Isolation and insecticidal activities of new cyclic peptides from mangrove endophytic fungus Aspergillus sp. GXNU-4QQY1a.

An investigation on bioactive metabolites from the mangrove endophytic fungus Aspergillus sp. GXNU-4QQY1a led to the isolation of two undescribed cyclic peptides, guaspertide A (1) and guaspertide B (2), together with six known compounds, 3-8. These structures and the new compounds' absolute configuration were determined by mass spectrometry analysis, nuclear magnetic resonance spectrum, electronic circular dichroism, and single-crystal X-ray diffraction. Insecticidal assays were carried out with compounds 1-8, and the results showed that compounds 1-3 and 8 exhibited good insecticidal activity against citrus psyllids.

Phloroglucinol derivatives rhotomensones A-G from Rhodomyrtus tomentosa.

Undescribed phloroglucinol derivatives, rhotomensones A-G, and a known derivative rhodomyrtosone B, were isolated from the leaves of Rhodomyrtus tomentosa. Rhotomensones A-D and G have unreported structural characteristics, in which rhotomensone A substitutes a benzene ring, rhotomensones B-D are bonded with a 2-methylbutanoyl group, and rhotomensone G has two fewer carbons. The structures of these compounds were determined by NMR spectroscopy, circular dichroism (CD) spectroscopy and X-ray crystallography. The inhibitory activities against α-glucosidase of rhotomensones E and F were evaluated in vitro, with IC50 values of 0.50 ± 0.14 mg/mL and 0.07 ± 0.02 mg/mL. Moreover, rhodomyrtosone B showed significant antibacterial activity against some bacteria, with MIC values ranging from 0.50 to 16.00 µg/mL.

α-Glucosidase inhibitory and anti-inflammatory activities of dammarane triterpenoids from the leaves of Cyclocarya paliurus.

Diabetes mellitus is caused by chronic inflammation and affects millions of people worldwide. Cyclocarya paliurus leaves have been widely used in traditional folk tea as a remedy for diabetes, but the antidiabetic constituents remain to be further studied. The α-glucosidase inhibitory and anti-inflammatory activities were examined to evaluate their effects on diabetes mellitus, and bioassay-guided separation of C. paliurus leaves led to the identification of twenty dammarane saponins, including eleven new dammarane saponins (1-11). The structures of the isolates were elucidated by spectroscopic methods. Bioactivity assay results showed that compounds 1 and 2 strongly inhibited α-glucosidase activity, with IC50 values ranging from 257.74 µM, 282.23 µM, and strongly inhibited the release of NO, with IC50 values of 9.10 µM, 9.02 µM. Moreover, compound 2 significantly downregulated the mRNA expression of iNOS, COX-2, IL-1ß, NF-κB, IL-6 and TNF-α in LPS-mediated RAW 264.7 cells and markedly suppressed the protein expression of iNOS, NF-κB/p65, and COX-2. Dammarane glucoside 2 exhibited the strongest α-glucosidase inhibitory and anti-inflammatory activities. In addition, the structure-activity relationships (SARs) of the dammarane saponins were investigated. In summary, C. paliurus leaves showed marked α-glucosidase inhibitory and anti-inflammatory activities, and dammarane saponins are responsible for regulating α-glucosidase, inflammatory mediators, and mRNA and the protein expression of proinflammatory cytokines, which could be meaningful for discovering new antidiabetic agents.

Bioactivity-guided isolation of anti-inflammatory constituents from the bark of Streblus zeylanicus.

Based on anti-inflammatory activity to evaluate the effects to the release of NO, bio-assay guided separation of the bark of Streblus zeylanicus led to identify fifteen compounds, including four new terpenes (1, 2, 9, and 10), one new pentanoid glycoside (12), one new rumenic ester (13), together with nine known compounds (3-8, 11, 14, and 15). Their structures were elucidated using extensive NMR and HRESIMS spectroscopic data analyses. The stereochemistry of compound 10 was established by comparing the calculated and experimental ECD spectroscopic data. Compounds 1 and 2 showed moderate inhibition on nitric oxide (NO) production, with IC50 values of 10.21 µM and 15.53 µM, respectively.

3,4-seco-Dammarane Triterpenoid Saponins with Anti-Inflammatory Activity Isolated from the Leaves of Cyclocarya paliurus.

Cyclocarya paliurus is commonly used for the prevention and treatment of hypertension, diabetes, and inflammation in South China. Although research on the anti-inflammatory effects of C. paliurus leaves has been reported, no active anti-inflammatory compounds have been identified. In the present study, RAW 264.7 cells were used to establish a bioactivity-guided identification model to verify the inhibitory effects of C. paliurus leaves on inflammation and identify the anti-inflammatory constituents. The active fraction was isolated to yield 18 dammarane triterpenoid saponins, including 11 new 3,4-seco-dammarane triterpenoid saponins (1-11), the structures of which were identified on the basis of analyses of nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) and comparison with literature data. Compounds 7, 8, 10, and 11 showed strong inhibition on nitric oxide (NO) productions, with IC50 values ranging from 8.23 to 11.23 µM. These four compounds significantly decreased the secretion of tumor necrosis factor-alpha (TNF-α), prostaglandin E2 (PGE2), and interleukin 6 (IL-6) in lipopolysaccharide-activated RAW 264.7 cells. Furthermore, compound 7 decreased the expression of the proteins cyclooxygenase-2 (COX-2), inducible nitric-oxide synthase (iNOS), and nuclear factor kappa-B (NF-κB/p65). In addition, the structure-activity relationships of the isolates were investigated. The results suggest that 3,4-seco-dammarane triterpenoid saponins may be used as potential anti-inflammatory drugs and warrant further investigation.

