Pentacyclic triterpenoids from Embelia schimperi

Five oleanane-type pentacyclic triterpenoids were isolated by chromatographic separation of a chloroform extract of the stem bark of Embelia schimperi. Three of these compounds have a methyleneoxy bridge. Two compounds, embelinone and schimperinone, are reported here for the first time from a natural source (they have been synthesized previously during chemical transformations). Their structures were determined by spectroscopic techniques, among which 2-D NMR was useful for complete characterization. Three of the triterpenoids exhibited mild antibacterial properties against the gram-positive bacterial strain Rhodococcus sp.     

21beta-Hydroxy-oleanane-type triterpenes from Hippocratea excelsa

Stem bark of Hippocratea excelsa afforded six pentacyclic triterpenes, five oleanane and one ursane types. They were identified as 11beta,21beta-dihydroxy-olean-12-ene-3-one (2), 3alpha,11alpha,21beta-trihydroxy-olean-12-ene (3), 3alpha,21beta-dihydroxy-11alpha-methoxy-olean-12-ene (4), 3alpha,21beta-dihydroxy-olean-9(11),12-diene (5), 3alpha,21beta-dihydroxy-olean-12-ene (6) and 3alpha,21beta-dihydroxy-11alpha-methoxy-urs-12-ene, isolated as its diacetate derivative (7), as well as 3alpha,21beta-dihydroxy-olean-12-ene (1) previously isolated from the root bark. The known alpha- and beta-amyrin, oleanoic and ursolic acids, trans-polyisoprene, and the ubiquitous beta-sitosterol were also isolated. Structures were elucidated on the basis of spectroscopic analyses, including homo- and heteronuclear correlation NMR experiments (COSY, ROESY, HSQC and HMBC) and comparison with literature data. The antigiardial activity of compounds 2-5 was not significant.     

Antimicrobial activity of pentacyclic triterpenes isolated from African Combretaceae

Four pentacyclic tritepenes were isolated from Combretum imberbe Engl. & Diels, of which two are novel glycosidic derivatives of 1alpha,3beta,23-trihydroxyolean-12-en-29-oic acid (hydroxyimberbic acid). Terminalia stuhlmannii Engl. & Diels stem bark yielded two glycosides of hydroxyimberbic acid, one of which is reported for the first time. The structures of the isolated compounds were elucidated by spectroscopic methods. Several of the compounds had antibacterial activity, imberbic acid showing particularly potent activity against Mycobacterium fortuitum and Staphylococcus aureus.     

Flavonol and drimane-type sesquiterpene glycosides of Warburgia stuhlmannii leaves

An investigation of methanolic extract of Warburgia stuhlmannii leaves has led to the isolation of two new drimane-type sesquiterpene glycosides characterized as mukaadial 6-O-beta-D-glucopyranoside, mukaadial 6-O-alpha-L-rhamnopyranoside together with two other novel flavonol glycosides identified as 3',5'-O-dimethylmyricetin 3-O-beta-D-2",3"-diacetylglucopyranoside and 3'-O-methylquercetin 3-O-beta-D-2",3",4"-triacetylglucopyranoside. The known compounds; mukaadial, deacetylugandensolide, quercetin, kaempferol, kaempferol 3-O-alpha-L-rhamnopyranoside, quercetin 3-O-beta-D-glucopyranoside, kaempferol 7-O-beta-D-glucopyranoside, myricetin 3-O-alpha-L-rhamnopyranoside, quercetin 3-O-alpha-L-rhamnopyranoside, quercetin 3-O-sophoroside and isorhamnetin 3-O-beta-D-glucopyranoside were also isolated from the same extract.     

nor-Oleanene type triterpene glycosides from the leaves of Acanthopanax japonicus

