Anti-asthmatic and Immunomodulatory properties of extracts of Acacia xanthophloea, Strychnos henningsii and Microglossa pyrifolia in asthma-induced mice

Abstract

The increasing prevalence of asthma in developing countries during the last decade continues to represent a significant public health problem, causing both economic and social burdens. It remains an area of considerable unmet medical need which affects 235–330 million and kills about 300,000 people worldwide. Low and middle income countries make up more than 80% of the mortality and the prevalence of Asthma in Kenya is 15.8%. Treatment of asthma is hindered by severe side effects and high cost of the treatment. Methanol and aqueous extracts of Acacia xanthophloea, Strychnos henningsii and Microglossa pyrifolia have shown efficacy on antimicrobial and antioxidant properties but have not been investigated for anti-asthmatic activities. This study was aimed at evaluating the anti-asthmatic activities of extracts of Acacia xanthophloea, Strychnos henningsii and Microglossa pyrifolia on asthma-induced mice. A total of 81 female Swiss Albino mice grouped into 9 major groups with 9 mice each, aged 8weeks old and weighing 20 +/- 2g, were asthma-induced by Intraperitoneal injection of 1% Ovalbumin (grade VI; Sigma, Steinheim, Germany) followed by treatment using methanol and water extracts of A xanthophloea, S henningsii and M pyrifolia in concentrations of 50, 100 and 200mg/kg body weight except for positive control group of mice which was induced and not treated. Standard reference drug control group was given 10mg/kg Prednisolone. After treatment, serum total Immunoglobin E (IgE) levels were determine using mouse OVA specific IgE Enzyme Linked Immunosorbent Assay (ELISA) (Legend MaxTM). Bronchoalveolar lavage fluid eosinophils level was also determined using Diff-Quick staining Technique. Cytotoxicity determination of the plant extracts was tested on Vero E6 cells using MTT viability assay. Phytochemical Screening of the plant extracts was done using thin layer chromatography. Data were analyzed and expressed as Means and Standard Deviation and the parametric data was statistically analyzed using one way Analysis of Variance (ANOVA) followed with unpaired student’s t-test at p-value < 0.001, GraphPad software was used. Cytotoxicity results were analyzed by Almar blue assay software to determine the Cytotoxic concentration 50 (CC50). The key results showed that the extracts were able to reduce the serum total IgE levels and Balf eosinophils level by upto100% in reference to the positive control. The standard drug Prednisolone also demonstrated the same effects. Based on this study the extracts tested therefore have the ability to reduce IgE and eosinophils levels in an asthmatic attack. TLC revealed presence of Phenols, Alkaloids, and Flavonoids in the methanol and aqueous extracts of the medicinal plants. These results can be used as a guideline in setting other experiments using human cells or human subjects since this was a pilot study.