Antisickling properties, thermal and photochemical degradations of anthocyanin extracts from Annona senegalensis (Annonaceae)

Anthocyanin crude extracts and fractions of Annona senegalensis leaves were screened for their antisickling properties using a validated in vitro bioassay model of sickle cell anaemia. Preparative thin layer chromatography of acetylated anthocyanin crude extracts carried out with chloroform as solvent provided two active fractions named Ac1 and Ac2. Fraction Ac2 was  quantitatively isolated and submitted to physicochemical investigations. Thermo-degradation kinetics of the above fraction Ac2 at 80 °C and 100 °C revealed first order reaction with the rate constants k (s-1) of 8.10 10-4 and 11.0 10-4, respectively. Anthocyanin crude extracts and the separated fractions showed in vitro antisickling activity. This activity justifies the use of this plant by congolese traditional healers; thus anthocyanins could be the major active principles. However, these natural pigments are unstable towards UV-vis light irradiations and heat. The conservation of this plant should then be performed in the absence of heat and/or light.Keywords: Sickle cell anemia, Annona senegalensis, anthocyanins, light irradiation, thermodegradatio