Anti-HIV Macrocyclic Daphnane Orthoesters with an Unusual Macrocyclic Ring from Edgeworthia chrysantha.

Edgeworthianins A-E (1-5) were isolated from Edgeworthia chrysantha as a class of macrocyclic daphnane orthoesters with an unusual macrocyclic ring formed from a C14 aliphatic chain. Their structures were elucidated by extensive physicochemical and spectroscopic analyses. Compounds 2, 4, and 5 exhibited potent anti-HIV activity against HIV-1 infection of MT4 cells with EC50 values of 29.3, 8.4, and 2.9 nM, respectively. These compounds broaden the findings of the structure-activity relationship of macrocyclic daphnane orthoesters for further anti-HIV drug development.

Isolation, Structural Elucidation, and Anti-HIV Activity of Daphnane Diterpenoids from Daphne odora.

Five new [daphneodorins D-H (1, 5, and 10-12)] and seven known daphnane diterpenoids (2-4 and 6-9) were isolated from Daphne odora. The structures of the new compounds were elucidated by extensive physicochemical and spectroscopic analysis. The isolated compounds were evaluated for their anti-HIV activity against HIV-1 infection of MT4 cells. Nine daphnane diterpenoid orthoesters (1-9) showed potent anti-HIV activity with EC50 values of 1.5-7.7 nM.

Daphneodorins A-C, Anti-HIV Gnidimacrin Related Macrocyclic Daphnane Orthoesters from Daphne odora.

Three novel gnidimacrin related macrocyclic daphnanes (GMDs), daphneodorins A-C (2-4), were isolated from Daphne odora Thunb., together with gnidimacrin (1). Their structures were established by extensive physicochemical and spectroscopic analyses. Compounds 2 and 3 potently inhibited HIV-1 replication at subnanomolar concentrations (EC50 0.16 and 0.25 nM, respectively). Compounds 2-4 represent a novel type of GMDs that are highly oxygenated on the macrocyclic ring, suggesting good potential for anti-HIV drug development by further chemical modification.

Synthesis and Structure-Activity Relationship Correlations of Gnidimacrin Derivatives as Potent HIV-1 Inhibitors and HIV Latency Reversing Agents.

Currently, due to the HIV latency mechanism, the search continues for effective drugs to combat this issue and provide a cure for AIDS. Gnidimacrin activates latent HIV-1 replication and inhibits HIV-1 infection at picomolar concentrations. This natural diterpene was able to markedly reduce the latent HIV-1 DNA level and the frequency of latently infected cells. Therefore, gnidimacrin is an excellent lead compound, and its anti-HIV potential merits further investigation. Twenty-nine modified gnidimacrin derivatives were synthesized and evaluated in assays for HIV replication and latency activation to establish which molecular structures must be maintained and which can tolerate changes that may be needed for better pharmacological properties. The results indicated that hydroxyl substituents at C-5 and C-20 are essential, while derivatives modified at 3-OH with aromatic esters retain anti-HIV replication and latent activation activities. The half-lives of the potent GM derivatives are over 20 h, which implies that they are stable in the plasm even though they contain ester linkages. The established structure-activity relationship should be useful in the development of gnidimacrin or structurally related compounds as clinical trial candidates.

Antimutagenic components in Spatholobus suberectus Dunn against N-methyl-N-nitrosourea.

BACKGROUND: An extract from Spatholobus suberectus (S. suberectus) Dunn has been reported to show potent antimutagenic effects against N-alkyl-N-nitrosoureas in umu screening. The aim of this study was to identify the antimutagenic components from extracts of S. suberectus against N-methyl-N-nitrosourea (MNU) in the Ames assay with Salmonella typhimurium strain TA1535 and to elucidate the antimutagenic mechanism of the flavonoids. RESULTS: From the ethyl acetate fraction obtained from fractionation of the methanol extract of S. suberectus Dunn, medicarpin, formononetin and isoliquiritigenin were successfully isolated through a combination of normal- and reversed-phase chromatography. Genistein and naringenin, which were already reported to be contained in S. suberectus Dunn, were also tested for their antimutagenicity towards MNU, along with formononetin, isoliquiritigenin and medicarpin. Our results demonstrated that genistein, isoliquiritigenin, medicarpin and naringenin were antimutagenic against MNU without showing cytotoxicity. MNU is reported to cause not only DNA alkylation but also induce reactive oxygen species. The hydroxyl radical scavenging capacity of the flavonoids was correlated with the antimutagenic capacity, indicating that the hydroxyl radical scavenging activity was involved in their antimutagenicity towards MNU. CONCLUSIONS: It is important to prevent DNA damage by N-nitrosamines for cancer chemoprevention. Genistein, isoliquiritigenin, medicarpin and naringenin were demonstrated to possess an antigenotoxic effects against carcinogenic MNU due to their radical scavenging activity.

