Abietane Diterpenes from Medusantha martiusii and Their Anti-Neuroinflammatory Activity.

Seven new abietane diterpenoids, comprising medusanthol A-G (1-3, 5, 7-9) and two previously identified analogs (4 and 6), were isolated from the hexane extract of the aerial parts of Medusantha martiusii. The structures of the compounds were elucidated by HRESIMS, 1D/2D NMR spectroscopic data, IR spectroscopy, NMR calculations with DP4+ probability analysis, and ECD calculations. The anti-neuroinflammatory potential of compounds 1-7 was evaluated by determining their ability to inhibit the production of nitric oxide (NO) and the proinflammatory cytokine TNF-α in BV2 microglia stimulated with LPS and IFN-γ. Compounds 1-4 and 7 exhibited decreased NO levels at a concentration of 12.5 µM. Compound 1 demonstrated strong activity with an IC50 of 3.12 µM, and compound 2 had an IC50 of 15.53 µM; both compounds effectively reduced NO levels compared to the positive control quercetin (IC50 11.8 µM). Additionally, both compounds significantly decreased TNF-α levels, indicating their potential as promising anti-neuroinflammatory agents.

Modified ent-Abietane Diterpenoids from the Leaves of Suregada zanzibariensis.

The leaf extract of Suregada zanzibariensis gave two new modified ent-abietane diterpenoids, zanzibariolides A (1) and B (2), and two known triterpenoids, simiarenol (3) and ß-amyrin (4). The structures of the isolated compounds were elucidated based on NMR and MS data analysis. Single-crystal X-ray diffraction was used to establish the absolute configurations of compounds 1 and 2. The crude leaf extract inhibited the infectivity of herpes simplex virus 2 (HSV-2, IC50 11.5 µg/mL) and showed toxicity on African green monkey kidney (GMK AH1) cells at CC50 52 µg/mL. The isolated compounds 1-3 showed no anti-HSV-2 activity and exhibited insignificant toxicity against GMK AH1 cells at ≥100 µM.

Pharmacokinetic characterization of carnosol from rosemary (Salvia Rosmarinus) in male C57BL/6 mice and inhibition profile in human cytochrome P450 enzymes.

Rosemary (Salvia Rosmarinus) is a rich source of dietary diterpenes with carnosol as one of the major polyphenols used to standardize rosemary extracts approved as a food preservative, however, at present there is not any information on the murine pharmacokinetic profile of carnosol or its potential for drug interactions. The present study utilizes cell-free, cell-based, and animal-based experiments to define the pharmacokinetic profile of the food based phytochemical carnosol. Mice were administered carnosol (100 mg/kg body weight) by oral gavage and plasma levels were analyzed by LC-MS/MS to establish a detailed pharmacokinetic profile. The maximum plasma concentration exceeded 1 µM after a single administration. The results are significant as they offer insights on the potential for food-drug interactions between carnosol from rosemary and active pharmaceutical ingredients. Carnosol was observed to inhibit selected CYP450 enzymes and modulate metabolic enzymes and transporters in in vitro assays.

Diterpenoids with Aromatase Inhibitory Activity from the Rhizomes of Kaempferia elegans.

Investigation of bioactive compounds from the rhizomes of Kaempferia elegans led to the isolation and characterization of ten new diterpenoids, namely, five 12,13-seco-diterpenoids named elegansins A-E (1-5) and five new abietanes, elegansols A-E (6-10), together with seven known diterpenoids (11-17). The structure elucidation of the new compounds was achieved by HRESIMS, NMR, and ECD spectroscopic analysis. Compounds (1-5) are the first examples of 12,13-seco-diterpenoid-type compounds representing a decalin fused dihydropyran skeleton. Plausible biosynthetic pathways for compounds 1-5 are proposed. Aromatase inhibitory activities of all compounds were evaluated, and abieta-8,11,13-trien-11-ol (16) was found to be the most potent aromatase inhibitor with an IC50 value of 3.7 µM.

