ISOLATION AND CHARACTERISATION OF ANTI-ULCER CONSTITUENTS FROM CURCULIGO PILOSA (SCHUMACH. & THONN.) ENGL. (HYPOXIDACEAE) AND SPHENOCENTRUM JOLLYANUM PIERRE (MENISPERMACEAE)

Abstract

Peptic ulcer is a gastrointestinal disorder affecting about four million people globally. Some currently used anti-ulcer drugs have side effects such as central nervous system disorder and depression. This necessitated a search for potent anti-ulcer compounds from natural sources. Curculigo pilosa (CP) and Sphenocentrum jollyanum (SJ) have been identified from Nigerian ethnomedicine for the treatment of gastric ulcer. However, there has been no scientific evidence to support their use. This study was designed to investigate the gastroprotective activity of CP and SJ, isolate and characterise their bioactive compounds. Methanol extracts of CP rhizomes (FHI 111263) and SJ seeds (FHI 110510) were assessed for acute toxicity using Lorke’s method. Forty-five Wistar rats (120-150 g, n=5) were pre-treated with CP and SJ crude extracts (50, 100, and 200 mg/kg b.w.) for seven days before gastric ulcer induction using indomethacin (40 mg/kg b.w.) orally. Cimetidine (100 mg/kg) was used as standard. Percentage inhibition of ulcer was determined by the gastric ulcer index. Histopathological evaluation, total gastric protein and in vivo antioxidant markers such as superoxide dismutase (SOD) and Glutathione were determined. The extracts were successively partitioned into n-hexane, dichloromethane, ethyl acetate (EtOAc), n-butanol and aqueous fractions. Fractions were screened for antacid and urease inhibitory activities using titrimetric method and urease inhibitory assay with sodium bicarbonate and acetohydroxamic acid as standards. Compounds were isolated from active fractions of CP and SJ using chromatographic techniques. Structures of isolated compounds were elucidated using spectroscopic techniques (MS, 1-D and 2-D NMR). Compounds were screened for urease inhibitory and antacid activities. Data were analysed using one-way ANOVA and Dunnet multiple comparison test at α0.05. The LD50 values of both CP and SJ extracts were > 5000 mg/kg b.w. Curculigo pilosa (50 mg/kg) gave the highest ulcer inhibition (85.4%) followed by SJ (200 mg/kg, 72.5%) compared to cimetidine (97.5%). Histopathological evaluation of the untreated group revealed severe lesions, necrosis and blood vessel congestion, which were ameliorated in CP and SJ extracts treated groups. A significant increase in total gastric protein and SOD was observed in CP and SJ treated rats. The baseline pH value (1.2) was increased by EtOAc fractions of SJ and CP at 50 and 100 mg to 1.61±0.00, 1.53±0.00 and 1.78±0.00, 1.82±0.01, respectively compared with the iii antacid activity of sodium bicarbonate: 1.53±0.00, 1.47±0.00. The n-hexane, n-butanol and aqueous fractions of SJ gave significant urease inhibitory activity of 25.4±3.02, 28.6±0.41, and 20.2±0.96 respectively while acetohydroxamic acid gave 19.6±0.34 inhibition. Palmatine (1), and 5 – (hydroxymethyl) furan-2-carbaldehyde (2) were isolated from CP. A new diterpene; 2, 3- dihydroxypropyl-(E)-octadec-5-enoate, five ecdysteroids and four clerodane diterpenoids were isolated from SJ. The isolated compounds exhibited urease inhibitory and antacid activities with polypodine B (an ecdysteroid) having the highest urease inhibitory activity (IC50 7.0±0.56). The gastroprotective activities of Curculigo pilosa and Sphenocentrum jollyanum were reported. The isolated ecdysteroids exhibited significant urease inhibitory activity, which could be linked with the anti-ulcerogenic property of the plants. These compounds could serve as leads in drug discovery for development of novel anti-ulcer drugs.