Diterpenoids from Salvia greggii

From the aerial part of Salvia greggii a previously known diterpenoid, isopimaric acid, and four new natural substances, 3β- and 14α-hydroxy-isopimaric acids, 14α,18-dihydroxy-7,15-isopimaradiene and 7,8β-dihydro-salviacoccin, have been isolated. The structures of these diterpenoids have been established by chemical and spectroscopic means and, in some cases, by comparison with previously known synthetic compounds.     

New labdane diterpenoids from Sideritis chamaedryfolia

From the aerial parts of Sideritis chamaedryfolia six previously known ent-kaurene diterpenoids have been isolated. In addition, seven new labdane derivatives have also been obtained from the same source. The structures of these new natural diterpenoids have been established by chemical spectroscopic means and by correlation with known products.     

Diterpenoids from Teucrium scorodonia, three neo-clerodane derivatives

From the aerial parts of Teucrium scorodonia the previously known diterpenoid teupolin I and the flavone luteolin have been isolated. In addition, three new neo-clerodane derivatives have also been obtained from the same source. The structures of these new natural diterpenoids have been established by chemical and spectroscopic means and by correlation with known products.     

Diterpenoids from Pinus massoniana resin and their cytotoxicity against A431 and A549 cells

Five diterpenoids and 14 known diterpenoids were isolated from the petroleum ether extract of Pinus massoniana resin. Their structures were elucidated by spectroscopic data interpretation. The cytotoxic activities of these compounds were evaluated using the MTT method. The results showed that three of the less polar diterpenoids had strong cytotoxicity against A431 and A549 cancer cells, whereas those of high polarity had none.     

Production of Bioactive Diterpenoids in the Euphorbiaceae Depends on Evolutionarily Conserved Gene Clusters

The Euphorbiaceae produce a diverse range of diterpenoids, many of which have pharmacological activities. These diterpenoids include ingenol mebutate, which is licensed for the treatment of a precancerous skin condition (actinic keratosis), and phorbol derivatives such as resiniferatoxin and prostratin, which are undergoing investigation for the treatment of severe pain and HIV, respectively. Despite the interest in these diterpenoids, their biosynthesis is poorly understood at present, with the only characterized step being the conversion of geranylgeranyl pyrophosphate into casbene. Here, we report a physical cluster of diterpenoid biosynthetic genes from castor (Ricinus communis), including casbene synthases and cytochrome P450s from the CYP726A subfamily. CYP726A14, CYP726A17, and CYP726A18 were able to catalyze 5-oxidation of casbene, a conserved oxidation step in the biosynthesis of this family of medicinally important diterpenoids. CYP726A16 catalyzed 7,8-epoxidation of 5-keto-casbene and CYP726A15 catalyzed 5-oxidation of neocembrene. Evidence of similar gene clustering was also found in two other Euphorbiaceae, including Euphorbia peplus, the source organism of ingenol mebutate. These results demonstrate conservation of gene clusters at the higher taxonomic level of the plant family and that this phenomenon could prove useful in further elucidating diterpenoid biosynthetic pathways.     

Diterpenoids from Sideritis foetens

From the aerial parts of Sideritis foetens, the previously known ent-13(16),14-labdadiene-6α,8α,18-triol (andalusol) has been isolated. In addition, two new natural andalusol monoacetates and the novel ent-6α-acetoxy-13(16),14-labdadiene-3β,8α-diol have also been obtained from the same source. The structures of these new diterpenoids have been established by chemical and spectroscopic means.     

Neo-clerodane diterpenoids from teucrium lepicephalum and teucrium buxifolium

Three new neo-clerodane diterpenoids, teulepicin, 19-acetylteulepicin and teulepicephin, have been isolated, together with the previously known flavone cirsiliol from the aerial parts of Teucrium lepicephalum. The structures of the diterpenoids were established by chemical and spectroscopic means and by correlation with known substances. In addition, 19-acetylteulepicin and the already known neo-clerodane diterpenoid 19-acetylgnaphalin have been isolated from the species T. buxifolium.     

