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In efforts to find new bioactive beta-lactamase inhibitors, this study investigated 16 Cameroonian plants belonging to 10 families which were evaluated for anti-beta-lactamase activity. The investigation showed that extracts 2, 6, 3 and 5 of the 16 plants investigated presented interesting in vitro beta-lactamase inhibition (over 90%), respectively, of the beta-lactamases TEM-1, OXA-10, IMP-1 and P99. These extracts were from Mammea africana (all beta-lactamases), Garcinia lucida, G. kola (OXA-10, IMP-1 and P99), Bridelia micrantha (OXA-10, P99), Ochna afzelii (OXA-10, P99), Prunus africana (IMP-1) and Adenia lobata (TEM-1). After elimination of tannins (according to the European Pharmacopoeia) the extracts from B. micrantha, G. lucida and M. africana were tested further for their anti-beta-lactamase activity. The extracts from B. micrantha and G. lucida exhibited potent inhibitory activity, respectively, of beta-lactamase OXA-10 (IC(50) = 0.02 mg/mL) and P99 (IC(50) = 0.01 mg/mL). The anti-beta-lactamase activity of M. africana extract was weak. The isolation and the structural elucidation of the active constituents of G. lucida and B. micrantha will provide useful leads in the development of beta-lactamase inhibitors. [ABSTRACT FROM AUTHOR]

Sorindeia nitidula (Anacardiaceae) is used by traditional practitioners to treat influenza illnesses with cephalgia and febrile aches. However, the potential active ingredients for its remarkable antioxidant, anti-HIV and antitrypanosomal activities remain unexplored. The present study aims to evaluate the antioxidant, anti-HIV and antitrypanosomal activities of the ethyl acetate extract of S. nitidula (SN) in order to screen out the bioactive compounds and to analyze their possible mechanisms of action. Overall, 21 phenolic compounds were annotated, by using the MS and MS/MS information provided by the QTOF-MS. In vitro assays on the extract revealed potent antioxidant (IC 50  = 0.0129 ± 0.0001 mg/mL), anti-HIV (IC 50  = 1.736 ± 0.036 µM), antitrypanosomal (IC 50  = 1.040 ± 0.010 µM) activities. Furthermore, SN did not present cytotoxic effect on HeLa cancer cell lines. The integrated strategy based on LC-ESI-QTOF-MS/MS provided a powerful tool and a multidimensional perspective for further exploration of active ingredients in S. nitidula responsible for the antioxidant, anti-HIV and antitrypanosomal activities., (© 2024. The Author(s).)

Rauvolfia mannii is a plant from western and eastern areas of African continent and is widely used in folk medicine for the treatment of various diseases including malaria. Herein, one previously undescribed acylated triterpene ( 1 ), together with five already published natural products ( 2 - 6 ) were removed from its roots. The chemical structures of these compounds were determined by spectroscopic and spectrometric means (NMR, HRESIMS, IR and UV). In addition to the isolated triterpenoids, components 5 and 6 are also newly reported from the genus Rauvolfia . Moreover, some constituents were further tested against the chloroquine-sensitive strain of P. falciparum (3D7). It has been found that 3 and 4 showed a moderate antiplasmodial activity with IC 50 values of 46.25 and 39.79 µM respectively.

One monoterpene indole alkaloid, atheruramine ( 1 ) bearing an ether bridge linking, one hydrobenzoin derivative, tricalydioloside ( 2 ) and two ursane-type triterpenes, atherurosides (A and B) ( 3 and 4 ) were isolated from the leaves of Tricalysia atherura , together with eight known compounds. The structures of these new compounds were elucidated on the basis of the results of spectroscopic analysis, and the relative configurations of compounds 1-3 were established by NOE difference. Four of the metabolites were screened in vitro against both chloroquine (CQ)-sensitive (3D7) and -resistant (Dd2) strains of Plasmodium falciparum ; they were found to exhibit moderate activity against chloroquine-resistant (Dd2) (IC 50 64.99-92.29 μg/mL). Meanwhile, crude extract possesses high antiplasmodial activity against both 3D7 and Dd2 strains of P. falciparum (IC 50 4.39-7.54 μg/mL) and high selectivity indices values (SI > 10) and was found to be safe.

