Rapid Screening of Antioxidant Anthocyanins in Autochthonous Nero d’Avola Grape Clones by Pre-column DPPH Reaction Coupled to UHPLC-UV/Vis-IT-TOF: a Strategy to Combine Chemical data and Genetic Diversity

Advancing profiling of secondary antioxidant metabolites in Allium cepa PDO leaf extract: Online comprehensive two-dimensional liquid chromatography with high-resolution mass spectrometry and pre-column DPPH assay

The food and agricultural processing industries generate significant amounts of phenolic-rich by-products, which hold potential as natural antioxidant sources for a wide range of applications, including functional ingredients and nutraceutical formulations. Allium cepa leaves represent a promising source of bioactive compounds. However, due to the complexity of their chemical composition, advanced analytical techniques are required to fully characterize the secondary metabolite profile and identify specific phytochemical classes or fractions with high nutraceutical potential. In this context, an online comprehensive two-dimensional liquid chromatography (LC×LC) approach was developed and optimized for the in-depth characterization of the phytochemical profile of Allium cepa PDO leaf extract. Key parameters in both dimensions, including flow rate, stationary phase chemistry, and mobile phase composition, were investigated to enhance peak capacity and orthogonality. The optimized method combined reversed phase in both dimension (RP-LC×RP-LC), offering high orthogonality (A0: 70.46 %) and peak capacity (nc: 1788.88). and significantly improving the separation of multiple secondary metabolite classes by effective employment of the 2D separation space. Further hyphenation with high-resolution mass spectrometry (HRMS), enhanced compound annotation compared to mono-dimensional (1D-LC) techniques. A total of 147 compounds were tentatively annotated belonging to multiple classes such as flavonoids, saponins, phenylpropanoids, isoprenoids, terpenes, dipeptides, fatty acids, and lipids. Additionally, the antioxidant activity of Allium cepa leaf extract was assessed by coupling a pre-column 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay with the LC×LC-DAD-HRMS platform. This integrated approach enabled the identification of individual contributions of flavonoids, isoprenoids, and phenylpropanoids to radical scavenging activity. The method allowed an in-depth exploration of Allium cepa phytochemical profile, demonstrating to hold significant potential for the standardization of antioxidant biomarkers, with promising applications in the nutraceutical industry.

Citrus sinensis and Vitis vinifera Protect Cardiomyocytes from Doxorubicin-Induced Oxidative Stress: Evaluation of Onconutraceutical Potential of Vegetable Smoothies

The interest towards nutraceuticals able to counteract drug side effects is continuously growing in current chemotherapeutic protocols. In the present study, we demonstrated that smoothies containing mixtures of Citrus sinensis and Vitis vinifera L. cv. Aglianico N, two typical fruits of the Mediterranean diet, possess bioactive polyphenols that protect cardiomyocytes against doxorubicin-induced oxidative stress. The polyphenolic extracts isolated from Citrus sinensis- and Vitis vinifera-based functional smoothies were deeply characterized by Liquid Chromatography-Mass Spectrometry methods. Subsequently, the functional smoothies and relative mixtures were tested to verify their ability to affect cellular viability and oxidative stress parameters in embryonic cardiomyocyte cells (H9c2), and human breast adenocarcinoma cell line (MCF-7) exposed to doxorubicin. Interestingly, we found that the mix resulting from Citrus sinensis and Vitis vinifera association in ratio 1:1 was able to reduce cardiomyocytes damage induced by anthracyclines, without significantly interfering with the pro-apoptotic activity of the drug on breast cancer cells. These results point out the potential use of vegetable smoothies as adjuvants functional foods for chemotherapeutic anticancer protocols.

Fast Profiling of Natural Pigments in Different Spirulina (Arthrospira platensis) Dietary Supplements by DI-FT-ICR and Evaluation of their Antioxidant Potential by Pre-Column DPPH-UHPLC Assay

Arthrospira platensis, better known as Spirulina, is one of the most important microalgae species. This cyanobacterium possesses a rich metabolite pattern, including high amounts of natural pigments. In this study, we applied a combined strategy based on Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) and Ultra High-Performance Liquid Chromatography (UHPLC) for the qualitative/quantitative characterization of Spirulina pigments in three different commercial dietary supplements. FT-ICR was employed to elucidate the qualitative profile of Spirulina pigments, in both direct infusion mode (DIMS) and coupled to UHPLC. DIMS showed to be a very fast (4 min) and accurate (mass accuracy ≤ 0.01 ppm) tool. 51 pigments were tentatively identified. The profile revealed different classes, such as carotenes, xanthophylls and chlorophylls. Moreover, the antioxidant evaluation of the major compounds was assessed by pre-column reaction with the DPPH radical followed by fast UHPLC-PDA separation, highlighting the contribution of single analytes to the antioxidant potential of the entire pigment fraction. β-carotene, diadinoxanthin and diatoxanthin showed the highest scavenging activity. The method took 40 min per sample, comprising reaction. This strategy could represent a valid tool for the fast and comprehensive characterization of Spirulina pigments in dietary supplements, as well as in other microalgae-based products.

