Rapid determination of flavonoids and phenolic acids in grape juices and wines by RP-HPLC/DAD: Method validation and characterization of commercial products of the new Brazilian varieties of grape

Determining 1-kestose, nystose and raffinose oligosaccharides in grape juices and wines using HPLC: method validation and characterization of products from Northeast Brazil

The objective of this work was to validate a method for direct determination in grape juice and wine of 1-kestose, nystose and raffinose oligosaccharides by reversed-phase high-performance liquid chromatography with refractive index detection using a new type of RP-C₁₈ column (150 × 4.6 mm, 4 µm) with polar end-capping. The validated methodology was also used to characterize grape juice and fine wine products from Northeastern Brazil; and presented suitable linearity, precision, recovery, limits of detection and quantification. The method presented good specificity, revealing that sugars, organic acids, and ethanol (the main interferences in refraction detection) did not influence the quantification of the studied oligosaccharides. The main oligosaccharide found was 1-kestose (approximately 50% of the samples), followed by raffinose (20% of the samples). The results obtained in this are an indication that grape juices and wines have the potential to be functional beverages in relation to the presence of prebiotics.

Synergistic effect of fruit-seed mixed juice on inhibition of angiotensin I-converting enzyme and activation of NO production in EA.hy926 cells

Commonly consumed fruit juices possess low inhibitory activity of angiotensin I-converting enzyme (ACE), which plays central role in elevation of blood pressure. The ACE inhibitory activity of fruit-seed mixed juice may be improved via synergistic interactions. In this study, the investigated synergistic, additive, and antagonistic effects of fruit-seed combination on ACE inhibition were investigated. Thirteen fruits and 15 seeds including legumes, nuts, and cereals were combined in pairs; pear-hemp seed-pumpkin seed juice (3-mixed juice) displayed the highest ACE inhibition resulting from synergistic interactions. Additionally, nitric oxide production in human endothelial cells was promoted by 3-mixed juice. Three-mixed juice showed antioxidant activities such as DNA protective, DPPH radical scavenging, and reducing effects. These results suggested that combinations of different food categories are beneficial for improving biological functions such as vascular health. Three-mixed juice, which shows high ACE inhibitory activity, may be useful as an anti-hypertensive agent and for treating hypertension.

Grape juices produced from new hybrid varieties grown on Brazilian rootstocks - Bioactive compounds, organic acids and antioxidant capacity

The objective of this study was to assess the content of bioactive compounds, organic acids and antioxidant capacity of grape juices from Isabel Precoce, BRS Carmem, BRS Cora and IAC 138-22 Máximo varieties grown on the 'IAC 766' and 'IAC 572' rootstocks under tropical conditions in Brazil. In general, the color attributes of the 'Isabel Precoce' juice were inferior to those of the other juices due to their low anthocyanin content. In contrast, 'IAC 138-22 Máximo' juices showed the highest content of most individual anthocyanins, flavonols, trans-resveratrol and total phenolic compounds, and thus, higher antioxidant capacity. Except for 'BRS Carmem', all the juices presented higher sugar accumulation when 'IAC 766' was used. This rootstock also contributed to the accumulation of t-resveratrol and most of individual anthocyanins in the 'IAC 138-22 Máximo' juices. However, the monomeric anthocyanin content was higher in 'BRS Carmem' juices when 'IAC 572' rootstock was used.

Processing methods with heat increases bioactive phenolic compounds and antioxidant activity in grape juices

In this work, the influence of the method of processing on phenolic composition and the in vitro antioxidant activity (AOX) of grape juices was studied. The classic methods of producing "Hot Press" (HP), "Hot Break" (HB), and "Cold Press" (CP), and an artisanal method using steam were compared. Among the methods of elaboration of evaluated grape juices, those that heated the grape showed higher content of bioactive phenolics and AOX. The artisanal method using steam presented acceptable bioactive content and could be simple alternative for grape juice production. The main bioactive compounds quantified in the studied juices were procyanidin B1, quercetin-3-pyranoside, chlorogenic acid, malvidin-3-glucoside, cyanidin-3-glucoside, and petunidin-3-glucoside. These were correlated by principal component analysis (PCA) with the antioxidant activity. The characteristics obtained from the different juice elaboration methods demonstrate that the HB method was responsible for the greatest extraction of bioactive compounds from the grapes. PRACTICAL APPLICATIONS: Worldwide consumption of grape juice has been increasing. The factors that have contributed to this growth include the good sensory acceptance and the nutritional appeal related to bioactive compounds. The bioactive compounds of grape juice are mainly flavonoids and phenolic acids, and several factors exert influence on the phenolic composition of this beverage, among them, the method of elaboration. The present work presents new information on the influence of grape juice processing methods on the profile of bioactive compounds of nutritional interest and contributes to improvements in the production processes of this beverage.

