Policosanol attenuates statin-induced increases in serum proprotein convertase subtilisin/kexin type 9 when combined with atorvastatin.

Objective. Statin treatment alone has been demonstrated to significantly increase plasma proprotein convertase subtilisin/kexin type 9 (PCSK9) levels. The effect of policosanol combined with statin on PCSK9 is unknown. Methods. Protocol I: 26 patients with atherosclerosis were randomly assigned to receive either atorvastatin 20 mg/d or policosanol 20 mg/d + atorvastatin 20 mg/d for 8 weeks. Protocol II: 15 healthy volunteers were randomly assigned to either policosanol 20 mg/d or a control group for 12 weeks. Serum levels of PCSK9 were determined at day 0 and the end of each protocol. Results. Protocol I: atorvastatin 20 mg/d significantly increased serum PCSK9 level by 39.4% (256 ± 84 ng/mL versus 357 ± 101 ng/mL, P = 0.002). However, policosanol 20 mg/d + atorvastatin 20 mg/d increased serum PCSK9 level by only 17.4% without statistical significance (264 ± 60 ng/mL versus 310 ± 86 ng/mL, P = 0.184). Protocol II: there was a trend toward decreasing serum PCSK9 levels in the policosanol group (289 ± 71 ng/mL versus 235 ± 46 ng/mL, P = 0.069). Conclusion. Policosanol combined with statin attenuated the statin-induced increase in serum PCSK9 levels. This finding indicates that policosanol might have a modest effect of lowering serum PCSK9 levels.

Interaction of proteins with aluminum(III)-chlorophosphonazo III by resonance Rayleigh scattering method.

In weak acid medium, aluminum(III) can react with chlorophosphonazo III [CPA(III), H(8)L] to form a 1:1 coordination anion [Al(OH)(H(4)L)](2-). At the same time, proteins such as bovine serum albumin (BSA), lysozyme (Lyso) and human serum albumin (HSA) existed as large cations with positive charges, which further combined with [Al(OH)(H(4)L)](2-) to form a 1:4 chelate. This resulted in significant enhancement of resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency doubling scattering (FDS). In this study, we investigated the interaction between [Al(OH)(H(4)L)](2-) and proteins, optimization of the reaction conditions and the spectral characteristics of RRS, SOS and FDS. The maximum RRS wavelengths of different protein systems were located at 357-370 nm. The maximum SOS and FDS wavelengths were located at 546 and 389 nm, respectively. The scattering intensities (ΔI) of the three methods were proportional to the concentration of the proteins, within certain ranges, and the detection limits of the most sensitive RRS method were 2.6-9.3 ng/mL. Moreover, the chelate reaction mechanism or the reasons for the enhancement of RRS were discussed through absorption spectra, fluorescence spectra and circular dichroism (CD) spectra.

Determination of torasemide by fluorescence quenching method with some dihalogenated fluorescein dyes as probes.

A novel fluorescence quenching method for the determination of torasemide (TOR) with some dihalogenated fluorescein dyes as fluorescence probes was developed. In acidulous medium, TOR could interact with some dihalogenated fluorescein dyes such as dichlorofluorescein (DCF), dibromofluorescein (DBF) and diiodofluorescein (DIF) to form binary complexes, which could lead to fluorescence quenching of above dihalogenated fluorescein dyes. The maximum fluorescence emission wavelengths were located at 532 nm (TOR-DCF), 535 nm (TOR-DBF) and 554 nm (TOR-DIF). The relative fluorescence intensities (ΔF=F0-F) were proportional to the concentration of TOR in certain ranges. The detection limits were 4.8 ng mL(-1) for TOR-DCF system, 9.8 ng mL(-1) for TOR-DBF system and 35.1 ng mL(-1) for TOR-DIF system. The optimum reaction conditions, influencing factors were studied; and the effect of coexisting substances was investigated owing to the highest sensitivity of TOR-DCF system. In addition, the reaction mechanism, composition and structure of the complex were discussed by quantum chemical calculation and Job's method. The fluorescence quenching of dihalogenated fluorescein dyes by TOR was a static quenching process judging from the effect of temperature and the Stern-Volmer plots. The method was satisfactorily applied to the determination of TOR in tablets and human urine samples.

Determination of carbazochrome by fluorescence quenching method.

A sensitive, simple and selective spectrofluorimetric method for the reaction of carbazochrome (CBZC) and Eosin Y (EY) or Phloxine B (PB) in acidic medium is developed for the determination of carbazochrome in biological fluids, which gives a highly fluorescent derivative measured at 545 and 565 nm at excitation wavelengths of 301 and 305 nm. The fluorescence quenching extent (ΔF) is proportional to the concentration of CBZC for CBZC-EY and CBZC-PB system at the range of 0.03-1.50 µg/mL and 0.08-1.25 µg/mL, respectively. The detection limit is 9.1 ng/mL for EY system and 22.7 ng/mL for PB system. The intra-day and inter-day reproducibility (RSD values) are less than 8.3% under three concentrations. Moreover, the affecting factors of fluorescence intensity of the product are carefully investigated and optimized, as well as the effect of coexisting substances. Judging from temperature, the Stern-Volmer plots and fluorescence emission decay curves, the quenching of fluorescence of EY and PB by CBZC is a static quenching process, caused by electrostatic attraction and aromatic stacking interaction.

A dual-wavelength overlapping resonance Rayleigh scattering method for the determination of chondroitin sulfate with nile blue sulfate.

A dual-wavelength overlapping resonance Rayleigh scattering (DWO-RRS) method was developed to detect chondroitin sulfate (CS) with nile blue sulfate (NBS). At pH 3.0-4.0 Britton-Robinson (BR) buffer medium, CS interacted with NBS to form an ion-association complex. As a result, the new spectra of resonance Rayleigh scattering (RRS), second order scattering (SOS) and frequence doubling scattering (FDS) appeared and their intensities were enhanced greatly. Their maximum wavelengths were located at 303 nm (RRS), 362 nm (RRS), 588 nm (SOS) and 350 nm (FDS), respectively. The scattering intensities of the three methods were proportional to the concentration of CS in certain ranges. The methods had high sensitivity and the detection limits were between 1.5 and 7.1 ng mL(-1). The DWO-RRS method had the highest sensitivity with the detection limit being 1.5 ng mL(-1). The characteristics of the spectra and optimal reaction conditions of RRS method were investigated. The effects of coexistent substances on the determination of CS were evaluated. Owing to the high sensitivity, RRS method had been applied to the determination of CS in eye drops with satisfactory results. The recovery range was between 99.4% and 104.6% and the relative standard deviation (RSD) was between 0.4% and 0.8%. In addition, the reasons for RRS enhancement were discussed and the shape of ion-association complex was characterized by atomic force microscopy (AFM).