Cistus incanus as “biofactory”: chemical characterization and antioxidant activity of enriched fractions differing in polyphenolic composition

Cistus incanus (Cistaceae), an evergreen shrub widely distributed in the Mediterranean basin, has long been used as a source of health promoting substances. Recent studies have described Cistus polyphenols as being the most bioactive compounds, especially for their anti-inflammatory, antimicrobial and antioxidant properties [1 – 3].

Nonetheless, the whole polyphenolic spectrum of C. incanus leaves has not been conclusively assessed, and there is still uncertainty about the relative significance of various classes of polyphenols in conferring antioxidant activities to its extracts.

The purpose of this study was to characterise the major polyphenolic compounds present in the leaves of C. incanus as well as to develop a method for their fractionation. In addition, DPPH (1,1-diphenyl-2-picrylhydrazyl) scavenging assay coupled with EPR (Electron Paramagnetic Resonance) spectroscopy has been employed to evaluate the antioxidant properties of the obtained fractions.

Three enriched fractions, one “flavonoid-enriched-fraction”(FE-fraction) and two “tannin-enriched-fractions”(TE-fractions) were obtained through a liquid-liquid partitioning with ethyl acetate and water. Furthermore, an ethanolic “crude extract”, containing the total amount of phenylpropanoids was prepared. The LC-MS/MS analyses revealed that the TE-fractions were mostly composed of cathechin derivates, whereas the main constituents of the FE-fraction were myricetin derivatives. In addition, EPR results indicated that, among the four fractions, the FE-one exerted the highest DPPH scavenging activity, as indicated by the lowest EC₅₀ value. These results indicate that ethyl acetate is more efficient than water and ethanol in extracting antioxidant compounds from C. incanus. This finding provides new perspectives for the use of this enriched fraction in both the pharmacological and nutraceutical fields.

Keywords: DPPH radical-scavenging activity, solvent extraction, flavonoids, tannins.

References:

[1] Bouamama H, Villard J, Benharref A, Jana M. Antibacterial and antifungal activities of Cistus incanus and C. monspeliensis leaf extracts. Therapie 1998; 54: 731 – 733

[2] Wittpahl G, Kölling-Speer I, Basche S, Herrmann E, Hannig M, Speer K, Hannig C. The polyphenolic composition of Cistus incanus herbal tea and its antibacterial and anti-adherent activity against Streptococcus mutans. Planta Med 2015; 81: 1727 – 1735

[3] Attaguile G, Russo A, Campisi A, Savoca F, Acquaviva R, Ragusa N, Vanella A. Antioxidant activity and protective effect on DNA cleavage of extracts from Cistus incanus L. and Cistus monspeliensis L. Cell Biol Toxicol 2000; 16: 83 – 90

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