Antioxidant extracts of coffee leaves and its active ingredient 5-caffeoylquinic acid reduce chemically-induced inflammation in mice

Abstract

Leaves from Coffea arabica L. have been considered an agricultural residue of little value; however, these leaves are a potentially sustainable source of phenolic compounds. Investigation of the properties of these leaves is a crucial strategy for identifying agents that may be beneficial to the health. This study evaluates the antioxidant and anti-inflammatory activity of extracts of C. arabica leaves and 5-caffeoylquinic acid (5-CQA) in a mouse model. Hexane (HFCAL), dichloromethane (DFCAL), ethyl acetate (EFCAL), and butanol (BFCAL) fractions were obtained by partition of the methanol extract (MECAL). High performance liquid chromatography with UV-diode array detection (HPLC-UV-DAD) and spectrophotometric methods were used to identify and quantify the chemical constituents. The antioxidant activity of the extracts were determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), and β-carotene/linoleic acid assays. Ear edema was induced in Swiss mice by the topical application of Croton oil, phenol, or histamine. Tissues were analyzed histopathologically, and myeloperoxidase and N-acetyl-β-d-glucosaminidase activities were assessed. 5-CQA and mangiferin were identified in MECAL, EFCAL, and BFCAL. The total phenolic and flavonoid contents ranged from 1.65 to 20.60 g gallic acid equivalents/100 g of extract and 0.26 to 14.96 g of rutin equivalents/100 g of extract, respectively. The content of 5-CQA ranged from 2.29 to 5.50 g/100 g of extract, while that of mangiferin was 1.46–4.00 g/100 g of extract. The IC50 values ranged from 7.47 ± 0.12 to 122.76 ± 1.38 μg/mL as determined by DPPH assay and from 4.67 ± 0.02 to 71.90 ± 0.22 μg/mL as determined by FRAP. The greatest inhibitor of lipid peroxidation was HFCAL (49.19 ± 1.10%). The MECAL and 5-CQA (0.1, 0.5, and 1.0 mg/ear) reduced the edema thickness and weight induced by croton oil and phenol. After histamine application, the edema thickness and weight were inhibited by MECAL but not by 5-CQA. Treatment with either MECAL or 5-CQA decreased inflammatory parameters and the activity of myeloperoxidase and N-acetyl-β-d-glucosaminidase. The results suggest that 5-CQA and extracts from coffee leaves (C. arabica) possess antioxidant and anti-inflammatory properties, indicating new possibilities for the treatment of disorders involving oxidative and cutaneous damage.