Three new (1-3) and two known (4-5) triterpene glycosides were isolated from the leaves of Acanthopanax japonicus (Araliaceae) and elucidated structurally by mass, 1D, and 2D NMR spectroscopy. All the compounds possessed a nor-oleanene triterpene skeleton as the aglycone. The structures of 1-5 were established as 28-O-alpha-L-rhamno-pyranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranosyl ester of 3beta-hydroxy- 30-nor-olean-12,20(29)-diene-23,28-dioic acid, designated as acanjaposide A, 3beta- hydroxy-23-oxo-30-nor-olean-12,20(29)-diene-28-oic acid, named acanjaposide B, 3beta,20alpha-dihydroxy-23-oxo-30-nor-olean-12-en-28-oic acid, named acanjaposide C, and nipponoside E, a known saponin, respectively.     

Secondary metabolites from the leaves of Feijoa sellowiana Berg

The investigation of the lipid extract of leaves of Feijoa sellowiana cultivated along the east coast of Sicily has yielded in addition to the widespread secondary metabolites: alpha-tocopherol, flavone, stigmasterol and beta-carotene, an inseparable mixture of tyrosol esters of lignoceric (1a), cerotic (1b) and montanic (1c) acids, and a novel galactolipid identified as (2S)-1,2,6'-tri-O-[(9Z,12Z,15Z)-octadeca-9,12,15-trienoyl]-3-O-beta-D-galactopyranosyl glycerol (2).     

Tirucallane-type triterpenes from Juliania adstringens

Five tirucallane-type triterpenes were isolated along with nine known triterpenes from the bark of Juliania adstringens. The structures of the five triterpenes were determined by analysis of their 1H and 13C NMR and mass spectral data, and each compound exhibited growth inhibitory activity against leukemia cells (L-1210).     

Benzoquinone derivatives of Myrsine africana and Maesa lanceolata

The fruits of Myrsine africana afforded two new benzoquinone derivatives, methylvilangin and methylanhydrovilangin. On the other hand, from the fruits of Maesa lanceolata two more novel compounds; 2,5-dihydroxy-3-(nonadec-14-enyl)-benzoquinone and lanciaquinone were isolated. Their structural elucidation was achieved by spectroscopic measurements including 2D NMR experiments.     

Tirucallane triterpenes from the roots of Ozoroa insignis

Eight tirucallane triterpenes, methyl 3alpha,24S-dihydroxytirucalla-8,25-dien-21-oate (2), methyl 3alpha-hydroxy-24-oxotirucalla-8,25-dien-21-oate (3), methyl 3alpha-hydroxy-25,26,27-trinor-24-oxotirucall-8-en-21-oate (4), 3alpha,25-dihydroxy-24-(2-hydroxyethyl)-tirucall-8-en-21-oic acid (5), 3alpha,24S,25-trihydroxytirucall-8-en-21-oic acid (6), 3alpha,24R,25-trihydroxytirucall-8-en-21-oic acid (7), 3alpha,25-dihydroxytirucall-8-en-21-oic acid (8), and methyl 3alpha,25-dihydroxytirucall-8-en-21-oate (9), together with alpha-elemolic acid methyl ester (1), were isolated from the roots of Ozoroa insignis. Their structures were elucidated on the basis of spectroscopic evidence.     

