Antibacterial diterpenoids from Fabiana densa var. ramulosa

A biologically monitored fractionation of the resinous exudate of Fabiana densa Remy var. ramulosa Wedd. led to the isolation of the two new diterpenes: ent-beyer-15-en-18-O-succinate and ent-beyer-15-en-18-O-oxalate as the unique compounds responsible for the observed antibacterial activity of this extract. Their structures were determined by 1D and 2D NMR spectroscopy.     

Cytotoxic diterpenoids from Euphorbia pekinensis

A new diterpenoid, named euphpekinensin, along with three known diterpenoids, was isolated from the roots of Euphorbia pekinensis for the first time and the structures were elucidated by spectral analysis. The 2D-NMR techniques such as 1H-1H COSY, HMQC, HMBC and NOESY spectra were mainly applied to determine the structure of the new diterpenoid. The four diterpenoids showed cytotoxic activity against human KB cells in vitro.     

Cytotoxic diterpenoids from Isodon enanderianus

Five new ent-kaurane diterpenoids, enanderianins K-O (1-5), and one new ent-abietane diterpenoid, enanderianin P (6), together with five known ent-kaurane diterpenoids, rabdocoetsin A (7), rabdocoetsin B (8), rabdocoetsin D (9), megathyrin A (10), megathyrin B (11) were isolated from the aerial parts of Isodon enanderianus. Their structures were determined by spectral means. Some diterpenoids were tested for their cytotoxicity against the human tumor K562 cells. Compounds 1, 2, 6, 8, 9 showed significant inhibitory activities against K562 cells with IC50 values ranging from 0.13 to 0.87 microg/mL.     

New diterpenoids from Sapium discolor

Abstract

Chemical fractionation of the ethanolic extract generated from the twigs and leaves of Sapium discolor led to the isolation and identification of four new macrocyclic diterpenoids including three members of the rare casbane family, sapidisins A-C (1–3), and an analog of the cembrane class, sapidisin D (4), a new 3,4-seco ent-kaurane diterpenoid (5), and 18 known phenolic compounds. Their structures were elucidated by comprehensive spectroscopic analyses especially 1D NMR ¹H-¹H couplings and 2D NMR ROESY data. The discovery of 1–4 from S. discolor provides a clue for further study on the biogenetic evolution of the widely existent tigliane-type diterpenoids in the Sapium species.     

New diterpenoids from Semiaquilegia adoxoides

Two new ent-kaurane-type diterpenoids, E-semiaquilegin (1) and Z-semiaquilegin (2), together with eight known compounds (3-10) were isolated from the dried roots of Semiaquilegia adoxoides (DC.) Makino. The structures of compounds 1 and 2 were elucidated mainly by 2D NMR techniques including 1H-1H COSY, HSQC, HMBC, NOESY as 16alpha-hydroxy-ent-kaurane-17,20-di-(3,4-dihydroxy-E-cinnamoyl) ester and its (Z)-isomer.     

Cytotoxic diterpenoids from Pteris ensiformis

Phytochemistry investigation on Pteris ensiformis led to the isolation of a new ent-kaurane diterpenoid, ent-kaurane-6β,16α-diol-3-one (1), along with five known diterpenoids (2–6) and three known sesquiterpenes (7–9). Their structures were established by means of spectroscopic methods. The ethanol extract and the isolated compounds (1–9) were evaluated for their antitumor activity against three cancer cell lines.     

Neoclerodane diterpenoids from Scutellaria barbata

Eight new neoclerodane diterpenoids (1- 8), scutebatas H-O, together with eight known compounds, have been isolated from the whole plant of Scutellaria barbata D. Don. Their structures were elucidated on the basis of spectroscopic studies. In vitro cytotoxicity of selected compounds against cancer cell lines HL-60, SMMC-7721, A-549, MCF-7, and SW480 was evaluated. Compounds 5, 6, 7 showed moderate cytotoxicities against several human cancer cell lines, with IC50 values ranging from 12.6-31.4?μM. In addition, compound 1 showed selective cytotoxicity against MCF-7.     

New diterpenoids from Semiaquilegia adoxoides

Two new ent-kaurane-type diterpenoids, E-semiaquilegin (1) and Z-semiaquilegin (2), together with eight known compounds (3–10) were isolated from the dried roots of Semiaquilegia adoxoides (DC.) Makino. The structures of compounds 1 and 2 were elucidated mainly by 2D NMR techniques including ¹H–¹H COSY, HSQC, HMBC, NOESY as 16α-hydroxy-ent-kaurane-17,20-di-(3,4-dihydroxy-E-cinnamoyl) ester and its (Z)-isomer.     

