Antisickling effect of crude flavonoids in the methanolic leaf extract of Persea americana Mill

Abstract

Introduction: Sickle-cell anemia, a difficult-to-treat genetic disease, causes synthesis of abnormal hemoglobin in which erythrocytes assume a sickle shape and become susceptible to hemolysis. Research about Persea americana Mill has shown that this plant has an antisickling effect, but the metabolites responsible for such activity have not been identified. Objectives: Determine the effect of a fraction of flavonoids isolated from P. americana in sickle-cell anemia. Method: A methanolic leaf extract was obtained from P. americana using Soxhlet methodology. 55.23 % of the crude flavonoids were isolated by sequential extraction of the aqueous fraction with ether, ethyl acetate and n-butanol. Effect in sickle-cell anemia was determined by counting the sickle-shaped cells in a blood sample taken from a sickle-cell patient. Upon exposure of the cells to 2, 4, 8 and 10 mg/ml of the extract, five readings were taken every 30 min. Para-hydroxybenzoic acid (5 mg/ml) was used as positive control, whereas the negative control was 0.9 % sodium chloride. The Pearson correlation coefficient was estimated and linear regression was determined. P-values equal to or under 0, 05 were considered to be significant. Mean effective concentration (EC50) was estimated at 120 min. Results: Crude flavonoids displayed time- and dose-dependent antisickling activity. At 120 min and 10 mg/ml of the extract, no sickle-shaped cell was detected, whereas with the para-hydroxybenzoic acid 61 abnormal cells were observed. The lowest concentrations of the extract showed a large number of abnormal cells. Significant correlations were obtained Lukyamuzi John 19, 3:08 PM with 10 mg/ml of the extract and with para-hydroxybenzoic acid. A notable negative linear correlation was found at this concentration between the presence of abnormal cells and time. EC50 was 8.050. Conclusions: High concentrations of flavonoids in P. americana leaves may be responsible for the effect of the latter in sickle-cell anemia, which increases with time.