Yong Ling

Novel pleuromutilin derivatives as antibacterial agents: Synthesis, biological evaluation and molecular docking studies

Owing to the increasingly serious problems caused by multidrug resistance in community-acquired infection pathogens, it has become an urgent need to develop new classes of antibiotics for overcoming the resistance. In this paper, we describe the design and synthesis of novel pleuromutilin derivatives containing the (2-aminothiazol-4-yl)-4-methyl group, as well as their in vitro antibacterial activities against Gram-positive clinical bacteria. Most of the tested compounds displayed strong antibacterial activities against these methicillin-susceptible and methicillin-resistant bacteria. Particularly noteworthy compound 15 and its derivative 16e, both showed potent antibacterial properties (0.0625-0.5μg/mL) that are superior to amoxicillin and tiamulin. Molecular docking studies suggested that the amino thiazole ring on the side chains of the pleuromutilin derivatives can in general be accommodated near the mutilin core in the binding pocket, and thus play an important role in the activity of the whole molecule. The findings reported herein may provide a new insight into the design of novel pleuromutilin derivatives for human clinical use.

Microbial transformation of 20(S)-protopanaxadiol by Absidia corymbifera. Cytotoxic activity of the metabolites against human prostate cancer cells

Biotransformation of 20(S)-protopanaxadiol (1) by the fungus Absidia corymbifera AS 3.3387 yielded five metabolites (2-6). On the basis of spectroscopic data analyses, the metabolites were identified as 26-hydroxyl-20(S)-protopanaxadiol (2), 23, 24-en-25-hydroxyl-20(S)-protopanaxadiol (3), 25-hydroxyl-20(S)-protopanaxadiol (4), 7β-hydroxyl-20(S)-protopanaxatriol (5), and 7-oxo-20(S)-protopanaxatriol (6), respectively. Among them, 5 and 6 are new compounds. These results indicated that A. corymbifera AS 3.3387 could catalyze the side-chain oxidation-reduction, 7β hydroxylation, and the specific C-7 dehydrogenation of derivatives of 20(S)-protopanaxadiol. The metabolites 2, 5, and 6 showed the more potent inhibitory effects against DU-145 and PC-3 cell lines than the substrate.

Synthesis and biological evaluation of novel derivatives of gambogic acid as anti-hepatocellular carcinoma agents

A series of novel derivatives of gambogic acid (GA) were synthesized and evaluated for their in vitro cytotoxicity against human hepatocellular carcinoma (HCC) cells. All derivatives showed better aqueous solubility than GA, and compounds 3a, 3e, and 3f displayed potent inhibition of HCC cell proliferation (IC(50): 0.045-0.59 μM on Bel-7402 cells and 0.067-0.94 μM on HepG2 cells) superior to GA and taxol. Additionally, the most potent compound 3e did not affect significantly the proliferation of non-tumor liver cells, suggesting that it might selectively inhibit HCC proliferation. Furthermore, 3e induced high frequency of Bel-7402 cell apoptosis. Our findings suggest that these novel GA derivatives may hold a great promise as therapeutic agents for the intervention of human HCC.

Design, Synthesis, and Antibacterial Activity of Novel Pleuromutilin Derivatives Bearing an Amino Thiazolyl Ring

A series of novel pleuromutilin derivatives containing the amino thiazolyl ring were designed, synthesized, and evaluated for their antibacterial activities in vitro against Gram‐positive clinical bacteria. All the target compounds showed better aqueous solubility compared with the lead compound (10). Most compounds displayed strong antibacterial activities against both susceptible and resistant bacteria, particularly for the compound (12f) which showed extraordinary antibacterial properties superior to amoxicillin and tiamulin. Molecular docking studies revealed that the amino thiazolyl ring, the side chains of the pleuromutilin derivatives, can be adopted in the binding pocket of the 50S ribosomal subunit near the mutilin core. Therefore, our novel findings may provide new insights into the design of novel pleuromutilin derivatives and lay the basis for further studies on these promising antibiotics for human clinical use.

