Polyphenolic Characterization of Rhus coriaria L. Extracts by Comprehensive Two-Dimensional Liquid Chromatography

Importance of the Topic

Comprehensive profiling of polyphenolic compounds in plant extracts is essential for understanding bioactive composition, assuring quality control, and guiding nutraceutical or pharmaceutical development. Sumac (Rhus coriaria L.) has longstanding culinary and medicinal uses; detailed chemical characterization enhances its valorization as a functional ingredient and potential source of novel health-promoting agents.

Objectives and Study Overview

This study aimed to apply comprehensive two-dimensional liquid chromatography coupled with photodiode array and mass spectrometry detection (LC×LC-PDA-ESI/MS) to characterize polyphenolic profiles of six different Rhus coriaria L. fruit samples, including fresh, air-dried, overripe, and commercial powders, and to assess chromatographic performance and relative compound abundance.

Methodology

• Sample Preparation: 20 g ground fresh or dried drupes were extracted with 100 mL water at 40 °C for 1 h. Extracts were frozen and lyophilized (-50 °C, 0.011 mbar, 72 h) and reconstituted 1:4 in 0.1 % formic acid in MeOH:ACN (70:30 v/v).
• Standards and Reagents: LC–MS grade water, methanol, acetonitrile, acetic acid; key standards: gallic acid, protocatechuic acid, isoquercetin, myricetin, cyanidin.

Instrumentation

• Shimadzu LC×LC system: CBM-20A controller, LC-Mikros binary pump (1D), LC-40BX3 dual-plunger pumps (2D), LC-30AD make-up pump, CTO-40C column oven, SIL-40CX3 autosampler, SPD-M40 PDA detector.
• Two high-pressure six-port switching valves (Shimadzu FCV-32AH) with C18 guard columns; 1D on HILIC (150 × 1.0 mm, 3.5 μm), 2D on core–shell C18 (50 × 4.6 mm, 2.7 μm).
• MS detection via Shimadzu LCMS-8050 triple-quadrupole with ESI interface, m/z 100–2000, positive and negative ion modes.
• Mobile phases: 1D gradient of 0.1 % formic acid in ACN/water; 2D 0.1 % formic acid in water/ACN with active modulation (water make-up flow) for trap enrichment.

Main Results and Discussion

• A total of 83 polyphenolic compounds were positively identified by combining PDA spectra (λmax), accurate m/z values, and literature data.
• Major classes: 37 gallic acid derivatives, 11 quercetin derivatives, plus cyanidin, luteolin, myricetin, and apigenin derivatives.
• Chromatographic performance: theoretical peak capacities ranged 2673–3381; orthogonality (AO) from 0.72 to 0.90; corrected peak capacity up to 1161.
• Semi-quantitative analysis by class: Samples 1, 4, and 3 exhibited highest total polyphenol content (approx. 2608, 2489, 2367 mg/100 g fresh weight); commercial powders (Samples 5, 6) were lowest (253, 338 mg/100 g). Gallic acid derivatives predominated (220–2317 mg/100 g).

Benefits and Practical Applications

This LC×LC-PDA-ESI/MS approach delivers superior resolution and compound coverage compared to one-dimensional methods, enabling detailed profiling and reliable semi-quantification. It supports quality assessment of sumac products, guides selection of high-value cultivars, and informs nutraceutical or pharmaceutical development.

Future Trends and Potential Applications

• Integration of automated data-processing workflows and advanced MSⁿ for structural elucidation.
• Extension to diverse plant matrices and complex food products for comprehensive phenolic profiling.
• Development of absolute quantification strategies using isotopically labeled standards.
• Combination with bioactivity assays and chemometric modeling to correlate composition with health effects.

Conclusion

The comprehensive LC×LC-PDA-ESI/MS analysis of six Rhus coriaria L. samples enabled identification of 83 polyphenolic constituents, revealed significant variation among fresh, dried, and commercial forms, and confirmed the predominance of gallic acid derivatives. High-resolution separation supports future quality control and valorization of sumac extracts in food and health-related applications.

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