An ethnobotanical survey of medicinal plants used locally for treating tuberculosis (TB) and other respiratory diseases was conducted from November 2004 to March 2005 in Niger State-Nigeria. The survey was aimed at identifying plants used in traditional medicine for treating TB and other pulmonary ailments in Niger State. Tuberculosis, cough, asthma, hemoptysis and bronchitis were the major ailments treated in this survey. The interviews were conducted among the traditional medical practitioners and herbal traders in both urban and rural areas of the state. It was observed that the use of traditional medicine for treating respiratory diseases was predominantly widespread in Niger State among all the ethnic groups and intertwines with orthodox medication. A total of 95 medicinal plants belonging to 48 families used in 86 herbal recipes were surveyed. In many recipes, admixtures of plants were used. A total of 12 different kinds of respiratory ailments were encountered in this study. The index of performance (Ip) was calculated for each plant species. The plants with high Ip are often confirmed to possess biologically active chemical substances in the literature. A good number of plants identified in this survey for treating tuberculosis with (Ip>O) have been reported to possess significant anti-tubercular activity. Therefore, further screening of those plants with high performance indices as sources of 'lead' for antitubercular agents is highly recommended.

Terminalia avicennioides is used to treat tuberculosis in the folk medicine of the Nupes of North Central Nigeria. Activity guided fractionation of the extract resulted in the isolation of triterpenoid friedelin. The structure of the isolated compound was elucidated with the aid of spectral comparison of IR, UV, one and two dimensional NMR experiments values. To the best of our knowledge, this is the first time friedelin is reported from this plant. The in vitro antimycobacterial activity of the isolated compound (friedelin) was performed against Bacillus Calmette Guerin (BCG) with MIC value at 4.9 μg/mL.

Tri-0-methylflavellagic acid and its glucoside (reported for the first time) were isolated from Anogeissus leocarpus. These compounds were analysed by GC-MS, IR, 1D and 2D-NMR, and also as acetates. Antimicrobial effect of the glucoside on S. aureus, E. coli, Ps. aeruginosa and C. albicans show that it possesses growth inhibitory effect a t various concentrations.

Ten Nigerian medicinal plants Abrus precatorius, Annona senegalensis, Anogeissus leiocarpus, Crateva adansonii, Detarium microcarpum, Faba spp, Neocarya macrophylla, Ocimum gratissimum, Securidaca longpenduculata and Terminalia avicennioides used by traditional medicine practitioners for the management of infectious and chronic diseases such as tuberculosis and whooping cough were investigated for in vitro antimycobacterial activity against attenuated strains of Mycobacterium bovis (BCG). Hexane and methanol extracts of the plant materials were obtained by maceration. The antimycobacterial activity was determined by the broth microdilution method. The hexane extracts of Anogeissus leiocarpus and Terminalia avicennioides showed strong inhibitory activity at 312µg/ml. Eight of the ten plant extracts showed moderate inhibitory activity in either hexane or methanol extract at 1250µg/ml. While the hexane and methanol extracts of Detarium microcarpum and Neocarya macrophylla did not exhibit any significant activity. These observed activities could be associated with secondary metabolites in these plants. This study demonstrates the efficacy of Nigerian medicinal plants as potential agents in the management of the tuberculosis disease.

Terminalia avicennioides Guill. & Perr. (Combretaceae) has been traditionally used as traditional medicine for centuries in Nupeland, North Central Nigeria for the treatment of respiratory diseases such as tuberculosis and cough. This study evaluates the in vitro antimycobacterial activities of the isolated compounds in order to support the therapeutic use of T. avicennioides for treating these infectious diseases. Chemical investigation by bioassay-guided fractionation led to the isolation of three triterpenoids namely, arjunolic acid (1), α-amyrin (2) and 2, 3, 23-trihydroxylolean-12-ene (3). Among them, arjunolic acid manifested the most potent antimycobacterial activity against a strain of Mycobacterium bovis (BCG). Structure elucidation of the isolated compounds were based primarily on the analysis of 1-D and 2-D NMR spectral data including HMQC, HMBC, COSY and NOESY correlations, as well as comparison with reported authentic data of arjunolic acid, α-amyrin and 2, 3, 23-trihydroxylolean-12-ene. To the best of our knowledge, this is the first time these compounds (1-3) are reported from this plant. The present result further confirms the value of ethnopharmacological investigations into traditional herbs for leads for potential drug development.

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The global threat of tuberculosis (TB) demands for search for alternative antimycobacterial drugs. Some Nigerian medicinal plants used in the treatment of TB and other respiratory diseases were evaluated for activity against a clinical isolate of Mycobacterium tuberculosis and a strain of Mycobacterium bovis (BCG). The crude methanolic extracts of eight plant species were screened for activity against a clinical isolate of M. tuberculosis using broth microdilution method. Four out of the eight plant extracts exhibited inhibitory activities against M. tuberculosis at 78 and 1250 µg/mL. The crude extracts of Entada africana, Hymenocardia acida, Sterculia setigera and Stereospermum kunthianum did not inhibit significantly even at high concentration of 1250 µg/mL. The hexane fractions obtained after fractionation were the most active fractions for all the plants tested against BCG, having Anogeissus leiocarpus and Terminalia avicennioides exhibiting the highest activity at 312 and 200 µg/mL, respectively. Fractions Ta5 and Al4 obtained on further purification exhibited most significant activity (MIC of 4.7 and 7.8 µg/mL, respectively). From the results of phytochemical analysis, terpenes and triterpenoid saponins are the most prominent compounds in these fractions and several reports earlier indicated that these metabolites are potential antimycobacterial agents. This class of metabolites presents interesting area for further investigation with special attention on the Combretaceae family from Nigeria flora.

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