Trichothiazole A, a dichlorinated polyketide containing an embedded thiazole isolated from Trichodesmium blooms

Two new triterpenoids from the roots of Phyllanthus emblica

Facile synthesis of a luminescent copper(I) coordination polymer containing a flexible benzotriazole-based ligand: An effective catalyst for three-component azide-alkyne cycloaddition

Characterization of polychlorinated biphenyl congeners in surface sediments of the Changjiang Estuary and adjacent shelf by high-resolution sampling and high-resolution mass spectrometry

The medicinal plant Knema angustifolia has been used in Thai folk medicine for the treatment of various diseases, especially related to body tonic or blood tonic agent. Chemical data on this plant are scarce. A novel para-benzoquinone, angustiquinone (3), along with ten known compounds, rapanone (1), embelin (2), quercetin (4), kaempferol (5), bergenin (6), 11-O-acetyl bergenin (7), catechin (8), isovanillic acid (9), protocatechuic acid (10) and gallic acid (11) were isolated from the n-hexane and EtOAc extracts of the stems of K. angustifolia. Their structures were unambiguously elucidated using extensive 1D and 2D NMR analyses, high-resolution mass spectrometry along with comparison with literature data. Compounds 1-2 and 4-11 were tested for anti-tyrosinase and α-glucosidase inhibitory activity. Quercetin (4) and kaempferol (5) revealed as potent inhibitors of tyrosinase activity, in which the IC50 42.3±0.26, 156.5±0.34 µM, respectively. Notably, rapanone (1) and embelin (2) exhibited excellent α-glucosidase inhibitory activity with IC50 1.3±0.17 and 9.25±0.26 µM, respectively which much higher than commercial drug acarbose (93.6±0.49 µM).

A new steroidal ester bearing n-nonadecanoyl moiety (1) and a mixture of isomeric cerebrosides (2) along with two known compounds were isolated from the methanol extract of the stem-bark of Anacardium occidentale. The structure of the new steroidal ester was determined as 3-n-nonadecanoyl-β-sitosterol on the basis of modern spectroscopic techniques (IR, ESI-MS, HR-ESIMS, 1D and 2D NMR) and chemical degradation studies. The structures of the known compounds were identified as gallic acid and tanacetene by comparison of the spectroscopic data with those of reported data. The mixture of cerebrosides was confirmed based on the analysis of 1D and 2D NMR. These compounds were evaluated for cytotoxicity against human cancer cell lines A549, SCOV3 and rat normal cell line NRK49f.

Herein, we report the targeted isolation and characterization of four linear nonribosomally synthesized tetrapeptides (pseudoxylaramide A–D) and two cyclic nonribosomal peptide synthetase‐polyketide synthase‐derived natural products (xylacremolide A and B) from the termite‐associated stowaway fungus Pseudoxylaria sp. X187. The fungal strain was prioritized for further metabolic analysis based on its taxonomical position and morphological and bioassay data. Metabolic data were dereplicated based on high‐resolution tandem mass spectrometry data and global molecular networking analysis. The structure of all six new natural products was elucidated based on a combination of 1D and 2D NMR analysis, Marfey's analysis and X‐ray crystallography.

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Secondary metabolites of Peucedanum tauricum fruits

Comparison of fipronil sources in North Carolina surface water and identification of a novel fipronil transformation product in recycled wastewater

Elucidation of the structure of a bioactive hydrophilic polysaccharide from Cordyceps sinensis by methylation analysis and NMR spectroscopy

From L. racemosa leaves eight compounds were isolated: myricetin (1), quercetin (2), myricetin 3-O-α-L-rhamnopyranoside (3), myricetin 3-O-(2"-O-galloyl-α-L-rhamnopyranoside) (4), myricetin 3-O-(3"-Ogalloyl-α-L-rhamnopyranoside) (5), 3-Omethylellagic acid (6), (3S,5R,6S,7E)-3,5,6- trihydroxy-7-megastigmen-9-one (7) and gallic acid (8). Their chemical structures were unambiguously elucidated by analysis of 1D and 2D NMR and high resolution ESI mass spectroscopic data, as well as by comparison with those reported in the literature. The α- glucosidase inhibition was evaluated on isolated compounds. Among them, 1, 4, 5, 6 and 8 exhibited good activities with the IC50 values in the range of 1.3-19.3 µM.

A new depside and two new diphenyl ether compounds from the lichen Ramalina farinacea (L.) Ach

New azaphilone, isocoumarin and α-pyrone derivatives from the marine-derived gut fungus Paraphaeosphaeria sp. XZD2-1

Nine new limonoids, meliazedarines A-I (1-9), seven known analogues (10-16), and five known triterpenoids (17-21) were isolated from the fruits of Melia azedarach. Their structures were determined by analysis of 1D and 2D NMR, HRESIMS, X-ray diffraction, and electronic circular dichroism (ECD) data. Compound 7 showed significant cytotoxicity against the HCT116 cell line with IC50 values of 0.3 ± 0.1 μM.

Through a phytochemical investigation of Abrus mollis Hance, a folk medicinal plant in China, we isolated and identified three undescribed compounds, including two flavonoids and one amides alkaloid, along with nine known from this plant. Their structures were elucidated by analyses of 1D, 2D NMR, HR-ESI-MS, ECD, and DP4+ analysis. Furthermore, we evaluated the hepatoprotective effects of all twelve compounds on D-GalN-induced Brl-3 A cells. According to the results, at a concentration of 25 μM, the cell survival rates were observed to be 71.92±0.34 %, 70.03±1.29 %, and 69.11±1.90 % for compound 2, 4, and 11, respectively. Further experimental studies showed that compound 2 (EC50 5.76±0.37 μM) showed more significant protective activity than the bicyclol.