In our ongoing research program on the proapoptotic function of saponins, two previously undescribed saponins, named zygiaosides E (1: ) and F (2: ), were isolated from the leaves of Albizia zygia . Their structures were established based on extensive analysis of 1D and 2D NMR data, HR-ESI-MS analysis, and by chemical degradation. The proapoptotic effect of zygiaoside E (1: ) was evaluated on human malignant melanoma (A375), human epidermoid cancer (A431), and normal Homo sapiens skin tissue (TE 353.SK.) cell lines by cytometric analysis. Zygiaoside E (1: ) induced apoptosis of the two human cancer cell lines (A375 and A431) in a dose-dependent manner at 1 µM but did not induce apoptosis in noncancerous skin cells (TE 353.Sk), even when treated with concentrations up to 15 µM. The underlying mechanism of the apoptosis induction activity of zygiaoside E (1: ) on the mitochondrial membrane potential status in A375 cells was further assessed by monitoring the uptake rate of DiOC6, a mitochondrial specific and voltage-dependent fluorescent dye. The number of malignant melanoma cells emitting high fluorescence levels was decreased when cells were treated with 3 or 5 µM of zygiaoside E (1: ) during either 12 or 24 h, thereby revealing a drop of mitochondrial membrane potential in A375 cells upon treatment, which indicated mitochondrial perturbation., Competing Interests: The authors declare that they have no conflict of interest. The findings described herein are a consolidation of independent research carried out in the laboratories of the authors. As such, none of its content in any shape or form is deemed liable to any other individual or organization., (Thieme. All rights reserved.)

In our continuing search of saponins from the plants of Fabaceae family, phytochemical investigation of the roots of Acacia polyacantha, led to the isolation and structural characterization of six undescribed triterpenoid saponins, named polyacosides A-F (1-6). Their structures were established, using extensive analysis by NMR techniques, mainly 1D NMR ( 1 H, 13 C, and DEPT) and 2D NMR (COSY, NOESY, HSQC, TOCSY and HMBC) experiments, HRESIMS and by comparison with the literature data, as 3-O-[β-d-xylopyranosyl-(1 → 4)- [β-d-galactopyranosyl-(1 → 2)-β-d-xylopyranosyl-(1 → 2)]-α-l-arabinopyranosyl]-21-O-[Cis-2-methoxycinnamoyl] machaerinic acid (1), 3-O-[β-d-xylopyranosyl-(1 → 4)- [β-d-galactopyranosyl-(1 → 2)-β-d-xylopyranosyl-(1 → 2)]-α-l-arabinopyranosyl]-21-O- [Cis-3,4-dimethoxycinnamoyl] machaerinic acid. (2), 3-O- [β-d-galactopyranosyl-(1 → 2)-β-d-xylopyranosyl-(1 → 2)-α-l-arabinopyranosyl]-21-O- [Trans-4-methoxycinnamoyl] machaerinic acid (3), 3-O- [β-d-glucopyranosyl-(1 → 2)-β-d-glucopyranosyl] -21-O- [Cis-3,4-dimethoxycinnamoyl] machaerinic acid (4), 3-O- [β-d-glucopyranosyl-(1 → 2)-β-d-glucopyranosyl] -21-O- [Cis-2-methoxycinnamoyl] machaerinic acid (5) and 3-O- [β-d-glucopyranosyl-(1 → 2)-β-d-glucopyranosyl] -21-O- [Trans-4-methoxycinnamoyl] machaerinic acid (6). Our findings highlight the presence of methoxycinnamoyl group linked to C-21 of the machaerinic acid aglycone moiety as first report of 21-methoxycinnamoyl-machaerinic acid derivative from the plants of Acacia genus (Fabaceae). This represents therefore a valuable contribution to the chemotaxonomy of the Acacia genus of Fabaceae family, which is known to be a rich source of triterpenoid saponins., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

