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Context: The roots of Lophira lanceolata Van Tiegh. Ex Keay (Ochnaceae) have numerous medicinal values in the Central African region. Even though the MeOH extract of the roots has shown antimycobacterial activities, the constituents responsible for this inhibitory activity remain unknown.Objective: Phytochemical investigation of the MeOH root extract of L. lanceolata and determination of the antimycobacterial activities of that extract and constituents against the growth of Mycobacterium tuberculosis.Materials and methods: Column chromatography was used to provide bioactive phytoconstituents. Those compounds were elucidated using MS and NMR spectroscopic data. Antimycobacterial screening of the extract (4.882– 5000 µg/mL in DMSO during 24 h at 37 °C) and isolated compounds (0.244–250 µg/mL in DMSO during 24 h at 37 °C) was performed by microplate alamar blue assay (MABA) against two mycobacterial strains.Results: The investigation of L. lanceolata MeOH roots extract provided of mixture of unseparated biflavonoids with a newly described one, dihydrolophirone A (1a) associated to lophirone A (1b). The bioactive compounds that effectively inhibited the growth of M. tuberculosis AC45 were found to be compounds 1 and 2. They exhibited MIC values of 31.25 and 15.75 µg/mL, respectively, and their MIC was found to be 62.5 µg/mL against resistant strain AC83.Discussion and conclusions: It is clearly evident from the results obtained that the mycobacterial activity of L. lanceolata could be related mainly to its steroid and flavonoid contents. Therefore, this study suggests the potential of the above- mentioned classes of compounds as promising candidate agents for developing new anti-tuberculosis drugs.

Seven flavonoids, hemerocallone (1), 6,7-dimethoxy-3′,4′-dimethoxyisoflavone (2), amentoflavone (4), agathisflavone (6), cupressuflavone (8), robustaflavone (9) and epicatechin (10), together with three other compounds, lithospermoside (3), β-D- fructofuranosyl-α-D-glucopyranoside (5) and 3β-O-D-glucopyranosyl-β-stigmasterol (7), were isolated from the ethyl acetate extract of the stem bark of Ochna schweinfurthiana F. Hoffm. All the compounds were characterised by spectroscopic and mass spectrometric methods, and by comparison with literature data. Cytotoxicity of the extracts and compounds against cervical adenocarcinoma (HeLa) cells was evaluated by MTT assay. Compounds 4 and 6 exhibited good cytotoxic activity, with IC50 values of 20.7 and 10.0 μM, respectively.

A new cerebroside, Contortamide (1) together with nine known compounds spegatrine (2), affinisine (3), Nb-methylaffinisine (4), ursolic acid (5), α-amyrin (6), bauerenol acetate (7), lupeol (8), betulinic acid (9) and β-sitosterolglycoside (10) were isolated from the trunk bark of Tabernaemontana contorta Stapf. The new compound 1 showed significant activity against Caco-2 colon cancer cells with the MTT method. Compounds 1–4 and 6–9 were isolated for the first time from this species.

Triclisinone (2), a new ochnaflavone derivative, was isolated from the aerial parts of Triclisia gilletii, along with known drypemolundein B (1) and eight other known compounds. The chemical shifts of drypemolundein B (1) have been partially revised based on reinterpretation of NMR spectroscopic data. The eight other secondary metabolites are composed of: (+)-nonacosan-10-ol (3); stigmasterol (4), 3-O-β-D- glucopyranosylsitosterol (5), 3-O-β-D-glucopyranosylstigmasterol (6); oleanic acid (7); myricetin (8), quercetin (9) and 3-methoxyquercetin (10). Their structures were elucidated using IR, MS, NMR 1D and 2D, 1H and 13C and comparison with literature data. Furthermore, compounds 1, 2, 5, 6, 8, 9 and the crude extract were tested against Mycobacterium tuberculosis. Compounds 1, 2, 8 and 9 displayed moderate to very good activity against resistant strain (codified AC 45) of M. tuberculosis with minimum inhibitory concentrations MICs ranging from 3.90 to 62.5 μg/mL.

