Structural diversification of bioactive bibenzyls through modular co-culture leading to the discovery of a novel neuroprotective agent

Bibenzyls, a kind of important plant polyphenols, have attracted growing attention for their broad and remarkable pharmacological activities. However, due to the low abundance in nature, uncontrollable and environmentally unfriendly chemical synthesis processes, these compounds are not readily accessible. Herein, one high-yield bibenzyl backbone-producing Escherichia coli strain was constructed by using a highly active and substrate-promiscuous bibenzyl synthase identified from Dendrobium officinale in combination with starter and extender biosynthetic enzymes. Three types of efficiently post-modifying modular strains were engineered by employing methyltransferases, prenyltransferase, and glycosyltransferase with high activity and substrate tolerance together with their corresponding donor biosynthetic modules. Structurally different bibenzyl derivatives were tandemly and/or divergently synthesized by co-culture engineering in various combination modes. Especially, a prenylated bibenzyl derivative ( 12) was found to be an antioxidant that exhibited potent neuroprotective activity in the cellular and rat models of ischemia stroke. RNA-seq, quantitative RT-PCR, and Western-blot analysis demonstrated that 12 could up-regulate the expression level of an apoptosis-inducing factor, mitochondria associated 3 (Aifm3), suggesting that Aifm3 might be a new target in ischemic stroke therapy. This study provides a flexible plug-and-play strategy for the easy-to-implement synthesis of structurally diverse bibenzyls through a modular co-culture engineering pipeline for drug discovery.

Functional characterization of a cycloartenol synthase and four glycosyltransferases in the biosynthesis of cycloastragenol-type astragalosides from Astragalus membranaceus

Astragalosides are the main active constituents of traditional Chinese medicine Huang-Qi, of which cycloastragenol-type glycosides are the most typical and major bioactive compounds. This kind of compounds exhibit various biological functions including cardiovascular protective, neuroprotective, etc. Owing to the limitations of natural sources and the difficulties encountered in chemical synthesis, re-engineering of biosynthetic machinery will offer an alternative and promising approach to producing astragalosides. However, the biosynthetic pathway for astragalosides remains elusive due to their complex structures and numerous reaction types and steps. Herein, guided by transcriptome and phylogenetic analyses, a cycloartenol synthase and four glycosyltransferases catalyzing the committed steps in the biosynthesis of such bioactive astragalosides were functionally characterized from Astragalus membranaceus. AmCAS1, the first reported cycloartenol synthase from Astragalus genus, is capable of catalyzing the formation of cycloartenol; AmUGT15, AmUGT14, AmUGT13, and AmUGT7 are four glycosyltransferases biochemically characterized to catalyze 3-O-xylosylation, 3-O-glucosylation, 25-O-glucosylation/O-xylosylation and 2'-O-glucosylation of cycloastragenol glycosides, respectively. These findings not only clarified the crucial enzymes for the biosynthesis and the molecular basis for the structural diversity of astragalosides in Astragalus plants, also paved the way for further completely deciphering the biosynthetic pathway and constructing an artificial pathway for their efficient production.

Biocatalytic access to diverse prenylflavonoids by combining a regiospecific -prenyltransferase and a stereospecific chalcone isomerase

Prenylflavonoids are valuable natural products that have diverse biological properties, and are usually generated biologically by multiple metabolic enzymes in nature. In this study, structurally diverse prenylflavonoids were conveniently synthesized by enzymatic catalysis by combining GuILDT, a regiospecific chalcone prenyltransferase, and GuCHI, a stereospecific chalcone isomerase that has promiscuous activity for both chalcones and prenylchalcones as substrates. Our findings provided a new approach for the synthesis of natural/unnatural bioactive prenylflavonoids, including prenylchalcones and optical prenylflavanones with chalcone origins.

The anti-neuroinflammatory effects of dehydromiltirone and related mechanisms / 中国药理学通报

Aim To investigate the anti-neuroinflam-matory activities of dehydromiltirone and the underlying mechanisms in LPS-stimulated microglial cell line BV2 cells. Methods BV2 cells were pre-treated with de-hydromiltirone, then stimulated by LPS. The levels of nitric oxide( NO) were measured by Griess assay, and the concentrations of pro-inflammatory cytokines were measured by ELISA assay. Confocal fluorescence mi-croscopy was used to measure the expression of MAC-1, the biomarker of activated BV2 cells. The levels of-inducible nitric oxide synthase ( iNOS ) , cyclooxygen-ase-2 ( COX-2 ) , NF-κB and PI3 K/Akt were deter-mined by Western blot analysis. Results The treat-ment of dehydromiltirone significantly inhibited the pro-duction of NO, TNF-α and IL-6, attenuated the ex-pression of iNOS and COX-2 protein, and dampened the microglial activation in LPS-stimulated BV2 cells. The mechanistic study revealed that dehydromiltirone inhibited the phosphorylation of PI3 K and Akt in LPS-stimulated BV2 cells, and decreased NF-κB activation by suppressing the degradation of IκB. Conclusion dehydromiltirone shows significant anti-neuroinflamma-tory effects through inhibiting PI3 K/Akt phosphoryla-tion and then inhibiting NF-κB signaling pathway.

