Synthesis of N-acetylglucosaminyl- and N-acetylgalactosaminylceramides as cerebroside analogs and their anti-human immunodeficiency virus type 1 activities

Reverse-phase HPLC method for the quantification of two antihyperglycemic glycolipids in Oplismenus burmannii

Glycolipids and sphingolipids are well known for their diverse biological activities like anticancer, anti-inflammatory, antistress, anti-HIV, hepatoprotective and antimicrobial. The present study deals with the activity-guided isolation and characterization of two antihyperglycemic glycolipids, (2S)-1,2-di-O-octadecanoyl-3-O-[α-d-galctopyranosyl-(1'' → 6')-O-β-d-galactopyranosyl] glycerol (1) and 1-O-β-d-glucopyranosyl-(2S,3S,4R,8E)-2-[(2R)-2-hydroxy-tetracosanoylamino]-2,3,4-octadecanetriol-8-ene (2) from Oplismenus burmannii and the development of a simple and validated reverse-phase HPLC analytical method for their quantification in the methanolic extracts of O. burmannii. The marker compounds 1 and 2 were isolated from the methanolic extract of O. burmannii and characterized on the basis of their spectroscopic data. Their antihyperglycemic potential was evaluated by determining their glucose uptake-stimulating potential in L6-GLUT4myc myotube cells. Finally, these analytes were separated on a Waters Spherisorb ODS 2 column with a binary gradient of methanol and water at a constant flow rate of 0.8 mL/min and detected using a photodiode array detector at 230 nm. The calibration curve was linear (r(2)  > 0.999) over 1.2 orders of magnitude with acceptable accuracy, reproducibility and recovery (98.16-100.50%). The limits of detection and quantification for 1 and 2 were 1.36, 4.11 and 1.11, 3.35 µg/mL respectively. The method is simple, accurate, precise and selective and may be routinely used for the quality control analysis of whole plant extract of O. burmannii for these two glycolipids.

B-type natriuretic Peptide in isolated severe tricuspid regurgitation: determinants and impact on outcome

BACKGROUND

The plasma B-type natriuretic peptide (BNP) level is a useful prognostic marker in heart failure and valvular heart disease. In patients with isolated severe tricuspid regurgitation (TR), little is known about the determinants of plasma BNP levels and the correlation with future outcome. The purpose of this study was to identify the determinants of plasma BNP levels in patients with isolated severe TR and the value of the BNP level in predicting postoperative outcomes after corrective surgery.

METHODS

We prospectively enrolled 39 patients with isolated, severe TR undergoing corrective surgery. A plasma BNP assay and cardiac magnetic resonance (CMR) imaging were performed before surgery. The combined end-point was the occurrence of cardiac death or readmission due to heart failure.

RESULTS

Linear regression analysis showed that the left ventricular ejection fraction and right ventricular end systolic volume were the most important determinants of the BNP levels (p = 0.002, R(2) = 0.315). Based on the receiver operating characteristics (ROC) curve, we were able to derive an optimal cutoff value (200 pg/mL) to predict postoperative cardiac death with a sensitivity of 80% and a specificity of 85%. The one-year survival rate was 96% in patients with a BNP < 200 pg/mL and 53% in patients with a BNP ≥ 200 pg/dL (p = 0.001).

CONCLUSION

An elevation in the BNP level is determined by the functional status of the right and left ventricles in patients with isolated, severe TR. An elevated BNP predicts adverse events after corrective surgery. Therefore, the BNP level should be included in the clinical evaluation and risk stratification of patients with isolated TR.

Synthesis and biological evaluation of peptide mimics derived from first extracellular loop of CCR5 toward HIV-1

Peptide mimics derived from the first extracellular loop of CCR5 bearing non-peptide spacers in place of Ala-Ala-Ala sequence in the peptide moiety were synthesized, and the effects of these compounds on the inhibition against HIV-1 were examined. Compound 2b having m-aminophenoxyacetic acid derivative as a non-peptide spacer significantly inhibited HIV-1.

Synthesis of single- and double-chain fluorocarbon and hydrocarbon galactosyl amphiphiles and their anti-HIV-1 activity

Galactosylceramide (GalCer) is an alternative receptor allowing HIV-1 entry into CD4(-)/GalCer(+) cells. This glycosphingolipid recognizes the V3 loop of HIV gp120, which plays a key role in the fusion of the HIV envelope and cellular membrane. To inhibit HIV uptake and infection, we designed and synthesized analogs of GalCer. These amphiphiles and bolaamphiphiles consist of single and double hydrocarbon and/or fluorocarbon chain beta-linked to galactose and galactosamine. They derive from serine (GalSer), cysteine (GalCys), and ethanolamine (GalAE). The anti-HIV activity and cytotoxicity of these galactolipids were evaluated in vitro on CEM-SS (a CD4(+) cell line), HT-29, a CD4(-) cell line expressing high levels of GalCer receptor, and/or HT29 genetically modified to express CD4. GalSer and GalAE derivatives, tested in aqueous medium or as part of liposome preparation, showed moderate anti-HIV-1 activities (IC50 in the 20-220 microM range), whereas none of the GalCys derivatives was found to be active. Moreover, only some of these anti-HIV active analogs inhibited the binding of [3H]suramin (a polysulfonyl compound which displays a high affinity for the V3 loop) to SPC3, a synthetic peptide which contains the conserved GPGRAF region of the V3 loop. Our results most likely indicate that the neutralization of the virion through masking of this conserved V3 loop region is not the only mechanism involved in the HIV-1 antiviral activity of our GalCer analogs.