A new lupane-type triterpene, 2 α ,3 β -dihydroxylupan-29-oic acid ( 1 ), and one new ceramide derivative: (2 S* ,2' R* ,3 S* ,4 R* ,5 R*, 7' E ,11 E ,12' E ,20 E )- N -[2'-hydroxyoctadeca-6,11-dienoyl]-2-aminohexacosa-11,20-diene-1,3,4,5-tetrol ( 2 ) were isolated from the ethyl acetate fraction obtained from the methanol extract of the stem barks of Cassia arereh together with seven known compounds. Their structures were characterized using two-dimensional NMR, mass spectrometry, and compared with reported data. To date, this is the first report of the isolation of a multiple double bonds sphingolipid type (2) from this genus. The ethyl acetate extract and selected isolates were examined for antimicrobial and cytotoxic activities in vitro . Betulinaldehyde ( 5 ) has shown to be active against all bacterial strains whereas, cassiaric acid ( 1) and betulinic acid ( 6) have demonstrated to be moderately active. In addition, cassiaric acid ( 1 ) showed the best cytotoxic result against HeLa and MCF-7 cell lines tested with IC 50 75.00 µM, while lupeol ( 3) and betulinic acid ( 6) displayed weak cytotoxicity at 100.00 µM.

The aim of this study was to identify bioactive secondary metabolites from Ochna rhizomatosa with potential inhibitory effects against HIV and Plasmodium falciparum. A phytochemical study of O. rhizomatosa root barks resulted in the identification of three new biflavonoids ( 1 - 3 ), along with four known ones ( 4 - 7 ). Compound 7 (Gerontoisoflavone A) was a single flavonoid present in the rootbark of the plant and was used as a reference. Compound 1 (IC 50 = 0.047 µM) was the only one with a noteworthy inhibitory effect against HIV-1 integrase in vitro. Chicoric acid (IC 50 = 0.006 µM), a pure competitive inhibitor of HIV-1 integrase, was used as control. Compound 2 exhibited the highest antiplasmodial activity (IC 50 = 4.60 µM) against the chloroquine-sensitive strain of Plasmodium falciparum NF 54 . Computational molecular docking revealed that compounds 1 and 2 had the highest binding score (-121.8 and -131.88 Kcal/mol, respectively) in comparison to chicoric acid and Dolutegravir (-116 and -100 Kcal/mol, respectively), towards integrase receptor (PDB:3LPT). As far as Plasmodium-6 cysteine s48/45 domain inhibition is concerned, compounds 1 and 2 showed the highest binding scores in comparison to chloroquine, urging the analysis of these compounds in vivo for disease treatment. These results confirm the potential inhibitory effect of compounds 1 and 2 for HIV and malaria treatment. Therefore, our future investigation to find inhibitors of these receptors in vivo could be an effective strategy for developing new drugs.

Twenty indole alkaloids, among which two undescribed ones named rauvolfianoids A ( 1 ) and B ( 2 ), were isolated from the stem barks of Rauvolfia caffra Sond along with eight other compounds from other biosynthetic pathways. The structures were elucidated by analysis of spectroscopic data, including 1 D and 2 D NMR; absolute configurations of 1 and 2 were determined by CD exciton chirality method. Compounds 1 and 2 were evaluated for antimicrobial and anticancer activities against three bacterial strains ( Escherichia coli , Shigella sp and Salmonella sp ) and CRC-related opportunistic pathogens. 1 showed moderate antibacterial activity against Salmonella sp with the MIC value of 25 μg/ml, while 2 exhibited weak selective activity against all tested pathogens. In addition, these alkaloids were characterized as weak apoptosis inducers in HCT116 human colon carcinoma cell line.