Resistance reversal effect of a novel taxane compound NPB304 and its collaboration with verapamil / 药学学报

The tumor multidrug resistance reversal effect of NPB304, a novel taxane, was studied. MTT assay was used to determine the IC50 of chemotherapy drugs. Western blotting assay was applied to analyze the expression of P-glycoprotein (P-gp). The effect of compounds on the P-gp function and P-gp ATPase activity was determined by rhodamine 123 (Rh123) accumulation assay and analysis kit, respectively. Molecular docking was employed to predict the binding force between compounds and P-gp. Transmembrane transport of NPB304 was analyzed using MDCK II and MDR1-MDCK II cell model. NPB304 displayed multidrug resistance reversal effect on KBV cells and MCF-7/paclitaxel cells, NPB304 collaborative with P-glycoprotein (P-gp) inhibitors verapamil enhanced the reversal activity, specifically, 10 μmol x L(-1) verapamil in combination with paclitaxel reversed resistance by 56.5-fold, while combined with NPB304 increased the reversal fold; NPB304 synergistically increased Rh123 accumulation in the resistant cells when combined with verapamil, and NPB304 at 0-1 μmol x L(-1) enhanced the ATPase activity activated by verapamil was observed. NPB304 existed the hydrophobic interactions with the TM regions of P-gp, and the binding force between NPB304 and the A chain of the TM region was stronger. P-gp ATPase activity assay demonstrated NPB304 at lower concentrations (0-1.5 μmol x L(-1)) could activate the P-gp ATPase, playing a role on inhibition of P-gp function. However, NPB304 did not have an obvious feature of P-gp substrate. NPB304 exerted itself and synergy with verapamil activity on reversing tumor resistance via inhibiting the P-gp function.

Meroterpenoids and isoberkedienolactone from endophytic fungus Penicillium sp. associated with Dysosma versipellis / 药学学报

Seven meroterpenoids and five small-molecular precursors were isolated from Penicillium sp., an endophytic fungus from Dysosma versipellis. The structures of new compounds, 11beta-acetoxyisoaustinone (1) and isoberkedienolactone (2) were elucidated based on analysis of the spectral data, and the absolute configuration of 2 was established by TDDFT ECD calculation with satisfactory match to its experimental ECD data. Meroterpenoids originated tetraketide and pentaketide precursors, resepectively, were found to be simultaneously produced in specific fungus of Penicillium species. These compounds showed weak cytotoxicity in vitro against HCT-116, HepG2, BGC-823, NCI-H1650, and A2780 cell lines with IC 50 > 10 micromol x L(-1).

Research progress in aromatic prenyltransferases originated from microorganisms / 药学学报

The prenylation of aromatic compounds plays an important role in the natural product research because it not only gives rise to an astounding diversity of primary and secondary metabolites in plants, fungi and bacteria but also enhances the bioactivities and bioavailabilities of these compounds. However, further investigation of prenylated aromatic compounds is frequently hindered due to their low content in nature and difficulties in chemical synthesis. Cloning aromatic prenyltransferase genes followed by heterologous expression would be attractive tools for the chemoenzymatic synthesis of bioactive molecules. This review summarizes the classifications, structural investigations, enzymatic catalysis and other progress in aromatic prenyltransferases originated from microorganisms.

Sesquiterpenes and monoterpene from Aquilaria sinensis / 中国中药杂志

The column chromatography on silica gel, semi-preparative HPLC were used to separate and purify the compounds from the petroleum ether and ethanol extract of Aquilaria sinensis. Nine compounds were isolated. On the basis of their spectroscopic data, the structures were identified as 3, 3, 7-trimethyltricycloundecan-8-one (1), longifolene (2), norlongilactone (3), caryophyllenol-II (4), humulene diepoxide A (5), kobusone (6), (-)-bornyl ferulate (7), (24R) -24-ethylcholesta-4, 22-dien-3-one (8), (24R)-24-3-ono-4-en-sitosterone (9). Compounds 2-9 were isolated from this plant for the first time. compounds 1-6 are sesquiterpenes, compound 7 is a monoterpene derivative, compound 8 and 9 are steroids.

