Five new seco-labdane-type diterpenoids from Caesalpinia latisiliqua.

Five new seco-labdane-type diterpenoids, caesalatisics A-E (1-5), were isolated from the leaves of Caesalpinia latisiliqua (Cav.) Hattink. Their chemical structures were determined using 1D and 2D NMR, mass spectra, and circular dichroism spectroscopies.

New Compounds and Potential Candidates for Drug Discovery from Medicinal Plants of Vietnam.

The study of natural products introduces interesting new bioorganic structures and potential candidates for the drug discovery stage in the development of innovative drugs. Vietnam enjoys a broad biodiversity of native plant species, microorganisms, marine organisms, and a long tradition of using herbal remedies. Thus, the study of medicinal plants in determining the basis of their efficacy and safety is an important task for modern researchers in Vietnam. The present review covers literature on new compounds elucidated from the systematic study of medicinal plants within some popular genera in Vietnam, as well as their significant biological activities.

A New Taraxastane-type Triterpenoid from Cleistocalyx operculatus.

Ten known compounds including a chalcone, a long-chain alcohol, two flavonols, and six triterpenoids/steroids together with a new taraxastane-type triterpenoid, named cleistocalyxin, were isolated from the leaves of Cleistocalyx operculatus. The structure of cleistocalyxin was determined on the basis of IR, MS and NMR spectroscopic methods.

Application of the taraxerane-oleanane rearrangement to the synthesis of seco-oleanane triterpenoids from taraxerone.

Synthetic oleananes and seco-oleananes form a group of promising anti-inflammatory and cancer chemopreventive agents with an excellent safety profile. These compounds are usually prepared by semi-synthesis from natural oleanane triterpenoids. Since a taraxer-14-ene was reported to be rearranged into an olean-12-ene under mild reaction conditions, a rapid synthesis of seco-oleananes from taraxerone, which is a readily available starting material, was explored by us. Treatment of taraxerone with m-chloroperoxybenzoic acid gave 14,15-epoxy lactones, which underwent the taraxerane-oleanane rearrangement leading to new seco-oleanane triterpenoids.

Three new eudesmanes from Artemisia japonica.

Three new eudesmanes, named artemisidiols A-C, together with eight known compounds, were isolated from the leaves of Artemisia japonica Thunb. (Asteraceae). Their structures were determined on the basis of spectroscopic data. Although oxygenated eudesmanes frequently occur in Asteraceae plants, the 1α,6α,8α-oxygenated pattern of artemisidiols A-C has not been previously reported.

Unexpected course of Beckmann rearrangement of taraxerone oxime with Ac2O/AcOH.

The chemistry of pentacyclic taraxerane-type triterpenoids has not been extensively studied. In the course of our synthesis of nitrogen-containing heterocyclic compounds from taraxerone using Beckmann rearrangement with Ac2O/AcOH as the rearrangement agent, unexpected synthetic pathways were discovered leading to new types of modified taraxerane skeletons.

A new guaianolide from Artemisia roxburghiana.

A new member of 5αH,6ßH,7αH,11αH-guaian-12,6α-olides, 11-epi-8α-hydroxyarborescin, together with a mixture of (24R)- and (24S)-cycloart-25-en-3b,24-diols, palmitic acid and 1-octacosanol were isolated from the leaves of Artemisia roxburghiana Bess. (Asteraceae) of Vietnam. Their structures were determined on the basis of spectroscopic methods.

One new and several minor diarylheptanoids from Amomum muricarpum.

A new natural diarylheptanoid, designated muricarpin, together with four diarylheptanoids were isolated from the rhizomes of Amomum muricarpum Elmer (Zingiberaceae) growing in Vietnam. Three known compounds, 1,7-bis(3,4-dihydroxyphenyl)heptan-3-yl acetate, 1-(4'-hydroxyphenyl)-7- (3″,4″-dihydroxyphenyl)heptan-3-yl acetate and 1-(3',4'-dihydroxyphenyl)-7-(4″-hydroxyphenyl)-heptan-3-one were isolated for the first time from the genus Amomum, meanwhile (5R)-5-hydroxy-1,7-bis(4-hydroxyphenyl)-heptan-3-one was found for the first time in plants. Their structures were determined using spectroscopic analyses.