Taichunins E-T, Isopimarane Diterpenes and a 20-nor-Isopimarane, from Aspergillus taichungensis (IBT 19404): Structures and Inhibitory Effects on RANKL-Induced Formation of Multinuclear Osteoclasts.

Fifteen new isopimarane-type diterpenes, taichunins E-S (1-15), and a new 20-nor-isopimarane, taichunin T (16), together with four known compounds were isolated from Aspergillus taichungensis (IBT 19404). The structures of these new compounds were determined by NMR and mass spectroscopy, and their absolute configurations were analyzed by NOESY and TDDFT calculations of ECD spectra. Taichunins G, K, and N (3, 7, and 10) completely inhibited the receptor activator of nuclear factor-κB ligand (RANKL)-induced formation of multinuclear osteoclasts in RAW264 cells at 5 µM, with 3 showing 92% inhibition at a concentration of 0.2 µM.

(9ßH)- and 17-Nor-Pimaranes from Icacina oliviformis.

Eleven pimarane-type diterpenoids were isolated from the tubers of Icacina oliviformis, including three new compounds, icacinlactone M (9), icacinlactone H 2-O-ß-d-glucopyranoside (10), and icacinlactone N 3-O-ß-d-glucopyranoside (11), together with an artifact of acrenol (8). Among the known structures, icacinlactone A (2), icacinlactone B (3), icacinlactone H (4), 12-hydroxyicacinlactone A (5), 14α-methoxyhumirianthol (6), and annonalide (7) are reported from I. oliviformis for the first time, whereas icacinol (1) has previously been found in this plant. Icacinol, 14α-methoxyhumirianthol, and annonalide displayed moderate cytotoxic activity in a panel of human cancer cell lines.

Nor-abietane Diterpenoids from Perovskia abrotanoides Roots with Anti-inflammatory Potential.

Fractionation of an EtOAc extract of the roots of Perovskia abrotanoides yielded 28 diterpenoids, including 12 new analogues, 1-12. The structures of these diterpenoids were established using comprehensive spectroscopic data analysis, including 1D and 2D NMR, high-resolution electrospray ionization mass spectrometry, electronic circular dichroism spectroscopy, and comparison with literature data. The extract and some of the tested compounds showed significant anti-inflammatory activity on J774A.1 macrophage cells stimulated with E. coli lipopolysaccharide. In particular, the tested compounds significantly inhibited the release of nitric oxide and the expression of related proinflammatory enzymes, such as inducible nitric oxide synthase.

Bioassay-Guided Isolation of an Abetiane-Type Diterpenoid from Prunella vulgaris That Protects against Concanavalin A-Induced Autoimmune Hepatitis.

Prunella vulgaris is a widely used edible Chinese medicinal plant. In the present study, two new abietane-type diterpenoids, abietoquinones A (1) and B (2), were isolated from this plant by an immunosuppressive bioassay-guided isolation procedure. Their structures were elucidated unambiguously by NMR spectroscopic analysis, single-crystal X-ray crystallography, and electronic circular dichroism calculations. Compounds 1 and 2 bear a cyclohex-2-ene-1,4-dione moiety, which is uncommon among abietane diterpenes. Also, abietoquinone A (1) suppressed murine splenocyte proliferation and decreased the production of proinflammatory cytokines induced by concanavalin A (Con A) in vitro. In Con A-challenged mice, preinjection with 1 significantly ameliorated liver injury. Additionally, abietoquinone A (1) exhibited inhibitory activities against the proliferation of murine splenocytes and human T cells induced by anti-CD3/anti-CD28 monoclonal antibodies (mAbs).

Abietane Diterpenoids Isolated from Clerodendrum bracteatum and Their Antioxidant and Cytotoxic Activities.