As part of our continuing study of apoptosis-inducing saponins from Cameroonian Albizia genus, one new triterpenoid saponin, named adianthifolioside J ( 1 ), together with the known gummiferaoside E ( 2 ), were isolated from Albizia adianthifolia stems. The structure of the new saponin ( 1 ), was established on the basis of extensive analysis of 1 D and 2 D NMR ( 1 H-, 13 C-NMR, DEPT, COSY, TOCSY, NOESY, HSQC, HSQC-TOCSY and HMBC) and HRESIMS experiments, and by chemical evidence as 3- O -[ β -D-xylopyranosyl-(1→2)- β -D-fucopyranosyl-(1→6)- β -D-glucopyranosyl]-21- O -{(2E,6S)-2-(hydroxymethyl)-6-methyl-6- O -{4- O -[(2E,6S)-2,6-dimethyl-6- O -( β -D-quinovopyranosyl)octa-2,7-dienoyl]-( β -D-quinovopyranosyl)octa-2,7-dienoyl]}acacic acid-28- O - β -D-glucopyranosyl-(1→3)-[5- O -acetyl- α -L-arabinofuranosyl-(1→4)]- α -L-rhamnopyranosyl-(1→2)- β -D-glucopyranosyl ester ( 1). The pro-apoptotic activity of the new isolated saponin 1 was evaluated, using Annexin V-FITC binding assay, on the A431 human epidermoid cancer cell. The result showed that adianthifolioside J ( 1 ) displayed weak pro-apoptotic activity.

The methanolic extract of the waste seeds of Sesamum indicum L. (Pedaliaceae) was subjected to chromatographic fractionation; it led to the isolation of an alkyl benzene identified as 1,3-bis (pentadecyl)benzene ( 1 ) along with three known fatty acids: oleic acid ( 2 ), linoleic acid ( 3 ), and palmitic acid ( 4 ); one monosaturated cardanol, 3-pentadecylphenol ( 5 ) and two phytosteroids identified as sitostanol ( 6 ) and campestanol ( 7 ). The structures of these compounds were elucidated by chemical and spectroscopic analyses. Compounds 1 , 5 and 6 were evaluated against protozoan parasites. Compound 1 moderately inhibited the promastigote form of Leishmania donovani LG13 with IC 50 equal to 16.9 μM.

The present study deals with the isolation and the characterization of the chemical constituents from the leaves of Anthonotha macrophylla (Leguminosae). Using various chromatographic techniques (TLC, CC, HPLC), the methanolic extract of the leaves of Anthonotha macrophylla yielded one new alkaloid ( 1 ) as well as six known compounds amongst which an alkane ( 2 ), isolated for the first time from a natural product, an ester of fatty acid ( 3 ), two isocoumarines ( 4-5 ), a sterol ( 6 ) and a disaccharide ( 7 ). Their structures were elucidated using spectroscopic technics including extensive 1-D and 2-D NMR, HR-SM experiments.