New diarylheptanoids from Amomum muricarpum ELMER.

Two new diarylheptanoids, designated muricarpones A and B, together with three known diarylheptanoids, 1,7-di-(3',4'-dihydroxyphenyl)-4-hepten-3-one, 1-(3',4'-dihydroxyphenyl)-7-(4''-hydroxyphenyl)-4-hepten-3-one, and 1,7-bis(p-hydroxyphenyl)-4-hepten-3-one, were isolated from the rhizomes of Amomum muricarpum ELMER (Zingiberaceae). Their structures were determined using spectroscopic analyses.

Blockade of nuclear factor-kappaB signaling pathway and anti-inflammatory activity of cardamomin, a chalcone analog from Alpinia conchigera.

Nuclear factor-kappaB (NF-kappaB) and the signaling pathways that regulate its activity have become a focal point for intense drug discovery and development efforts. NF-kappaB regulates the transcription of a large number of genes, particularly those involved in immune, inflammatory, and antiapoptotic responses. In our search for NF-kappaB inhibitors from natural resources, we identified cardamomin, 2',4'-dihydroxy-6'-methoxychalcone, as an inhibitor of NF-kappaB activation from Alpinia conchigera Griff (Zingiberaceae). In present study, we demonstrated the effect of cardamomin on NF-kappaB activation in lipopolysaccharide (LPS)-stimulated RAW264.7 cells and LPS-induced mortality. This compound significantly inhibited the induced expression of NF-kappaB reporter gene by LPS or tumor necrosis factor (TNF)-alpha in a dose-dependent manner. LPS-induced production of TNF-alpha and NO as well as expression of inducible nitric-oxide synthase and cyclooxygenase-2 was significantly suppressed by the treatment of cardamomin in RAW264.7 cells. Also, cardamomin inhibited not only LPS-induced degradation and phosphorylation of inhibitor kappaBalpha (IkappaBalpha) but also activation of inhibitor kappaB (IkappaB) kinases and nuclear translocation of NF-kappaB. Further analyses revealed that cardamomin did not directly inhibit IkappaB kinases, but it significantly suppressed LPS-induced activation of Akt. Moreover, cardamomin suppressed transcriptional activity and phosphorylation of Ser536 of RelA/p65 subunit of NF-kappaB. However, this compound did not inhibit LPS-induced activation of extracellular signal-regulated kinase and stress-activated protein kinase/c-Jun NH(2)-terminal kinase, but significantly impaired activation of p38 mitogen-activated protein kinase. We also demonstrated that pretreatment of cardamomin rescued C57BL/6 mice from LPS-induced mortality in conjunction with decreased serum level of TNF-alpha. Together, cardamomin could be valuable candidate for the intervention of NF-kappaB-dependent pathological condition such as inflammation.

Chemical constituents of the essential oil from the bark of Cinnamomum illicioides A. Chev. from Vietnam.

The chemical constituents of the hydrodistilled essential oil from the bark of Cinnamomum illicioides A. Chev., Lauraceae, from Vietnam, have been studied by GC and GC-MS. Seventeen monoterpenoids, eugenol, and thirty-six sesquiterpenoids, accounting for 25, 41.2, and 27.9% of the oil, respectively, were identified. Terpinen-4-ol (10.4%), eugenol (41.2%), and δ-cadinene (5.6%) are the major components of the oil.

New megastigmane glucosides from Excoecaria cochinchinensis LOUR. var. cochinchinensis.

Two new megastigmane glucosides, called excoecariosides A and B were isolated from the leaves of a medicinal Vietnamese plant, Excoecaria cochinchinensis LOUR. var. cochinchinensis (Euphorbiaceae) together with seven known compounds. Their structures were elucidated by spectroscopic analyses and chemical reactions including the modified Mosher's method.

New bis-spirolabdane-type diterpenoids from Leonurus heterophyllus Sw.

Twelve natural bis-spirolabdane-type diterpenoids, including eight new, named leoheteronones A-E, 15-epileoheteronones B, D, and E, and four known leopersin B, 15-epileopersin B, leopersin C, and 15-epileopersin C, together with hispanone and galeopsin were isolated from the aerial parts of the medicinal plant Leonurus heterophyllus SW. (Lamiaceae) grown in Vietnam. Their structures were determined by spectroscopic analyses. The current study emphasized the accumulation of C-15 oxygenated bis-spirolabdane-type diterpenoids of both 13R and 13S configurations in L. heterophyllus.