Two new abietane diterpenoids (1,2), along with five known diterpenoids (3-7), were first isolated and purified from the stems of Clerodendrum bracteatum. The structures of the new compounds were established by extensive analysis of mass spectrometric and 1-D, 2-D NMR spectroscopic data. Their antioxidant activities were determined on DPPH radical scavenging and ABTS. The in vitro cytotoxic activities of the compounds were evaluated against the HL-60 and A549 cell lines by the MTT method.

Rubesanolides F and G: Two Novel Lactone-Type Norditerpenoids from Isodon rubescens.

A phytochemical investigation of the leaves of the medicinal plant Isodon rubescens led to the isolation of the two new degraded abietane lactone diterpenoids rubesanolides F (1) and G (2). Their structures were elucidated based on the analyses of the HRESIMS and 1D/2D NMR spectral data, and their absolute configurations were determined by ECD spectrum calculations and X-ray single crystal diffraction methods. Compounds 1 and 2, with a unique γ-lactone subgroup between C-8 and C-20, were found to form a carbonyl carbon at C-13 by removal of the isopropyl group in an abietane diterpene skeleton. Rubesanolide G (2) is a rare case of abietane that possesses a cis-fused configuration between rings B and C. The two isolates were evaluated for their biological activities against two cancer cell lines (A549 and HL60), three fungal strains (Candida alba, Aspergillus niger and Rhizopus nigricans) and three bacterial strains (Escherichia coli, Staphylococcus aureus and Bacillus subtilis).

Antibacterial and ATP Synthesis Modulating Compounds from Salvia tingitana.

A surface extract of the aerial parts of Salvia tingitana afforded a nor-sesterterpenoid (1) and eight new sesterterpenoids (2-̵9), along with five known sesterterpenoids, five labdane and one abietane diterpenoid, one sesquiterpenoid, and four flavonoids. The structures of the new compounds were established by 1D and 2D NMR spectroscopy, HRESIMS, and VCD data and Mosher's esters analysis. The antimicrobial activity of compounds was evaluated against 30 human pathogens including 27 clinical strains and three isolates of marine origin for their possible implications on human health. The methyl ester of salvileucolide (10), salvileucolide-6,23-lactone (11), sclareol (15), and manool (17) were the most active against Gram-positive bacteria. The compounds were also tested for the inhibition of ATP production in purified mammalian rod outer segments. Terpenoids 10, 11, 15, and 17 inhibited ATP production, while only 17 inhibited also ATP hydrolysis. Molecular modeling studies confirmed the capacity of 17 to interact with mammalian ATP synthase. A significant reduction of ATP production in the presence of 17 was observed in Enterococcus faecalis and E. faecium isolates.

ent-Pimarane diterpenoids from Siegesbeckia glabrescens with anti-inflammatory activity.

Nine new ent-pimarane-type diterpenoids, siegesbeckia A-I (1-9), together with four known analogues ent-3α,15,16,19-tetrahydroxypimar-8(14)-ene (10), 15,16-dihydroxypimar-8(14)-en-3-one (11), 14ß,16-epoxy-7-pimarene-3α,15ß-diol (12) and darutigenol (13), were obtained from the aerial parts of Siegesbeckia glabrescens Makino. The structures of these compounds were elucidated by the interpretation of HRESIMS, 1D NMR and 2D NMR data. Their configurations were determined by ECD analysis and the structure of compound 1 was confirmed by X-ray crystallography. Putative biosynthetic pathways were proposed for 1-13. The anti-inflammatory effects of the compounds were evaluated by testing their inhibition of LPS-induced NO production in BV2 microglial cells. The results revealed that new compounds 2, 6 and 8 exhibited potent inhibitory activities with IC50 values of 33.07, 42.39 and 63.26 µM, which compared well with the positive control minocycline (IC50 32.84 µM).

Anti-inflammatory effect of isopimarane diterpenoids from Kaempferia galanga.

