Phytochemical Analysis and Antioxidant Effects of Prunella vulgaris in Experimental Acute Inflammation

Prunella vulgaris (PV) is one of the most commonly used nutraceuticals as it has been proven to have anti-inflammatory and antioxidant properties. The aim of this study was to evaluate the phytochemical composition of PV and its in vivo antioxidant properties. A phytochemical analysis measuring the total phenolic content (TPC), the identification of phenolic compounds by HPLC-DAD-ESI, and the evaluation of the in vitro antioxidant activity by the DPPH assay of the extract were performed. The antioxidant effects on inflammation induced by turpentine oil were experimentally tested in rats. Seven groups with six animals each were used: a control group, the experimental inflammation treatment group, the experimental inflammation and diclofenac sodium (DS) treatment group, and four groups with their inflammation treated using different dilutions of the extract. Serum redox balance was assessed based on total oxidative status (TOS), nitric oxide (NO), malondialdehyde (MDA), total antioxidant capacity (TAC), total thiols, and an oxidative stress index (OSI) contents. The TPC was 0.28 mg gallic acid equivalents (GAE)/mL extract, while specific representatives were represented by caffeic acid, p-coumaric acid, dihydroxybenzoic acid, gentisic acid, protocatechuic acid, rosmarinic acid, vanillic acid, apigenin-glucuronide, hesperidin, kaempferol-glucuronide. The highest amount (370.45 μg/mL) was reported for hesperidin, which is a phenolic compound belonging to the flavanone subclass. The antioxidant activity of the extracts, determined using the DPPH assay, was 27.52 mmol Trolox/mL extract. The PV treatment reduced the oxidative stress by lowering the TOS, OSI, NO, and MDA and by increasing the TAC and thiols. In acute inflammation, treatment with the PV extract reduced oxidative stress, with lower concentrations being more efficient and having a better effect than DS.