Vergatic acid,a new pentacyclic triterpene from Salvia virgata

A new pentacyclic triterpene acid was isolated from the arial parts of Salvia virgata and its constitution was established as 3β-hydroxy-1-oxo-olean-12-en-28-oic acid and named virgatic acid.     

Ent-kauren-19-oic acid derivatives from the stem bark of Croton pseudopulchellus Pax

Two new ent-kauren-19-oic acid derivatives, ent-14S*-hydroxykaur-16-en-19-oic acid and ent-14S*,17-dihydroxykaur-15-en-19-oic acid together with eleven known compounds ent-kaur-16-en-19-oic acid, ent-kaur-16-en-19-al, ent-12β-hydroxykaur-16-en-19-oic acid, ent-12β-acetoxykaur-16-en-19-oic acid, 8R,13R-epoxylabd-14-ene, eudesm-4(15)-ene-1β,6α-diol, (?)-7-epivaleran-4-one, germacra-4(15), 5E,10(14)-trien-9β-ol, acetyl aleuritolic acid, β-amyrin, and stigmasterol were isolated from the stem bark of Croton pseudopulchellus (Euphorbiaceae). Structures were determined using spectroscopic techniques. Ent-14S*-hydroxykaur-16-en-19-oic acid, ent-kaur-16-en-19-oic acid, ent-12β-hydroxykaur-16-en-19-oic acid, ent-12β-acetoxykaur-16-en-19-oic acid and 8R,13R-epoxylabd-14-ene were tested for their effects on Semliki Forest virus replication and for cytotoxicity against human liver tumour cells (Huh-7 strain) but were found to be inactive. Ent-kaur-16-en-19-oic acid, the major constituent, showed weak activity against the Plasmodium falciparum (CQS) D10 strain.     

Plectranthoic acid,acetylplectranthoic acid and plectranthadiol,three triterpenoids from Plectranthus rugosus

Sitosterol and three new pentacyclic triterpenoids, plectranthoic acid, acetylplectranthoic acid and plectranthadiol, have been isolated from leaves of P. rugosus. From spectroscopic evidence and chemical behaviour the structure of plectranthoic acid was established as (19S)-3α-hydroxy-18α-urs-12-en-29β-oic acid and acetylplectranthoic acid is the 3α-acetyl derivative of this compound. Plectranthadiol is (19S)- 3α-hydroxy-18α-urs-12-en-29β-ol.     

The potential of Cyathus africanus for transformation of terpene substrates

The insecticidal sesquiterpenes cadina-4,10(15)-dien-3-one and aromadendr-1(10)-en-9-one were administered to the fungus Cyathus africanus ATCC 35853. Biotransformation of the former produced (4R)-9α-hydroxycadin-10(15)-en-3-one, while the latter gave 2β-hydroxyaromadendr-1(10)-en-9-one, 2α-hydroxyaromadendr-1(10)-en-9-one and 10α-hydroxy-1β,2β-epoxyaromadendran-9-one. The bioconversion of santonin led to the production of two analogues, 11,13-dihydroxysantonin and the hitherto unreported 8α,13-dihydroxysantonin, while cedrol yielded 3β,8β-dihydroxycedrane and 3α,8β-dihydroxycedrane. Stemod-12-ene, a diterpene, was transformed to 2-oxostemar-13-ene, a hitherto unknown analogue with a rearranged carbon framework. When methyl betulonate, a triterpenoid belonging to the lupane family, was supplied to the fungus 18α-ursane and 18α-oleanane derivatives, namely 19β-hydroxy-3-oxo-18α-oleanan-28-oic acid and 19α-hydroxy-3-oxo-18α-ursan-28-oic acids, were generated. There are no previous reports of fungal transformation of a triterpene in which a skeletal rearrangement occurred. All substrate administration experiments were done in the presence of the terpene cyclase inhibitor chlorocholine chloride (CCC), using the single phase – pulse feed method.     

The microbiological transformation of some ent-beyerene diterpenoids by Gibberella fujikuroi to beyergibberellins and beyerenolides

The microbiological transformation by Gibberelia fujikuroi of ent-beyer-15-ene into the beyergibberellins A₉ and A₁₃, 7β-hydroxy- and 7β,18-dihydroxybeyerenolides, and of ent-beyer-15-en-19-ol into beyergibberellins A₄, A₇, A₉, A₁₃ and A₂₅,and 7β-hydroxy-and 7β,18-dihydroxybeyerenolides is described. In contrast, ent-beyer-15-en-18-ol gave _ent-7α, 18,19-trihydroxybeyer-15-ene, 7β,18-dihydroxybeyerenolide and _ent-7α,18-dihydroxybeyer-15-en-19-oic acid again revealing the inhibitory effect of an 18-hydroxyl group on oxidative transformations at C-6β by Gibberella fujikuroi.     