Two new diterpenoids from Coleus forskohlii

Two new diterpenoids, forskolins I and J, have been isolated in our further investigation on Coleus forskohlii (Willd.) Briq. collected in Yunnan Province. Their structures have been determined as 1alpha,6beta-diacetoxy-7beta,9alpha-dihydroxy-8,13-epoxylabd-14-en-11-one (1) and 1alpha,9alpha-dihydroxy-6beta,7beta-diacetoxy-8,13-epoxylabd-14-en-11-one (2) by spectral methods (including 1D and 2D NMR techniques).     

Novel antimicrobial diterpenoids from Turraeanthus africanus

The dichloromethane-methanol (1/1) extract of the stem bark of Turraeanthus africanus (Meliaceae) showed remarkable antimicrobial activity against Cryptococcus neoformans, Staphylococcus aureus and methicillin-resistant S. aureus. Phytochemical investigation of this extract afforded six new diterpenoid derivatives, (+)-16-acetoxy-12,15-epoxylabda-8(17),12,14-triene ( 3), [16( E),12 S,15 R]-16-acetoxy-12,15-epoxy-15-isopropoxy- ent-labda-8(17),13(16)-diene (turraeanin A, 4), [16( E),12 R,15 S]-16-acetoxy-12,15-epoxy-15-isopropoxy- ent-labda-8(17),13(16)-diene (turraeanin B, 5), [16( E),12 S,15 R]-16-acetoxy-12,15-epoxy-15-methoxy- ent-labda-8(17),13(16)-diene (turraeanin C, 6), [16( E),12 R,15 S]-16-acetoxy-12,15-epoxy-15-methoxy- ent-labda-8(17),13(16)-diene (turraeanin D, 7) and (12 S,13 S,15 R)-12,15-epoxy-15-methoxy- ent-labd-8(17)-en-16-al (turraeanin E, 9) together with the known compounds, 15,16-epoxy- ent-labda-8(17),13(16),14-triene ( 1), (+)-pumiloxide ( 2), ent-labda-8(17),12 ( E)-diene-15,16-dial ( 8) and 16-acetoxy-12( R),15-epoxy-15beta-hydroxylabda-8(17),13 (16)-diene ( 10). Compound 10 was obtained as its acetoxy derivative ( 10a) and compound 11 was the product of hydrolysis of 6. Antimicrobial activity of the isolates was assayed and compounds 8, 9, 10a and 11 exhibited significant activities.     

Rearranged abietane diterpenoids from Clerodendrum mandarinorum

Five new abietane derivatives which have a commonly rearranged abietane skeleton contained a 17(15 → 16),18(4 → 3)-diabeo-abietane framework, mandarones D-H, were isolated from the stem of Clerodendrum mandarinorum Diels (Verbenaceae). The structures were characterized as (16S)-12,16-epoxy-11-hydroxy-17(15 → 16),18(4 → 3)-diabeo-abieta-3,5,8,11,13-pentaene-7-one (mandarone D, 1), 12,16-epoxy-11,14-dihydroxy-17(15 → 16),18(4 → 3)-diabeo-abieta-3,5,8,11,13,15-hexaene-7-one (mandarone E, 2), 12,16-epoxy-6,11,14-trihydroxy-17(15 → 16),18(4 → 3)-diabeo-abieta-3,5,8,11,13,15-hexaene-7-one (mandarone F, 3), 12,16-epoxy-11,14-dihydroxy-6-methoxy-17(15 → 16),18(4 → 3)-diabeo-abieta-3,5,8,11,13,15-hexaene-2,7-dione (mandarone G, 4) and 12,16-epoxy-11,14-dihydroxy-17(15 → 16),18(4 → 3)-diabeo-abieta-3,5,8,11,13,15-hexaene-1,7-dione (mandarone H, 5) respectively, mainly based on the spectral analysis and by comparison with those of closely related compounds.     

Two new diterpenoids from coleus forskohlii

Two new diterpenoids, forskolins I and J, have been isolated in our further investigation on Coleus forskohlii (Willd.) Briq. collected in Yunnan Province. Their structures have been determined as 1α,6β-diacetoxy-7β,9α-dihydroxy-8,13-epoxylabd-14-en-11-one (1) and 1α,9α-dihydroxy-6β,7β-diacetoxy-8,13-epoxylabd-14-en-11-one (2) by spectral methods (including 1D and 2D NMR techniques).     

Six new diterpenoids from Croton laevigatus

Abstract

Six new ent-labdane-type diterpeniods (1?6), along with one known compound, were identified from the twigs and leaves of Croton laevigatus. Their structures were elucidated on the basis of extensive spectroscopic interpretation. Compounds 2 and 7 showed inhibitory activity against protein tyrosine phosphatase 1B (PTP1B) with IC₅₀ values of 4.11 and 8.33 μg/ml, respectively.     