Cytotoxic triterpenes from the aerial roots of Ficus microcarpa

Six triterpenes, 3beta-acetoxy-12,19-dioxo-13(18)-oleanene (1), 3beta-acetoxy-19(29)-taraxasten-20alpha-ol (2), 3beta-acetoxy-21alpha,22alpha-epoxytaraxastan-20alpha-ol (3), 3,22-dioxo-20-taraxastene (4), 3beta-acetoxy-11alpha,12alpha-epoxy-16-oxo-14-taraxerene (5), 3beta-acetoxy-25-methoxylanosta-8,23-diene (6) along with nine known triterpenes, 3beta-acetoxy-11alpha,12alpha-epoxy-14-taraxerene (7), 3beta-acetoxy-25-hydroxylanosta-8,23-diene (8), oleanonic acid (9), acetylbetulinic acid (10), betulonic acid (11), acetylursolic acid (12), ursonic acid (13), ursolic acid (14), and 3-oxofriedelan-28-oic acid (15) were isolated from the aerial roots of Ficus microcarpa, and their structures elucidated by spectroscopic methods. The in vitro cytotoxic efficacy of these triterpenes was investigated using three human cancer cell lines, namely, HONE-1 nasopharyngeal carcinoma, KB oral epidermoid carcinoma, and HT29 colorectal carcinoma cells. Compound 8 and pentacyclic triterpenes 9-15 possessing a carboxylic acid functionality at C-28 showed significant cytotoxic activities against the aforementioned cell lines and gave IC50 values in the range 4.0-9.4 microM.     

Tirucallane triterpenes from the leaf extract of Entandrophragma angolense

From the leaves of Entandrophragma angolense, three triterpenoidal compounds were isolated and structurally elucidated by mass and NMR spectroscopy. They belong to the tirucallane group but two of them possess the rare seco-ring-A feature. The phytochemical data are discussed from a chemotaxonomic and biogenetic points of view.     

Pentacyclic triterpenes from Euphorbia stygiana

Two pentacyclic triterpenes, D-friedomadeir-14-en-3beta-yl acetate and D:C-friedomadeir-7-en-3beta-yl acetate, named madeiranyl acetate and isomadeiranyl acetate, respectively, were isolated from leaves of Euphorbia stygiana, together with the two known madeiranes, D-friedomadeir-14-en-3-one and D:C-friedomadeir-7-en-3-one, which were obtained from the stem bark. In addition, four known lupane and taraxerane-type triterpenes, namely lupenyl acetate, lupenone, taraxeryl acetate and taraxerone, were also isolated from the same source. Structures were elucidated by physical, chemical and spectroscopic methods (1H NMR, 13C NMR, IR and mass spectra) and by comparison with literature data, and in the case of D:C-friedomadeir-7-en-3beta-yl acetate by X-ray analysis as well.     

Lipid peroxidation inhibitory compounds from daylily (Hemerocallis fulva) leaves

Daylilies (Hemerocallis spp.) have been used as food and in traditional medicine for thousands of years in eastern Asia. The leaves of the plant are used in the treatment of inflammation and jaundice. In studies of the aqueous methanol extracts of fresh Hemerocallis fulva leaves, 1',2',3',4'-tetrahydro-5'-deoxy-pinnatanine (1), pinnatanine (2), roseoside (3), phlomuroside (4), lariciresinol (5), adenosine (6), quercetin 3-O-beta-D-glucoside (7), quercetin 3,7-O-beta-D-diglucopyranoside (8), quercetin 3-O-alpha-L-rhamnopyransol-(1-->6)-beta-D-glucopyranosol-7-O-beta-D-glucopyranoside (9), isorhamnetin-3-O-beta-D-6'-acetylglucopyranoside (10) and isorhamnetin-3-O-beta-D-6'-acetylgalactopyranoside (11) were isolated. All of these compounds were tested for their in vitro lipid peroxidation inhibitory activities. Compounds 3-5 and 7-11 were found to possess strong antioxidant properties, inhibiting lipid oxidation by 86.4, 72.7, 90.1, 79.7, 82.4, 89.3, 82.2, and 93.2%, respectively at 50 microg/mL. Compound 1 is novel and compounds 3-6 and 8-11 described here in are isolated for the first time from daylily leaves.     