Trihydroxy-C18-acids and a labdane from rudbeckia fulgida

Extraction of Rudbeckia fulgida furnished 13αH-labd-8(17)-en-15-al-19-oic acid, two new C₁₈-acids tentatively formulated as 9 (S*),12 (S*),13 (S*)-trihydroxyoctadeca-10(E),15 (Z)-dienoic acid and 9 (S*),12 (S*),13 (S*)-trihydroxyoctadec-10 (E)-enoic acid, several known C₁₄-polyacetylenes and several flavone glycosides.     

Narcissiflorine,narcissiflorinine and narcissifloridine,three triterpene saponins from Anemone narcissiflora

Narcissiflorine, narcissiflorinine and narcissifloridine, three new saponins, have been isolated from the ethanolic extract of Anemone narcissiflora (Ranunculaceae). The structural elucidation of narcissiflorine, narcissiflorinine and narcissifloridine has showed them to be [α-l-arabinofuranosyl-(1 → 4)-β-d-glucuronopyranosyl-(1→3)]- 3β-hydroxy-olean-12-en-28-oic acid, [α,-l-arabinofuranosyl-(1→2)-α-l-rhamnopyranosyl-(1→4)-β-d- glucuronypyranosyl(1→3)]-3-β-hydroxy-olean-12-en-28-oic acid and [α-l-arabinofuranosyl-(1→2)-α-l- rhamnopyranosyl-(1→4)-β-d-glucopyranosyl-(1→3)]-3-β-hydroxy-olean-12-en-28-oic acid, respectively.     

Differential metabolism of diastereoisomeric diterpenes by Preussia minima,found as endophytic fungus in Cupressus lusitanica

The plant diastereoisomeric diterpenes ent-pimara-8(14)-15-dien-19-oic acid, obtained from Viguiera arenaria, and isopimara-8(14)-15-dien-18-oic acid, isolated from Cupressus lusitanica, were distinctly functionalized by the enzymes produced in whole cell cultures of the fungus Preussia minima, isolated from surface sterilized stems of C. lusitanica. The ent-pimaradienoic acid was transformed into the known 7β-hydroxy-ent-pimara-8(14)-15-dien-19-oic acid, and into the novel diterpenes 7-oxo-8 β-hydroxy-ent-pimara-8(14)-15-dien-19-oic and 7-oxo-9β-hydroxy-ent-pimara-8(14)-15-dien-19-oic acids. Isopimara-8(14)-15-dien-18-oic acid was converted into novel diterpenes 11α-hydroxyisopimara-8(14)-15-dien-18-oic acid, 7β,11α-dihydroxyisopimara-8(14)-15-dien-18-oic acid, and 1β,11α-dihydroxyisopimara-8(14)-15-dien-18-oic acid, along with the known 7β-hydroxyisopimara-8(14)-15-dien-18-oic acid. All compounds were isolated and fully characterized by 1D and 2D NMR, especially ¹³C NMR. The diterpene bioproduct 7-oxo-9β-hydroxy-ent-pimara-8(14)-15-dien-19-oic acid is an isomer of sphaeropsidin C, a phytotoxin that affects cypress trees produced by Shaeropsis sapinea, one of the main phytopathogen of Cupressus. The differential metabolism of the diterpene isomers used as substrates for biotransformation was interpreted with the help of computational molecular docking calculations, considering as target enzymes those of cytochrome P450 group.     

Triterpenoidal saponins of Pulsatilla koreana roots

Sixteen (1-16) triterpenoidal saponins were isolated from the roots of Pulsatilla koreana, of which four were determined as the previously unknown 23-hydroxy-3β-[(O-α-L-arabinopyranosyl)oxy]lup-20(29)-en-28-oic acid 28-O-β-D-glucopyranosyl ester (1), 23-hydroxy-3β-[(O-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosyl)oxy]lup-20(29)-en-28-oic acid 28-O-β-D-glucopyranosyl ester (2), 3β-[(O-α-L-rhamnopyranosyl-(1 → 2)-α-L-arabinopyranosyl)oxy]lup-20(29)-en-28-oic acid 28-O-β-D-glucopyranosyl-(1 → 6)-β-D-glucopyranosyl ester (3), and 3β-[(O-α-L-rhamnopyranosyl-(1 → 2)-O-[β-D-glucopyranosyl-(1 → 4)]-α-L-arabinopyranosyl)oxy]lup-20(29)-en-28-oic acid 28-O-α-L-rhamnopyranosyl-(1 → 4)-O-β-D-glucopyranosyl-(1 → 6)-β-D-glucopyranosyl ester (4), respectively, based on spectroscopic analysis. The inhibition of the lipopolysaccharide-induced nitric oxide production of sixteen isolated compounds was evaluated in RAW 264.7 cells at concentrations ranging from 1 μM to 100 μM.     

