NMR experiments, mass spectrometry, and comparison with literature data. Trigowiin A (1) exhibited moderate antiviral activity in a virus-cell-based assay for Chikungunya virus (CHIKV). Since the structure of compound 1 is closely related to those of well-known tigliane diterpenoids such as prostratin (2), phorbol (3), 12-O-tetradecanoylphorbol 13-acetate (TPA) (4), and 4α-TPA (5), the antiviral activity of the latter compounds was also evaluated against CHIKV, as well as in virus-cell-based assays of two additional members of the genus Alphavirus (Sindbis virus, SINV, and Semliki forest virus, SFV). Whereas prostratin inhibited CHIKV replication with a moderate EC(50) of 2.6 μM and a selectivity index (SI) approximating 30, compound 4 proved to be an extremely potent inhibitor, with an EC(50) of ∼3 nM and a SI near 2000. Interestingly, no or very little activity was observed on the replication of SINV and SFV.
Journal of Natural Products 12/2012; · 3.29 Impact Factor
[show abstract][hide abstract] ABSTRACT: Three new compounds, goniotamirine (1), goniotamiric acid (2), and 3,5-demethoxypiperolide (3) were isolated from the leaves of Goniothalamus tamirensis (Annonaceae), together with sixteen known compounds, (−)-N-nornuciferine (4), (−)-norisocorydine (5), (−)-isocorydine (6), (−)-3-hydroxynornuceferine (7), (−)-O-methylisopiline (8), (−)-anonaine (9), (−)-roemerine (10), (−)-roemeroline (11), (−)-boldine (12), glaunine (13), liriodenine (14), 9-deoxygoniopypyrone (15), 8-epi-9-deoxygoniopypyrone (16), 8-epi-9-deoxygoniopypyrone acetate (17), goniodiol (18) and goniothalamin (19). The structures were established from spectral analysis, including mass spectrometry and 2D-NMR. The absolute configuration of 1 was determined from analysis of its MTPA amide derivatives. The cytotoxicity of all isolates was evaluated against KB cells. Only compound 4 (N-nornuciferine) showed a moderate activity with an IC50 value of 12 μg/mL.
[show abstract][hide abstract] ABSTRACT: Bioassay-guided fractionation of an extract of leaves of Macaranga kurzii yielded four new compounds, a stilbene (furanokurzin, 1) and three flavonoids (macakurzin A-C, 2-4). Nine known compounds were also isolated (5-13). Their structures were determined by spectroscopic analyses including MS and 2D NMR. The isolates were all evaluated for acetylcholinesterase inhibitory activity. Compound 6 (trans-3,5-dimethoxystilbene) exhibited the greatest activity (IC(50) 9 μM). Cytotoxic evaluation against KB cells showed that compound 7 had an IC(50) of 4 μM, followed by 11 (IC(50) 10 μM) and 3 (IC(50) 13 μM).
Journal of Natural Products 11/2012; · 3.29 Impact Factor
[show abstract][hide abstract] ABSTRACT: Two new aryl-tetralin lignans, 1 and 2, were isolated from the fruits of Cleistanthus indochinensis by bioassay-guided purification. Their structures were determined by spectroscopic analysis including MS and 2D NMR. The absolute configurations of 1 and 2 were established from examination of their CD spectra. Compound 1 was cytotoxic against KB cells with an IC(50) value of 0.022 μM, while compound 2 had weaker cytotoxicity, with an IC(50) value of 1.4 μM. When tested against other cancer cell lines (MCF-7, MCF-7R, and HT29), 1 showed an IC(50) of 0.014 against MCF-7R cells and an IC(50) of 0.036 μM against MCF-7 cells. A series of amide derivatives of a new lactone, homoderivatives of 1, were prepared. Of these derivatives, only compound 3 had weak cytotoxicity against KB cells.