Studies on chemical constitutes from callus cultures of Stellera chamaejasme / 中国中药杂志

From callus cultures of Stellera chamaejasme, 17 compounds were isolated. Based on their physical and chemical data and spectroscopic analysis, they were identified as syringaresinol (1), medioresinol (2), pinoresinol (3), (1R, 2S, 5R, 6S)- 2-(4- hydroxyphenyl)-6-(3-methoxy-4-hydroxyphenyl)-3, 7-dioxabicyclo [3, 3, 0] octane (4), epipinoresinol (5), caruilignan D (6), 3-oxo-guai-4-ene-11, 12-diol (7), (-) -lariciresinol (8), tetrahydro-2-(4-hydroxy-3-methoxyphenyl)-4-[(4-hydroxyphenyl) methyl]-3-furanmethanol (9), 5'-methoxylariciresinol (10), vladinol D (11), cyclo (L-Pro-L-Val) (12), oxomatairesinol (13), (+) -guayarol (14); acutissimalignan B (15), isolariciresinol (16), and beta-sitosterol (17), respectively. Among these compounds, 12 was a cyclodipeptide, 7 was a sesquiterpene, and the others except 17 were lignans. All compounds were first isolated from callus cultures of S. chamaejasme.

Studies on constituents of cultures of fungus Phellinus igniarius / 中国中药杂志

<p><b>OBJECTIVE</b>To investigate the chemical constituents of the culture of Phellinus igniarius and their phamacological activities.</p><p><b>METHOD</b>The constituents were isolated by using a combination of various chromatographic techniques including column chromatography over silica gel, Sephadex LH-20, and reversed-phase HPLC. Structures of the isolates were identified by spectroscopic data analysis. Cytotoxic, neuroprotective, hepatoprotective, anti-inflammatory, and anti-HIV activities were screened by using cell-based models.</p><p><b>RESULT</b>Twenty-nine constituents were isolated. Their structures were identified as three sesquiterpenes: 3S,9R,10S-3-hydroxy-11, 12-O-isopropyldrimene(1), 3S, 9R, 10S-3, 11, 12-trihydroxydrimene (2), and 3S, 4S, 9R, 10S-11, 12, 14-trihydroxydrimene(3); three steriods: 24R-ergosta-4, 6, 8(14), 22-tetraen-3-one (4), stigmasta-7, 22-diene-3b, 5a, 6a-triol (5), and 5a, 8a-epi dioxyergosta-6, 22-diene-3b-ol (6); fourteen cyclo-dipeptide: cyclo (L-Pro-L-Val) (7), cycle (L-Leu-D-Pro) (8), cyclo (L-Leu-L-Pro) (9), cyclo (ILe-Pro) (10), cyclo (Gly-Leu) (11), cyclo (Phe-Ser) (12), cyclo (Ala-Pro) (13), cyclo (Ala-Phe) (14), cyclo (4-HyP-Phe) (15) , cyclo (L-Phe-D-Pro) (16), cyclo (D-Phe-D-Pro) (17), cyclo (6-HyP-Phe) (18), cycle (Gln-Pro) (19), and cycle (Asn-Leu) (20); and nine other compounds: N-acetyl-phenylalanine (21), adenosine (22), phenyldiethanol (23), o-hydroxy-phenylethanol (24), benzoic acid (25), p-methoxybenzoic acid (26), m-methoxybenzoic acid (27), hexadecanoic acid (28), and 3-pyridinecarboxylic acid (29). In the in vitro assays, at a concentration of 1 x 10(-5) mol x L(-1), compounds 5 and 8 showed neuroprotective activity against MPP+ induced PC12-syn cell damage, with a relative cell proliferation rate of 90.3% and 87.5% (P < 0.05). At 1 x 10(-5) mol x L(-1), compounds 12 and 18 showed hepatoprotective activities against DL-galactosamine-induced toxicity examined in WB-F344 cell, with cell survival rates of 25% and 24%, respectivily.</p><p><b>CONCLUSION</b>Compounds 1-29 were obtained from P. igniarius for the first time. Compounds 5 and 8 showed potent PC12-syn protective activities, while 12 and 18 showed hepato cytes (WB-F344 cells) protective activities.</p>

Studies on metabolites from marine microorganism Aspergillus terreus collected from nature reserve region of mangrove / 中国中药杂志

<p><b>OBJECTIVE</b>To search for new antitumor active lead compounds from marine microorganism.</p><p><b>METHOD</b>A marine strain, Aspergillus terreus, was cultured and up-scaled in artificial seawater media, from which the metabolites were isolated and elucidated by using modern spectroscopy techniques.</p><p><b>RESULT</b>Twelve compounds were isolated from mycelia and fermentation broth of A. terreus.</p><p><b>CONCLUSION</b>Compounds 1-4 were steroids, compounds 5-8 were organic acids and esters, compound 9 was an alkaloid, compound 10 was an isocoumarin, compound 11 was ceramide, compound 12 was propenyl cyclic pentanediol.</p>

