Phytochemistry最新文献

Daphne mezereum L. (Thymelaeaceae) was an important medicinal plant in Norway during the 18^th and 19^th centuries and used against diseases such as diarrhea, swelling, stomach pain, and tuberculosis. Five previously undescribed phenolic compounds, including two biflavonoids with a catechin core structure, two tricoumarins, and one bicoumarin, together with ten known compounds were isolated from a 50% EtOH extract of the bark of D. mezereum. Using NMR, HRESIMS, acid hydrolysis, and circular dichroism spectra, the biflavonoids were identified as 3'-hydroxygenkwanol A and 3'-hydroxydihydrodaphnodorin B, and the coumarins were identified as 3'''-O-acetyltriumbellin, triumbellin 4'''-O-β-D-glucopyranoside, and daphnogitin-7-O-β-D-glucopyranoside. The absolute configuration of dihydrodaphnodorin B was for the first time established as 2R, 3S, 2''S, 3''S. Daphnin, syringin, 3'-hydroxydihydrodaphnodorin B, dihydrodaphnodorin B, and neochamaejasmin A and B were identified as the major secondary metabolites in the extract. Neochamaejasmin A and B showed the most potent inhibition of TNF-α secretion in Con A stimulated peripheral blood mononuclear cells (PBMCs) with 71.3 ± 3.4 and 83.5 ± 11.5% inhibition, respectively, at 50 μM.

Parrotia subaequalis, an endangered Tertiary relict tree native to China and a member of the Hamamelidaceae family, is one of several host plant species in this family that exhibit unique ecological habits, such as gall formation. Tree galls are the results of complex interactions between gall-inducing insects and their host plant organs. The formation of galls may serve to protect other regions of the plant from potential damage, often through the production of phytoalexins. In this study, a preliminary investigation was carried out on the metabolites of the 90% MeOH extract derived from the closed spherical galls on the twigs of P. subaequalis. Consequently, nine previously undescribed benzofuran-type and dibenzofuran-type phytoalexins (parrotiagallols A-I, 1-9, respectively) were isolated and characterized, along with several known miscellaneous metabolites (10-17). Their chemical structures and absolute configurations were elucidated using spectroscopic methods, a combination of calculated and experimental electronic circular dichroism data, and single crystal X-ray diffraction analyses. Among these compounds, 1 and 2 are identified as neolignan derivatives, while compounds 3-5 are classified as 9,10-dinorneolignans. Compound 6 represents a rare 2,3-seco-neolignan, and compounds 7-9 are dihydroxy-dimethyl-dibenzofuran derivatives. Parrotiagallol A (1) showed considerable antibacterial activity against Staphylococcus aureus, with an MIC value of 14 μM. Additionally, parrotiagallol E (5) and methyl gallate (17) exhibited inhibitory effects against ATP-citrate lyase (ACL), a potential therapeutic target for hyperlipidemia, with IC₅₀ values of 5.1 and 9.8 μM, respectively. The findings underscore that galls not only serve as physical defense barriers but also benefit from the chemical defense system of the host plants. These insights provide avenues for exploring potential new therapeutic agents for S. aureus infections and ACL-related diseases, while also promoting scientific conservation strategies for P. subaequalis.

Ten undescribed leucosceptrane-type sesterterpenoids with antipodal cyclopentenone moieties were isolated from the leaves of Leucosceptrum canum. Their structures including absolute configurations were elucidated by comprehensive spectroscopic analyses (including 1D and 2D NMR, and HRMS) and ECD calculations. In vitro immunosuppressive effects of these sesterterpenoids against the proliferation of T cells and the secretion of cytokine IFN-γ were evaluated. Among them, 11α-H-leucosceptroid C, 5,13-dehydro-11α-H-leucosceptroid C, 5,13-dehydro-11β-hydroxy-leucosceptroid C, and 5,13-dehydro-11α-hydroxy-leucosceptroid C significantly inhibited IFN-γ secretion with IC₅₀ values of 12.55-23.62 μM. More remarkable inhibitory effects against IFN-γ secretion were observed for 5,13-dehydro-11β-hydroxy-leucosceptroid D, leucosceptroid U, 14-epi-leucosceptroid U, leucosceptroid V, and 14-epi-leucosceptroid V, with IC₅₀ values of 4.32-9.47 μM.

The liverwort Frullania tamarisci (L.) Dumort produces large amounts of terpenoids, among others the sesquiterpene alcohol tamariscol. Tamariscol has an earthy woody fragrance, and the use in perfurmes and production of it was patented in 1984. The microbial terpene synthase-like (MTPSL) enzyme FtMTPSL6 is shown to be responsible for the biosynthesis of tamariscol. FtMTPSL6 was obtained through RNA sequencing of wild growing F. tamarisci along with six other MTPSLs (FtMTPSL1-7). The biochemical activity was determined for three of them, and two others where metabolic active, but the product could not be identified. The three characterized enzymes are the tamariscol synthase (FtMTPSL6), copaene synthase (FtMTPSL1) and gurjunene synthase (FtMTPSL3). Thus, the biosynthesis of the economically attractive compound tamariscol is established, and this opens up for further exploitation of this molecule.

