Synthesis and conformational studies of 3,4-di-O-acylated furanoid sugar amino acid-containing analogs of the receptor binding inhibitor of vasoactive intestinal peptide

Structural analysis of the di-O-caprylated Gaa-containing analog of the receptor binding inhibitors of vasoactive intestinal peptide by various NMR techniques and constrained molecular dynamics (MD) simulation studies established a well-defined β-turn structure in DMSO-d₆ with an intramolecular hydrogen bond between TyrNH → MetCO.     

Identification and quantitative investigation of the effects of intestinal microflora on the metabolism and pharmacokinetics of notoginsenoside Fc assayed by liquid chromatography with electrospray ionization tandem mass spectrometry

Notoginsenoside Fc, which is a protopanaxdiol‐type saponin isolated from the leaves of Panax notoginseng, exhibits an exceptional antiplatelet aggregatory effect. To study the modulating effect of gastrointestinal contents on the metabolic profile and pharmacokinetics, pseudo germ‐free rats were used to study the influence of the bacterial community structure on the metabolic profile. Glycosidase activities were measured using the spectrophotometric method. Biotransformations of notoginsenoside Fc in normal and pseudo germ‐free rat intestinal microflora were systematically investigated using ultra high performance liquid chromatography with tandem quadrupole/time‐of‐flight mass spectrometry. Moreover, a liquid chromatography with tandem mass spectrometry method was established for simultaneous determination of the notoginsenoside Fc prototype and its degradation products. Through an in vivo pharmacokinetic study, the pharmacokinetic characteristics were compared between normal rats and pseudo germ‐free rats. During the in vitro biotransformation, seven deglycosylated products were detected and identified after incubation in the intestinal bacteria of normal rats. In pseudo germ‐free rats, glycosidase activities were significantly decreased, and no obvious degradation occurred. In an in vivo study, the systemic exposure was significantly increased 40%, as evidenced by the area under the blood concentration–time curve from time zero to infinity value and half‐life value, which were prolonged more in the pseudo germ‐free group than in normal rats. The results demonstrate that patients who use intestinal bacteria‐metabolized herbs, such as panax notoginseng, should understand the profile of intestinal bacteria to ensure therapeutic efficacy.     

Comparative metabolism of the eight main bioactive ingredients of gegen qinlian decoction by the intestinal flora of diarrhoeal and healthy piglets

Diarrhoeal diseases alter the composition of intestinal flora, thereby affecting the efficacy of herbal medicinal formulations. Gegen Qinlian decoction (GQD), a Chinese traditional herbal formulation, is widely used to treat infectious diarrhoea. However, little is known about the microbial disposition of GQD in the diarrhoeal state. In this study, the comparative metabolism of components of GQD by diarrhoeal and normal intestinal flora was investigated in vitro. UPLC–MS/MS was performed for simultaneous analysis of eight ingredients of GQD in bacterial solution. The type, activities, and sources of microbial enzymes were also investigated. Microbial metabolism of daidzin, genistin and liquiritin (metabolized by β‐glucosidase); baicalin, wogonoside and glycyrrhizin (metabolized by β‐glucuronidase); and berberine and coptisine (metabolized via nitroreductase) was faster in the diarrhoeal group than in the normal group. Moreover, the activities of these enzymes in the diarrhoeal group were higher than those in the normal group. This difference might be associated with the increase in Escherichia spp. Thus, a change in the metabolism of components by diarrhoeal intestinal flora is associated with a preponderance of Escherichia spp., which might improve the efficacy of GQD. These findings have implications for understanding the action mechanism of GQD for diarrhoea treatment in terms of the microbial milieu.     

Human intestinal microbiota derived metabolism signature from a North American native botanical Oplopanax horridus with UPLC/Q-TOF–MS analysis

Oplopanax horridus, widely distributed in North America, is an herbal medicine traditionally used by Pacific indigenous peoples for various medical conditions. After oral ingestion, constituents in O. horridus extract (OhE) could be converted to their metabolites by the enteric microbiome before absorption. In this study, in order to mimic gut environment, the OhE was biotransformed using the enteric microbiome of healthy human subjects. For accurate and reliable data collection with optimized approaches in sample preparation and analytical conditions, ultra-performance liquid chromatography and quadrupole time-of-flight mass spectrometry were used to characterize parent constituents and their metabolites. In the extract, 20 parent compounds were identified including polyynes, sesquiterpenes, monoterpeondids, phenylpropanoids and phenolic acids. After the biotransformation, a total of 78 metabolites were identified, of which 37 belonged to polyynes metabolites. The common biotransformation pathways are hydroxylation, acetylization, methylation and demethylation. Based on the pathway distributions, the metabolism signature of OhE has been explored. The metabolism pathways of OhE compounds are dependent on their structural classifications and hydrophilic/hydrophobic properties. In summary, with comprehensive analysis, we systematically investigated human microbiome-derived OhE metabolites. The enteric microbial metabolism signature provides novel information for future effective use of O. horridus.     