New diarylheptanoids from Alpinia pinnanensis.

Three new diarylheptanoids, called alpinnanins A-C (1-3), together with two known chalcones, 2',4'-dihydroxy-6'-methoxychalcone and 4',6'-dimethylchalconaringenin, two known flavanones, alpinetin and naringenin 5-O-methyl ether, a known diarylheptanoid, (3S,5S)-trans-3,5-dihydroxy-1,7-diphenyl-1-heptene, stigmasterol and beta-sitosterol as a mixture, and beta-sitosterol 3-O-beta-D-glucopyranoside were isolated from the rhizomes of Alpinia pinnanensis T. L. WU et SENJEN (Zingiberaceae). Their structures were elucidated by spectroscopic analyses.

New labdane-type diterpenoids from Leonurus heterophyllus SW.

Five new natural labdane-type diterpenoids (5-9), designated leoheteronins A-E, together with four known diterpenoids (1-4), two phytosterols as a mixture of beta-sitosterol and stigmasterol, and the flavone genkwanin (10) were isolated from the aerial parts of Leonurus heterophyllus SW. (Lamiaceae) collected in northern Vietnam. Compound 1 was isolated for the first time from a Leonurus species, and 10 is considered to be a chemotaxonomic marker of the Leonurus genus. Their structures were determined using spectroscopic analyses.

NMR studies of darutoside, a rare ENT-pimarane glucoside.

NMR spectral data in various solvents (DMSO-d6, CD3OD, C5D5N) for the rare ent-pimar-8(14)-ene-15, 16-diol 3-O-beta-D-glucoside, darutoside, are reported. Complete assignments are made on the basis of 1D and 2D (COSY, HMQC, HMBC, NOESY) spectra.

ent-pimarane-type diterpenoids from Siegesbeckia orientalis L.

A new ent-pimarane glucoside, named hythiemoside B (4), was isolated from the aerial part of Siegesbecikia orientalis L. (Asteraceae) together with four known ent-pimarane-type diterpenoids: darutigenol (1), darutoside (2), hythiemoside A (3), and ent-(15R),16,19-trihydroxypimar-8(14)-ene 19-O-beta-D-glucopyranoside (5). The structure of the new compound was elucidated by spectroscopic analyses and chemical transformation. The NMR data of compounds 1 (1H-) and 5 (1H- and 13C-) were also compiled in this study on the basis of 2D experiments.

Four ent-kaurane-type diterpenoids from Croton tonkinensis Gagnep.

From the leaves of the endemic Vietnamese medicinal plant Croton tonkinensis GAGNEP. (Euphorbiaceae) the four new ent-kaurane-type diterpenoids ent-1alpha,14alpha-diacetoxy-7beta-hydroxykaur-16-en-15-one (1), ent-1alpha,7beta-diacetoxy-14alpha-hydroxykaur-16-en-15-one (2), ent-18-acetoxy-14alpha-hydroxykaur-16-en-15-one (3), and ent-(16S)-18-acetoxy-7beta-hydroxykauran-15-one (4) were isolated. Their structures were elucidated by spectroscopic analyses.

ent-Kaurane diterpenoids from croton tonkinensis inhibit LPS-induced NF-kappaB activation and NO production.

Four ent-kaurane diterpenoids including two known, ent-7alpha,14beta-dihydroxykaur-16-en-15-one (1) and ent-18-acetoxy-7alpha-hydroxykaur-16-en-5-one (2), and two new, ent-1beta-acetoxy-7alpha,14beta-dihydroxykaur-16-en-15-one (3) and ent-18-acetoxy-7alpha,14beta-dihydroxykaur-16-en-15-one (4), were isolated from the leaves of Croton tonkinensis in a search for inhibitors of NF-kappaB activation and nitric oxide production. These ent-kauranoids inhibited LPS-induced NF-kappaB activation in murine macrophage RAW264.7 cells at IC50 values between 0.07 and 0.42 microM. Consistently, the ent-kauranoids markedly reduced LPS-induced NO production in a comparable concentration-dependent manner.