Discovery of anti-inflammatory terpenoids from Mallotus conspurcatus croizat.

ETHNOPHARMACOLOGICAL RELEVANCE: Mallotus conspurcatus croizat (Euphorbiaceae), a plant native to Jinxiu in Guangxi, is popularly used in folk medicine to treat pelvic inflammatory disease. The anti-inflammatory activities of the compounds obtained from M. conspurcatus root were evaluated in this study. AIM OF THE STUDY: This study explored the major anti-inflammatory components of this plant. MATERIALS AND METHODS: The ethyl acetate fraction of the ethanol extract from M. conspurcatus was separated using chromatographic techniques. The structures of the isolates were elucidated from NMR, MS and X-ray data as well as from ECD. The anti-inflammatory activities of the isolates from M. conspurcatus were evaluated using LPS-stimulated RAW 264.7 cell models. The production of NO, TNF-α and PGE-2 was determined by ELISA and Griess tests. The expression levels of COX-2, NF-κB/p65 and iNOS were measured by western blotting. RESULTS: Two new diterpenoids, malloconspur A (1) and malloconspur B (2), and sixteen known terpenoids (3-18) were identified by comprehensive spectroscopic analyses and comparison with literature data. Malloconspur B (2) and 17-hydroxycleistantha-12,15-dien-3-one (3) substantially inhibited the release of NO with IC50 values of 10.47 µM and 9.32 µM, respectively. Compounds 1, 2 and 3 markedly decreased the secretion of PGE2 and TNF-α (P < 0.01) by LPS-induced RAW264.7 cells. Compounds 2 and 3 markedly decreased iNOS, NF-κB/p65 and COX-2 protein expression. CONCLUSIONS: Our identification of these diterpenoids provides strong evidence for the use of M. conspurcatus among the Yao people as a medicinal plant for the treatment of inflammation. The dramatic differences in the chemical structures of the active diterpenoids of this plant from those on the market suggest these compounds have potential as anti-inflammatory lead compounds for follow-up research.

Ethylnaphthoquinone derivatives as inhibitors of indoleamine-2, 3-dioxygenase from the mangrove endophytic fungus Neofusicoccum austral SYSU-SKS024.

Bioassay-guided fractionation of the dichloromethane extract of the fungus Neofusicoccum austral SYSU-SKS024 led to the isolation of three new ethylnaphthoquinone derivatives, neofusnaphthoquinone A (1), 6-(1-methoxylethy1)-2,7-dimethoxyjuglone (2), (3R,4R)-3-methoxyl-botryosphaerone D (6), together with six known analogs (3-5 and 7-9). Their structures were elucidated by spectroscopic analysis and single crystal X-ray diffraction analysis. Neofusnaphthoquinone A (1) is the third example of the unsymmetrical naphthoquinone dimer, which is rarely found in natural source. All of the isolates were evaluated for their indoleamine 2, 3-dioxygenase (IDO) inhibitory activity, compounds 1-6 showed in vitro inhibitory effects against IDO with IC50 values ranging from 0.11 to 10.92µM. This is the first time naphthoquinone dimer (1), as a novel carbon skeleton possessing IDO inhibitory activity, was reported.

Structural Characterization and Assessment of the Cytotoxicity of 2,3-Dihydro-1H-indene Derivatives and Coumarin Glucosides from the Bark of Streblus indicus.

A pair of enantiomers and a pair of 2,3-dihydro-1H-indene epimers, rac-indidene A (rac-1), indidenes B and C (2, 3); four new coumarin glucosides (4-7); and four known coumarin glucosides (8-11) were isolated from the bark of Streblus indicus (Bur.) Corner. The structures of 1-11 were defined by physical data analyses, including MS, NMR, and single-crystal X-ray diffraction. The absolute configurations of the 2,3-dihydro-1H-indene derivatives were defined via experimental and calculated ECD data. rac-Indidene A and indidenes B and C showed inhibitory activity against A549 and MCF-7 tumor cells with IC50 values in the range of 2.2 ± 0.1 to 7.2 ± 0.9 µM.

A new anti-acetylcholinesterase α-pyrone meroterpene, arigsugacin I, from mangrove endophytic fungus Penicillium sp. sk5GW1L of Kandelia candel.

Arigsugacin I (1), a new α-pyrone meroterpene, along with two known compounds, arigsugacins F (2) and territrem B (3), were isolated from the mangrove endophytic fungus Penicillium sp. sk5GW1L from Kandelia candel. Their structures were identified through mass spectrometry and NMR experiments, and the absolute configuration of compound 1 was further confirmed by low-temperature (100 K) single crystal X-ray diffraction with Cu Kα radiation. The absolute configuration of compound 2 was first reported by using X-ray copper radiation. Compounds 1-3 showed inhibitory activities against acetylcholinesterase with IC50 values of 0.64 ± 0.08 µM, 0.37 ± 0.11 µM, and 7.03 ± 0.20 nM, respectively.

[Study on chemical constituents of Cyclocarya paliurus].

Phytochemical investigation of chemical constituents of the CHCl3 fraction of 75% alcohol extract from the leaves of Cyclocarya paliurus has resulted in the isolation of five compounds, alpha-boswellic (I), beta-boswellic (II), Oleanolic acid (III), 4-hydroxyl-3-methoxyl-benzoic acid (IV) and 3,6,3',5'-tetramenthox-5,7,4'-trihydroxy-flavonol (V). Their structures were elucidated on the basis of spectroscopic analyses, especially NMR. Compunds I, II, IV and V were obtained from this plant for the first time.