Counter-current chromatography for the separation of terpenoids: A comprehensive review with respect to the solvent systems employed

Copyright @ 2014 The Authors.This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.Natural products extracts are commonly highly complex mixtures of active compounds and consequently their purification becomes a particularly challenging task. The development of a purification protocol to extract a single active component from the many hundreds that are often present in the mixture is something that can take months or even years to achieve, thus it is important for the natural product chemist to have, at their disposal, a broad range of diverse purification techniques. Counter-current chromatography (CCC) is one such separation technique utilising two immiscible phases, one as the stationary phase (retained in a spinning coil by centrifugal forces) and the second as the mobile phase. The method benefits from a number of advantages when compared with the more traditional liquid-solid separation methods, such as no irreversible adsorption, total recovery of the injected sample, minimal tailing of peaks, low risk of sample denaturation, the ability to accept particulates, and a low solvent consumption. The selection of an appropriate two-phase solvent system is critical to the running of CCC since this is both the mobile and the stationary phase of the system. However, this is also by far the most time consuming aspect of the technique and the one that most inhibits its general take-up. In recent years, numerous natural product purifications have been published using CCC from almost every country across the globe. Many of these papers are devoted to terpenoids-one of the most diverse groups. Naturally occurring terpenoids provide opportunities to discover new drugs but many of them are available at very low levels in nature and a huge number of them still remain unexplored. The collective knowledge on performing successful CCC separations of terpenoids has been gathered and reviewed by the authors, in order to create a comprehensive document that will be of great assistance in performing future purifications. © 2014 The Author(s)

Farnesoid X Receptor Induces Murine Scavenger Receptor Class B Type I via Intron Binding

Farnesoid X receptor (FXR) is a nuclear receptor and a key regulator of liver cholesterol and triglyceride homeostasis. Scavenger receptor class B type I (SR-BI) is critical for reverse cholesterol transport (RCT) by transporting high-density lipoprotein (HDL) into liver. FXR induces SR-BI, however, the underlying molecular mechanism of this induction is not known. The current study confirmed induction of SR-BI mRNA by activated FXR in mouse livers, a human hepatoma cell line, and primary human hepatocytes. Genome-wide FXR binding analysis in mouse livers identified 4 putative FXR response elements in the form of inverse repeat separated by one nucleotide (IR1) at the first intron and 1 IR1 at the downstream of the mouse Sr-bi gene. ChIP-qPCR analysis revealed FXR binding to only the intronic IR1s, but not the downstream one. Luciferase assays and site-directed mutagenesis further showed that 3 out of 4 IR1s were able to activate gene transcription. A 16-week high-fat diet (HFD) feeding in mice increased hepatic Sr-bi gene expression in a FXR-dependent manner. In addition, FXR bound to the 3 bona fide IR1s in vivo, which was increased following HFD feeding. Serum total and HDL cholesterol levels were increased in FXR knockout mice fed the HFD, compared to wild-type mice. In conclusion, the Sr-bi/SR-BI gene is confirmed as a FXR target gene in both mice and humans, and at least in mice, induction of Sr-bi by FXR is via binding to intronic IR1s. This study suggests that FXR may serve as a promising molecular target for increasing reverse cholesterol transport

Simultaneous Control of Intermediate Diabetes Outcomes Among Veterans Affairs Primary Care Patients

BACKGROUND: Guidelines recommend tight control of hemoglobin A1c (HbA1c), low-density lipoprotein cholesterol (LDL-C), and blood pressure (BP) for patients with diabetes. The degree to which these intermediate outcomes are simultaneously controlled has not been extensively described. OBJECTIVE: Describe the degree of simultaneous control of HbA1c, LDL-C, and BP among Veterans Affairs (VA) diabetes patients defined by both VA and American Diabetes Association (ADA) guidelines. DESIGN: Cross-sectional cohort. PATIENTS: Eighty-thousand two hundred and seven VA diabetes patients receiving care between October 1999 and September 2000. MEASURMENTS: We defined simultaneous control of outcomes using 1997 VA Guidelines (in place in 2000) (HbA1c<9.0%; LDL-C<130 mg/dL; systolic BP<140 mmHg; and diastolic BP<90 mmHg) and 2004 ADA guidelines (HbA1c<7.0%; LDL-C<100 mg/dL; systolic BP<130 mmHg; and diastolic BP<80 mmHg). A patient is considered to have simultaneous control of the intermediate outcomes for a given definition if the average of measurements for each outcome was below the defined threshold during the study period. RESULTS: Using VA guidelines, 31% of patients had simultaneous control. Control levels of individual outcomes were: HbA1c (82%), LDL-C (77%), and BP (48%). Using ADA guidelines, 4% had simultaneous control. Control levels of individual outcomes were: HbA1c (36%), LDL-C (41%), and BP (23%). Associations between individual risk factors were weak. There was a modest association between LDL-C control and control of HbA1c (odds ratio [OR] 1.51; 95% confidence interval [CI] 1.44, 1.58). The association between LDL-C and BP control was clinically small (1.26; 1.21, 1.31), and there was an extremely small association between BP and HbA1c control (0.95; 0.92, 0.99). Logistic regression modeling indicates greater body mass index, African American or Hispanic race-ethnicity, and female gender were negatively associated with simultaneous control. CONCLUSION: While the proportion of patients who achieved minimal levels of control of HbA1c and LDL-C was high, these data indicate a low level of simultaneous control of HbA1c, LDL-C, and BP among patients with diabetes