PHARMACOGNOSTIC STUDY AND ANTIMALARIAL ACTIVITY OF THE METHANOL EXTRACT AND FRACTIONS OF BIXA ORELLANA L., (FAMILY BIXACAEA) LEAVES (ANNATTO PLANT) ON ALBINO MICE

The emergence of anti-malarial resistant parasites has posed a serious threat to the control and elimination of malaria. Therefore, there is a need for an alternative drug that is highly efficacious, affordable and safer for the treatment of malaria; hence, interest is now on the use of herbal medicine to treat malaria. Ogidi community in the Anambra State of Nigeria depends mainly on plants for the treatment of malaria. Bixa orellana plant, belonging to the family Bixaceae, is a very popular medicinal plant in Nigeria where it is used to treat malaria, jaundice, diarrhoea, dysentery, hypertension, as well as diabetes. The ethnomedicinal use against malaria prompted this investigation on the anti-plasmodial activity of the leaf of Bixa orellana. Bixa orellana leaves were obtained from Ogidi, Anambra, Nigeria, it was dried and pulverized to smaller particle size and extraction was by cold maceration with methanol which was fractionated into n-hexane and ethyl acetate fractions. The phytochemical analysis was carried out using standard procedures. The evaluation of anti-malarial activity was done according to standard methods. Phytochemical analysis revealed the presence of saponins, tannins, terpenoids, proteins, alkaloids and flavonoids and absence of starch and phenols. Quantitatively, the percentage phytochemical content of the leaves of the plant are as follows; saponins (10.11%), tannins (11.11%), flavonoids (21.89%), glycosides (31.86%). Bixa orellana leaf has low moisture content and ash value of 6.13% and 4.58% respectively. The significant decrease in the parasitemia levels in mice was dose-dependent for example in n-hexane extract 50 mg/kg dose gave a percentage decrease of 34.50% while the 100 mg/kg gave a percentage decrease of 80.15% after treatment which is the highest inhibition among all the other fractions. The positive control (Arthemeter and lumefantrine) was more potent since it gave a 69.99% inhibition at a dose of 0.37 mg/kg. The treated groups were all very significant (p<0.05) except groups 1 and 3 (p≥0.05). From the results obtained, Bixa orellana has antimalarial activity especially the n-hexane fraction of the leaf extract which confirms the claim of Ogidi community of Anambra State Nigeria.