The chemical investigation of the extract of the dried leaves of Rauvolfia caffra (Sond) (synonym Rauvolfia macrophylla) (Apocynaceae) led to isolation of a new glycoside derivative, rauvolfianine (1) as well as six known compounds: oleanolic acid (2), sitosterol-3-O-β-D-glucopyranoside (3), betulinic acid (4), vellosimine (5), sarpagine (6) and D-fructofuranosyl-β-(2→1)-α-D-glucopyranoside (7). Compounds 1, 2, 3, 4 and 7 were evaluated for antitubercular activity. Compounds 1 and 2 were the most active (MIC = 7.8125 and 31.25 μg/mL) towards the Isoniazid resistant strain of Mycobacterium tuberculosis AC45. Their structures and relative stereochemistry were elucidated by spectroscopic methods.

A new C-glycosylflavone, apigenin 7-methyl ether 6-C-[β-xylopyranosyl-(1→3)-β- glucopyranoside] named distemonanthoside was isolated from the stem bark of Distemonanthus benthamianus Baill., Fabaceae, along with six known compounds, sitosterol 3-O-β-d-glucopyranoside, 4-methoxygallic acid, syringic acid, quercetin, 6″- O-acetylvitexin, quercetin 3-O-β-d-glucopyranoside. The structures of those compounds and others were determined through spectral analyses. Compounds distemonanthoside, sitosterol 3-O-β-d-glucopyranoside, 4-methoxygallic acid and quercetin were tested against a clinical isolate strain of Mycobacterium tuberculosis AC 45; they exhibited good to moderate antitubercular activities with MIC values ranged from 31.25 to 125μg/ml.

Phytochemical investigation of the stem bark of Campylospermum zenkeri led to the isolation of five known compounds: (Z,Z)-9,12-octadecadienoic acid (1), serotobenine (2), agathisflavone (3), lophirone A (4) and lophirone F (5), together with a new derivative of procyanidin B, a catechin dimer named zenkerinol (6). Serotobenine (2) is structurally related to decursivine which shows moderate activity against D6 and W2 strains of Plasmodium falciparum. For a better understanding of structure-activity relationships, three new semi-synthetic derivatives of serotobenine (2) have been prepared. These are: serotobenine monopropionate (2a), serotobenine monopivalate (2b) and serotobenine cyclohexyl ether (2c) respectively. Two of them (2a) and (2b), were evaluated for their antiplasmodial activity against P. falciparum 3D7 strain in a parasite lactate-dehydrogenase (pLDH) assay. Compound 2b was more active than compound 2a based on their IC50 values (36.6 and 123 μM, respectively).

Context: The roots of Lophira lanceolata Van Tiegh. Ex Keay (Ochnaceae) have numerous medicinal values in the Central African region. Even though the MeOH extract of the roots has shown antimycobacterial activities, the constituents responsible for this inhibitory activity remain unknown.Objective: Phytochemical investigation of the MeOH root extract of L. lanceolata and determination of the antimycobacterial activities of that extract and constituents against the growth of Mycobacterium tuberculosis.Materials and methods: Column chromatography was used to provide bioactive phytoconstituents. Those compounds were elucidated using MS and NMR spectroscopic data. Antimycobacterial screening of the extract (4.882– 5000 µg/mL in DMSO during 24 h at 37 °C) and isolated compounds (0.244–250 µg/mL in DMSO during 24 h at 37 °C) was performed by microplate alamar blue assay (MABA) against two mycobacterial strains.Results: The investigation of L. lanceolata MeOH roots extract provided of mixture of unseparated biflavonoids with a newly described one, dihydrolophirone A (1a) associated to lophirone A (1b). The bioactive compounds that effectively inhibited the growth of M. tuberculosis AC45 were found to be compounds 1 and 2. They exhibited MIC values of 31.25 and 15.75 µg/mL, respectively, and their MIC was found to be 62.5 µg/mL against resistant strain AC83.Discussion and conclusions: It is clearly evident from the results obtained that the mycobacterial activity of L. lanceolata could be related mainly to its steroid and flavonoid contents. Therefore, this study suggests the potential of the above- mentioned classes of compounds as promising candidate agents for developing new anti-tuberculosis drugs.