In our continuing search of saponins from the plant of Sapindaceae family, phytochemical investigation of the stem barks of Pancovia turbinata Radlk., led to the isolation and structural characterization of two new triterpenoid saponins, named turbinatosides A-B (1-2), one new farnesyl glycoside, named turbinoside A (3), one new coumarin glucoside, named panturboside A (4), together with a known saponin (5). The structures of the new compounds were established, using extensive analysis of NMR techniques, mainly 1D NMR ( 1 H, 13 C, and DEPT) and 2D NMR (COSY, NOESY, HSQC, HSQC-TOCSY and HMBC) experiments, HRESIMS and by comparison with the literature data, as 3-O-β-d-xylopyranosyl-(1 → 3)-α-l-arabinopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 3)-α-l-rhamnopyranosyl-(1 → 2)-α-l-arabinopyranosylhederagenin 28-O-β-d-glucopyranosyl ester (1), 3-O-α-l-arabinopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 3)-α-l-rhamnopyranosyl-(1 → 2)-α-l-arabinopyranosylhederagenin 28-O-β-d-xylopyranosyl-(1 → 4)-β-d-glucopyranosyl ester (2), 1-O-{β-d-glucopyranosyl-(1 → 3)-α-l-rhamnopyranosyl-(1 → 2)-[α-l-rhamnopyranosyl-(1 → 6)]-β-d-glucopyranosyl}-(2E,6E)-farnes-1,12-diol (3), and 5-O-β-d-glucopyranosyl-5,6,7-trihydroxy-8-methoxycoumarin (4), respectively. Our findings highlight the presence of - 3 Rha- 2 Ara- 3 hederagenin oligosaccharidic sequence usually described in saponins from Sapindoideae subfamily of Sapindaceae family, as well as farnesol glycosides, and represent therefore a valuable contribution to the chemotaxonomy of the Sapindoideae subfamily., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Five undescribed carboxy-indole alkaloids with corynanthe skeleton, penduflorines A-E (1-3) as well as a voacangine-N-oxide alkaloid, tabernaemontine (4), were isolated along with eight other known compounds (5-12) from the trunk bark of Tabernaemontana penduliflora K. Schum (Apocynaceae). Their structures were determined by means of spectroscopic and spectrometric methods such as UV, IR, NMR and HR-ESI-MS. Antiplasmodial activities of new isolates were evaluated against two strains of Plasmodium falciparum 3D7 and Dd2 by the Sybr green I-based fluorescence assay setup. Those compounds showed good in vitro activities. Among them, penduflorines A and B (1a and 1b) as well as tabernaemontine (4) showed significant inhibitory activities against the two strains with IC 50 values ranged between 1.85 and 7.88 μg/mL. This is the first report of quaternary-N-indole alkaloids (1a, 1b, 2, 3a, 3b and 4) occurring in the form of zwitterion from Tabernaemontana genus., (Copyright © 2021 Elsevier B.V. All rights reserved.)

In a continuation of our study on constituents of P. guineense now focusing on the search for saponins, phytochemical investigation of the n-BuOH fraction of P. guineense stem bark led to the isolation of three previously undescribed triterpenoid saponins, named guineenosides A─C (1─3). Their structures were established on the basis of extensive analysis of 1D and 2D NMR ( 1 H, 13 C NMR, DEPT, COSY, TOCSY, NOESY, HSQC, HSQC-TOCSY and HMBC) and HRESIMS experiments, and by chemical evidence as 3-O-{α-l-rhamnopyranosyl-(1 → 3)-β-d-xylopyranosyl-(1 → 2)-α-l-arabinopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 3)-[α-l-arabinofuranosyl-(1 → 4)]-α-l-rhamnopyranosyl-(1 → 3)-β-d-fucopyranosyl} polygalacic acid 28-O-α-l-rhamnopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 3)-β-d-xylopyranosyl ester (1), 3-O-{α-l-rhamnopyranosyl-(1 → 3)-β-d-xylopyranosyl-(1 → 2)-α-l-arabinopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 3)-[α-l-arabinofuranosyl-(1 → 4)]-α-l-rhamnopyranosyl-(1 → 3)-β-d-fucopyranosyl} polygalacic acid 28-O-β-d-glucopyranosyl-(1 → 3)-α-l-rhamnopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 3)-β-d-xylopyranosyl ester (2), and 3-O-{α-l-rhamnopyranosyl-(1 → 2)-β-d-xylopyranosyl-(1 → 3)-β-d-fucopyranosyl} polygalacic acid 28-O-[α-l-rhamnopyranosyl-(1 → 4)-α-l-rhamnopyranosyl-(1 → 3)-β-d-xylopyranosyl ester (3). This is the first report of triterpenoid saponins from P. guineense., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The phytochemical study of leaves of Funtumia elastica led to the isolation of three undescribed ursane derivatives, funtumic acids A, B and C (1-3), as well as one steroidal alkaloid, elasticine (4) and five other known compounds (5-9). Their structures were elucidated on the basis of NMR, MS, IR, UV spectroscopic data as well as by comparison with the literature. The compound 5-hydroxypyridine-3-carboxamide (9) was isolated for the first time from the Apocynaceae family. All the isolated compounds were evaluated for their antiparasitic effects against 3D7 and Dd2 strains of Plasmodium falciparum and promastigotes of Leishmania donovani (MHOM/SD/62/1S). Compounds 1-4 possessed good in vitro antimalarial activities against CQR Dd2 with IC 50 values ranging from 4.68 to 5.36 μg/mL and moderate on CQS 3D7. Only compounds 1 and 2 showed leishmanicidal activities with IC 50 values ranging between 10.49 and 13.21 μg/mL. In addition, crude extract exhibited potent antiplasmodial (IC 50 0.91 and 3.12 μg/mL) and antileishmanial (IC 50 3.32 μg/mL) activities, thus demonstrating their potential synergistic action., (Copyright © 2021 Elsevier B.V. All rights reserved.)

