Ethnopharmacological survey and evaluation of anti-inflammatory activity of Quercus suber L.

Abstract

For centuries, nature has served as humanity's primary pharmacy, and among its many treasures is the cork oak (Quercus suber L.), traditionally used for treating gastric ulcers. Our study aimed to scientifically validate these long-held beliefs by delving into the chemical and biological properties of its root extract. An ethnopharmacological study was conducted to highlight its traditional uses. Then our investigation began by uncovering the chemical richness of the Quercus suber methanolic root extract. We found it to be exceptionally rich in polyphenols, measuring 281.54±3.35 µg gallic acid equivalent (GAE) per milligram of dried extract (DE). Significant amounts of flavonoids (2.40±0.64µg quercetin equivalent/DE) and tannins (82.49±1.89µg catechin equivalent/DE) were also identified, known contributors to the beneficial properties of plants. Beyond its chemical composition, we rigorously tested the extract's capacity to combat inflammation, a fundamental process in many diseases. In our in vitro experiments, the extract demonstrated remarkable power in inhibiting protein denaturation, a key indicator of antiinflammatory activity. Strikingly, it surpassed the efficacy of aspirin at the highest concentration (96.14% versus 93.88%). Furthermore, in vivo studies using the xylene-induced ear edema model in mice revealed a significant anti-inflammatory effect, achieving an 81.48±2.95% inhibition at a dose of 2 mg/ear, closely mirroring the potency of indomethacin (87.65%)—a well-known antiinflammatory drug. Crucially, safety is paramount for any potential therapeutic agent. Our acute toxicity study showed excellent results: mice administered a very high dose of 5000 mg/kg of the extract exhibited no mortality or behavioral changes over a 14-day monitoring period. This classifies the extract as "acutely non-toxic" according to OECD guidelines, with an LD50 exceeding 5000 mg/kg. In conclusion, our findings strongly suggest that Quercus suber L.