Identification, structural modification, and dichotomous effects on human immunodeficiency virus type 1 (HIV-1) replication of ingenane esters from Euphorbia kansui.

Euphorbia kansui showed potent anti-HIV-1 activity during screening of a library composed of plant extracts from Euphorbiaceae and Thymelaeaceae families. Bioassay-guided isolation led to identification of ingenane esters as the active compounds. Further chemical modification resulted in 3-(2-naphthoyl)ingenol (23), which exhibited the most potent anti-HIV-1 activity. Compound 23 also acted as an HIV-1-latency-reversing agent on activation of HIV-1 replication in a latently infected U1 cell model and a T cell latent HIV-1 model JLat-A2.

Isolation, Structural Elucidation, and Liquid Chromatography-Mass Spectrometry Analysis of Steroidal Glycosides from Polygonatum odoratum.

The rhizomes of Polygonatum odoratum represent a traditional Chinese medicine and functional food. A phytochemical investigation resulted in the isolation of eight steroidal glycosides (1-8), including two new compounds, polygonatumosides F (1) and G (2). The structures were elucidated by spectroscopic data and chemical reactions. Compound 7 showed antiproliferation activity against human hepatocellular carcinoma cell line HepG2 (IC50 of 3.2 µM). The chemical profile and contents of steroidal glycosides of P. odoratum rhizomes collected at different dates and geographical locations were also investigated, indicating that the rational harvest of P. odoratum in spring and autumn is preferable to obtain higher levels of steroidal glycosides. Compounds 1 and 7 showed the highest contents in all P. odoratum samples and have potential to serve as chemotaxonomic and chemical markers for quality control of this important plant material. 14-Hydroxylation may be a key step for the biosynthesis of compounds 1-7.

Phellilane L, Sesquiterpene Metabolite of Phellinus linteus: Isolation, Structure Elucidation, and Asymmetric Total Synthesis.

A new cyclopropane-containing sesquiterpenoid, phellilane L (1), was isolated from the medicinal mushroom Phellinus linteus ("Meshimakobu" in Japanese), a member of the Hymenochaetaceae family and a well-known fungus that is widely used in East Asia. The planar structure of 1 was determined on the basis of spectroscopic analysis. The authors achieved the first total synthesis of 1. Our protecting group-free synthesis features a highly stereoselective one-pot synthesis involving an intermolecular alkylation/cyclization/lactonization strategy for construction of the key cyclopropane-γ-lactone intermediate. Additionally, our synthesis determined the absolute configuration of phellilane L (1).

Corrigendum: γ-Ionylidene-type sesquiterpenoids possessing antimicrobial activity against Porphyromonas gingivalis from Phellinus linteus and their absolute structure determination.

This corrects the article DOI: 10.1038/ja.2017.35.

Impact of the SCF signaling pathway on leukemia stem cell-mediated ATL initiation and progression in an HBZ transgenic mouse model.

Adult T-cell leukemia (ATL) is a malignant disease caused by human T-lymphotropic virus type 1. In aggressive ATL, the response to chemotherapy is extremely poor. We hypothesized that this poor response is due to the existence of chemotherapy-resistant cells, such as leukemic stem cells. Previously, we successfully identified an ATL stem cell (ATLSC) candidate as the c-kit+/CD38-/CD71- cells in an ATL mouse model using Tax transgenic mice. Here, with a new ATL mouse model using HBZ-transgenic mice, we further discovered that the functional ATLSC candidate, which commonly expresses c-kit, is drug-resistant and has the ability to initiate tumors and reconstitute lymphomatous cells. We characterized the ATLSCs as c-kit+/CD4-/CD8- cells and found that they have a similar gene expression profile as T cell progenitors. Additionally, we found that AP-1 gene family members, including Junb, Jund, and Fosb, were up-regulated in the ATLSC fraction. The results of an in vitro assay showed that ATLSCs cultured with cytokines known to promote stem cell expansion, such as stem cell factor (SCF), showed highly proliferative activity and maintained their stem cell fraction. Inhibition of c-kit-SCF signaling with the neutralizing antibody ACK2 affected ATLSC self-renewal and proliferation. Experiments in Sl/Sld mice, which have a mutation in the membrane-bound c-kit ligand, found that ATL development was completely blocked in these mice. These results clearly suggest that the c-kit-SCF signal plays a key role in ATLSC self-renewal and in ATL initiation and disease progression.