B Type and Complex A/B Type Epicatechin Trimers Isolated from Litchi pericarp Aqueous Extract Show High Antioxidant and Anticancer Activity

Litchi (Litchi chinensis Sonn.) fruit is known for its rich source of phenolics. Litchi pericarp contains high levels of epicatechin that may form oligomers of various lengths. Except for several A or B type epicatechin dimers, other soluble oligomers have rarely been identified in the pericarp. Here, bioassay-guided column fractionation was applied to isolate bioactive phenolics from aqueous pericarp extract. A fraction (S3) was obtained by two rounds of Sephadex LH-20 column chromatography, and showed higher antioxidant activity and inhibition on the proliferation of human lung cancer cells (A549) than Litchi anthocyanins. S3 was further separated to isolate fractions P1–P4, which all showed higher antioxidant activity than vitamin C. P3 showed 32.9% inhibition on A549 cells at 30 μg/mL, higher than other fractions and cis-Dichlorodiamineplatinum (DDP, 0.5 μg/mL), but not as high as the combination of the four fractions. Using HPLC-Q-TOF-MS/MS, one B-type and complex A/B type epicatechin trimers were identified in P3; another B-type and two A/B-type trimers were identified in P4. P1 and P2, containing epicatechin and proanthocyanidin B2, respectively, showed no cell inhibition at 30 μg/mL. It is the first time that the two B type trimers of epicatechins (Litchitannin B1 and B2), have been found in Litchi species. The identified proanthocyanidins were detected in the pericarp of the young fruit, and the levels of the compounds decreased as the fruit developed, correlating to the decreasing patterns of the expression of LcLAR and LcANR, two key genes in the catechin biosynthesis pathway.

Flavonoid Composition of Tarocco (Citrus sinensis L. Osbeck) Clone "Lempso" and Fast Antioxidant Activity Screening by DPPH-UHPLC-PDA-IT-TOF

INTRODUCTION

Clonal selection and hybridisation are valid strategies to obtain fruits with enhanced sensorial and nutraceutical properties. Within Citrus sinensis varieties, Tarocco clone "Lempso" is a typical product of the Calabria region (Italy) characterised by its red pulp. This is the first report concerning its accurate profiling.

OBJECTIVE

To characterise in detail the flavonoid composition of Lempso clone and to compare its antioxidant potential with other Citrus varieties by a fast screening method.

METHODOLOGY

Extracts were subjected to solid phase extraction and the qualitative/quantitative profile was elucidated through ultra-high performance liquid chromatography (UHPLC) coupled to photodiode array (PDA) and ion trap time-of-flight (IT-TOF) mass spectrometry detection, and compared to both Cleopatra mandarin (Citrus reticulata) and blood orange (Citrus sinensis (L.) Osbeck) Sanguinello varieties. The antioxidant activity was assessed by pre-column 2,2'-diphenyl-1-picrylhydrazyl (DPPH) reaction coupled to UHPLC-PDA.

RESULTS

Lempso is characterised by flavonoids (17) and anthocyanins (8). Flavanones content (Hesperidin: 57.19 ± 0.49, Vicenin-2: 4.59 ± 0.03, Narirutin: 5.78 ± 0.13 mg/100 mL) was considerably higher than Cleopatra and Sanguinello varieties. The developed DPPH-UHPLC-PDA method provides information regarding the single contributions to antioxidant activity, highlighting how Ferulic acid, Quercetin and Cyanidin derivatives possess considerable radical scavenging activity (> 50%). The total antioxidant activity was also evaluated and compared with positive controls, showing higher scavenging activity than Cleopatra and Sanguinello (IC₅₀ : 333.76 ± 10.81 μg/mL vs. 452.62 ± 10.81 and 568.39 ± 26.98 μg/mL, respectively).

CONCLUSION

These data evidence the nutraceutical potential of Lempso variety, which could be an ingredient for functional beverages. Copyright © 2017 John Wiley & Sons, Ltd.