Aphrodisiac activity and screening for acute toxicity of Asian swamp eel, Monopterus albus extracts on male mice

Abstract

Monopterus albus is one of the terrestrial animal sources that is widely consumed by the local people, who believe in the medicinal properties offered by the species. However, there is not many research has been done on the species to prove the claims. Therefore, this study was conducted to evaluate the potential of M. albus extracts as an aphrodisiac and to characterize the components of the extracts. This study comprises of three phases of study: aphrodisiac, fertility and acute toxicity test. Two types of extraction were used; aqueous and lipid. Prior to treatment, the extracts were analysed for the mineral contents and fatty acid analysis using inductively coupled plasma optical emission spectrometry (ICP-OES) and Gas Chromatography Mass Spectrometry (GC-MS), respectively. Then, the sexual behaviour was observed in eight groups of ICR male mice with four animals in each group (n = 4). The doses used for both extracts were 50, 100 and 200 mg/kg. Negative control group received 0.9% saline, meanwhile positive control group received 5 mg/kg Sildenafil citrate or known as Viagra®. After an hour administration (i.p.) of the respective doses, the observation of sexual behaviour was conducted. The male mouse was paired with a female mouse for three hours to determine the effect of extracts on sexual behaviour. In addition, mating assessment also was carried out at similar dose level. On the sixth day, the copulatory plug was observed on the female mice used to confirm the presence of ejaculation. Afterwards, the male mice were slaughtered to evaluate the sperm count and motility as well as testicular histology. Another group of male mice were used for the analysis of testosterone levels. After that, toxicity test was conducted to determine the effect of a single dose of lipid extract in rats. The rats administered orally with the doses of 5, 50, 300 and 2000 mg/kg of M. albus lipid extract and control group received 0.9% saline. The survival and toxicity signs were observed for 14 days. Besides that, the blood analysis and histopathological examination of liver and kidney tissues also were investigated. From the analysis of free fatty acid, it shows that lipid extracts of M. albus contained higher level of arachidonic acid (AA), the essential fatty acid which influences the reproduction. The results obtained shows that all doses of lipid extract has significantly increased (p ≤ 0.05) the mounting frequency (MF) and sperm count as compared to negative control. Meanwhile, in aqueous extract, only the dose of 200 mg/kg shows significant difference of MF but no improvement in sperm count. In the analysis of testosterone levels, only the dose of 200 mg/kg lipid extract and positive control group showed tendency to increase the hormone levels in treated mice. Whereas, in the toxicity study, the haematological, biochemical and histological analyses showed no significant difference (p ≥ 0.05) as compared to the control. The treated rats showed no acute signs of toxicity and no mortality was observed. Therefore, the M. albus was safe to be consumed by the people and has great potential as an aphrodisiac agent. Thus, the study suggests that M. albus lipid extract could be used as an alternative source for sexual activity in men.