The ergogenic activity of cider vinegar: A randomized cross-over, double-blind, clinical trial.

This randomized, double-blind, clinical trial was designed to compare the endurance capacity (ergogenic property) in healthy athletes after consumption of apple cider vinegar (ACV) and a commercial sports drink (CSD) before and during endurance exercise. Fourteen healthy participants were enrolled in this trial and were divided into two groups as ACV and CSD with seven participants in each. Participants were requested to consume 500 mL of either commercial ACV or CSD 1 h before endurance exercise (bicycle ergometer). Blood samples were collected at baseline, 0, 20, 40, 60 min until exhaustion to assess glucose, lactate, ammonia and non-esterified fatty acids (NEFA). Respiratory exchange rate (RER) score was measured every 15 min and the heart rate (HR) was measured every 5 min. The outcome of the present trial clearly showed that no significant differences were observed between ACV and CSD except in the blood level of ammonia (only at exhaustion time). Thus, these results show that ACV and the CSD both possessing the ergogenic property, enhanced blood glucose, NEFA, and suppress the production of lactate as well as maintains normal RER score, and HR throughout the endurance exercise. Overall this trial showcases that ACV did not significantly improve the ergogenic activity over the CSD.

Improving liquid chromatography-tandem mass spectrometry determinations by modifying noise frequency spectrum between two consecutive wavelet-based low-pass filtering procedures.

This paper employs one chemometric technique to modify the noise spectrum of liquid chromatography-tandem mass spectrometry (LC-MS/MS) chromatogram between two consecutive wavelet-based low-pass filter procedures to improve the peak signal-to-noise (S/N) ratio enhancement. Although similar techniques of using other sets of low-pass procedures such as matched filters have been published, the procedures developed in this work are able to avoid peak broadening disadvantages inherent in matched filters. In addition, unlike Fourier transform-based low-pass filters, wavelet-based filters efficiently reject noises in the chromatograms directly in the time domain without distorting the original signals. In this work, the low-pass filtering procedures sequentially convolve the original chromatograms against each set of low pass filters to result in approximation coefficients, representing the low-frequency wavelets, of the first five resolution levels. The tedious trials of setting threshold values to properly shrink each wavelet are therefore no longer required. This noise modification technique is to multiply one wavelet-based low-pass filtered LC-MS/MS chromatogram with another artificial chromatogram added with thermal noises prior to the other wavelet-based low-pass filter. Because low-pass filter cannot eliminate frequency components below its cut-off frequency, more efficient peak S/N ratio improvement cannot be accomplished using consecutive low-pass filter procedures to process LC-MS/MS chromatograms. In contrast, when the low-pass filtered LC-MS/MS chromatogram is conditioned with the multiplication alteration prior to the other low-pass filter, much better ratio improvement is achieved. The noise frequency spectrum of low-pass filtered chromatogram, which originally contains frequency components below the filter cut-off frequency, is altered to span a broader range with multiplication operation. When the frequency range of this modified noise spectrum shifts toward the high frequency regimes, the other low-pass filter is able to provide better filtering efficiency to obtain higher peak S/N ratios. Real LC-MS/MS chromatograms, of which typically less than 6-fold peak S/N ratio improvement achieved with two consecutive wavelet-based low-pass filters remains the same S/N ratio improvement using one-step wavelet-based low-pass filter, are improved to accomplish much better ratio enhancement 25-folds to 40-folds typically when the noise frequency spectrum is modified between two low-pass filters. The linear standard curves using the filtered LC-MS/MS signals are validated. The filtered LC-MS/MS signals are also reproducible. The more accurate determinations of very low concentration samples (S/N ratio about 7-9) are obtained using the filtered signals than the determinations using the original signals.

Using orthogonal array to obtain gradient liquid chromatography conditions of enhanced peak intensity to determine geniposide and genipin with electrospray tandem mass spectrometry.

The conditions to determine geniposide and genipin using gradient liquid chromatography-tandem mass spectrometry (LC-MS/MS) via electrospray ionization were obtained using fractional factorial experimental design approaches, guided with Taguchi orthogonal arrays to enhance peak intensity. Geniposide, the major iridoid glycoside component of Gardenia herbs, which has been recognized to have choleretic effects, is transformed to genipin in animals. In this paper, the gradient establishment times, ionization source temperatures, and the concentrations of volatile additive ammonium acetate were investigated under the guidance of experimental designs to obtain LC-MS/MS signals of the highest peak intensity. Using geniposide and genipin standards, the methods are validated at the concentration ranges of 0.5-1000ng/mL and 10-5000ng/mL using ammonium adducts. The correlation coefficients of geniposide and genipin standard curves are greater than 0.999. Compared with the sensitivities of previously published LC-MS/MS methods, the methods developed in this work provide 6-fold sensitivity improvement. The lowest concentrations of geniposide and genipin, 0.19 and 2ng/mL, respectively, to generate detectable LC-MS/MS signal peaks are one order of magnitude lower than the repoered values in previous publications. The measurement accuracy and precision of geniposide are within 23% and 15%, respectively. The accuracy and precision of genipin are within 16% and 12.5%, respectively. When the validated calibration curves of geniposide and genipin are used to determine spiked control samples in rat blood dialysates, the geniposide determination errors are within 15% accuracy and within 5.8% precision, respectively, and the genipin determination errors are within 23% accuracy and within 3.6% precision, respectively.