A DNA Repair Inhibitor Isolated from an Ecuadorian Fungal Endophyte Exhibits Synthetic Lethality in PTEN-Deficient Glioblastoma.

Disruption of the tumor suppressor PTEN, either at the protein or genomic level, plays an important role in human cancer development. The high frequency of PTEN deficiency reported across several cancer subtypes positions therapeutic approaches that exploit PTEN loss-of-function with the ability to significantly impact the treatment strategies of a large patient population. Here, we report that an endophytic fungus isolated from a medicinal plant produces an inhibitor of DNA double-strand-break repair. Furthermore, the novel alkaloid product, which we have named irrepairzepine (1), demonstrated synthetic lethal targeting in PTEN-deficient glioblastoma cells. Our results uncover a new therapeutic lead for PTEN-deficient cancers and an important molecular tool toward enhancing the efficacy of current cancer treatments.

Antigastritis effects of Armillariella tabescens (Scop.) Sing. and the identification of its anti-inflammatory metabolites.

OBJECTIVES: This study demonstrates the biological and chemical analysis of the mushroom Armillariella tabescens (Scop.) Sing. (Tricholomataceae). METHODS: Chemical structures of the isolates were determined by 1D and 2D NMR, and ESI-MS, as well as comparison with previously reported data. All isolates were tested for anti-inflammatory effects based on their ability to inhibit LPS-stimulated nitric oxide (NO) production in RAW264.7 cells. KEY FINDINGS: We found that the MeOH extract of the fruiting bodies of A. tabescens showed antigastritis activity against ethanol-induced gastric damage in rats and notably reduced the gastric damage index compared to control in a concentration-dependent manner. Chemical investigation of the MeOH extract led to the isolation of four steroids (1-4), three alkaloids (5-7), two nucleic acids (8-9) and four fatty acids (10-13). This is the first study to report the identification of all isolates, except for compound 7, from A. tabescens. Compounds 1, 2, 3, 4 and 10 showed inhibition on LPS-stimulated NO production. Treatment with compound 10 inhibited expression of iNOS, COX-2, phospho-IKKα, IKKα, phospho-IκBα, IκBα and NF-kappa B in LPS-stimulated RAW264.7 cells. CONCLUSIONS: Compound 10 likely contributes to the health benefits of A. tabescens as an antigastritis agent through its anti-inflammatory effects.

A grayanotox-9(11)-ene derivative from Rhododendron brachycarpum and its structural assignment via a protocol combining NMR and DP4 plus application.

A growing body of evidence points to the useful roles of computational approaches in the structural characterization of natural products. Rhododendron brachycarpum has been traditionally used for the control of diabetes, hepatitis, hypertension, and rheumatoid arthritis and classified as an endangered species in Korea. A grayanotox-9(11)-ene derivative along with five known diterpenoids, were isolated from the MeOH extract of R. brachycarpum. Extensive 1D and 2D NMR experiments were conducted to establish the 2D structure and relative configuration of the grayanotox-9(11)-ene derivative. Comparison of simulated and experimental ECD spectra resulted in an inconclusive outcome to assign its absolute configuration. Alternatively, gauge-including atomic orbitals (GIAO) NMR chemical shift calculations, with support by the advanced statistical method DP4 plus, and acid hydrolysis were employed to establish its absolute configuration. This work exemplifies how NMR analysis, combined with quantum mechanics calculations, is a viable approach to accomplish structural assignment of minor abundance molecules in lieu of X-ray crystallography or chiroptical approaches.

Arborinane Triterpenoids from Rubia philippinensis Inhibit Proliferation and Migration of Vascular Smooth Muscle Cells Induced by the Platelet-Derived Growth Factor.

The abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) are associated with cardiovascular diseases and related complications. Such deleterious proliferation and migration events are triggered by cytokines and growth factors, and among them, platelet-derived growth factor (PDGF) is recognized as the most potent inducer. Despite the genus Rubia being researched to identify valuable commercial and medicinal virtues, Rubia philippinensis has rarely been investigated. Nine arborinane-type triterpenoids (1-9) were identified from this underutilized plant species. In particular, 4 was identified as the first arborinane derivative carrying a ketocarbonyl motif at C-19. The presence of the cyclopentanone moiety and the associated configurational assignment were determined by utilizing NOE and coupling constant analysis. These compounds were assessed for their inhibitory potential on PDGF-induced proliferation and the migration of VSMCs. Treatment with 5 µM compound 5 (62.6 ± 10.7%) and compound 9 (41.1 ± 4.7%) impeded PDGF-stimulated proliferation without exerting cytotoxicity. Compound 7 exhibited antimigration activity in a dose-dependent manner (38.5 ± 3.0% at 10 µM, 57.6 ± 3.2% at 30 µM). These results suggest that the arborinane-type triterpenoids may be a pertinent starting point for the development of cardiovascular drugs capable of preventing the intimal accumulation of VSMCs.

A new rearranged eudesmane sesquiterpene and bioactive sesquiterpenes from the twigs of Lindera glauca (Sieb. et Zucc.) Blume.

A new rearranged eudesmane sesquiterpene, named eudeglaucone (1), and five known sesquiterpenes including (+)-faurinone (2) and four eudesmane-type sesquiterpenes (3-6), were isolated from the twigs of Lindera glauca (Sieb. et Zucc.) Blume. The structure of 1 was elucidated by a combination of extensive spectroscopic analyses, including extensive 2D NMR (1H-1H COSY, HMQC, HMBC, and NOESY) and HR-MS. Compound 1 was a relatively rare rearranged eudesmane sesquiterpene in terpenoids. All isolates were evaluated for their antiproliferative activities against four human tumor cell lines (A549, SK-OV-3, SK-MEL-2, and HCT-15). Compounds 3 and 6 showed significant cytotoxicity against SK-MEL-2 and HCT-15 cell lines with IC50 values ranging from 9.98 to 12.20 µM. We also investigated the anti-neuroinflammatory activities of the isolates (1-6) in the lipopolysaccharide (LPS)-stimulated murine microglia BV-2 cell line by measuring nitric oxide (NO) levels. All isolates significantly inhibited NO production with IC50 values of 3.67-26.48 µM without inducing cell toxicity.

Bioactivity-guided isolation of antioxidant triterpenoids from Betula platyphylla var. japonica bark.

The bark of Betula platyphylla var. japonica (Betulaceae) has been used to treat pneumonia, choloplania, nephritis, and chronic bronchitis. This study aimed to investigate the bioactive chemical constituents of the bark of B. platyphylla var. japonica. A bioassay-guided fractionation and chemical investigation of the bark of B. platyphylla var. japonica resulted in the isolation and identification of a new lupane-type triterpene, 27-hydroxybetunolic acid (1), along with 18 known triterpenoids (2-19). The structure of the new compound (1) was elucidated on the basis of 1D and 2D NMR spectroscopic data analysis as well as HR-ESIMS. Among the known compounds, chilianthin B (17), chilianthin C (18), and chilianthin A (19) were triterpene-lignan esters, which are rarely found in nature. Compounds 4, 6, 7, 17, 18, and 19 showed significant antioxidant activities with IC50 values in the range 4.48-43.02µM in a DPPH radical-scavenging assay. However, no compound showed significant inhibition of acetylcholine esterase (AChE). Unfortunately, the new compound (1) exhibited no significance in both biological activities. This study strongly suggests that B. platyphylla var. japonica bark is a potential source of natural antioxidants for use in pharmaceuticals and functional foods.

Four flavonoids from Echinosophora koreensis and their effects on alcohol metabolizing enzymes.

A new prenylated dihydroflavonol, 3-hydroxy-kenusanone B 1, as well as three other known isoflavanones, sophoronol 2, sophoraisoflavanone A 3 and kenusanone H 4, were isolated from the rhizomes of Echinosophora koreensis. The structures of these compounds were elucidated using spectroscopic analyses that included extensive 2D NMR, optical rotation spectrometry and mass spectrometry. All four flavonoids enhanced the activities of alcohol metabolizing enzymes such as alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) at micromolar concentrations. Sophoronol 2 showed a nine-fold increased activation of alcohol dehydrogenase and aldehyde dehydrogenase than a negative control group at concentrations of 100 microg/mL and 50 microg/mL, respectively. This study suggests that prenylated flavonoids have the potential to prevent 'hangovers' after alcohol intake.