Use of multivariate statistical techniques to optimize the separation of 17 capsinoids by ultra performance liquid chromatography using different columns

Simultaneous determination by UHPLC-PDA of major capsaicinoids and capsinoids contents in peppers

Capsaicinoids and capsinoids compounds have been a focus of special attention for their health benefits. An effective and rapid Ultra-High-Performance Liquid Chromatography (UHPLC-PDA) method has been developed and validated for the simultaneous separation and quantitative determination of the major capsaicinoids and capsinoids present in peppers. The separation of all the compounds of interest was achieved in less than 2 min by means of an ACQUITY UPLC BEH rp-C18 column (100 mm × 2.1 mm i.d., 1.7 µm particle size). The variables that have been optimized are the mobile phase (water as solvent A and acetonitrile as solvent B, both acidified by adding 0.1% acetic acid), separation gradient, column temperature (35-70 °C), flow rate (0.6-0.95 mL min^-1), and injection volume (2.5-3.5 µL). The evaluation of the chromatographic performance revealed excellent resolution, retention factor, and selectivity. The method was satisfactorily validated in terms of linearity, detection and quantification limits, precision, and robustness.

Fast Determination of Phenolic Compounds in Rice Grains by Ultraperformance Liquid Chromatography Coupled to Photodiode Array Detection: Method Development and Validation

There are several phenolic compounds in rice grains providing benefits for human health. The concentration of phenolic compounds in rice is strongly affected by the polishing steps during rice production. A new sensitive ultraperformance liquid chromatography-ultraviolet-visible spectroscopy method with a photodiode array detection protocol has been developed and validated for the quantitation of phenolic compounds in rice grains. Several working variables and two different columns were evaluated. Finally, a less than 3 min analysis time was developed to achieve enough resolution for the simultaneous determination of the 20 most common phenolic compounds in rice. The analytical properties for the separation method produced an adequate sensitivity for all phenolic compounds in the regular range for phenolics in rice, 0.5-100 mg L^-1 ( R² > 0.997), with high precisions for both repeatability and intermediate precisions (coefficients of variation less than 0.4 and 2.5% for the retention time and area of the peaks, respectively).

Quantitation of capsiate and dihydrocapsiate and tentative identification of minor capsinoids in pepper fruits (Capsicum spp.) by HPLC-ESI-MS/MS(QTOF)

A highly sensitive, selective method has been developed and validated for determination of capsiate and dihydrocapsiate for the first time using HPLC-ESI/MS(QTOF). For both capsinoids, LODs and LOQs were 0.02 and 0.05 µmol/l, respectively. The intra- and interday repeatability values (RSD %) were 0.26-0.41% for retention time, and 2.25-2.11% for peak area. Recoveries were up to 98% and 97% for capsiate and dihydrocapsiate, respectively. This method was successfully applied to quantify capsiate and dihydrocapsiate in eight pepper fruit accessions. Capsinoids were found in the range of 1.21-544.59 μg/g DW for capsiate and of 0.61-81.95 μg/g DW for dihydrocapsiate. In the 'Tabasco' accession, capsiate and dihydrocapsiate were quantified for the first time, ranging from 3.09 to 58.76 and 1.80 to 6.94 μg/g DW, respectively. Additionally, the ESI-MS/MS(QTOF) analysis has allowed the tentative identification of two other minor capsinoids by exact mass and fragmentation pattern, in the 'Bhut Jolokia' accession.

Brazilian Capsicum peppers: capsaicinoid content and antioxidant activity

BACKGROUND

Capsicum peppers are known as a source of capsaicinoids, phenolic compounds and antioxidants. Brazilian Capsicum peppers are important spices used in foods worldwide. However, little information is available on the chemical composition and antioxidant activity of these peppers.

RESULTS

Capsaicin, dihydrocapsaicin, total phenolic compounds and antioxidant activity were investigated in extracts of three Brazilian peppers: Capsicum frutescens, C. chinense and C. baccatum var. pendulum, in two different harvest years and at two ripening stages. The bioactive compound content was dependent on harvest year, and changes in the concentration profiles were found for capsaicin. Mature fruits of C. chinense harvested in the first year had the highest capsaicin concentration (2.04 mg g^-1 fresh pepper), and mature fruits of C. frutescens harvested in the same first year had the highest dihydrocapsaicin content (0.95 mg g^-1 fresh pepper). Mature fruits of C. frutescens harvested in the first year showed the major total phenolic compound content (2.46 mg g^-1 fresh pepper). The total phenolic compound content was directly related to antioxidant activity.

CONCLUSION

Our results suggest that phenolic compounds significantly contribute to the antioxidant activity of the investigated peppers. Also, these data add valued novel information that enhances current knowledge of Brazilian pepper fruits. © 2017 Society of Chemical Industry.