Strawberry Decreases Intraluminal and Intestinal Wall Hydrolysis of Testosterone Undecanoate

Male hypogonadism is often treated by testosterone (T) replacement therapy such as oral administration of the ester prodrug, testosterone undecanoate (TU). However, the systemic exposure to T following oral TU is very low due to esterase-mediated metabolism, particularly in the small intestine. The aim of this work was to examine the esterase-inhibitory effect of natural fruit extract of strawberry (STW) on the intestinal degradation of TU as a potential approach to increasing the oral bioavailability of T. Herein, the hydrolysis of TU was assessed in fasted state simulated intestinal fluid with added esterase activity (FaSSIF/ES) and Caco-2 cell homogenates in the presence of STW extract. It is noteworthy that STW substantially inhibited the degradation of TU in FaSSIF/ES and Caco-2 cell homogenates at concentrations that could be achieved following oral consumption of less than one serving of STW fruit. This can significantly increase the fraction of unhydrolyzed TU in the intestinal lumen as well as in enterocytes. In addition, it was demonstrated that TU has high intestinal lymphatic transport potential as the association of TU with plasma-derived human chylomicrons was in the range of 84%. Therefore, oral co-administration of TU with STW could potentially increase the intestinal stability of TU and consequently the contribution of lymphatically delivered TU to the systemic exposure of T in vivo.     

The assessment of absorption of periplocin in situ via intestinal perfusion of rats by HPLC

Periplocin is an important compound of Cortex Periplocae, which shows poor absorption when administered orally. The effective intestinal permeability of periplocin was investigated using single-pass intestinal perfusion technique in male Wistar rats. SPIP was performed in rat jejunum. The samples of perfusate were collected at the designated time points after rat intestinal perfusion and analyzed by HPLC. The specificity of this method was demonstrated by the absence of interference of the drug peak with the intestinal sac artifacts and the components of the KRB solution. Recovery studies, as well as the intra-day and inter-day variations, were within statistical limits. This technique was applied to the study of the intestinal absorption of periplocin. The determined fraction absorbed (F(a)) of periplocin was 0.151 +/- 0.072 (n = 6) at a concentration of 6 microg/mL; the absorption rate constant (K(a)) was 0.0102 +/- 0.0039/min and the effective permeability coefficient (P(eff)) was 0.0021 +/- 0.0012 cm/min. These data suggest that periplocin has high permeability and might be absorbed in rat intestine.     

LCST demixing in poly(vinyl methyl ether)/water studied by means of a High Resolution Ultrasonic Resonator

The inhibitory effects of three berberine alkaloids (BAs) from Coptis chinensis Franch on Bifidobacterium adolescentis growth were investigated by microcalorimetry. The growth rate constant (k) and maximum heat-output power (Pmax) decreased and peak time of maximum heat-output power (tp) prolonged with the increase of BAs concentration. Half inhibitory ratios (IC50) BAs were respectively 790.3 (berberine), 339.6 (coptisine) and 229.8 μL⁻¹ (palmatine), which indicated the sequence of their antimicrobial activity: berberine<coptisine<palmatine. Combined with previous findings, the sequence which could show the bioactivity of Bacillus shigae and Escherichia coli was: berberine>coptisine>palmatine. The structure-function relationship of BAs indicated that the functional group methylenedioxy or methoxyl at C2 and C3 might be the major group inducing the activities of BAs on E. coli and B. adolescentis. Meanwhile, the substituent groups at C2, C3, C9 and C10 almost had equal effect on B. shigae.     

肠癌患者尿中核苷排放的高效液相法研究

 用反相高效液相法测定尿中核苷。通过苯基硼酸亲和法提取尿中核苷,在柱(4 6mmi d ×250mm,5μm)上以25mmol/L磷酸二氢钾溶液(pH4 55)和60%的甲醇水溶液作为流动相进行二元梯度淋洗,于22℃下进行反相分离,260nm处紫外检测。用该法测定了41例肠癌患者和52例正常人尿中15种核苷的含量(用核苷与肌酐的摩尔比表示,下同),结果表明肠癌患者中有12种核苷的含量比正常人显著性增高(P<0 001)。以15种核苷的含量作为参量,结合主成分分析区分正常人和肠癌患者,对癌症病人的识别率达76%(31/41)。