Xenimanadins A-D, a family of xenicane diterpenoids from the Indonesian soft coral Xenia sp.

Four novel xenicane diterpenoids, xenimanadins A-D (1-4), characterized by the unusual 2,6-dimethoxytetrahydropyran functionality, have been isolated from the Indonesian soft coral Xenia sp., together with three known xeniolides. The stereostructure of these metabolites has been established through extensive interpretation of NMR data and application of the modified Mosher method. Xenimanadins were tested against tumor cell lines, revealing details about the cytotoxic potential of xenicane diterpenoids.     

Bioactive diterpenoid containing a reversible "spring-loaded" (E,Z)-dieneone Michael acceptor

Three new briarane diterpenoids, briareolate esters L-N (1-3), have been isolated from a gorgonian Briareum asbestinum. Briareolate esters L (1) and M (2) are the first natural products possessing a 10-membered macrocyclic ring with a (E,Z)-dieneone and exhibit growth inhibition activity against both human embryonic stem cells (BG02) and a pancreatic cancer cell line (BxPC-3). Briareolate ester L (1) was found to contain a "spring-loaded" (E,Z)-dieneone Michael acceptor group that can form a reversible covalent bond to model sulfur-based nucleophiles.     

Dichotellides A-E, five new iodine-containing briarane type diterpenoids from Dichotella gemmacea

Five new briarane type diterpenoids, dichotellides A−E (1−5), were isolated from the South China Sea gorgonian Dichotella gemmacea together with four known analogues (6−9). Compounds 1−5 represent the first examples of iodine-containing briarane type diterpenoids from nature. The structures of these diterpenoids were elucidated by spectroscopic analysis, including 1D, 2D-NMR, and HRESIMS, and the absolute configuration of 1 was further confirmed by single crystal X-ray diffraction analysis. All the isolates were evaluated for cytotoxicity activity against four human tumor cell lines, and only 3 exhibited marginal activity against SW1990 (human pancreatic cancer).     

Novel abietane diterpenoids and aromatic compounds from Cladonia rangiferina and their antimicrobial activity against antibiotics resistant bacteria

From Cladonia rangiferina were isolated two novel abietane diterpenoids, hanagokenols A (1) and B (2). Also in this investigation, four known abitetane diterpenoids (3-6), four known labdane diterpenoids (7-10), one known isopimarane diterpenoid (11), and six known aromatic compounds were isolated. These structures were elucidated primarily through extensive NMR experiments. Hanagokenol A (1) was a unique abietane diterpene having an ether linkage between C-6 and C-18 of sugiol. Hanagokenol B (2) is also a unique secoabietane diterpene, having gamma-lactone which occurred by cleavage and subsequently oxidation between C-6/C-7 of 12-hydroxydehydroabietinol. Furthermore, all the isolated compounds (1-17) were tested for the antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE).     

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.     

Castanolide and epi-castanolide, two novel diterpenoids with a unique seco-norabietane skeleton from Salviacastanea Diels f. pubescens Stib.

Castanolide (1) and epi-castanolide (2), two novel diterpenoids possessing a unique seco-norabietane skeleton, were isolated from Salviacastanea Diels f. pubescens Stib. Their structures and relative stereochemistry were elucidated by extensive NMR analysis and confirmed by single-crystal X-ray diffraction study. A possible biosynthetic pathway of these two compounds was also proposed.     

A novel sulfur-containing diterpenoid from Fritillaria anhuiensis

Two novel diterpenoids were isolated from the bulbs of Fritillaria anhuiensis S. C. Chen and S. E. Yin. Compound 1 was the first diterpenoid containing a sulfonyl group isolated from nature. Compound 2 was a novel kaurane-type diterpenoid. Their structures were determined by extensive spectroscopic analysis (IR, MS, NMR, and X-ray diffraction). Compound 1 significantly attenuated nitric oxide (NO) production of a macrophage cell line of Raw 264.7 cells stimulated with IFN-γ.     

Study of the secretion from a scale insect (Ceroplastes ceriferus) diterpenoids and sesterterpenoids

Structures of four new minor sesterterpenoids 1–3,18 and three new diterpenoids 12–14 isolated from the secretion of Ceroplastes ceriferus are described. All four sesterterpenoids are 14-membered monocyclic compounds; one of them has been chemically correlated with cericeroic acid¹ of proven absolute stereochemistry. The “cyclic wax” was a complex mixture of esters consisting of fatty acids (C₁₀-C₃₂) and unusual cyclic alcohols (diterpenoids and sesterterpenoids)     

Five new diterpenoids, viteagnusins A--E, from the fruit of Vitex agnus-castus

Two new halimane-type diterpenoids, viteagnusins A and B, and three new labdane-type diterpenoids, viteagnusins C, D, and E, were isolated from the fruit of Vitex agnus-castus L. (Chasteberry, Verbenaceae) along with two known diterpenoids. Their chemical structures were determined on the basis of spectroscopic data.     

Cytotoxic and apoptosis-inducing ent-kaurane-type diterpenoids from the Japanese liverwort Jungermannia truncata NEES

Five new ent-kaurane-type diterpenoids and a new gymnomitrane (=barbatane)-type sesquiterpenoid have been isolated from the Japanese liverwort Jungermannia truncata NEES, together with twelve previously known ent-kaurane-type diterpenoids. The structures of the new compounds were elucidated by two-dimensional (2D) NMR experiments and chemical reaction. Some of the isolated compounds showed cytotoxicity against human leukemia cell lines and induced apoptosis.     