Thirty-six compounds were isolated from extract of the stem bark of Illicium burmanicum, including twelve previously undescribed prenylated C6-C3 compounds and a norsesquiterpene lactone: illicidione D (1), illicidione E (2), illicidione F (3), illicidione G (4), (2R,4S,11R)-12-O-ethylillifunone C (5), (2R,4S,11R)-illifunone C-12-O-β-d-glucopyranoside (6), (2R,4S,11R)-2-hydroxyillifunone C (7), 4-epi-2,3-dehydroillifunone C (8), illiburmanone A (9), illiburmanone B (10), illiburmanlactone A (11), (2S,4S,5S,11R)-2,3-dihydroillicione E (12), and illiburmanolside A (13). Their structures were determined based on extensive spectroscopic data analyses, including MS, NMR, and ECD spectra. The anti-inflammatory activity of the isolated compounds (1-36) was evaluated, and compounds 7, 12, 14, and 18 exhibited inhibitory effects in RAW 264.7 cells induced by LPS.

Plant enzymes often present advantages in the synthesis of natural products with specific configurations. Farnesene is a pharmacologically active sesquiterpene with three natural Z/E configurations, among which the enzyme selectively responsible for the biosynthesis of (3Z,6E)-α-farnesene remains elusive. Herein, a sesquiterpene synthase TwSTPS1 biosynthesizing (3Z,6E)-α-farnesene as the major product was identified from Taxus wallichiana through genome mining. Utilizing molecular dynamics simulations and mutation analysis, the catalytic mechanism of TwSTPS1, especially Z/E configuration control, was explored. Moreover, the crucial residues associated with the specific catalytic activity of TwSTPS1 was elucidated through mutagenesis experiments. The findings contribute to our understanding of the Z/E configuration control by plant terpene synthases and also provide an alternative tool for manipulating (3Z,6E)-α-farnesene production using synthetic biology.

Eight cyclopenta[b]benzofurans (1, 2, 4, and 5-9) and eight cyclopenta[bc]benzopyrans (3, 10-16), including a revised (4) and three undescribed compounds (1-3), were isolated from the twigs and leaves of Aglaia edulis (Roxb.) Wall. Their structures were determined by a combination of spectral analysis in conjunction with NMR and ECD calculations. Moreover, based on the findings from ¹³C NMR calculations and DP4+ statistical analysis, an empirical guideline was established to differentiate the structures of cyclopenta[bc]benzopyrans and cyclopenta[b]benzofurans by aggregating chemical shift data from known compounds. This guideline facilitated the proposal of structural revisions for three previously reported analogs (R-1, R-2, R-3). Biological assay indicated that cyclopenta[b]benzofuran flavalines (2, and 4-8) could significantly inhibit NO production in LPS-induced BV-2 cells with IC₅₀ values from 0.002 to 0.05 μM.

Aspongpyridiniums A-J (1-10), ten previously undescribed amino acid-derived pyridinium salts were isolated and identified from the n-BuOH fraction of the 50% MeOH extract of insect species Aspongopus chinensis, well-known for its use in traditional Chinese medicine for the treatment of pain, indigestion and kidney diseases. Their structures were determined by extensive spectroscopic data as well as electronic circular dichroism calculations and comparisons. Aspongpyridiniums A-J are structurally characterized by a unique 1,3,4-trisubstituted pyridinium skeleton with a variable functional group derived from an amino acid unit. In bioassays, Compounds 5 and 10 exhibited certain inhibitory activities against α-glucosidase, while 1-10 showed moderate to weak acetylcholinesterase inhibitory effects.

Nine undescibed abietane diterpenoid alkaloids (DAs), salviamines G‒H (1-2), isosalviamines G‒J (3-6), and miltiorramines A‒C (7-9) were isolated from the roots of Salvia miltiorrhiza. Their chemical structures including absolute configurations were elucidated by extensive spectroscopic analysis (including 1D and 2D NMR, and HRESIMS), combined with the calculated ECD method and single-crystal X-ray diffraction analysis. Among them, compounds 1-6 are unusual 20-nor- or 19,20-bisnor-abietane DAs with an oxazole ring. Compounds 7-8 are the first examples of DAs with a nitro group isolated from plant sources. Notably, compound 9 possesses a rare hexahydropyrrolo[2,1-b]oxazole unit that is fused in the ring B of the abietane skeleton. Bioactivity assay indicated that compound 3 showed significant anti-inflammatory activity by decreasing the gene expressions of IL-1β, IL-6, and TNF-α in LPS-induced RAW264.7 cells in a dose-dependent manner.

Eleven undescribed steroids, bipolaristeroids A-K, and one known compound, demethylincisterol A₃, were isolated from the fungus Bipolaris maydis. Bipolaristeroid A is a 5,6-seco-9,10-seco-steroid with a rearranged B ring, in which the A and C rings are connected by an ester bond. Bipolaristeroid B is a rearranged 1(10→6)-abeosteroid with an aromatic B ring. Their planar structures and absolute configuration were determined using NMR, HRESIMS, DP4+ analysis, ECD calculation, and single-crystal X-ray diffraction. Bipolaristeroid A shows excellent inhibitory effects against the cancer cell lines HepG2, A549, SW620, and C4-2B with IC₅₀ values of 7.94, 5.11, 5.13, and 3.83 μM, respectively.