Alterations on phenolic compounds and antioxidant activity during sour grape juice concentrate processing

The alterations of phenolic compounds and antioxidant capacity of sour grape juice were investigated during the concentration process stages. Phenolics and antioxidant properties of the samples changed more at the vacuum evaporation stage than that of the other stages. After evaporation, the antioxidant capacity of the samples decreased approximately between 14.2 and 17.0 % for DPPH and ABTS methods, respectively. Besides, phenolic contents also decreased approximately as 14.8%. HPLC data on phenolics of sour grape juice during concentrate processing gave 12 polyphenols, including gallic acid, (+)-catechin, (-)-epigallocatechin, vanillic acid, (-)-epigallocatechin gallate, (-)-epicatechin, caftaric acid, caffeic acid and p-coumaric acid, which were determined as 1.05-1.83 mg/100 g, 5.40-7.83 mg/100 g, 6.35-9.21 mg/100 g, 3.01-5.18 mg/100 g, 0- 1.95 mg/100 g, 2.33-3.54 mg/100 g, 12.40-37.60 mg/100 g, 1.44-2.26 mg/100 g and 0.27-0.44 mg/100 g, respectively. Ferulic, sinapic acids and quercetin were only detected at concentrate step of the sour grape juice processing and were found as 0.18 mg/100 g, 0.28 mg/100 g and 0.76 mg/100 g, respectively.

Development and Validation of a Reversed Phase HPLC Method for Determination of Anacardic Acids in Cashew (Anacardium occidentale) Nut Shell Liquid

Cashew nut shell liquid (CNSL) contains phenolic lipids with aliphatic chains that are of commercial interest. In this work, a chromatographic method was developed to monitor and quantify anacardic acids (AnAc) in CNSL. Samples containing AnAc were analyzed on a high-performance liquid chromatograph coupled to a diode array detector, equipped with a reversed phase C18 (150 × 4.6 mm × 5 μm) column using acetonitrile and water as the mobile phase both acidified with acetic acid to pH 3.0 in an isocratic mode (80:20:1). The chromatographic method showed adequate selectivity, as it could clearly separate the different AnAc. To validate this method, AnAc triene was used as an external standard at seven different concentrations varying from 50 to 1,000 μg mL-1. The Student's t-test and F-test were applied to ensure high confidence for the obtained data from the analytical calibration curve. The results were satisfactory with respect to intra-day (relative standard deviation (RSD) = 0.60%) and inter-day (RSD = 0.67%) precision, linearity (y = 2,670.8x - 26,949, r2 > 0.9998), system suitability for retention time (RSD = 1.02%), area under the curve (RSD = 0.24%), selectivity and limits of detection (19.8 μg mg-1) and quantification (60.2 μg mg-1). The developed chromatographic method was applied for the analysis of different CNSL samples, and it was deemed suitable for the quantification of AnAc.

Glucuronidated Flavonoids in Neurological Protection: Structural Analysis and Approaches for Chemical and Biological Synthesis

Both plant and mammalian cells express glucuronosyltransferases that catalyze glucuronidation of polyphenols such as flavonoids and other small molecules. Oral administration of select polyphenolic compounds leads to the accumulation of the corresponding glucuronidated metabolites at μM and sub-μM concentrations in the brain, associated with amelioration of a range of neurological symptoms. Determining the mechanisms whereby botanical extracts impact cognitive wellbeing and psychological resiliency will require investigation of the modes of action of the brain-targeted metabolites. Unfortunately, many of these compounds are not commercially available. This article describes the latest approaches for the analysis and synthesis of glucuronidated flavonoids. Synthetic schemes include both standard organic synthesis, semisynthesis, enzymatic synthesis and use of synthetic biology utilizing heterologous enzymes in microbial platform organisms.