Stereochemical assignment of clerodane-type diterpenes from the fruits of Casearia grewiifolia and their ability to inhibit PCSK9 expression.

More than 20 natural products have been reported to modulate PCSK9-mediated cholesterol regulation, and small-molecule-derived proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors continue to be developed and identified. Here, twelve undescribed clerodane-type diterpenes (1-9 and 12-14) and two known compounds were isolated from the chloroform-soluble extract of the dried fruits of Casearia grewiifolia Vent. using a PCSK9 mRNA expression monitoring assay. Among the undescribed compounds, the stereochemistry of two diastereomeric grewiifolins A and B (1 and 2) were extensively elucidated using 2D Nuclear Overhauser Effect Spectroscopy (NOESY) experiments, excitation-sculptured indirect detection experiments (EXSIDE), interproton distance analyses, and computational calculations that included quantum chemical shift calculations combined with DP4+ analysis. All isolates were assessed for their inhibitory activity against PCSK9 and IDOL mRNA expression. Among the compounds tested, compound 3 inhibited PCSK9 and IDOL mRNA expression.

Salicinoyl Quinic Acids and Their Prostaglandin E2 Production Inhibitory Activities from the Fruits of Casearia grewiifolia.

Phytochemical investigation on the dried fruits of Casearia grewiifolia led to the identification of 10 new salicinoyl quinic acid derivatives (1-10), a new benzoyl quinic acid (11), and two known compounds (12 and 13). The structures of the new compounds were elucidated by interpreting 1D and 2D NMR spectroscopic data including HMBC and EXSIDE along with a chemical method for sugar unit analysis. All isolates were evaluated for their inhibitory activities against prostaglandin E2 (PGE2) production in ultraviolet B (UVB)-irradiated HaCat keratinocytes. Of the isolates tested, compounds 6 and 12 were found to inhibit PGE2 production with IC50 values of 20.5 and 28.8 µM, respectively.

A stilbene dimer and flavonoids from the aerial parts of Chromolaena odorata with proprotein convertase subtilisin/kexin type 9 expression inhibitory activity.

Investigation of components of the chloroform-soluble and ethyl acetate-soluble extracts of the aerial parts of Chromolaena odorata L. selected by PCSK9 mRNA expression monitoring assay in HepG2 cells led to the isolation of a new stilbene dimer, (+)-8b-epi-ampelopsin A (1), and 30 known compounds (2-31). The structures of the isolates were established by interpretation of NMR spectroscopic data and the stereochemistry of the new stilbene (1) was proposed based on ECD and NMR calculations. Among the isolates, 1, 5,6,7,4'-tetramethoxyflavanone (6), 5,6,7,3',4'-pentamethoxyflavanone (7), acacetin (18), and uridine (21) were found to inhibit PCSK9 mRNA expression with IC50 values of 20.6, 21.4, 31.7, 15.0, and 13.7 µM, respectively. Furthermore, the most abundant isolate among the selected compounds, 6, suppressed PCSK9 and low-density lipoprotein receptor protein expression in addition to downregulating the mRNA expression of HNF-1α.

Dipterocarpus obtusifolius attenuates the effects of lipopolysaccharide­induced inflammatory response in RAW264.7 macrophages.

Dipterocarpus obtusifolius has been traditionally used as a herbal medicine and is considered to have anticancer properties. The biological activity of D. obtusifolius in inflammation and the underlying mechanisms of its activity remain to be elucidated. The present study investigated the effects of D. obtusifolius methanolic extract (DOME) on lipopolysaccharide (LPS)­stimulated inflammation in RAW264.7 cells. The effects of DOME on the production of nitric oxide, prostaglandin E2 and pro­inflammatory cytokines were assessed by ELISA, western blot analysis and reverse transcription­quantitative polymerase chain reaction. It was demonstrated that expression of inducible nitric oxide synthase, cyclooxygenase­2, interleukin­1ß and tumor necrosis factor­α was suppressed by DOME in LPS­stimulated cells. Furthermore, treatment with DOME suppressed phosphorylation of mitogen activated protein kinase (MAPK) molecules, including extracellular signal­regulated kinase, c­Jun N­terminal kinase and p38 MAPK. Translocation of the nuclear factor­κB p65 subunit into the nucleus was additionally inhibited by DOME. Phosphorylation of MAPK promoter activity was inhibited by treatment with DOME, PD98059, SB202190 and SP600125. These results demonstrated that DOME inhibits LPS­induced inflammatory responses. Therefore, DOME may be a potential therapeutic approach for the treatment of inflammatory diseases.

Plant-derived juvenile hormone III analogues and other sesquiterpenes from the stem bark of Cananga latifolia.