Diterpenoids from Chinese eaglewood / 中国中药杂志

Column chromatography on silica gel, Sephadex LH-20, semi-preparative HPLC were used to separate and purify the compounds from the petroleum ether and ethanol extract of Chinese eaglewood. Nine compounds were isolated. On the basis of their spectroscopic data, their structures were identified as dehydroabietic acid (1), methyl dehydroabietate (2), methyl 7-oxodehydroabietate (3), 7alpha, 15-dihydroxydehydroabietic acid (4), 7alpha-hydroxypodocarpen-8(14)-en-13-on-18-oic acid (5), pimaric acid (6), pimarol (7), 18-norpimara-8 (14), and 15-dien-4alpha-ol (8), 18-norisopimara-8 (14), 15-dien-4beta-ol (9). All of the compounds were isolated from this plant for the first time, and compounds 5, 8 and 9 are norditerpenoids.

Chemical constituents of an endophytic fungus from Annona muricata / 中国中药杂志

<p><b>OBJECTIVE</b>To investigate the chemical constituents of an endophytic fungus, F-31, from Annona muricata and search antitumor natural products.</p><p><b>METHOD</b>After scaling up, the fermentation broth and mycelia were extracted by macroporous resin and chromatographied by silica gel column, Sephadex LH-20 gel column and semi-preparative HPLC. The structures of compounds were determined by the means of extensive spectroscopic data The activity of the compounds were evaluated through MTT assay.</p><p><b>RESULT</b>Six compounds were isolated from the fermentation broth and mycelia of this fungus, their structures were identified as 5-(3-hydroxybutyl)furan-2(5H)-one(1), chloranthalactone E(2), 5, 7-dimethyl-6-hydroxycoumarin(3), 1, 2, 4-triazole-(1'R, 2'R, 3'R, 4'R)-nucleosides(4), L-tryptophan(5), L-phenylalanine(6). The in vitro pharmalogical evaluation results displayed that the above compounds exhibited no inhibitory effects on the proliferation of six tumor cell lines (HCT-8, Bel-7402, BGC-823, A549, A2780 and MCF-7).</p><p><b>CONCLUSION</b>Among these obtained compounds, compound 1 was a new compound.</p>

Lactone constituents of Saussurea involucrata / 中国中药杂志

<p><b>OBJECTIVE</b>To study the chemical constituents of Saussurea involucrata.</p><p><b>METHOD</b>Compounds were isolated and purified by column chromatography, and their structures were elucidated by chemical and spectroscopic methods.</p><p><b>RESULT</b>Eight compounds were yielded and identified as beta-sitosterol (1), dotriacontanoic acid (2), hexacosan-4-olide (3), (+)-11alpha, 13-dihydrodehydrocostuslactone (4), 8alpha-acetoxydehydrocostus lactone (5), zaluzanin C (6), 11,13beta-dihydrozaluzanin C (7), 8alpha-hydroxy-11beta-11,13-dihydrodehydrocostuslactone (8).</p><p><b>CONCLUSION</b>Compounds 2-7 were first isolated from S. involucrate.</p>

Biotransformation of 6β-santonin by Phytolacca acinosa cell suspension cultures / 药学学报

Aim To obtain more valuable derivatives for the further structural modification of 6β-santonin (1) via biotransformation by using cell suspension cultures of Phytolacca acinosa. Methods The substrate 1 was incubated with cell suspension cultures of P.acinosa, the products were obtained by chromatography, and identified on the basis of their physical and spectral data (HRMS, 1D NMR, 2D NMR, NOE and IR). Results After incubation with cell suspension cultures of P.acinosa, 1 was converted into five products (2-6). Among them, 3 is a new compound. Conclusion 6β-santonin could be selectively reduced and hydroxylated by the cell suspension cultures of P.acinosa, which would provide valuable intermediates for its further structural modification.

Biotransformation of cantharidin by cell suspension cultures of Platycodon grandiflorus / 中草药

Object To investigate the biotransformation of cantharidin by cell suspension cultures of Platycodon grandiflorus (Jacq ) A DC Methods Cantharidin was added into cell suspension cultures of P grandiflorus and incubated for another six days The culture supernatant was extracted with EtOAc and then subjected to silica gel chromatography Results Two products were isolated as a mixture in a molar ratio of about 2∶1 Their structures were identified on the basis of spectroscopic data as 1? OH cantharidin (Ⅱa) and 1? OH cantharidin (Ⅱb) The relative configuration was elucidated according to NOESY spectrum Conclusion The two products were new cantharidin derivatives