Preliminary Metabolomics and Determination of a Potent Anti-inflammatory Fraction of Freshwater Brown Algae

Abstract

Objective: The study aims to perform preliminary metabolomics and identify the potent anti-inflammatory fractions from freshwater brown algae extract. Materials and Methods: The brown algae sample was harvested from the exposed rocks in  Ebonyi River in Nigeria, and was subjected to cold maceration in a methanol-dichloromethane (2:1) solvent mixture for 72 hours, for extraction. The resulting extract was concentrated and subsequently fractionated via vacuum liquid chromatography (VLC) using solvent gradients of n-hexane and ethyl acetate. Acute toxicity was evaluated in Swiss albino mice according to Lorke’s method, with mortality rates employed to determine the LD50. The anti-inflammatory potential of the fractions was assessed using both in vitro (protein denaturation and heat-induced hemolysis assays) and in vivo (acetic acid-induced vascular permeability and xylene-induced edema) models. Doses of 50 and 100 mg/kg as well as 1 and 2 mg of the fractions (3:7, 5:5, 7:3) were administered orally and topical for the in vivo models respectively, while doses ranging from 62.5 to 1000 μg were used for the in vitro test. Dexamethasone was used as the positive control. High-performance liquid chromatography (HPLC) dereplication was employed to identify the phytoconstituents of the fractions. Results: Many anti-inflammatory compounds, including quercetin, ellagic acid and Kaempferol were identified in the fractions which would have accounted for the pronounced anti-inflammatory properties observed. Fraction 5:5 showed a superior anti-inflammation compared to dexamethasone in the xylene-induced edema model, although not statistically significantly different. Conclusion: These fractions, especially 5:5 can be further developed for the treatment of inflammation.