Juvenile hormone III (JH III) is a larval metamorphosis-regulating hormone present in most insect species. JH III was first isolated from the plant, Cyperus iria L., but the presence of JH III has not been reported in other plant species. In the present study, proof of the existence of JH III and its analogues from Cananga latifolia was established. From an aqueous MeOH extract of C. latifolia stem bark, six compounds were isolated along with nine known compounds. These were identified by using spectroscopic analyses as: (2E,6E,10R)-11-butoxy-10-hydroxy-3,7,11-trimethyldodeca-2,6-dienoic acid methyl ester, (2E,6E)-3,7,11-trimethyl-10-oxododeca-2,6-dienoic acid methyl ester, (2E)-3-methyl-5-[(1S,2R,6R)-1,2,6-trimethyl-3-oxocyclohexyl]-pent-2-enoic acid methyl ester, 1ß-hydroxy-3-oxo-4ß, 5α,7α-H-eudesmane 11-O-α-l-rhamnopyranoside, 4-epi-aubergenone 11-O-2',3'-di-O-acetyl-α-l-rhamnopyranoside and 4-epi-aubergenone 11-O-2',4'-di-O-acetyl-α-l-rhamnopyranoside. Three of the previously known compounds, (2E,6E,10R)-10-hydroxy-3,7,11-trimethyldodeca-2,6,11-trienoaic acid methyl ester, (2E,6E,10R)-10,11-dihydroxy-3,7,11-trimethyldodeca-2,6-dienoic acid and (2E,6S)-3-methyl-6-hydroxy-6-[(2R,5R)-5-(2-hydroxypropan-2-yl)-2-methyltetrahydrofuran-2-yl]-hex-2-enoaic acid methyl ester have now been found in a plant species. Ultra performance liquid chromatography-quadruple time-of-flight mass spectroscopy (UPLC-QTOF/MS) analysis of the chemical constituents of C. latifolia showed that several were predominant in the sub-fractions of a C. latifolia stem bark extract.

Ingenane-type diterpenes with a modulatory effect on IFN-γ production from the roots of Euphorbia kansui.

A new ingenane-type diterpene, (3S,5R)5-O-(2,3-dimethylbutanoyl)-13-O-dodecanoyl-20-O-deoxyingenol (1), and six known compounds,3-O-(2,3-dimethylbutanoyl)-13-O-dodecanoyl-20-O-deoxyingenol (2), 20-O-decanoylingenol (3), 20-O-acetylingenol-3-O-(2'E,4'Z) decadienoate (4), kansuiphorin A (5), 3-O-(2,3-dimethylbutanoyl)-13-O-dodecanoylingenol (6), and kansuinin F (7) were isolated and evaluated for their effect on IFN-γ production in NK92 cells. Interestingly, subjection to compounds 4 and 6 (10 nM) displayed the most significant response in IFN-γ production, comparable to that produced by the same dose of phorbol 12-myistate 13-acetate (PMA). High doses of compounds 3 (100 nM), 1 (1. 25 µM) and 5 (5.0 µM) have also been shown to activate the IFN-γ production.

Cytotoxic terpenes from the stems of Dipterocarpus obtusifolius collected in Cambodia.

From the stems of Dipterocarpus obtusifolius, five new triterpenes, 3-oxo-20-hydroxy-30α-methyl,17(29)α-epoxy-28-norlupane (1), 3-oxo-20-hydroxy-30ß-methyl-17(29)α-epoxy-28-norlupane (2), 3,20-dioxo-28,29-norlupan-17α-ol (3), 27-demethyl-20(S)-dammar-23-ene-20-ol-3,25-dione (4), and 3-epi-cecropic acid (5) together with 13 known compounds including diterpene, sesquiterpenes and triterpenes were isolated and characterized. All isolates were tested for their cytotoxicities against a small panel of human cancer cell lines. Of the tested compounds, compounds 4-11 were found to be cytotoxic against one or more human cancer cell lines.

Anti-allergic effect of a chloroform-soluble extract of Cinnamomum cambodianum in bone marrow-derived mast cells.

Cinnamomum cambodianum has been used as a traditional medicine in Cambodia. Its effect on the bone marrow-derived mast cells (BMMCs) mediated allergic response remains unknown. In this study, a chloroform-soluble extract of C. cambodianum was evaluated for its effect on allergic mediators, including prostaglandin D2 (PGD2), leukotriene C4 (LTC4), ß-hexosaminidase and cyclooxygenase-2 (COX-2) protein, in phorbol 12-myristate 13-acetate (PMA) plus calcimycin-stimulated BMMCs. The results revealed that the chloroform-soluble extract inhibited the production of interleukin-6, PGD2 and LTC4, and the expression of COX-2 in PMA plus calcimycin-stimulated BMMCs, implying a potential benefit of C. cambodianum in the treatment of allergy.

Anti-inflammatory diterpene from Thyrsanthera suborbicularis.

Bioactivity-guided isolation on a n-hexane-soluble fraction of Thyrsanthera suborbicularis led to the isolation of a new rosane-type diterpene, 19-hydroxy-1(10), 15-rosadiene (1), along with three known compounds, taraxerol, acetyl aleuritolic acid, and spathulenol. The structures of isolated compounds were determined by interpretation of NMR spectroscopic data and mass spectrometry. Compound 1 demonstrated significantly inhibitory activity on nitric oxide production in RAW264.7 lipopolysaccharide (LPS)-activated mouse macrophages with an IC(50) value of 2.91 µg/ml via the suppression of inducible nitric oxide synthase (iNOS) mRNA expression.