查看更多>>摘要：? 2022 Elsevier LtdStudies on an organic extract of a marine fungus, Periconia sp. (strain G1144), led to the isolation of three halogenated cyclopentenes along with the known and recently reported rhytidhyester D; a series of spectrometric and spectroscopic techniques were used to elucidate these structures. Interestingly, two of these compounds represent tri-halogenated cyclopentene derivatives, which have been observed only rarely from Nature. The relative and absolute configurations of the compounds were established via mass spectrometry (MS), nuclear magnetic resonance (NMR) spectroscopy, Mosher's esters method, optical rotation and GIAO NMR calculations, including correlation coefficient calculations and the use of both DP4+ and dJ DP4 analyses. Several of the isolated compounds were tested for activity in anti-parasitic, antimicrobial, quorum sensing inhibition, and cytotoxicity assays and were shown to be inactive.
查看更多>>摘要：? 2022 Elsevier LtdTwelve undescribed sesquiterpene lactones and seven known sesquiterpene lactones were isolated from the whole plant of Artemisia mongolica. Their structures were elucidated based on the interpretation of NMR, HRESIMS, and electronic circular dichroism (ECD) data. The absolute configurations of mongolicolide A (1), mongolicolide C (3), 1R, 3S-Dihydroxy-7S, 11R-germacra-4Z.9Z-dien-12, 6S-olide (5), indicumolide E (9), indicumolide F (10), and indicumolide G (11) were determined by single-crystal X-ray crystallography. The X-ray crystal structure of artabsinolide E (15) was reported for the first time. In addition, beibersteneolide-B (13) showed moderate anti-inflammatory activity and marked antitumor activity, artemyriantholide E (18) show moderate antitumor activity.
查看更多>>摘要：? Elsevier LtdFive undescribed benzopyran containing meroterpenoids, ganodercins Q－U, two undescribed benzofuran containing meroterpenoids, ganodercins V and W, and two known meroterpenoids were isolated from Ganoderma cochlear. Their structures were elucidated by using HRESIMS, NMR spectroscopy and computational methods. The results of biochemical studies using a palmitic acid (PA) induced insulin resistance (IR) model show that (?)-ganodercin Q, (+)-ganodercins R and W activate phospho-AKT (p-AKT) at 20 μM and improve glucose uptake in a concentration dependent manner. The results of renoprotection studies show that (+)-ganodercin S, cochlearol F, (+)- and (?)-ganodercins V reduce the expression of collagen I.
查看更多>>摘要：? 2022 Elsevier LtdThe fruits, twigs and leaves of Daphniphyllum oldhamii (Hemsl.) K. Rosenthal, collected from Longshan County, Hunan Province, China, were chemically investigated. Three undescribed daphniphyllum alkaloids, namely longshanoldhamines A?C, and six known related ones have been isolated from the fruits, whereas two undescribed triterpenoids and one undescribed lignan, along with six known triterpenoids, were found in the twigs and leaves. Their structures were elucidated by extensive spectroscopic analysis, X-ray diffraction analysis and comparison with the reported data.
查看更多>>摘要：? 2022 Elsevier LtdFive undescribed compounds, including three diterpenoids namely, saraburol, saraburanes A and B, and two p-methoxycinnamic acid monoterpene diol esters, named E/Z-saraburinic esters, together with ten known oxygenated isopimarane diterpenoids, were isolated from the whole plant of Kaempferia saraburiensis Picheans. Among these compounds, saraburol possesses an unusual 6/9/6 tricyclic ring system bearing a 1,3-dioxonane-4-one scaffold, which is rarely found in natural products. The structure of isolated compounds was elucidated by spectroscopic methods, including HRESIMS, FTIR, 1D and 2D-NMR, and by comparison with published data, and their absolute configurations were determined by comparison of experimental with calculated ECD spectra and hydrolysis reaction. Using gauge-independent atomic orbital (GIAO) NMR shift calculations coupled with DP4+ probability analyses, biogenetic considerations, and optical rotation allowed for the complete characterization of saraburol. A plausible biosynthetic pathway for saraburol and saraburane A was proposed. The cytotoxicity result indicated that E-saraburinic ester exhibited the most potent activity with an IC50 value of 12.0 μM against MOLT-3 cells with a selectivity index of 12.5. Saraburane B exhibited the most potent activity against Gram-positive bacteria strain Staphylococcus epidermidis with MIC (MBC) value of 25 (50) μg/mL.
查看更多>>摘要：? 2022 Elsevier LtdPrimary and secondary antioxidant activities of pyridoxal have been investigated by using density functional theory (DFT) at the M05–2X level combined with 6–311++G(d,p) basis set for non-metallic atoms and LanL2DZ for metallic ions. The former has been examined by its free radical scavenging activity towards HOO●, HO●, and NO2● via different mechanisms including formal hydrogen transfer (FHT), proton transfer (PT), single electron transfer (SET), and radical adduct formation (RAF). The latter has been accomplished through its transition metal-chelating ability with Fe(III)/Fe(II) and Cu(II)/Cu(I) ions. The results show that pyridoxal illustrates as an efficient radical scavenger, especially, for HO● and NO2● in water. The overall rate constants (koverall) for the reactions with HOO●, HO●, and NO2● radicals are 1.30 × 104, 5.76 × 109, and 1.43 × 109 M?1s?1, respectively. The SET from the anionic state is the most dominant for the HOO● and NO2● scavenging reactions, while both RAF and SET contribute largely to the reaction with highly reactive HO● radicals. Moreover, the anionic form of pyridoxal demonstrates a better role as a metal chelator than the neutral. However, the pro-oxidant risks of the formed complexes could be observed if there are superoxide radical anion (O2●–) and ascorbate (Asc–) in aqueous media.
