Screening of the antimycobacterial activity of novel lipophilic agents by the modified broth based method

Abstract

Most of the introduced susceptibility methods of Mycobacterium tuberculosis have some disadvantages for screening. Therefore, the selection of susceptibility assay for evaluating candidate agents must be determined case by case. In this study, we evaluated the validity of a modified broth dilution-based assay in comparison to the gold standard proportional method for microbial sensitivity test of new lipophilic compounds candidate as antitubercular agents. The in-vitro susceptibilities of 114 M. tuberculosis strains were separately tested against isoniazid and two lipophilic antitubercular agents (derivative of dihydropyridines) by employing the standard proportional method and a modified broth dilution-based assay. The results for isoniazid testing showed 100% concordance for sensitivity, specificity and reproducibility. In the case of microbial sensitivity test of lipophilic compounds, comparison of the results obtained from these two methods indicates a significant superiority of the modified method over the standard method. Considering the other advantages of this modified method, we concluded that this modified broth dilution-based assay could be utilized effectively for the susceptibility testing of new lipophilic compounds candidate as antitubercular agents.

Antibacterial, Antifungal and Anti-tubercular Activities of Chloroform Fraction of the Leaf Extract of Irvingia Gabonensis (African Bush Mango)

“…The phytochemical analysis of the chloroform fraction revealed the presence of alkaloid, tannin, flavonoid, phenol, saponin and coumarin. The presence of these families of compounds in fraction confirms the results of previous studies on the extracts of I. gabonensis [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. These phytochemicals confirm the pharmacological properties reported previously such as anti-ulcer and anti-diarrhoea [23], antioxidant [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24], anti-inflammatory [6], anti-cancer [25] and anti-microbial activities [11][12][13][14][15]…”

“…The result obtained reveals highest antifungal activity value against C. albicans at 2.5 mg/mL (5 mm) and lowest activity value for C. albicans at 25 mg/mL (14 mm). The MIC values obtained in this study are compared favourably with those reported in the literature for some of the test organisms [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29]. Figs (3 and 4) show the MIC charts for both bacteria and fungi against the chloroform fraction.…”

“…Agar proportion method using Lowenstein Jensen media was employed for the susceptibility test [20,21]. The clinical isolates of Mycobacterium tuberculosis (drug susceptible and drug resistant) were tested against chloroform fraction from leaves of I. gabonensis, alongside with two reference drugs, which are rifampicin and levofloxacin.…”

“…The result of anti-mycobacterial activity of the chloroform fraction on seven M. tuberculosis strains is shown in Table 1. These strains were performed on standard L-J media method, and incubated for 42 days [20][21][22]. The Table shows that DS-MTB-1 to DS-MTB-5 strains and the H37Rv strain were all susceptible to the chloroform fraction of the leaf extract of I. gabonensis.…”