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Isolation of polyphenols from Clinopodium vulgare L. with different solvents and a study of their biological activity
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1  The University of Plovdiv, Faculty of Chemistry, Department of Organic chemistry, Plovdiv, 4000, Bulgaria
Academic Editor: Blaž Likozar


Clinopodium vulgare L. (Lamiaceae) has a wide range of uses in Bulgarian folk medicine for cardiovascular disorders, kidney stones, an inflamed and enlarged prostate, night urination, diabetes, and others. Clinopodium vulgare L. is attracting the attention of phytotherapists and researchers. For this reason, we fractionated the polyphenol composition with solvents of different polarities using hexane, chloroform, and ethyl acetate. The hexane fraction had the highest yield (85.58 %), followed by the ethyl acetate fraction (5.61 %), and the lowest yield was found for the chloroform fraction (1.14 %). Antioxidant activity depends on total phenols and total tannins. Total Phenolic Content (TPC) values range from 15.65 to 462.78 mg gallic acid equivalent per gram extract (mg GAE/g extract), and Total Tannin Content (TTC) from 32.71 to 410.68 mg tannic acid equivalent per gram extract (mg TAE/g extract). The results showed that the contents of TPC and TTC were highest in the ethyl acetate fraction.

Through a UHPLC-MS/MS analysis of all fractions, 24 components of the polyphenolic complex were identified in the studied herb. Dicaffeoylquinic acid, the flavonoid glycosides - eriodictyol-7-O-glucuronide, quercetin-3-O-glucoside, luteolin glycosides, apigenin-7-O-rutinoside, apigenin-7-O-glucoside and apigenin-7- O-glucuronide, and the aglycone luteolin, which have not been reported so far, were found in the polyphenolic composition of Clinopodium vulgare.

We used modern biochemical analysis methods to evaluate the in vitro biological activity of polyphenols from Clinopodium vulgare L. The antioxidant activity was evaluated via hydrogen peroxide scavenging activity. The ethyl acetate fraction showed the highest antioxidant activity (IC50 38 μg/mL). Ethyl acetate and chloroform fractions are characterized by high in vitro anti-inflammatory activity, evaluated as the inhibition of albumin denaturation (IC50 95.83 and 83.73 µg/mL, respectively). The same fractions showed high in vitro anti-arthritic activity evaluated as anti-tryptic activity with IC50 values of 147.95 and 136.40 µg/mL, respectively.

Keywords: Clinopodium vulgare L; Total Phenolic Content (TPC); Total Tannin Content (TTC); UHPLC-MS/MS; polyphenols; Hydrogen peroxide scavenging activity; In vitro; anti-inflammatory activity; anti-arthritic activity;