Anti-inflammatory oleanane triterpenes from Tripterygium wilfordii cell suspension cultures by fungal elicitation

Summary Treatment of cell suspension cultures of Tripterygium wilfordii with an autoclaved Botrytis sp. homogenate rapidly increased the synthesis of a family of oleanane and friedelane triterpenes, including the antiinflammatory oleanane triterpene 3,22-dihydroxyolean-12-en-29-oic acid. This compound exceeded 30 mg · l^–1 in 13 day elicitations with 12 l bioreactors, in contrast to control levels of less than 5 mg · l^–1. Cell cultures treated with the fungal elicitor provided higher triterpene yields in less time than cultures in a diterpene production medium or whole plants. Elicited production has been developed for commercial application in light of the successful treatment of rheumatoid arthritis with Tripterygium extracts.     

Acylated anthocyanins from leaves of Oxalis triangularis

The novel anthocyanins, malvidin 3-O-(6-O-(4-O-malonyl-alpha-rhamnopyranosyl)-beta-glucopyranoside)-5-O-beta-glucopyranoside (2), malvidin 3-O-(6-O-alpha-rhamnopyranosyl-beta-glucopyranoside)-5-O-(6-O-malonyl-beta-glucopyranoside) (3), malvidin 3-O-(6-O-(4-O-malonyl-alpha-rhamnopyranosyl)-beta-glucopyranoside)-5-O-(6-O-malonyl-beta-glucopyranoside) (4), malvidin 3-O-(6-O-(4-O-malonyl-alpha-rhamnopyranosyl)-beta-glucopyranoside) (5) and malvidin 3-O-(6-O-(Z)-p-coumaroyl-beta-glucopyranoside)-5-O-beta-glucopyranoside (6), in addition to the 3-O-(6-O-alpha-rhamnopyranosyl-beta-glucopyranoside)-5-O-beta-glucopyranoside (1) and the 3-O-(6-O-(E)-p-coumaroyl-beta-glucopyranoside)-5-O-beta-glucopyranoside (7) of malvidin have been isolated from purple leaves of Oxalis triangularis A. St.-Hil. In pigments 2, 4 and 5 a malonyl unit is linked to the rhamnose 4-position, which has not been reported previously for any anthocyanin before. The identifications were mainly based on 2D NMR spectroscopy and electrospray MS.     

Microwave-assisted extraction of embelin from <Emphasis Type="Italic">Embelia ribes</Emphasis>

A rapid and efficient microwave-assisted extraction (MAE) process for the selective extraction of embelin from Embelia ribes was developed. Solvent selection, microwave energy input and solid loading were optimized. The rate of extraction and purity of embelin depended upon the solvent used and exposure time to microwaves. Maximum MAE was achieved in acetone with total yield of 92% (w/w) embelin with 90% (w/w) purity with 1% (w/v) raw material loading at 150 W power level in 80 s. Non-polar solvents, such as hexane and dichloromethane, were not effective for the selective extraction of embelin.     

Oleanane-type triterpenes from the flowers, pith, leaves, and fruit of Tetrapanax papyriferus

Four oleanane-type triterpenes, 3alpha,21beta,22alpha-trihydroxy-11,13(18)-oleanadien-28-oic acid (1), 3-epi-papyriogenin C (2), 21-O-acetyl-21-hydroxy-3-oxo-11,13(18)-oleanadien-28-oic acid (3) and 3beta-hydroxy-21-oxo-11,13(18)-oleanadien-28-oic acid methyl ester (4), together with four known triterpenes, were isolated from Tetrapanax papyriferus (Hook) K. Koch. Papyriogenin A (8) exhibited anti-HIV activity and low cytotoxicity in acutely infected H9 lymphocytes. Their structures were determined by analysis of spectroscopic data, including by 1D and 2D NMR.     

Isolation and structure determination of triterpenes from Iris tectorum

Four iridal-type triterpenoids, two of which were new compounds, have been isolated from rhizomes of Iris tectorum Maxim. Their structures were determined by 1D and 2D NMR spectroscopy and ESI-MS spectrometry. The compounds were identified as the iritectols A and B, and the known iridobelamal A and isoiridogermanal. The presence of epoxide and tetrahydrofuran functions are not common in previously isolated iridal-type triterpenoids.