Phytochemical, Biological And Toxicological Studies Of The Extracts Of Young Twigs And Leaves Of Gray Nicker Nut (Caesalpinia Bonduc (Linn)) Roxb

ABSTRACT

This study involved the isolation, purification and characterisation of the bioactive

phytochemicals from the ethanolic extract of young twigs and leaves of C. bonduc, the

determination of the antimalarial activity of each isolated phytochemical, and the investigation of

their in vivo toxicological effects. Further extractions were carried out using petroleum ether,

ethyl acetate, butanol and water. Bioassay-guided fractionations of petroleum ether and ethyl

acetate fractions were carried out with a series of chromatographic separation techniques.

Structural elucidation of the compounds was done by spectroscopic methods. The in vitro

antimalarial activity and selective indices determinations of the extracts and compounds were

carried out on chloroquine sensitive strain of Plasmodium falciparum FCR-3 and mouse

mammary tumor cells FM3A respectively. The anticancer activity of the extracts and compounds

was carried out on BGC-823 and HeLa cell lines. In vivo toxicity studies of the ethanolic extract

of the plant were also undertaken. Recovery was assessed 14 days after dosing. Biochemical,

haematological and histopathological examinations were carried out. The percentage yield of

The ethanolic, petroleum ether, ethyl acetate, butanol and water fractions were 12.7%, 13.4%,

10.7%, 15.1% and 56.3% respectively. Phytochemical screening revealed the presence of all

major classes of phytochemicals except phlobatannins. A total of fourteen characterised

compounds (1 - 14) and thirteen uncharacterised pure samples (TCB 28 - 45) were isolated from

C. bonduc. Two new compounds, 12a-ethoxyl-1a,14β-dihydroxyl-cass-13(15)-en-16,12-olide

and 1a,7a-diacetoxy-5a,6β-dihydroxyl-cass-14(15)-epoxy-16,12-olide, are reported for the first

time. Eleven others are reported from C. bonduc for the first time. The antimalarial activity of

the ethyl acetate and petroleum ether fractions showed moderate activities. Three compounds

also showed antimalarial activities. Moderate anticancer activity against HeLa cell lines was

observed with the petroleum ether, water and ethyl acetate fractions. Six compounds showed

various anticancer activities against HeLa cells. However, only two compounds showed high

anticancer activity against BGC-823 cell lines. The 28 days toxicological assessment of the plant

indicated that evaluated biomarkers remained unchanged in rats dosed with extract at 200 mg/kg

body weight, while significant changes were observed in rats at extract doses of 400 mg/kg body

weight and above. There were no noticeable histopathological alterations in the cellular

architecture of the tested organs of the control rats. Similarly, there were no alterations at an

extract dose of 200 mg/kg body. However, at extract doses of 400 mg/kg body weight and above,

there were induced histopathological alterations in the cellular architecture of the liver and

kidney. No significant change was observed in the tested groups and the recovery groups in the

sub-acute toxicity study. In the acute toxicological investigation, there was no mortality in the

experimental animals at all treatment doses. However, there were significant alterations in the

biomarkers of toxicity and induced cellular damage to the liver. In conclusion, the ethanolic

extract of C. bonduc could be toxic to selected organs in the rat body on continuous high dosage.

Moreover, C. bonduc contains a wide range of bioactive flavonoids, most of which possess good

anticancer activities; some have moderate inhibitory activities against P. falciparum, but have poor selectivity indices for the mouse mammary tumor cell line.