ISOLATION AND SCREENING OF ANTIPNEUMONIC COMPOUNDS FROM Acacia stuhlmannii Taub

Abstract

Multidrug resistant pathogens, re-emerging and new infections remains a threat despite the discovery of antibiotics and vaccines globally, hence search for novel drugs. The purpose for this study was to validate folklore medicinal application of Acacia stuhlmannii, isolate and attempt to characterize bioactive compounds against some pneumonic bacteria. Baseline studies in Kenya, validated through Delphi analysis revealed that, about 94% of the respondents believed the plant treated pneumonia whereas about 63% of them believed the plant treated neonatal sepsis. Peptic ulcer disease, vulvo-vaginitis, pyomyositis and pelvic inflammatory disease were notably treated using the plant by about 57% of the respondents. About 31% of the respondents used the plant to treat enteric fevers and a similar number used it against deep neck infection. Another 25% used it to heal dysentry, and a further 19% used it to cure for gingivitis and a similar percentage used it against pyrexia of unknown origin. Phytochemical screening of the root bark extracts revealed the presence of saponins, alkaloids, tannins, cardiac glycosides, reducing sugars, flavonoids, steroids, terpenoids and coumarins. Bioassay-guided column chromatographic fractionation of the root bark Methanol extract (M) of A. stuhlmannii using Mercherey-Nagel GmbH 60M (0.04- 0.063mm) silica gel, yielded five purified sub-fractions M1A, M1B, M1C, M1D and M1E. Disc diffusion on Mueller Hinton agar with 5% sheep blood (MHSBA 5%) at a disc content of 800μg/disc, revealed M1A had mean inhibition zone diameters (IZDs) of 17.00mm, 16.33mm, 16.00mm and 16.00mm against S. pneumoniae (ATCC 49619), S. aureus (ATCC 25923), H. influenzae (ATCC 49247) and E. coli (ATCC 25922), respectively. On the other hand, M1B had mean IZDs of 17.00mm, 16.67mm, 16.33mm and 15.33mm against the same test organisms, while M1E had mean IZDs of 16.67mm, 17.33mm, 15.00mm and 9.33mm respectively. Minimum inhibition concentration (MIC), using Cation adjusted Mueller Hinton broth with 5% sheep blood revealed M1A had MIC values of 10μg/mL, 40μg/mL, 20μg/mL and 20μg/mL for the S. pneumoniae, S. aureus, H. influenzae and E. coli, respectively, while M1B had MIC values of 20μg/mL, 40μg/mL, 20μg/mL and 20μg/mL for the same micro-organisms whereas M1C had vi MIC values of 20μg/mL, 40μg/mL, 20μg/mL and 20μg/mL, respectively. ANOVA revealed significant (P  0.001) combined interaction for test organisms and sub-fractions tested in both disc diffusion assay and MIC susceptibility tests. Preliminary results using HPLC-MS, UV-Vis and 1H NMR for sub-fraction M1A revealed compound 67 of formula C37H65N5O7. There is need for a detailed study to unequivocally identify the structure of this compound. An equipment for defibrinating blood for use in bioassays was innovated.