查看更多>>摘要：? 2022Phenolic acids are the major bioactive metabolites produced in Salvia miltiorrhiza, a traditional Chinese medicine called Danshen. Many phytohormone elicitor treatments induce phenolic acid biosynthesis, even though the underlying mechanism remains obscure. Expression pattern analysis showed that SmMAPK3 was highly expressed in leaves, and SmMAPK3 was significantly induced by salicylic acid (SA) and methyl jasmonate (JA). Bioinformatics analysis revealed that SmMAPK3 belongs to group A and contains a TEY motif in the activation loop together with three conserved regions (P-loop, C-loop and CD-domain). A previous study speculated that SmMAPK3 is likely a positive regulator in the biosynthesis of phenolic acids in S. miltiorrhiza. In this study, overexpression of SmMAPK3 increased phenolic acid biosynthetic gene expression and enhanced the accumulation of phenolic acids in S. miltiorrhiza plantlets. Yeast two-hybrid (Y2H) analysis and firefly luciferase complementation imaging (LCI) assays revealed that SmMAPKK2/4/5/7-SmMAPK3-SmJAZs form a cascade that regulates the accumulation of phenolic acids. In summary, this work deepens our understanding of the posttranscriptional regulatory mechanisms of phenolic acid biosynthesis and sheds new light on metabolic engineering in S. miltiorrhiza.
查看更多>>摘要：? 2022 The AuthorsAs part of a project aiming at the discovery of environmentally friendly alternatives to copper in organic agriculture, a 96% ethanolic extract from the leaves of Inga sapindoides showed potent inhibitory activity against grapevine downy mildew (Plasmopara viticola) in vitro (MIC100 25 μg/mL). Separation of the n-BuOH soluble fraction by silica gel column chromatography followed by a combination of RP18 and HILIC HPLC resulted in the isolation of a series of bidesmosidic saponins characterized by the presence of a monoterpenoid unit attached to a triterpenoid aglycone, a p-methoxycinnamoyl residue, and rare sugar residues such as N-acetyl-D-glucosamine, D-quinovose, and D-fucose. The isolated compounds inhibited the formation or activity of P. viticola zoospores with MIC100 values of 3 or 6 μg/mL, respectively. I. sapindoides, a tree which is often cultivated for shading coffee plantations in Central America, may represent a sustainable source of fungicidal products to be used in the replacement of copper.
查看更多>>摘要：? 2022 Elsevier LtdThe investigation of the metabolites from the endophytic fungus Xylaria sp. YM 311647 in solid fermentation resulted in the isolation of six undescribed compounds, namely xylarioxides A–F, respectively. These included one eremophilane sesquiterpene, three guaiane sesquiterpene glycosides, and two ergostane glycosides. The structures of the compounds were determined by extensive analyses of spectroscopic data, including 1D and 2D NMR, as well as HRESIMS data. The stereochemistry of xylarioxide A was confirmed by X-ray crystallographic analysis. All of the isolated compounds were assayed for their antifungal activities against seven phytopathogenic fungi and two human pathogenic fungi. Among them, xylarioxides A, E and F showed potent activities against the tested phytopathogens. Particularly, xylarioxide E exhibited the highest activity against Gibberella saubinetii, Curvularia lunata, and Colletotrichum gloeosporioides with MIC values of 4, 4, and 8 μg/mL, respectively, which were comparable to the positive control of nystatin. Interestingly, guaiane sesquiterpene glycosides have been rarely reported from fungal sources. Additionally, xylarioxide E represented an unusual naturally occurring 3,4-seco-steroidal glycoside with a seven-membered lactone in ring A.
查看更多>>摘要：? 2022In the present study, purine alkaloid analysis and transcriptome of Camellia gymnogyna Hung T. Chang (Theaceae) from Dayao Mountain were performed by high-performance liquid chromatography (HPLC) and RNA-Seq, respectively. The results showed that the major purine alkaloids accumulated in Camellia gymnogyna Hung T. Chang (Theaceae) were theobromine together with a small amount of theacrine and caffeine. Through polymerase chain reaction (PCR), three types of cDNA encoding N-methyltransferases were isolated from the leaves of Camellia gymnogyna Hung T. Chang (Theaceae) and designated GCS1, GCS2, and GCS3. We subsequently expressed GCS1, GCS2, and GCS3 in Escherichia coli and incubated lysates of the bacterial cells with a variety of xanthine substrates in the presence of S-adenosyl-L-methionine as the methyl donor. We found that the recombinant GCS1 proteins catalyzed 1,3,7-trimethyluric acid to produce theacrine, the recombinant GCS3 proteins catalyzed 7-methylxanthine to produce theobromine, while the recombinant GCS2 proteins did not catalyze any xanthine derivatives. Simultaneous analysis of the expressions of GCS1, GCS2, GCS3, and a caffeine synthase gene (TCS1) in Camellia gymnogyna Hung T. Chang (Theaceae) and other tea plants provided a reference for further research on the functions of these genes.
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