Leaves and stem bark from Allophylus africanus P. Beauv.: An approach to anti-inflammatory properties and characterization of their flavonoid profile.

The small tree Allophylus africanus, widespread in the African continent, has long been considered valuable, as noted by the number of reports on their multiple medicinal uses. With this work, we aimed to extend the current, and so far restricted, knowledge on the chemical composition of the plant, particularly as source of flavonoids, as well as to assess its potential anti-inflammatory properties. The chemical characterization of the aqueous extract obtained from the leaves allowed the identification and quantitation of 30 flavones, predominantly apigenin derivatives, but also four luteolin derivatives, while the stem bark extract was solely characterized by apigenin di-C-glycosides and mono-C-glycosides-O-glycosylated. Strong inhibitory effects towards 5-lipoxygenase were observed with the aqueous extracts obtained from the leaves and stem bark, with IC50 values of 41.28 and 107.77 μg mL-1, respectively. Both extracts were also found to reduce NO levels in LPS-challenged RAW 264.7 macrophages, without noticeable cytotoxicity. The flavonoid profile of the plant is disclosed for the first time, allowing the identification of several molecules that may contribute to mitigate the inflammatory response. Jointly, with the current study the anti-inflammatory use of the leaves and stem bark is partially validated.