Design, synthesis, and bioactivities of novel oxadiazole-substituted pyrazole oximes

A series of novel pyrazole oxime derivatives containing a substituted oxadiazole group were designed and synthesized. The bioassay results indicated that some title compounds displayed good acaricidal and insecticidal activities against Tetranychus cinnabarinus, Aphis medicaginis, Oriental armyworm, and Nilaparvata lugens. Especially, compounds 7a, 7b, and 7c had 80%, 90%, and 90% insecticidal activities against A. medicaginis at 20μg/mL, respectively. Interestingly, some of the designed compounds displayed wonderful fungicidal activities in vivo against cucumber Pseudoperonospora cubensis. Furthermore, compounds 7a (EC50=4.97μg/mL) and 7h (EC50=0.51μg/mL) showed excellent fungicidal activity against P. cubensis comparable or better than that of the control Pyraclostrobin (EC50=4.59μg/mL).

Synthesis and bioactivities of novel pyrazole oxime derivatives containing a 1,2,3-thiadiazole moiety.

A series of new pyrazole oxime compounds bearing a 1,2,3-thiadiazole ring were designed, synthesized, and evaluated for their insecticidal, acaricidal and antitumor activities. Bioassays demonstrated that some title compounds displayed satisfactory insecticidal and acaricidal properties. Especially, compounds 8d and 8h exhibited 90% insecticidal activities against Aphis craccivora at the concentration of 100μg/mL. Interestingly, some of the target compounds possessed significant antitumor activities against four human cancer cell lines in vitro. Among them, compounds 8e (IC50=7.19μM), 8l (IC50=6.56μM), 8m (IC50=8.12μM), and 8r (IC50=7.06μM) had better inhibitory activities against HCT-116 cells than the control 5-fluorouracil (IC50=29.50μM). Additionally, compounds 8j, 8m, and 8r showed wonderful inhibitory activities against SGC-7901 cells with the IC50 values of 11.46, 9.41, and 8.64μM, respectively, which were superior to that of the control 5-fluorouracil.

Polysaccharides from Chrysanthemum morifolium Ramat ameliorate colitis rats by modulating the intestinal microbiota community

The gut microflora dysbiosis has been closely related with the inflammatory bowel disease (IBD). In this study, the effect of polysaccharides from Chrysanthemum morifolium Ramat on the gut microbiota was evaluated by ulcerative colitis (UC) rat model. Physiological and pathological analyses suggested that Chrysanthemum polysaccharides possessed notably protective effects on UC in vivo. Based on the Illumina MiSeq platform, 16S rRNA sequencing of the rat colonic contents indicated that the intestinal flora structure remarkably changed in the model rats and the tendency was alleviated to a certain degree by treatment with different dosages of Chrysanthemum polysaccharides. In normal groups, there were more Firmicutes than Bacteroidetes, but this change lost at the pathological state. Following Chrysanthemum polysaccharides, rising Firmicutes/Bacteroidetes ratio was validated. Besides the microbial diversity and the community richness of the UC rats were improved by Chrysanthemum polysaccharides, the composition of intestinal microflora in the model group were also restored after oral administration of Chrysanthemum polysaccharides. The abundance of opportunistic pathogens was decreased (Escherichia, Enterococcus and Prevotella), while the levels of protective bacteria such as Butyricicoccus and Clostridium (butyrate-producing bacteria), Lactobacillus and Bifidobacterium (probiotics), Lachnospiraceae and Rikenellaceae elevated in various degrees. Correlation analysis between intestinal flora and biochemical factors suggested that the relative abundance of protective bacteria was positively correlated with the levels of anti-inflammatory cytokines such as IL-4, IL-10 and IL-11, while aggressive bacteria were positively correlated with proinflammatory cytokine such as IL-23、IL-6、 IF-17、TNF-α、IL-1β and IFN-γ. The above results showed that the intestinal flora were closely related to the secretion and expression of cytokines in the body, and they interacted with each other to regulate immune function. Thus, Chrysanthemum polysaccharides could ameliorate ulcerative colitis by fostering beneficial intestinal flora growth, modulating the balance of intestinal microecology and restoring the immune system.