Journal of Natural Products 08/2012; 75(9):1578-83. · 3.29 Impact Factor
[show abstract][hide abstract] ABSTRACT: An extract of Styrax agrestis fruits, collected in Vietnam, significantly inhibited acetylcholinesterase (AChE) in vitro. Bioassay-guided fractionation revealed three new egonol-type benzofurans: egonol-9(Z),12(Z) linoleate (1), 7-demethoxyegonol-9(Z),12(Z) linoleate (2), and 7-demethoxyegonol oleate (4). Ten known egonol-type benzofurans were also isolated (3, 5, 6-13). In order to better understand structure-activity relationships in this series, egonol derivatives 14-19 were prepared by chemical modifications and evaluated for their inhibition of AChE, butyrylcholinesterase (BChE), and AChE-induced Aβ aggregation. Compounds 1-4 were the most potent inhibitors of the series, which exhibited inhibitory activity against AChE (IC50 1.4-3.1 μM) and, for 1, Aβ aggregation (77.6%). Molecular docking studies were also performed to investigate interaction of these compounds with the active site of AChE.
Journal of Natural Products 09/2011; 74(10):2081-8. · 3.29 Impact Factor
[show abstract][hide abstract] ABSTRACT: The Derris genus is known to contain flavonoid derivatives, including prenylated flavanones and isoflavonoids such as rotenoids, which are generally associated with significant biological activity.
To develop an efficient preparative isolation procedure for bioactive cajaflavanone.
Fast centrifugal partition chromatography (FCPC) was optimised to purify cajaflavanone from Derris ferruginea stems in a single step as compared to fractionation from the cyclohexane extract by successive conventional solid-liquid chromatography procedures. The purification yield, purity, time and solvent consumption per procedure are described. The anti-fungal, anti-bacterial, anti-leishmanial, anti-plasmodial, anti-oxidant activities and the inhibition of advanced glycation end-products (AGEs) by cajaflavanone accumulation are described.
FCPC enabled cajaflavanone purification in a single separation step, yielding sufficient quantities to perform in vitro biological screening. Interestingly, cajaflavanone had an inhibitory effect on the formation of AGEs, without displaying any in vitro anti-oxidant activity.
A simple and efficient procedure, in comparison with other preparative methods, for bioactive cajaflavone purification has been developed using FCPC.
[show abstract][hide abstract] ABSTRACT: Four new steroids, 3-epi-gitingensine (1), N-acetylgitingensine (6), kibalaurifoline (7) and kibalaurifenone (8), along with the known paravallarine (2), 7α-hydroxyparavallarine (3), gitingensine (4), and N-methylgitingensine (5) were isolated from the leaves of Kibatalia laurifolia. Their structures were determined primarily from mass spectrometry and 2D NMR analyses. On the basis of the known absolute configurations of 2 and 4, the absolute configurations of the new compounds were proposed. Due to the structural relationships of compounds 1-8, a biosynthetic pathway was suggested. Compound 2 was cytotoxic to KB cells (IC50 12.8 μM), followed by 1 with IC50 21.2 μM.
Journal of Natural Products 03/2011; 74(5):1236-40. · 3.29 Impact Factor
[show abstract][hide abstract] ABSTRACT: Two new lignans, palatiferin A (1) and palatiferin B (2), were isolated from the roots of Pseuderanthemum palatiferum, together with five known triterpenes, epifriedelanol (3), lupeol (4), lupenone (5), betulin (6), pomolic acid (7), and a dipeptide asperglaucide (8). Their structures were established from 2D NMR and mass spectroscopy. The absolute configuration of 1 and 2 was proposed based on the comparison of their optical rotation activities with those of compounds with similar structures such as wodeshiol and paulownin. The new lignans, palatiferin A (1) and palatiferin B (2) exhibited a moderate cytotoxicity against KB and HepG2 cell lines. However, betulin and lupeol, two abundant compounds from the roots of P. palatiferum, showed cytotoxic and antimicrobial activities.
