Triterpenes from Angelica cartilagino-marginata var. foliata Yuan et Shan and their significance as chemosystematic characters

One new and three known triterpenes were isolated from roots of Angelica cartilagino-marginata var. foliata Yuan et Shan. The structures of the new compounds were determined by modern spectroscopic techniques, including 2D NMR experiments. These triterpenes are important characters in chemosystematics of Umbelliferae.     

Three triterpenes from Astraeus hygrometricus

Three new triterpenes, as well as two known steroids, were isolated fromAstraeus hygrometricus. The structures of the new triterpenes were established by chemical and spectroscopic means.     

Triterpenoids of Akebia quinata callus tissue

From tissue culture of Akebia quinata, three new triterpenes were isolated together with two known triterpenes, oleanolic acid and mesembryanthemoidgenic acid. The new triterpenes were characterized by spectroscopic means as 3β-hydroxy-30-norolean-12,20(29)-dien-28-oic acid, 3-epi-30-norolean-12,20(29)-dien-28-oic acid and 3β-hydroxy-29(or 30)-al-olean-12-en-28-oic acid.     

Composition of epicuticular wax layer of two species of Mandevilla (Apocynoideae,Apocynaceae) from Rio de Janeiro,Brazil

The chemical composition of epicuticular waxes of Mandevilla guanabarica and Mandevilla moricandiana was comparatively analyzed by extraction in n-hexane and chloroform. The mean wax content per unit of leaf area in the n-hexane extract was about 13–30 μg cm⁻² for M. guanabarica, containing 20–28% n-alkanes and 55–63% triterpenes; for M. mori-candiana, the mean content was 19 μg cm⁻², containing 73% n-alkanes and 14% triterpenes. In the chloroform extract, the wax yield was 40–80 μg cm⁻² for M. guanabarica, with about 9–11% n-alkanes and 75–82% triterpenes; while for M. moricandiana, the wax yield was 110 μg cm⁻², with 52% n-alkanes and 14% triterpenes. The major compounds identified were lupeol, pentacyclic triterpenes of the α- and β-amyrin class, and n-alkanes such as nonacosane, hentriacontane and tritriacontane. These results indicate that the quantitative chemical profiles of epicuticular waxes of M. guanabarica and M. moricandiana are distinct and could be used as an additional feature in taxonomic identification.     

Naphthoquinones and triterpenes from african Diospyros species

Investigation of the bark and/or wood of seventeen African species of Diospyros has revealed the presence of a number of triterpenes and naphthoquinones. The triterpenes lupeol, betulin and betulinic acid were detected in all samples but three other triterpenes were each found in only one species; betulinaldehyde in D. canaliculata, cerin in D. iturensis, and glutinol in D. zenkeri. Naphthoquinones were detected in fourteen of the seventeen species and the common dimeric compounds diospyrin, isodiospyrin and diosindigo-A were isolated. D. canaliculata differed from all other species in producing derivatives of plumbagin including its reduced form, isoshinanolone (1R,2R) and a novel stereoisomer which was given the trivial name epiisoshinanolone (1S,2R).     

Hopane triterpenes as chemotaxonomic markers for the scale insect pathogens Hypocrella s. lat. and Aschersonia

The scale insect pathogens Hypocrella s. lat. and their Aschersonia anamorphs, collected at various locations in Thailand, were surveyed for their productivity of three hopane triterpenes, zeorin (6α,22-dihydroxyhopane), dustanin (15α,22-dihydroxyhopane), and 3β-acetoxy-15α,22-dihydroxyhopane, when cultured in a liquid medium (potato-dextrose broth) under static conditions. Among 53 strains of Aschersonia species, 48 strains (91 %) produced at least one of these compounds. Hypocrella and Moelleriella species (43 strains) also frequently produced these triterpenoids; only two strains lacked all of these triterpenes. The results demonstrate that hopane triterpenes may be suitable for use as chemotaxonomic markers for Hypocrella and Moelleriella species and their Aschersonia anamorphs.     