Two new isopimarane diterpenes, 1α-hydroxy-14α-methoxyisopimara-8(9),15-diene (7) and 1α,14α-dihydroxyisopimara-8(9),15-diene (9) and eight known isopimarane diterpenes including (-)-sandaracopimaradiene (1), 6ß-acetoxysandaracopimaradiene-9α-ol (2), sandaracopimaradiene-7ß,9α-diol (3), sandaracopimaradiene-1α,9α-diol (4), 6ß-acetoxysandaracopimaradiene-9α-ol-1-one (5), 6ß-acetoxysandaracopimaradiene-1α,9α-diol (6), 6ß,14α-dihydroxyisopimara-8(9),15-diene (8), and 6ß,14ß-dihydroxyisopimara-8(9),15-diene (10) were isolated from hexane fraction of Kaempferia galanga ethanol extract. Compounds 5, 6, 8, and 9 exerted the good anti-inflammatory effect on lipopolysaccharide-stimulated nitric oxide production from RAW264.7 cells with IC50 of 11.2, 7.7, 14.3, and 12.1 µM, respectively. These four compounds inhibited nitric oxide synthase (iNOS) mRNA expression. Compounds 5 and 6 also suppressed cyclooxygenase 2 (COX-2) mRNA expression; in addition, compound 6 had mild inhibitory effect on TNF-α mRNA. Among these compounds, 5 dramatically inhibited iNOS and COX-2 mRNA expression. The influential structures were proposed to be oxygen substitute at C-1, C-6, and α-OH at C-14.

Two New Abietane Diterpenoids from Selaginella moellendorffii Hieron.

Two new abietane diterpenoids, (3S,5R,10S)-3-hydroxy-12-O-demethyl-11-deoxy-19(4→3)-abeo-cryptojaponol, 12,19-dihydroxyabieta-8,11,13-trien-7-one, were isolated from Selaginella moellendorffii Hieron., together with one known abietane diterpenoid and four known tetracyclic triterpenoids. Their structures were characterized by their 1D- and 2D-NMR, ECD and mass spectral studies. All compounds were tested for their inhibitory effects on proliferation of three human cancer cells (human non-small-cell lung carcinoma cell lines A549 and human breast adenocarcinoma cell lines MDA-MB-231 and MCF-7) in vitro. Among them, three compounds displayed modest cytotoxic activities against the above three human cancer cell lines with IC50 values ranging from 16.28 to 40.67 µM.

Plectrabarbene, a New Abietane Diterpene from Plectranthus barbatus Aerial Parts.

A new abietane diterpene namely plectrabarbene (2), together with two known compounds: sugiol (1) and 11,14-dihydroxy-8,11,13-abietatrien-7-one (3) have been isolated from the aerial parts of Plectranthus barbatus Andr. (Labiatae). The structures of these compounds were determined by various spectral techniques (e.g., UV, IR, NMR, and FAB) and by comparison with the literature data. A molecular docking study of the isolated diterpenes (1-3) was performed with AChE to gain an insight into their AChE inhibition mechanism. The results of docking experiments revealed that the all tested compounds showed binding affinity at the active site of AchE in comparison to donepezil.

Inhibition of tanshinone IIA on renin activity protected against osteoporosis in diabetic mice.

Context: Salvia miltiorrhiza Bge. (Labiatae) (SMB) is applied clinically for management of diabetic osteoporosis in China, and research results has suggested its potential action on renin-angiotensin system (RAS).Objective: This study screens and explores naturally occurring bioactive constituents from the root of SMB acting on renin activity and evaluates its osteoprotective efficacy in diabetic mice.Materials and methods: Human embryonic kidney (HEK) 293 cells, engineered to express human renin, were used as an in vitro model to identify bioactive compound, tanshinone IIA, inhibiting renin activity. The C57BL/6 mice (n = 10 in each group) with diabetes induced by streptozotocin (STZ) were intraperitoneally injected with tanshinone IIA (10 and 30 mg/kg). The mice without STZ treatment and the diabetic mice treated with aliskiren were used as non-diabetic control and positive control, respectively.Results: Tanshinone IIA was found to display inhibitory effects on renin activity of HEK-293 cells; moreover, it down-regulated protein expression of ANG II in human renin-expressed HEK-293 cells. Treatment of diabetic mice with tanshinone IIA with both doses could significantly decrease ANG II level in serum (from 16.56 ± 1.70 to 10.86 ± 0.68 and 9.14 ± 1.31 pg/mL) and reduce ANG II expression in bone, consequently improving trabecular bone mineral density and micro-structure of proximal tibial end and increasing trabecular bone area of distal femoral end in diabetic mice.Conclusions: This study revealed beneficial effects of tanshinone IIA on bone of diabetic mice, and potentially suggested the application of Salvia miltiorrhiza in the treatment of osteoporosis and drug development of tanshinone IIA as a renin inhibitor.

