Research have shown that both aqueous and ethanolic extracts of Anacardium occidentale possess antibacterial activities.This is due to the presence of bioactive substances in both the leaves and the bark extracts even though the ethanolic extract was more efficacious than the aqueous extract. The higher activity of the ethanolic extract is observed and is due to the ability of the active ingredient present in Anacardium occidentale to dissolve more in ethanol than in water. On the other hand, ethanol has been shown to be a stronger extractant than water. The ethanolic bark extracts of this plant was also found to be significantly more efficacious than the ethanolic leaves extract in terms of antibacterial activity. This may not be unconnected to the fact that the bioactive ingredient present in this plant is more concentrated in the bark of the plant than in the leaves (Thomas et al., 2012).
The antibacterial activities of the ethonolic and petroleum ether extracts of Anacardium occidentale showed significant variations. Among the Two extracts tested, ethanolic extract had greater antibacterial potential, followed by Petroleum ether extracts. The largest zones of inhibition were observed for ethanolic extract against Staphylococcus aureus (20mm) and Bacillus subtulis (19mm). Petroleum ether extract was very effective against E.Coli (16 mm) (Akash et al., 2009).
Oxidative stress has been shown to play important role in the development of various diseases. The result showed the ability of aqueous extract of Anacardium Occidentale to act as antioxidant in vitro demonstrated by the high free reducing antioxidant power value and the high percentage of inhibition of 1-Dighenyl-2-Picrylhydrazyl (DPPH) a scavenging free radical and in vitro demonstrated by the low malondialdehyde (MDA) level. The study also found that the extract was able to increase the level of certain antioxidant enzymes activity such as SOD and catalase thereby suggesting the potential beneficial usage of the plant to treat various diseases related to the oxidative stress. The presence of flavonoids compounds could be attributed for such effects (Frazali et al., 2011).
The anti-inflammatory activities of the aqueous and ethanolic extract of Anacardium occidentale were also evaluated using carrageenan-induced rat paw oedema method of Winter et al., 1962 and Adeyemi et al., 2002. Our results showed that the ethanolic extracts of this plant was more profound than the aqueous extracts but no significant difference occur between the ethanolic bark and leaves extract.
This observation assert that either to Control at the 4 hour t value p value the leaves or the bark extract can be used for treating inflammation. Equilibrium of anti-inflammatory activities between the lowest and highest concentrations of Anacardium occidentale clearly showed that the anti-inflammatory quality of the active constituent of the plant is largely dependent on the molecular weight and absorption rate in vivo than its concentration (Thomas et al., 2012).
ANTIFUNGAL AND ANTI-YEAST ACTIVITIES
The antifungal and anti-yeast activities of the ethanolic and petroleum ether extracts of Anacardium occidentale also varied significantly among the test organisms as shown. Ethanolic extract had greater antifungal potential and Petroleum ether extract showed mild antifungal activity. Antimicrobial potency of the leaf extract of Anacardium occidentale against the tested bacterial and fungal strains was expressed in minimal inhibitory concentration (MIC). The MIC values against these bacteria, and fungal strains ranged from 15.62 to 31.25μg/ml.
Subsequently, a wide range of human pathogenic microorganisms were examined, including not only Gram-positive and Gram-negative bacteria, but also fungi. Significant antifungal activities also found against C. albicans. This may indicate that the Anacardium occidentale extracts have broad inhibitory activities to pathogenic microorganisms and promising to act as potential antibacterial and antifungal agents from natural plant source (Akash et al., 2009).
Anti-diabetic properties and the body weight changes observed in the animals with administration of Anacardium occidentale L. stem-bark extract is due to the presence of some micronutrients, some secondary metabolites and some food substances in it. Flavonoids, alkaloids and saponins which are present in Anacardium occidentale L. stem-bark have been documented to have anti-oxidant effects blood glucose reduction effect and enhance natural resistance and recuperative powers of the body.
In conclusion, Anacardium occidentale L. stem-bark extract has antihyperglycaemic property and positive effect on weight gain and these actions may be attributed to the multiple physiological effects of the micronutrient and phytochemical composition of the herb (Eliakim-Ikechukwu et al., 2010). It is also shown that the methanol leaf extract of A. occidentale and its fractions had hypoglycaemic effect in streptozotocin-induced diabetic rats. Hexane and ethyl acetate fractions showed the most prominent actions suggesting the in presence of non-polar and polar hypoglycaemic that compounds in the plant (Sokeng et al., 2007).