Euphorins A-H: bioactive diterpenoids from Euphorbia fischeriana.

Phytochemical investigation of the roots of Euphorbia fischeriana resulted in the isolation of 23 diterpenoids (1-23), which were classified into five subtypes, namely, ent-rosane (1-9), ent-abietane (10-16), ent-kaurane (17), ingenane (18-22), and lathyrane (23). The chemical structures of eight new compounds, namely, euphorin A (4), B (5), C (7), D (9), E (13), F (14), G (15), and H (16), were elucidated on the basis of extensive 1D and 2D NMR spectroscopic analyses, as well as single crystal X-ray structure analysis. A number of compounds (2, 6, 7, 10, 11, 13, 16, 19, 20, 22, and 23) showed inhibitory activity on the formation of mammospheres in human breast cancer MCF-7 cells at a final concentration of 10 µM, suggesting the potential of these bioactive diterpenoids for further investigation of the action targeting cancer stem cells.

ent-Atisane diterpenoids from Euphorbia fischeriana inhibit mammosphere formation in MCF-7 cells.

The discovery of new drugs that target cancer stem cells (CSCs) is a critical approach to overcome the major difficulties of the metastasis, chemotherapeutic resistance and recurrence for successful cancer therapy. Chemical investigation of the roots of Euphorbia fischeriana resulted in the isolation of eight ent-atisane diterpenoids (1-8), including two new compounds: 19-O-ß-D-glucopyranosyl-ent-atis-16-ene-3,14-dione (7) and 19-O-(6-galloyl)-ß-D-glucopyranosyl-ent-atis-16-ene-3,14-dione (8). The structures were elucidated on extensive spectroscopic analyses, as well as chemical transformations. ent-3ß-Hydroxyatis-16-ene-2,14-dione (5), 7 and its aglycon, ent-19-hydroxy-atis-16-ene-3,14-dione (7a), showed significant inhibitory activity on mammosphere formation in human breast cancer MCF-7 cells at a final concentration of 10 µM.

Inhalation administration of the sesquiterpenoid aristolen-1(10)-en-9-ol from Nardostachys chinensis has a sedative effect via the GABAergic system.

Spikenard, the dried roots of Nardostachys chinensis, contains sesquiterpenoids and is widely used as an herbal tranquilizer. We previously demonstrated that spikenard vapor showed a sedative effect when administered by inhalation, and we identified hydrocarbon sesquiterpenoids as active components. Here we investigated the other components that contribute to the effects of spikenard. Six oxygenated sesquiterpenoids, including aristolane- and guaiane-types, were isolated from an acetone extract of spikenard. We evaluated the sedative activities of these oxygenated compounds using an inhalation administration method in a caffeine-treated excitatory mouse model. We identified aristolen-1(10)-en-9-ol and patchouli alcohol as highly effective sedative components. These compounds inhibited locomotion in mice by approximately 60% at a dose of 300 µg/cage. In addition, aristolen-1(10)-en-9-ol prolonged pentobarbital-induced sleep to the same extent as 1 mg/kg diazepam. This effect completely disappeared with the administration of the GABAA-benzodiazepine receptor antagonist flumazenil (3 mg/kg), suggesting that the sedative effect of aristolen-1(10)-en-9-ol is expressed via the GABAergic system. Furthermore, differently from diazepam, inhalation of aristolen-1(10)-en-9-ol for 1 h did not affect the motor coordination in the rota-rod test. In the present study, we identified active components and provided evidence supporting the traditional sedative use of spikenard. Our research suggests that aristolen-1(10)-en-9-ol may be an effective aromatherapy, providing mild sedation.

Cytotoxic activity of two natural sesquiterpene lactones, isobutyroylplenolin and arnicolide D, on human colon cancer cell line HT-29.