Stereochemistry of strictic acid and related furano-diterpenes from conyza japonica and grangea maderaspatana

Extraction of Conyza japonica gave strictic acid, ent-2β-hydroxy-15,16-epoxy-3,13(16),14-clerodatrien-18-oic acid and 5,7-dihydroxy-3,8,4′-trimethoxyflavone. Extraction of Grangea maderaspatana gave (-)-hardwickiic acid, ent-15,16-epoxy-1,3,13(16),14-clerodatetraen-18-oic acid and 3-hydroxy-8-acetoxypentadeca-1,9,14-trien-4,6-diyne. The structure of ent-2β-hydroxy-15,16-epoxy-3,13(16),14-cleroclatrien-18-oic acid was deduced by spectroscopic methods and by partial synthesis from (-)-hardwickiic acid and the stereochemistries of strictic acid and (ent-15,16-epoxy-1,3,13(16),14-clerodatraen-18-oic acid were established by correlation with ent-2β-hydroxy-15,16-epoxy-3,13(16),14-clerodatrien-18-oic acid.     

Diterpenoids from galeopsis angustifolia

The structures of two new diterpenoids, galeopsin and pregaleopsin, isolated from aerial parts of Galeopsis angustifolia (Labiatae) have been shown to be 8β-acetoxy-15,16-epoxy-9α-hydroxylabda-13(16),14-dien-7-one and 8β-acetoxy-9α,13R; 15,16-diepoxylabd-14-en-7-one, respectively, by chemical and spectroscopic studies. The previously known diterpenoid hispanolone (15,16-epoxy-9α-hydroxy-8α-labda-13(16),14-dien-7-one) has been also obtained from the same source. A thermal retroaldol reaction in the absence of solvent experienced by these 9-hydroxy-7-keto-labdanes is also described.     

Further triterpenoids and 13C NMR spectra of oleanane derivatives from Phytolacca acinosa

In addition to five known triterpenoids, namely acinosolic acid, phytolaccagenin, phytolaccagenic acid, esculentic acid and jaligonic acid, three new oleanane derivatives, designated as phytolaccagenin A, acinosolic acid A and acinosolic acid B, have been isolated and characterized from the defatted berries of Phytolacca acinosa. The new compounds have been identified as 3β-acetoxy-3β-methyloleanate-12-en-2β,23α-diol-28β-oic acid, 3β-acetoxy-28β-methyloleanate-12-en-2β-ol-30β-oic acid and 2β-acetoxy-28β-methyloleanate-12-en-3β-ol-30β-oic acid, respectively.     

Three new 18,19-seco-ursane glycosides from Elsholtzia bodinieri

Chromatographic separation of an extract of the aerial part of Elsholtzia bodinieri resulted in the isolation of three new 18,19-seco-ursane glycosides, bodiniosides E-G (1–3). Their structures were elucidated as 2α,12β,23-trihydroxy-3-(β-d-glucopyranosyl)-19-oxo-18,19-seco-urs-13(18)-en-28-O-β-d-glucopyranosyl ester (1), 3-β-d-glucopyranosyl-19-β-d-glucopyranosyl-12β,21-dihydroxy-18,19-seco-urs-13(18)-en-28-oic acid (2), and 2α,12β,21-trihydroxy-3-β-d-glucopyranosyl-19-β-d-glucopyranosyl-18,19-seco-urs-13(18)-en-28-oic acid (3), respectively, by extensive NMR techniques, including 1D- and 2D-NMR experiments, as well as comparing with spectral data with those of the known analogues.     

Triterpenoids from enkianthus campanulatus

From the leaves of Enkianthus campanulatus were isolated three new triterpenes, 3-oxo-19,23,24-trihydroxyurs-12-en-28-oic acid, 3β,6β, 19,23-tetrahydroxyurs-12-en-28-oic acid and 3β,6β,23-trihydroxyurs-12-en-28-oic acid.     

Periandrin II and IV,triterpene glycosides from Periandra dulcis

Investigation of the natural sweeteners of Periandra dulcis afforded new sweet triterpene glycosides, periandrin II (3-β-O-[β-d-glucuronopyranosyl-(1→-2)-β-d-glucuronopyranosyl]-25-formyl-olean-12(13)-en-30-oic acid) and periandrin IV (3-β-O-[β-d-glucuronopyranosyl-(1→2)-β-d-glucuronopyranosyl]-25-hydroxyolean-12(13)-en-30-oic acid). Evidence for the structures was obtained by correlation of their derivatives with known compounds.     