Triterpenoid-biosynthetic UDP-glycosyltransferases from plants

Triterpenoid saponins are naturally occurring structurally diverse glycosides of triterpenes that are widely distributed among plant species. Great interest has been expressed by pharmaceutical and agriculture industries for the glycosylation of triterpenes. Such modifications alter their taste and bio-absorbability, affect their intra?/extracellular transport and storage in plants, and induce novel biological activities in the human body. Uridine diphosphate (UDP)-glycosyltransferases (UGTs) catalyze glycosylation using UDP sugar donors. These enzymes belong to a multigene family and recognize diverse natural products, including triterpenes, as the acceptor molecules. For this review, we collected and analyzed all of the UGT sequences found in Arabidopsis thaliana as well as 31 other species of triterpene-producing plants. To identify potential UGTs with novel functions in triterpene glycosylation, we screened and classified those candidates based on similarity with UGTs from Panax ginseng, Glycine max, Medicago truncatula, Saponaria vaccaria, and Barbarea vulgaris that are known to function in glycosylate triterpenes. We highlight recent findings on UGT inducibility by methyl jasmonate, tissue-specific expression, and subcellular localization, while also describing their catalytic activity in terms of regioselectivity for potential key UGTs dedicated to triterpene glycosylation in plants. Discovering these new UGTs expands our capacity to manipulate the biological and physicochemical properties of such valuable molecules.     

Antitumour triterpenes of Maytenus diversifolia

The known compounds maytansine and sitosterol-β-D-glucoside as well as the new triterpenes maytenfoliol and maytenfolic acid were isolated as antileukemic agents from Maytenus diversifolia. Other triterpenes isolated included the new maytensifolin-A and -B as well as the known friedelin, canophyllal, β-amyrin, canophyllol, pachysonol, 29-hydroxyfriedelan-3-one and 30-hydroxyfriedelan-3-one.     

The pentacyclic triterpene Esters and the free,esterified and glycosylated sterols of Sorghum vulgare grain

The free, esterified and glycosylated sterols and triterpene esters of Sorghum vulgare grains were analysed by GLC. 4-Demethylsterols were found free, esterified and glycosidated. 4-Monomethyl-sterols were found completely free whilst the triterpenes were completely esterified. Three quarters of the total sterols in the grain were located in the embryo whilst the triterpenes were equally distributed between the embryo and endosperm.     

Inhibition of Human Neutrophil Elastase by Pentacyclic Triterpenes

Scope

Inhibiting human neutrophil elastase (HNE) is a promising strategy for treating inflammatory lung diseases, such as H1N1 and SARS virus infections. The use of sivelestat, the only clinically registered synthesized HNE inhibitor, is largely limited by its risk of organ toxicity because it irreversibly inhibits HNE. Therefore, potent reversible HNE inhibitors are promising alternatives to sivelestat.

Methods and Results

An in vitro HNE inhibition assay was employed to screen a series of triterpenes. Six pentacyclic triterpenes, but not tetracyclic triterpenes, significantly inhibited HNE. Of these pentacyclic triterpenes, ursolic acid exhibited the highest inhibitory potency (IC₅₀ = 5.51 µM). The HNE inhibitory activity of ursolic acid was further verified using a mouse model of acute smoke-induced lung inflammation. The results of nuclear magnetic resonance and HNE inhibition kinetic analysis showed that the pentacyclic triterpenes competitively and reversibly inhibited HNE. Molecular docking experiments indicated that the molecular scaffold, 28-COOH, and a double bond at an appropriate location in the pentacyclic triterpenes are important for their inhibitory activity.

Conclusion

Our results provide insights into the effects of pentacyclic triterpenes on lung inflammatory actions through reversible inhibition of HNE activity.     

Gas chromatography-mass spectrometry of oleanane- and ursane-type triterpenes—application to Chenopodium quinoa triterpenes

Nine trimethylsilylated pentacyclic triterpenes were separated by GLC on an OV-101 column employing temperature programming. Characteristic retro-Diels-Alder fragmentation was observed in their mass spectra. The fragmentation patterns allowed individual characterization except for certain isomers which, nevertheless, were resolved by GLC, thus permitting their identification. Oleanolic acid and hederagenin were confirmed to be major triterpenes of Chenopodium quinoa seed saponins.     

