Assessment of the Ovulation Inducing Activity of Extract and Various Solvent Fractions of Caralluma dalzieliiN E Brown

Abstract

IntroductionCaralluma dalzielii N E Brown (Asclepiadiaceae) is a cactus‐like shaped plant that grows mainly in the Sahel savannah region of Africa. Its decoction is traditionally used to promote fertility. The aim of the study was to determine the ovulation inducing effect of extract and various solvent fractions of Caralluma dalzielii.Materials and methodsThe DCM/methanol (1:1) extract (DME) was fractionated by chromatography in a silica gel (60‐200 mm mesh) column. The extract was eluted successively using petroleum ether, ethyl acetate and methanol in order of increasing polarity. Phytochemical studies were carried out on the extract and fractions following standard procedures. Acute toxicity study was conducted using OECD 425 guidelines at a limit dose of 2000 mg/kg. Female rats with regular 4‐day oestrus cycle were allotted into 11 groups (n=6). Treatment of the rats started at pro‐oestrus phase of oestrus cycle. The rats received 2 µg s.c. each of a GnRH‐antagonist, cetrorelix, at 1.00 p.m. which resulted in blockade of ovulation. Two hours later, rats were treated with DME, petroleum ether fraction (PEF) and methanol fraction (MF) (500 and 1000 mg/kg p.o), ethyl acetate fraction (EAF) (10, 25 and 40 mg/kg p.o.), distilled water (5 mL/kg) and hCG (75 IU/kg/s.c) as positive control. The next day after the treatment, rats were sacrificed, ovaries were excised and placed in Bouin’s solution for histological analysis. Blood samples were collected via cardiac puncture under anaesthesia for serum hormonal profile.ResultsA 3 g (10% w/w), 8.4 g (28% w/w) and 6.5 g (21.67 % w/w) of the PEF, EAF and MF respectively were realised. The extract, EAF and MF contained alkaloids, saponins, flavonoids, tannins, steroids and cardiac glycosides while PEF contained steroids and cardiac glycosides only. The LD50 of the extract and fractions were greater than 2000 mg/kg while that of EAF was calculated to be 70.71 mg/kg. LH levels decline immediately after ovulation. The extract, fractions and hCG produced significant (p<0.05) reduction in the LH levels. They thus reversed cetrorelix‐induced ovulation blockade. Only the 1000 mg/kg of the extract caused a significant (p<0.05) reduction in the LH levels. All the animals showed oestrus cycle phase the following day except the control animals. Amongst the extract and fractions, the PEF showed the greatest ability to reverse cetrorelix‐induced ovulation blockade by causing greater reduction of LH levels than the other groups. EAF at all dose levels also significantly (p<0.05) lowered the LH levels more than the control (Table 1). MF showed a significant (p<0.05) reduction of LH levels only at 1000 mg/kg. Histology of the ovaries of the treated animals showed the presence of fresh corpus lutea in their various numbers. However, this was not seen in the distilled water control and the 1000 mg/kg of MF groups (Figure 1).ConclusionThe result showed that Caralluma dalzielii extract and fractions possess ovulation inducing activity. Bioactive compounds could be isolated from both EAF and PEF which showed the highest ovulation inducing activity.