Isolation of anti-Candida albicans compounds from Markhamia obtusifolia (Baker) Sprague (Bignoniaceae)

An increase in clinical cases of Candidiosis globally as well as fungal resistance to drugs prompted the search for novel anti-Candida albicans agents from plant sources. Leaf extracts of Markhamia obtusifolia were screened for activity against C. albicans in vitro. An acetone extract obtained following serial exhaustive extraction contained mainly the active components with at least four active zones on the bioautogram. Bioassay guided fractionation of this extract led to the isolation of three compounds which inhibited the growth of three C. albicans strains. Based on spectroscopy studies (NMR and MS), the compounds were identified as 3β-hydroxyurs-12-en-28-oic acid, ursolic acid (1) 3β, 19α-dihydroxyurs-12-en-28-oic acid, pomolic acid (2) and 2β, 3β, 19α -trihydroxy-urs-12-en-28-oic acid, 2-epi-tormentic acid (3). The most active compound was 3β, 19α-dihydroxy-12-ursen-28-oic acid (2) with a minimum inhibitory concentration (MIC) value of 12.5 µg/mL for C. albicans isolated from dog and 25.0 µg/mL for C. albicans from cat and ATCC 90028 at 24 h following incubation. However, at 48 h of incubation MICs were > 400 µg/mL for all the three compounds isolated. This study indicated that M. obtusifolia could be a potential source of active principles against C. albicans.     

Labdane diterpenes from Cistus symphytifolius

The investigation of the aerial part of Cistus symphytifolius afforded, in addition to sitosterol, trimethoxykaempferol, cativic acid, labdenic acid, labdanolic acid and labdan-8α,15-diol, three new bicyclic diterpenes: cistadienic acid, cistenolic acid and labd-13(E)- ene-8α,15-diol. The structures of these were determined by spectral studies and correlations. CD spectral studies showed that cistenolic acid and salvic acid are enantiomeric compounds, so the stereochemistry of salvic acid (7α-hydroxy-labd-8(17)-ene-15-oic acid) should be changed to 7β-hydroxy-eperu-8(17)-ene-15-oic acid (7β-hydroxy-ent-labd-8(17)-ene-15-oic acid).     

锐尖山香圆叶中三萜类成分的研究

从锐尖山香圆(Turpinia arguta (Lindl.) Seem.)叶中分离得到了11个三萜类化合物。通过光谱分析,分别鉴定其结构为熊果酸(1), 3β,6β,23-trihydroxy-12-oleanen-28-oic acid (2), 3β,6β,23-trihydroxyurs-12-en-28-oic acid (3), 3β,6β,19α,23-tetrahydroxyurs-12-en-28-oic acid (4), 1 α, 3β,23-trihydroxy-12-oleanen-28-oic acid (5), arjunglucoside II (6), rosamultin (7), 3β-O-β-D-glucopyranoylcincholic acid (8), cinchonaglycoside C (9), mussaendoside S (10) 和3β-O-β-D-glucopyranosyl quinovic acid 28-O-β-D-glucopyranosyl ester (11)。除化合物1和6,其它化合物均为首次从山香圆叶中分离得到。     

Dammarane triterpenes from Cabralea canjerana (Vell.) Mart. (Meliaceae): Their chemosystematic significance

The stem of Cabralea canjerana (Vell.) Mart. yielded three new dammarane triterpenes 20S,24S-epoxy-7β,25-dihydroxy-3,4-secodammar-4(28)-en-3-oic acid, 20S,24S-epoxy-7β,15α,25-trihydroxy-3,4-secodammar-4(28)-en-3-oic acid and 20S,24R-epoxy-7β,22ξ,25-trihydroxy-3,4-secodammar-4(28)-en-3-oic acid, which were identified on the basis of spectroscopic methods. The known dammarane triterpenes ocotillone, eichlerianic acid, shoreic acid and the sterols sitosterol, campesterol, stigmasterol, sitostenone and stigmast-5-en-3-one were also isolated and identified. The branches yielded the above three known dammaranes and eichlerialactone. The dammaranes in C. canjerana display strong similarities with Trichilieae tribe, which contains several dammaranes. The data reported herein thus provide firm support for placing Cabralea within the subfamily Melioideae, Trichilieae tribe.     

Rivularinin,a new saponin from Anemone rivularis

A new saponin, rivularinin, has been isolated from the ethanolic extract of Anemone rivularis (Ranunculaceae). The saponin was shown to be [α-l-arabinofuranosyl(1→2)-α-l-rhamnopyranosyl (1→4)-β-d-glucopyranosyl(1→4)-β-d-glucuronopyranosyl(1→3)]-3β-hydroxy-olean-12-en-28-oic acid.