Diterpenoids from the roots of Euphorbia ebracteolata and their anti-tuberculosis effects

Euphorbia ebracteolata was a natural medicine for the treatment of tuberculosis. The present work has performed the investigation of bioactive chemical substances from the roots of E. ebracteolata. Using various chromatographic techniques, 15 compounds were obtained from the roots of E. ebracteolata. On the basis of widely spectroscopic data analyses, the isolated compounds were determined to be diterpenoids, including rosane derivatives (1–12), isopimarane (13), abietane (14), and lathyrane (15), among which compounds 1–4, and 9 were undescribed previously. The inhibitory effects of isolated diterpenoids against Mycobacterium tuberculosis were evaluated using an Alamar blue cell viability assay. And two rosane-type diterpenoids 3 and 8 displayed moderate inhibitory effects on with the MIC values of 18 μg/mL and 25 μg/mL, respectively. For the potential inhibitor 3, the inhibitory effect against the target enzyme GlmU was evaluated, which displayed a moderate inhibitory effect with the IC₅₀ 12.5 μg/mL. Therefore, the diterpenoids from the roots of E. ebracteolata displayed anti-tuberculosis effects, which would be pay more attentions for the anti-tuberculosis agents.     

Flavonoids of Wyethia angustifolia and W. helenioides

Seventeen flavonoids, including seven new natural products, were isolated from a dichloromethane extract of Wyethia angustifolia. Known compounds are:8-C-prenyleriodictyol, 6-C-prenyleriodictyol, 8-C-prenylnaringenin, 6-C-prenylnaringenin, orobol 7-methyl ether, orobol 3′-methyl ether, naringenin 4′-methyl ether, orobol, eriodictyol and naringenin. The new compounds are 6-C-prenylorobol, 6-C-prenylorobol 3′-methyl ether, orobol 7,3′-dimethyl ether, 8-C-prenyldihydroisorhamnetin, 7,8-dihydrooxepinocriodictyol, 7,8-dihydrooxepinodihydroquercetin and 3′,4′-dihydrooxepino-6′-hydroxybutein. A dichloromethane extract of Wyethia heleniodes yielded eleven compounds only five of which were previously reported from the species. All these compounds appear to occur on the leaf surface.     

Cytotoxicity of abietane diterpenoids from Perovskia abrotanoides and of their semisynthetic analogues

Seven known abietane diterpenoids and 11-O- and 12-O-acetylcarnosic acids were isolated from a methanol extract of Perovskia abrotanoides (Labiatae). Structure and cytotoxic activity relationships (SAR) of the natural and semisynthetic analogues of the presently isolated abietane diterpenoids were studied by using P388 murine leukemia cells.     

Neo-clerodane diterpenoids from baccharis incarum

Five new neo-clerodane diterpenoids were isolated from Baccharis incarum. Their structures were established by spectroscopic methods.     

NO inhibitory diterpenoids as potential anti-inflammatory agents from Euphorbia antiquorum

Two new ent-atisane-type diterpenoids (1 and 2), three new lathyrane-type diterpenoids (3–5), and seven known analogues (6–12) were isolated from Euphorbia antiquorum. The structures of these diterpenoids were established by analysis of their NMR, MS, and electronic circular dichroism data. The anti-inflammatory activities were evaluated biologically and compounds 1, 4, 7, 8, and 10 displayed strong NO inhibitory effects with IC₅₀ values less than 40 μM. The potential anti-inflammatory mechanism was also investigated using molecular docking and Western blotting.     

Isolation,reactivity, pharmacological activities and total synthesis of hispanolone and structurally related diterpenes from Labiatae plants

Hispanolone is a furolabdane diterpene isolated from Ballota hispanica, whose natural product chemistry has been summarized and updated here, including several aspects associated with the isolation, structure determination, hemisynthesis, total synthesis, and pharmacology, and related hispanolone diterpenoids that have attracted the interest of different laboratories from diverse perspective and expertise in the last forty-two years.     