Cytotoxic ent-kaurane diterpenoids from Isodon macrophyllus

Two new ent-kaurane diterpenoids, dayecrystals D–E (1–2), together with nine known compounds, isojaponin A (3), rabdosin A (4), lushanrubescensin J (5), wikstroemioidin B (6), maoyecrystal C (7), rabdosin B (8), isodonal (9), shikokianin (10), and effusanin A (11), were isolated from the leaves of Isodon macrophyllus. The structures of the new compounds were elucidated using 1D and 2D NMR spectroscopy. The ¹³C-NMR spectral data of compound 4 are reported for the first time. All of the compounds were tested for their cytotoxicities against DU145 and LoVo human tumor cells. Compounds 4, 10, and 11 showed inhibitory effects on DU145 cells with IC₅₀ values 5.90, 4.24, and 3.16 μM, and LoVo cells with IC₅₀ values 14.20, 17.55, and 3.02 μM, respectively.     

Three new diterpenoids from Aralia dumetorum

Three new diterpenoids, dumetoranes A (1) and B (2), melanocane B (3), together with four known ones including melanocane A (4), ent-15S,16-dihydroxypimar-8(14)-en-19-oic acid (5), ent-pimara-8(14),15-diene-19-oic acid (6), and ent-pimara-8(14),15-diene-19-ol (7) were obtained from the ethanol extract of the roots of Aralia dumetorum. Their structure elucidation was achieved by the methods of spectroscopic HRMS, IR, NMR, and by comparison with literature. The cytotoxicities of compounds 1–3 and 5 were assayed by in vitro MTT methods.     

Two new diterpenoids from Croton crassifolius

Two new clerodane-type diterpenoids were isolated from the roots of Croton crassifolius Geisel. The structures of these compounds were elucidated as 9-[2-(2(5H)-furanone-4-yl)ethyl]-4,8,9-trimethyl-1,2,3,4,5,6,7,8-octahydronaphthalene-4-carboxylic acid (1) and methyl 9-[2-(2(5H)-furanone-4-yl)ethyl]-4,8,9-trimethyl-1,2,3,4,5,6,7,8-octahydronaphthalene-4-carboxylic ester (2) by spectroscopic methods.     

Cytotoxic ent-kaurane diterpenoids from Isodon sculponeata

Four new ent-kaurane diterpenoids, sculponeatins F-I (1-4), together with six known compounds, sculponeatin E (5), epi-nodosin (6), epi-nodosinol (7), enmein (8), and macrocalyxoformins A and B (9 and 10), were isolated from the leaves of Isodon sculponeata. Also obtained were ursolic acid, 2alpha,3beta-dihydroxy-urs-12-en-28-oic acid, 2alpha,3beta,19alpha-trihydroxy-urs-12-en-28-oic acid, beta-sitosterol, daucosterol, quercetin, pedalitin, rosmarinic acid, caffeic acid and ethyl caffeic acid. Their structures were determined by spectral methods (1D-, 2D-NMR and MS). Some diterpenoids were tested for their cytotoxicity to inhibit three kinds of human tumor cells K562, A549 and T24. Compounds 3, 4, 6, 8, and 10 showed significant inhibitory effect toward K562 with IC(50) values ranging from 3.2 microg/ml to 8.2 microg/ml, while 3 and 6 exhibited potent antitumor activity against T24, but none exhibited cytotoxicity toward the cells of A549.     

New macrocyclic diterpenoids from Euphorbia esula

The structures of two new macrocyclic jatrophane diterpenoid esters from the whole herb of Euphorbia esula, were established as 11,14-epoxy-3beta,5alpha,7beta,8alpha,9alpha,15beta-hexaacetoxy-12-oxo-13alphaH-jatropha-6(17)-ene (1) and 1alpha,3beta-diacetoxy-5alpha,7beta-dibenzoyloxy-9,14-dioxo-11beta,12alpha-epoxy-2alpha,8alpha,15beta-trihydroxy-13betaH-jatropha-6(17)-ene (2) by a combination of 1D- and 2D-NMR techniques as well as UV, IR and mass spectral data. Bioassay evaluation of all isolates against the human tumor cell lines (B16, KB, SMMC and BGC) indicated that ester 2 was cytotoxic to B16 with the IC50 value being 1.81 microg/ml. In addition, the irritant activity assay indicated that both diterpenoids were inactive (ID(24)50 > 100 microg/ear).     

Bioactive ent-clerodane diterpenoids from Scutellaria barbata

Four new ENT-clerodane diterpenoids were isolated from the whole plant of Scutellaria barbata D. Don. (Labiatae). Their structures were elucidated by chemical methods and spectral analyses. in vitro, the four new compounds showed significant cytotoxic activities against three human cancer lines (HONE-1 nasopharyngeal, KB oral epidermoid carcinoma, and HT29 colorectal carcinoma cells), and gave IC50 values in the range 3.1-7.2 microM.