Basimarols A, B, and C, Highly Oxygenated Pimarane Diterpenoids from Basilicum polystachyon.

The highly oxygenated pimarane diterpenoids basimarols A, B, and C (3-5) were isolated from the plant species Basilicum polystachyon, which was collected within the Australian arid zone. Structure elucidation was performed using a suite of spectroscopic techniques, including X-ray crystallography. Anticancer and anti-DENV activity of 3-5 was explored, but only limited activity was observed. More extensive antiviral evaluation of stachyonic acid A (1), which was also isolated from B. polystachyon, revealed broad spectrum antiviral activity against West Nile virus (Kunjin strain, WNVKun) and human influenza viruses H1N1 and H3N2.

The isolation, absolute configuration and activities of 18(4 → 3)-abeo-abietane lactones from Tripterygium wilfordii.

Phytochemical studies on the leaves of Tripterygium wilfordii led to the isolation of seven new 18(4 → 3)-abeo-abietane lactones, triptergulides E - K (1 - 7). The structure of the new compounds was elucidated on the basis of their spectroscopic analysis, and the absolute configurations of compounds were confirmed by ECD, calculated ECD, and X-ray crystallographic analysis using anomalous scattering of Cu Kα radiation. Some compounds showed moderate inhibitory activities against NO, IL-6, and TNF-α production in LPS RAW 264.7 macrophage in vitro.

Discovery of cancer cell proliferation inhibitors from Salviae miltiorrhizae radix et rhizoma by a trace peak enrichment approach.

Salviae miltiorrhizae radix et rhizoma is a traditional herbal medicine with anti-cancer activities. In this work, a trace peak enrichment approach combined with a cell proliferation assay was applied for screening cancer cell proliferation inhibitors from the extract of S. miltiorrhiza. A set of 123 peak fractions were prepared, and by comprehensive screening, 21 tanshinones were screened out as cancer cell proliferation inhibitors and their structures were tentatively identified by liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry analysis. The inhibitory activities of nine available screened tanshinones were validated, with their IC50 values ranging from 0.63 to 28.40 µM, indicating their activities strongly inhibit the proliferation of cancer cells. This study presents tanshinones that are potential cancer cell proliferation inhibitors and may explain the anti-cancer activity of S. miltiorrhiza.

A New Pimarane Diterpenoid from the Botryotinia fuckeliana Fungus Isolated from Deep-Sea Water.

A new pimarane diterpenoid, named botryopimarene A (1), was discovered from the fungus Botryotinia fuckeliana MCCC 3 A00494 isolated from the deep-sea water, together with ten known compounds. The planar structure of 1 was established based on the extensive spectroscopic analyses. The absolute configurations of tricyclic system in 1 were resolved by the theoretical ECD calculation, while the 15,16-diol moiety in the side chain was resolved by the Mo2 (OAc)4 -induced ECD spectrum. Compound 1, featuring a Δ9(11) double bond, was rarely discovered in pimarane family. Compounds 1-11 were tested for their cytotoxic activities using six human cancer cell lines by the MTT method. However, none of the compounds exhibited detectable cytotoxicities (IC50 >20 µm).