Chemical constituents from Salacia amplifolia

The present phytochemical investigation on Salacia amplifolia led to the isolations of 13 triterpenes, including quinonemethides, friedelanes, oleananes and ursanes triterpenes, three simple phenolics, one polyol and one chromanone. All of them were isolated from this plant for the first time. The presences of quinonemethide triterpenoids might be employed as the common characteristic constituents of both Hippocrateaceae and Celastraceae families.     

Triterpenes and a triterpene glucoside from Dysoxylum cumingianum

Six triterpenes and a triterpene glucoside were isolated from the MeOH extract of the leaves of Dysoxylum cumingianum together with three known triterpenes. Their structures were elucidated by extensive spectroscopic analyses. In cytotoxicity assays against three human cancer cell lines, including a multi-drug resistant cancer cell line (KB-C2), compounds 1, 2 and 5 demonstrated significantly enhanced cytotoxicity against KB-C2 cells in the presence of 2.5 μM colchicine, as compared with those in the absence of colchicine. This result suggested that these triterpenes might show some MDR-reversing effects.     

Biosynthesis of sterols and triterpenes in Pelargonium hortorum

Although all parts of the geranium plant (Pelargonium hortorum) are capable of synthesizing sterols and triterpenes and their esters in vitro from mevalonic acid-[2-¹⁴C], the aerial portions are more active than other tissues. All plant parts were shown to incorporate mevalonic acid-[2-¹⁴C] into isoprenoids for at least 3 days. The leaves and petioles had the greatest incorporation on a wet weight basis. Chopped preparations showed comparable incorporations of mevalonate whereby rootlets incorporated about one half as much as most parts; the flower petals incorporated five times the average amount. In leaves the principal sterol synthesized was sitosterol. Metabolic studies with isolated leaves indicated a fairly rapid conversion of free tetracyclic triterpenes to 4-desmethyl-sterols, while β-amyrin was synthesized at a different rate than α-amyrin. Esterified tetracyclic triterpenes exhibited only a slight amount of conversion to 4-desmethylsterols.     

3β-hydroxy-21β-e-cinnamoyloxyolean-12-en-28-oic acid,a triterpenoid from enterolobium contorstisiliquum

The triterpenes 3β-hydroxy-21β-E-cinnamoyloxyolean-12-en-20-oic acid, 3β,21β-dihydroxyolean-12-en-28-oic acid (machaerinic acid) and its lactone (3β-hydroxyolean-12-en-21β→28-lactone) were isolated from the fruits of Enterolobium contorstisiliquum. Methyl and ethyl esters of 3β,21β-dihydroxyolean-12-en-oic acid were isolated and characterized as artifacts. The structures of these triterpenes have been established by a study of their chemical and spectroscopic (IR, MS and NMR) data.     

Triterpenes of Lithocarpus species

The triterpenes of the five Lithocarpus species examined comprised members of the friedo- and unrearranged oleanane groups, viz. friedelin, friedelan-3β-ol, taraxerol and β-amyrin. Glutinol was also present, except in L. harlandi where friedelan-2α,3β-diol was found. In addition, three new cycloartane triterpenes, lithocarpolone (21,24-epoxy-24-hydroxymethyl-cycloartan-3-one), lithocarpdiol (21,24-epoxy-24-hydroxymethyl-cycloartan-3β-ol). and 24-methylenecycloartan-3β,21-diol were found in L. polystachya, and their structures determined.     

Labdane and eudesmane derivatives from Ageratum fastigiatum

Several diterpenes, triterpenes, ent-labdanes, and eudesmane derivatives have been isolated from Ageratum fastigiatum. A previously unknown eud     

Two eudesmanolides from Sonchus macrocarpus

The aerial parts of Sonchus macrocarpus afforded, in addition to known triterpenes, two new eudesmanolides.     

Triterpenes of Sarcostemma asclepiadaceae

A mixture of n-alkanes, four pentacyclic triterpenes, and the butyrate of germanicol were isolated and their structures established.     

Triterpenes from Ferula linkii

Two new natural triterpenes, 3β-acetoxyolean-9,12-diene and 3β-acetoxy-6β-hydroxyolean-9,12-diene, were isolated from Ferula linkii.