The ketone body metabolite β-hydroxybutyrate induces an antidepression-associated ramification of microglia via HDACs inhibition-triggered Akt-small RhoGTPase activation

Direct induction of macrophage ramification has been shown to promote an alternative (M2) polarization, suggesting that the ramified morphology may determine the function of immune cells. The ketone body metabolite β‐hydroxybutyrate (BHB) elevated in conditions including fasting and low‐carbohydrate ketogenic diet (KD) can reduce neuroinflammation. However, how exactly BHB impacts microglia remains unclear. We report that BHB as well as its producing stimuli fasting and KD induced obvious ramifications of murine microglia in basal and inflammatory conditions in a reversible manner, and these ramifications were accompanied with microglial profile toward M2 polarization and phagocytosis. The protein kinase B (Akt)‐small RhoGTPase axis was found to mediate the effect of BHB on microglial shape change, as (i) BHB activated the microglial small RhoGTPase (Rac1, Cdc42) and Akt; (ii) Akt and Rac1‐Cdc42 inhibition abolished the pro‐ramification effect of BHB; (iii) Akt inhibition prevented the activation of Rac1‐Cdc42 induced by BHB treatment. Incubation of microglia with other classical histone deacetylases (HDACs) inhibitors, but not G protein‐coupled receptor 109a (GPR109a) activators, also induced microglial ramification and Akt activation, suggesting that the BHB‐induced ramification of microglia may be triggered by HDACs inhibition. Functionally, Akt inhibition was found to abrogate the effects of BHB on microglial polarization and phagocytosis. In neuroinflammatory models induced by lipopolysaccharide (LPS) or chronic unpredictable stress (CUS), BHB prevented the microglial process retraction and depressive‐like behaviors, and these effects were abolished by Akt inhibition. Our findings for the first time showed that BHB exerts anti‐inflammatory actions via promotion of microglial ramification.

Simultaneous determination of the bioactive components in rat plasma by UPLC‐MS/MS and application in pharmacokinetic studies after oral administration of radix Scutellariae extract

A highly sensitive and rapid ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method has been developed and validated for simultaneous quantification of the four main bioactive compounds, i.e. baicalin, baicalein, wogonoside and wogonin, in rat plasma after oral administration of Radix Scutellariae extract. Clarithromycin was used as an internal standard (IS). Plasma samples were processed by protein precipitation with methanol. The separation was performed on an Acquity BEH C18 column (100u2009×u20092.1u2009mm, 1.7u2009μm) at a flow rate of 0.4u2009mL/min, using 0.1% formic acid-acetonitrile as mobile phase. The MS/MS ion transit ions monitored were 447.5u2009→u2009270.1 for baicalin, 270.1u2009→u2009168.1 for baicalein, 461.2u2009→u2009284.0 for wogonoside, 284.2u2009→u2009168.1 for wogonin and 748.5u2009→u2009158.1 for IS. Method validation was performed according to US Food and Drug Administration guidelines and the results met the acceptance criteria. The lower limit of quantification (LLOQ) achieved was 1.13u2009ng/mL for baicalin, 1.23u2009ng/mL for baicalein, 0.82u2009ng/mL for wogonoside and 0.36u2009ng/mL for wogonin. The calibration curves obtained were linear (ru2009>xa00.99) over the concentration rangeu2009~u20091-1000u2009ng/mL. The intra- and inter-day precision was <15% and the accuracy was within ±14.7%. After validation, this method was successfully applied to a pharmacokinetic study of Radix Scutellariae extract.

UPLC-Q-TOF/MS-based Metabolic Profiles of Bioactive Components in Rehmannia glutinosa and Cornus officinalis Herb Pair by Rat Intestinal Bacteria

Abstract Objective To investigate the metabolic routes and metabolites of Rehmannia glutinosa and Cornus officinalis herb pair produced by gut microbiome from rats. Methods A rapid and sensitive ultra-performance liquid chromatography/quadrupole-time-of-flight mass spectrometry (UPLC-Q-TOF/MS) technique combined with Metabolynx™ software was established and successfully applied to identify the metabolites of the main bioactive components in the herb pair extract by rat intestinal bacteria. Results Four parent compounds (loganin, morroniside, catalpol, and acteoside) and their eight corresponding metabolites were detected and tentatively identified by the characteristics of their protonated ions. Hydrogenated and demethylated loganetin, dehydroxylated morronisid aglycone, caffeic acid, and its methylated product were the main metabolites. These metabolites suggested that the glycosides were firstly hydrolyzed to their aglycones by hydrolytic enzymes of the enteric microbial flora and subsequently to the other metabolites through hydrogenation, (de)-methylation, and de-hydroxylation. Conclusion The results may be helpful for the further investigation of the pharmacokinetic study of R. glutinosa and C. officinalis herb pair in vivo.