Claoxylones A–I,prenylbisabolane diterpenoids with anti-Coxsackie B virus activity from the branches and leaves of Claoxylon polot

Nine new prenylbisabolane diterpenoids, claoxylones A–I (1–9), were isolated from the branches and leaves of Claoxylon polot. This is the first example of prenylbisabolane diterpenoids with furan and tetrahydrofuran rings. Their structures and relative configurations were established by spectroscopic and conformational analysis, and the absolute configurations were determined by single-crystal X-ray diffraction and electronic circular dichroism (ECD) analysis. Compounds 1–9 exhibited antiviral activity against Coxsackie B3 virus, with IC₅₀ values of 6.0–33.3 μM.     

Hookerianolides A-C: three novel casbane-type diterpenoid lactones from Mallotus hookerianus

Three highly oxidized casbane-type diterpenoids with unique α,β-unsaturated γ-lactones, named Hookerianolides A (1), B (2), and C (3), were isolated from the methylene chloride extracts of Mallotus Hookerianus. Their structures were elucidated based on NMR spectroscopic data and chemical conversions. The stereochemistry was confirmed by combination of ROESY correlations and CD analyses.     

Secoeuphoractin,a minor diterpenoid with a new skeleton from Euphorbia micractina

A minor diterpenoid with a novel carbon skeleton,secoeuphoractin(1),was isolated from an ethanol extract of the roots of Euphorbia micractina.Its structure including the absolute configuration was determined by extensive spectroscopic studies,especially by 2D NMR and CD data analysis,in combination with a plausible biosynthetic pathway associated with co-occurring diverse diterpenoids.This compound showed activity against HIV-1 replication with an IC_(50) value of 1.76 ± 0.61 μmol/L.     

Neoclerodanes from Teucrium orientale

Two new neoclerodane diterpenoids, 6-deacetyl-teucrolivin A (5) and 8beta-hydroxy-teucrolivin B (6), were isolated from the aerial parts of Teucrium orientale, along with four already known neoclerodane diterpenoids, teucrolivin A (1), teucrolivin B (2), teucrolivin C (3) and teucrolivin H (4), previously isolated from Teucrium oliverianum. Their structures were elucidated on the basis of spectroscopic evidence and chemical transformations. Compounds 1-3 were assayed for antifeedant activity against Spodoptera littoralis, S. frugiperda and Heliocoverpa armigera. Teucrolivin A was the most potent of the three compounds tested.     

Neoirieone,a diterpenoid of a new skeletal class from the red marine alga Laurencia cf. Irieii

Neoirieone, a dibrominated diterpenoid of a new skeletal class, related to the irieol diterpenoids, has been isolated from Laurencia cf. irieii. The structure of neoirieone was elucidated by x-ray crystallographic analysis of its corresponding reduction product, neoirieol ($\text{7}$.     

Two new icetexane diterpenoids from Salvia przewalskii

Two new icetexane diterpenoids, przewalskin C, D (1, 2), together with sixteen known diterpenoids, were isolated from Salvia przewalskii. Eight of known ones (compounds 3, 12-18) were reported firstly from this plant. To the best of our knowledge, it's the first report of icetexane diterpenoids from this plant. The identification and structural elucidation of these compounds were based on 1D- and 2D-NMR spectral data analysis.     

Three New Diterpenoids from Euphorbia sororia L.

Three new diterpenoids with jatrophane‐type skeleton, sororianolides A–C ( 1 – 3 , resp.), were isolated from Euphorbia sororia. The identification and structure elucidation of these compounds were based on 1D‐ and 2D‐NMR‐spectral data analysis. It was the first time to isolate diterpenoids in this species.     

13C‐NMR data of daphnane diterpenoids

Daphnane diterpenoids are mainly distributed in Thymelaeaceae and Euphorbiaceae and have various bioactivities. About 100 daphnane diterpenoids have been isolated from natural plants. In this review, we systematically summarize the ¹³C‐NMR data of daphnane diterpenoids isolated from natural plants over the past several decades and briefly discussed their biological activities and basic structural–activity relationship. Copyright © 2013 John Wiley & Sons, Ltd.     

Divergent Total Synthesis of Atisane‐Type Diterpenoids

Atisane‐type diterpenoids are the principal constituent of tetracyclic C₂₀‐diterpenoids, widely isolated from the plant kingdom with varying degrees of structural complexity and pharmacological activity. The tetracarbocyclic system with the unique bicyclo[2.2.2]octane skeleton of this natural product family has generated interest within the synthetic community. Divergent total synthesis is an effective tactic to synthesize several atisane‐type diterpenoids using structural interconversion from a common intermediate. This account summarizes the divergent total synthesis of atisane‐type diterpenoids.     

New ent-kaurene-type diterpenoids possessing cytotoxicity from the New Zealand liverwort Jungermannia species

Two new ent-kaurene-type and a new rearranged ent-kaurene-type diterpenoids possessing cytotoxicity against a human leukemia cell line have been isolated from the New Zealand liverwort Jungermannia species, together with previously known ent-kaurene-type diterpenoids. Their structures were established based on extensive NMR techniques.