[show abstract][hide abstract] ABSTRACT: Two polyketide metabolites, nhatrangins A (1) and B (2), were isolated from a Vietnamese collection of Lyngbya majuscula. These compounds are related to the aplysiatoxin series of metabolites, which have also been isolated from this species of marine cyanobacterium. The use of 900 MHz cryoprobe NMR allowed the elucidation of the 2D structure of 1 from approximately 0.3 mg of compound. LC-MS analysis was utilized to direct the isolation of additional material as well as the isolation of 2. Conformational analysis was completed using J-based coupling constant analysis and selective NOE experiments.
Journal of Natural Products 04/2010; 73(4):784-7. · 3.29 Impact Factor
[show abstract][hide abstract] ABSTRACT: Two new compounds, an isoflavone (1, 6-methoxybarbigerone) and a bipterocarpan (2, pachylobin) were isolated from the grains of Millettia pachyloba (Leguminosae), together with seven known compounds, 5-methoxybarbigerone (3), calopogoniumisoflavone B (4), durmillone (5), jamaicin (6), ichthynone (7), (-)-pisatin (8) and (-)-rotenone (9). The structures were established from spectroscopic analyses, including mass spectrometry and 2D-NMR. Absolute configuration of 2 was proposed based on that of the known compound (-)-pisatine (8). Compounds 1 and 2 exhibited cytotoxicity against KB cells with IC(50) values of 2.0 and 17.6 µM, respectively.
[show abstract][hide abstract] ABSTRACT: In continuation of our efforts to find new antimalarial drugs, a systematic IN VITRO evaluation using a chloroquine resistant strain of PLASMODIUM FALCIPARUM (FcB1) was undertaken on extracts prepared from various parts of Vietnamese plants. The ethyl acetate extract obtained from the stem bark of ARTOCARPUS STYRACIFOLIUS (Moraceae) exhibited strong antiplasmodial activity (87 % at 10 µg/mL) whereas weak cytotoxicity was observed in a human fibroblast cell line (MRC-5). Phytochemical investigation of this extract led to isolation of two new prenylated flavonoids, styracifolins A and B ( 1 and 2), as well as the known artoheterophyllin A ( 3) and B ( 4), artonins A ( 5), B ( 6), and F ( 7), and heterophyllin ( 8). Structures of 1 and 2 were elucidated by spectroscopic methods and through comparison with data reported in the literature. Compounds 1- 8 exhibited antiplasmodial activities with IC (50) values ranging from 1.1 µM to 13.7 µM, and compounds 1, 2, 6, and 8 showed significant antitrypanosomal activities.
[show abstract][hide abstract] ABSTRACT: In an effort to discover potent inhibitors of the antiapoptotic protein Bcl-xL, a systematic in vitro evaluation was undertaken on extracts prepared from various parts of Vietnamese plants. The ethyl acetate extracts obtained from the leaves and flowers of Combretum sundaicum and the leaves of Lantana camara were selected for their interaction with the Bcl-xL/Bak association. Bioassay-guided purification of these species led to the isolation of 15 pentacyclic triterpenoids (1-15) possessing olean-12-en-28-oic acid and olean-12-en-29-oic acid aglycons, of which compounds 1-6 and 8-10 are new. Five compounds exhibited binding activity with K(i) values between 5.3 and 17.8 microM. The cytotoxic activity of 1-15 was also evaluated on various cancer cell lines.
Journal of Natural Products 08/2009; 72(7):1314-20. · 3.29 Impact Factor
[show abstract][hide abstract] ABSTRACT: Two new compounds, a cyclic peptide desmocyclopeptide (1) and a special flavone desmorostratone (2) were isolated from the stem bark of Desmos rostrata, along with two known compounds, desmosdumotins B (3) and C (4). Their structures were established on the basis of the spectral data, including mass spectrometry and 2D NMR. The total synthesis of desmorostratone (2) was performed in order to confirm its structure as well as that of desmosdumotin C (4), which was a tautomeric mixture in the solution. Finally, cytotoxity of these compounds were evaluated. Desmosdumotin C (4) displayed a moderate inhibition activity against KB cell line with an IC50 of 19.2μM, whereas the other products showed a weak inhibition against the same cell line target.