In this study, we found that two sesquiterpene lactones, isobutyroylplenolin and arnicolide D, from Centipeda minima L. (Compositae) exerted stronger cytotoxic activity than cisplatin on the human colon carcinoma HT-29 cell line. Furthermore, the cytotoxicity of these two compounds on normal cells was weaker than that of cisplatin. Treatment with isobutyroylplenolin and arnicolide D increased the levels of intracellular reactive oxygen species and decreased the levels of nuclear factor-κB protein, resulting in cell cycle arrest in G1 phase and apoptosis. We also discuss the difference in structure and activity between these two compounds.

Evaluation of licorice flavonoids as protein tyrosine phosphatase 1B inhibitors.

Protein tyrosine phosphatase 1B (PTP1B) is a major negative regulator in insulin- and leptin-signaling cascades as well as a positive regulator in tumorigenesis, and much attention has been paid to PTP1B inhibitors as potential therapies for diabetes, obesity, and cancer. In the present study, the screening of a compound library of licorice flavonoids allowed for the discovery of several compounds, including licoagrone (3), licoagrodin (4), licoagroaurone (5), and isobavachalcone (6), as new PTP1B inhibitors. It was revealed that these compounds inhibit the activity of PTP1B in different modes and with different selectivities and that they exhibit different cellular activity in the insulin-signaling pathway. Glycybenzofuran (1), a competitive PTP1B inhibitor, showed both excellent inhibitory selectivity against PTP1B and cellular activity on the insulin-stimulated Akt phosphorylation level. The similarity of its action profiling in the insulin-signaling pathway suggested its potential as a new anti-insulin-resistant drug candidate.

Antioxidant lignoids from leaves of Ribes nigrum.

Phytochemical investigation of the leaves of Ribes nigrum resulted in the isolation of fourteen compounds, including four 7,7'-epoxylignans, three tetrahydrofuran-type sesquilignans, and a spirocyclic dilignan. Their structures were elucidated by extensive spectroscopic analyses and by chemical transformations. The isolated compounds were evaluated for their antioxidant activities using superoxide anion scavenging assay and DPPH free radical scavenging assay. Ribesin D and ribesin G showed the most potent superoxide anion scavenging activity with EC50 values of 1.24 and 1.12 µM, respectively, and the structure-activity relationship was discussed.

Isolation, structure determination, and anti-HIV evaluation of tigliane-type diterpenes and biflavonoid from Stellera chamaejasme.

Five novel tigliane-type diterpenes, stelleracins A-E (3-7), a novel flavanone dimer, chamaeflavone A (8), and six known compounds were isolated from the roots of Stellera chamaejasme. Their structures were elucidated by extensive spectroscopic analyses. The isolated compounds were evaluated for anti-HIV activity in MT4 cells. New compounds 3-5 showed potent anti-HIV activity (EC90 0.00056-0.0068 µM) and relatively low or no cytotoxicity (IC50 4.4-17.2 µM). These new compounds represent promising new leads for development into anti-AIDS clinical trial candidates.

Tinospinosides D, E, and tinospin E, further clerodane diterpenoids from Tinospora sagittata.

Chemical investigation on the roots of Tinospora sagittata resulted in the isolation of three novel cis-clerodane diterpenoids, tinospinosides D, E, and tinospin E, together with two known compounds, columbin and columbin glucoside, and their structures were determined by extensive spectroscopic analyses, chemical reactions and computer-assisted calculations. The inhibitory activity of the isolated compounds and their chemical derivatives on nitric oxide production in lipopolysaccharide and interferon-γ activited J774.1 macrophage-like cells was also evaluated.

Labdane-type diterpenoids from hairy root cultures of Coleus forskohlii, possible intermediates in the biosynthesis of forskolin.

Significant attention has been devoted to studying hairy root cultures as a promising strategy for production of various valuable secondary metabolites. These offer many advantages, such as high growth rate, genetic stability and being hormone-free. In this study, a detailed phytochemical investigation of the secondary metabolites of Coleus forskohlii hairy root cultures was undertaken and which resulted in the isolation of 22 compounds, including four forskolin derivatives and a monoterpene. Their structures were elucidated by extensive spectroscopic analyses. These compounds could be classified into four groups viz.: labdane-type diterpenes, monoterpenes, triterpenes and phenylpropanoid dimers. Apart from one compound, all labdane type diterpenes are oxygenated at C-11 as in forskolin and a scheme showing their biosynthetic relationships is proposed.