ABSTRACT

Humanity is faced with numerous health challenges ranging from severe to chronic disease conditions, such health challenges common to mankind among others include pains, arthritis, inflammations and rheumatism. Newbouldia laevis P. Beauv (farm Bignoniaceae) is used in traditional herbal medicine for the treatment of the health challenges mentioned above. We are motivated by the use of N. laevis leaves in traditional medicine to extract, isolate and characterize the bioactive components which may be responsible for its analgesic properties. Pulverized leaves sample of N. laevis was extracted by cold maceration using methanol. The extract was concentrated in vacuo to yield a reddish brown solid 120.191 g. The crude methanol extract was partitioned into n-hexane 0.1 g, dichloromethane 2.5 g, ethlylacetate 4.6 g, and methanol 10.0 g, fractions via coarse chromatography. The phytochemical screening reveals the presence of secondary metabolites as 21.73±0.36 % alkaloids, 40.78±0.27 % flavonoids, 15.99±0.044 % saponins, 6.088±0.06 % Tannins, 3.086±0.03 % Trepenoids and 12.13±0.01 % Cardiac Glycosides, with alkaloids, flavonoids and saponins having the highest percentage. The methanol fraction gave the highest yield; and it was subjected to further purification using repeated column chromatography to yield pure components namely NLM 24 (Rf 0.48), EAc:n-hex:MeOH (4:5:1) and NLM 19 (Rf  0.47), EAc:n-hex:MeOH respectively. These pure fractions were subjected to 1H NMR, 13C, COSY, HSQC and HMBC spectroscopy. Pheophytin A and β-amyrin were proposed as the structures of the isolated compounds. Acute toxicity test and analgesic test were done using the crude methanol extract and fractions. The acute toxicity test shows no death of the white whisker rats administered with low dose (1000 mg/kg) and high dose (6000 mg/kg), meaning that the leaves are edible. The analgesic activities of the crude methanol extract and fractions on white whisker rats showed that at low dose of 4000 mg/kg of the extract and the fractions have percentage inhibition of pains as; methanol crude (63.48±4.62), methanol fraction (79.14±7.39), dichloromethane fraction (60.79±6.69), ethylacetate fraction (23.26±9.75), and n-hexane fraction (64.82±9.75). At high dose of 8000 mg/kg, the percentage inhibition of pain are 5200±2.00, 71.87±7.04, 80.31±6.20, 45.61±12.60, 43.87±8.13 percent respectively; a statistical analysis at (P>0.05), confidence level the methanol fraction had the highest analgesic activities while the ethylacetate fraction had the least analgesic activity. The non-toxic effect of the extract on the rats showed why the leaves of N. laevis are cooked and consumed for pain relief in folk medicine. Even though the pure fractions were not used for analgesic activity, literature work reveals that pheophytin A & β-amyrin are potent analgesics. This may be the first time pheophytin A and β-amyrin are isolated from N. laevis leaves P. Beauv.