Chemistry of Natural Compounds最新文献

A new chromone, 2,3-dihydroxy-5,6,7,8-tetramethylchromone (1), along with 13 known compounds, including o-hydroxybenzoic acid (2), p-hydroxybenzoic acid (3), p-hydroxybenzaldehyde (4), vanillin (5), isovanillin (6), vanillic acid (7), ferulic acid (8), isoferulic acid (9), methyl ferulate (10), protocatechuic acid (11), eugenitol (12), isoeugenitol (13), and 8-methyleugenitol (14), were isolated from the leaves of Kalanchoe beharensis (Crassulaceae). The structure of the new chromone derivative was elucidated by chemical and physical evidence.

A new megastigmane glycoside (1), viburcoside A, and four known analogs (2–5) were isolated from the methanol extract of Viburnum urceolatum fruits. The structure, including the absolute configuration of compound 1, was elucidated by extensive spectroscopic analysis (NMR and HR-ESI-MS), DP4+ NMR and ECD calculations, and enzyme hydrolysis. In the in vitro assay, viburcoside A (1) exhibited the potential inhibition of α-glucosidase with the IC₅₀ value of 16.03 μM, compared with the positive control acarbose (IC₅₀ = 18.84 μM).

Two novel water-soluble polysaccharides (ALPS-21 and ALPS-32) were isolated and purified from Acanthopanax leucorrhizus. Their structures were investigated by HPGPC, HPLC, IR, methylation and NMR, and the antioxidant activity was evaluated in vitro by 1,1-diphenyl-2-picrylhydrazyl radical (DPPH^·), hydroxyl radical (HO^·), and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS^·+) assay. Results showed that ALPS-21 was a 4.36 kDa neutral heteropolysaccharide composed of glucose, galactose, mannose, xylose in a ratio of 3.5:1.3:0.9:2.1, whereas ALPS-32 was a 5.78 kDa acidic heteropolysaccharide composed of glucose, galactose, mannose, and glucopyranuronic acid in a ratio of 4.5:1.3:1.1:1.0. Moreover, ALPS-21 and ALPS-32 can scavenge DPPH^·, HO^·, and ABTS^·+ in a dose-dependent manner, suggesting that ALPS-21 and ALPS-32 may be promising as a potential natural antioxidant.

Two previously undescribed iridoid glycosides, 6′-O-trans-caffeoyl-(4S,6R)-3,4-dihydro-3α- methylthioasperulosid (1) and 6′-O-trans-feruloyl-(4S,6R)-3,4-dihydro-2′-O-3α-paederosid (2), were isolated from the 90% EtOH extract of the aerial part of Paederia foetida L. The structures of the new compounds were elucidated by spectral methods such as 1D and 2D (¹H–¹H COSY, HMQC, and HMBC) NMR spectroscopy, HR-ESI-MS, as well as ECD data. The isolated compounds were tested in vitro for cytotoxic activity against five tumor cell lines. These results revealed that 2 exhibited some cytotoxicities against all the tested tumor cell lines with IC₅₀ value less than 20.0 μM and provided a scientific basis for further processing and utilization of P. foetida.

A novel class of isoaurone analogs was designed, synthesized, and investigated in vivo for their anti-inammatory activity using a xylene-induced ear edema model. Isoaurones 8a–e exhibited anti-inflammatory activity at a dose of 100 mg/kg with inhibition rates ranging from 21.75% to 34.46%. 3-(4-(3-((5-(3-Chlorophenyl)-4H-1,2,4-triazol-3-yl)thio)propoxy)benzylidene)-6-methoxybenzofuran-2(3H)-one (8e) showed the most potent growth inhibitory effects (34.46%), indicated by the slightly higher inhibitory effects of celecoxib (31.92%).

The compositions of nine fucoidan fractions from five species of brown alga, i.e., AbF from Arthrothamnus bifidus, AkF1 and AkF2 from A. kurilensis, CfF1 and CfF2 from Cymathaere fibrosa, CjF1 and CjF2 from C. japonica, and CtF1 and CtF2 from C. triplicata were studied. The main chains of AbF, AkF2, CfF2, CjF2, and CtF2 were constructed from 1,3-bound α-L-fucose. The studied polysaccharides were nontoxic at concentrations up to 400 μg/mL and exhibited weak inhibitory activity and pronounced inhibitory activity in combination with 2-deoxy-D-glucose on colony formation of SK-MEL-5 melanoma cells.

The herb of Saposhnikovia divaricata (Turcz.) Schischk. (Apiaceae) growing in Baikal District contained 15 compounds, among which were known dihydrofurochromones (3–6), flavonol O-glycosides (7–12), caffeoylquinic acids (13–15), and new chromones 1 and 2. The new compounds were cimifugin 4′-O-(6′′-O-β-D-apiofuranosyl)-β-D-glucopyranoside (divarichromone A, 1) and cimifugin 4′-O-(6′′-O-malonyl)-β-D-glucopyranoside (divarichromone B, 2) according to UV, NMR, and mass spectral data.

A new pyridine, 4-(1′-hydroxy-2′-methylpropyl)pyridine-2-carboxylic acid (16), along with fifteen known compounds including α-humulene (1), zerumbone (2), zerumbone epoxide (3), β-sitosterone (4), β-sitosterol (5), kaempferol-3-O-(3′′,4′′-O-diacetyl)rhamnoside (6), kaempferol-3-O-(4′′-O-acetyl)rhamnoside, kaempferol-3,4′-O-dimethylether (8), ferulic acid (9), vanillic acid (10), methyl indole-3-carboxylate (11), indole-3-carbaldehyde (12), indole-3-carboxylic acid (13), pyridine-2-carboxylic acid (picolinic acid) (14), and 3-methylpyridine-2-carboxylic acid (3-methylpicolinic acid) (15) were isolated from the rhizomes of Zingiber zerumbet (L.) Sm. (Zingiberaceae). The structure of the new pyridine was elucidated by physical evidence.