Phytochemical investigation of the trunks from Gnetum latifolium led to the isolation of a novel phenolic glucoside, 2E-2,4-di-(3,4-dihydroxyphenyl)but-2-en-1-yl-O-β-D-glucopyranoside (1), along with five known stilbene derivatives (2-6). Their structures were determined mainly using high-resolution electrospray ionisation mass spectrometry and nuclear magnetic resonance spectroscopic analyses, followed by comparisons of observed spectral data with reported values. The novel compound 1 in G. latifolium was found to be useful as a chemotaxonomic marker. Biological evaluation revealed that compound 6 had remarkable inhibitory effects on nitric oxide production, with a half-maximal inhibitory concentration (IC50) value of 4.85 ± 0.20 µM, which was much higher than that of the positive control dexamethasone (IC50 = 14.20 ± 0.54 µM).

Phytochemical investigation on the aerial parts of Gnetum parvifolium led to the isolation of 15 new and eight known structurally diverse stilbenes. The isolated compounds comprised (E)- or (Z)-stilbene (1-6, 15-20), dihydrostilbene (21), phenylbenzofuran (7, 8, 22), benzylated stilbene (9-11), benzylated stilbene dimer (12), and nitrogen-containing stilbene (13a, 13b, 14) types. The structures of the new compounds (1-12, 13a, 13b, 14) were established through spectroscopic analyses and experimental and calculated ECD data. Compound 12 is the first stilbene dimer connected through a benzyl group. In the anti-neuroinflammatory activity assay, compounds 4, 5, 9-11, 13b, and 16-21 displayed significant inhibitory effects against LPS-induced NO release in BV-2 microglial cells, with IC50 values of 0.35-16.1 μM. Compound 10 had the most potent activity (IC50 = 0.35 μM), and the further research indicated that it could decrease the mRNA levels of iNOS, IL-1β, IL-6, and TNF-α in a dose-dependent manner.

This article describes the complete chloroplast genome of Gnetum luofuense. The G. luofense plastome was 114,795 bp in length, containing a large single copy region (66,103 bp) and a small single copy region (9438 bp), separated by two inverted repeat regions (19,627 bp). The genome lost all ndh genes and contained 116 genes, including 68 protein-coding genes, 40 tRNA genes, and eight rRNA genes. The GC content was 33.3%, 12 genes all contained an intron, ycf3 gene contained two introns while rps12 was a transpliced gene. Phylogenetic analysis using 61 concatenated protein-coding genes suggests that G. luofuense with the rest of other gnetophytes were sister to or nested within all conifers.

Phytochemical study on the EtOAC-soluble extract of the leaves of Gnetum gnemon furnished the isolation of a new phenylheptanoid, gnetumal (1), along with five known compounds (2-6). Their isolation was carried out by using the column chromatography and their structures were elucidated based on the basis of the spectral interpretation. Bioactivity assay of these compounds indicated that gnetumal (1) and p-coumaric acid (5) possessed more potent tyrosinase inhibitory activity, with IC50 values of 31.6 and 2.3 µM, respectively, than that of a positive control kojic acid (IC50; 44.6 µM).

Oligostilbenes are polyphenol oligomers derived from resveratrol and are commonly produced by members of the Gnetaceae family, and many researchers have focused on their anti-inflammatory activities. The EtOAc fraction of a Gnetum latifolium extract showed inhibitory activity against neuroinflammation induced by the transfection of Aβ1-42 into microglial BV-2 cells. The bioassay-guided isolation of the 70% EtOH extract of this plant resulted in three previously undescribed resveratrol oligostilbenes and ten known stilbene derivatives. The structures of the isolated compounds were established based on extensive NMR spectroscopic analysis. The absolute configurations of the three undescribed compounds were confirmed by comparison with available compounds with known stereochemistry and by ECD calculations and molecular modelling. Latifoliols A and B are the first reported oligostilbenes with a bridged 3-oxabicyclo[3.3.0]octane moiety, and latifoliol C was formed by the condensation of gnemontanin G with oxyresveratrol. Moreover, the hypothetical biogenetic pathway of latifoliols A, B and C was proposed. The potential anti-inflammatory activities of the thirteen isolated compounds were tested by measuring their effect on the secreted NO concentrations induced by transfection with plasmids expressing the Aβ1-42 gene in the BV-2 cell line. Interestingly, cis- and trans-shegansu B and latifolol, whose structures contained double bonds, strongly inhibited NO secretion in BV-2 cells, supporting the double binding effect of the stilbene derivative on inhibitory activity.