Unusual ent-atisane type diterpenoids with 2-oxopropyl skeleton from the roots of Euphorbia ebracteolata and their antiviral activity against human rhinovirus 3 and enterovirus 71

Two novel ent-atisane type diterpenoids possessing the extra unusal 2-oxopropyl moiety (1 and 2) and four known analogues have been isolated from the roots of Euphorbia ebracteolata. The structures and absolute configurations of these compounds were determined by extensive spectroscopic data analysis, including 2D NMR, single-crystal X-ray crystallography, ¹³C NMR calculation, and electronic circular dichroism spectra calculation. Compounds 1 and 2 are the first examples of natural products with ent-atisane type diterpenoids possessing 2-oxopropyl skeleton. Compounds 2, 3, 5, and 6 show antiviral activities against human rhinovirus 3, with IC₅₀ values of 25.27–90.35 μM. Compounds 5 and 6 showed moderate antiviral activities against EV71 at a concentration of 100 μM.     

Chemical study of the seeds of Erythrophleum ivorense A. Chev. (Fabaceae)

The Chemical study of methanolic extract of the seeds from Erythrophleum ivorense led to the isolation of one original cassane diterpenoid (1) along with six known cassane diterpenoids (2–7). In addition, the known compounds (2–7) are isolated for the first time in E. ivorense. Their structures were established according to their spectral data (NMR, HRESIMS, IR). This result confirms that cassane-type diterpenoids are one of the major constituents of Erythrophleum species. The identification of these compounds and their chemotaxonomic significance is discussed.     

Grindelane diterpenoids from grindelia squarrosa and G. Camporum

An acid fraction of the dichloromethane extract of Grindelia squarrosa and a neutral fraction of the ethyl acetate extract of Grindelia camporum yielded a number of previously known grindelane diterpenoids and flavonoids. Along with the known isolates, two new grindelane diterpenoids, 13-isogrindelic acid and 17-grindeloxy grindelic acid, from G. squarrosa were isolated and identified spectroscopically.     

Rearranged labdane diterpenoids from Galeopsis angustifolia

From the aerial part of Galeopsis angustifolia collected in Spain, a labdane and three rearranged labdane diterpenoids have been isolated. The structures of these new substances have been established by chemical and spectroscopic means and by correlation with known compounds. A sample of the same species collected in Italy and other species of Galeopsis showed some remarkable chemical differences. The taxonomic significance of these results is discussed briefly.     

Rearranged abietane diterpenoid hydroquinones from aerial parts of Ajuga decumbens Thunb

Four new rearranged abietane diterpenoid hydroquinones, ajudecumins A–D (1–4), together with two known rearranged abietane diterpenoids, three neo-clerodane diterpenoids, four megastigmane derivatives, two flavonoids as well as a bisabolene sesquiterpenoid were isolated from the aerial parts of Ajuga decumbens. Their structures were established on the basis of extensive spectroscopic analysis and the stereochemistry of 1 was confirmed by single-crystal X-ray diffraction analysis. Among the diterpenoids, compounds 1 and 3 exhibited moderate inhibitory activity on the proliferation of human breast cancer MCF-7 cells.     

Troupin,A 4-methylcoumarin from Tamarix troupii

Troupin has been isolated for the first time as a natural product from the leaves of Tamarix troupii along with some known compounds. Based on its spectral and analytical data and comparison with a synthesized sample, it has been assigned the structure 4-methyl-6-hydroxy-7,8-dimethoxycoumarin.     

Rare,seven-membered cyclic ether labdane diterpenoid from Dodonaea polyandra

Previous phytochemical studies on the leaf resin of dioecious plant species Dodonaea polyandra have identified the presence of furanoclerodane diterpenoids. As part of ongoing research on this species the chemical profile of an individual plant displaying male flowers was investigated. Repeated chromatographic separation of a resinous extract from the leaves of the plant yielded three labdane diterpenoids, 13,17-epoxy-13-methyl-15-oxo-labda-7-ene (1), 17-hydroxy-13-methyl-labda-7,13Z-diene-15-oic acid (2) and 13-methyl-17-oxo-labda-7,13Z-diene-15-oic acid (3) and a fourth known labdane diterpenoid (4) reported as being isolated from a natural source for the first time. Structural elucidation was carried out using conventional 1D and 2D NMR and mass spectrometry together with other complementary techniques (UV and IR). The leaf extract from this individual of D. polyandra with male flowers present displays a marked difference in the chemical composition of diterpenoids compared to previously studied extracts from the leaves of this species.