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.

Background: Chemical and pharmacological investigations were performed on the stems of Cordia batesii (Boraginaeae); chemical studies included quantum calculations applied on a newly described compound., Results: A new derivative of allantoin (1) named batesiin (2) was characterized. Thirteen other known compounds involving allantoin (1) were either isolated or identified. GC-MS enabled the identification of six compounds from a fraction containing essential oil. MeOH extract and some isolated compounds were tested in vitro against Pf7G8 CQS and Pf Dd2 CQR strains of Plasmodium falciparum; extract disclosed a moderate antiplasmodial activity (IC 50  = 50 μg mL -1 ). Meantime, the CH 2 Cl 2 extract and essential oil fraction were tested on a resistant mycobacterial strain of Mycobacterium tuberculosis; a potent antimycobacterial activity with a MIC = 9.52 μg mL -1 was deduced from essential oil. Density functional theory (DFT) calculations were carried on batesiin (2). Calculated chemical shifts at B3LYP/6-31G(d,p) and MPW1PW91/6-31G+(d,p) showed much better correlations with the experimental data. Time dependent DFT at B3LYP/6-31G+(d,p) displayed a major absorption band 3.01 nm higher than the experimental value., Conclusion: Cordia batesii can be considered as promising in search of compounds with antimalarial and antitubercular properties. DFT studies are very helpful when trying to learn more about the spectroscopic insights of a derivative of allantoin (1).

The chemical investigation of the flowers and twigs of Calliandra calothyrsus (Fabaceae) led to the isolation of three new oleanane-type triterpenoid saponins, named calothyrsusosides AC (13). Their structures were established by direct interpretation of their spectral data, mainly HRESIMS, 1D NMR and 2D NMR ( 1 H, 1 H NMR DOSY, 13 C NMR, COSY, HSQC, HMBC, HSQC-TOCSY and NOESY) and by comparison with literature data. Compounds 1 and 2 were tested for their antiproliferative activity against two digestive carcinoma human cell lines: Hep3B (hepatocellular carcinoma) and Caco-2 (epithelial colorectal adenocarcinoma). Both compounds exhibited an antiproliferative activity against the Hep3B cell line, with IC 50 values of 6.0 and 6.5 μM, respectively, while no effect was detected against the epithelial colorectal adenocarcinoma Caco-2 (CC 50  > 25 μM)., Competing Interests: Declaration of Competing Interest The authors declare that there is no conflicting interest., (Copyright © 2020. Published by Elsevier B.V.)

Chemical investigation of the methanol extract of the roots of Lecaniodiscus cupanioides led to the isolation and characterisation of three new sesquiterpene glycosides, named cupanioidesosides A (1), B (2) and C (3), together with one new triterpenoid saponin named lecanioside A (4), Their structures were established by extensive analysis of spectroscopic methods including 1D and 2D NMR techniques (COSY, NOESY, TOCSY, HSQC, and HMBC) and HRESIMS. The four new compounds were evaluated for their antiproliferative activity against the Caco-2 cell line (human epithelial cell line). None of the isolated compounds showed positive activity in our assay. Our findings represent a valuable contribution to the chemotaxonomy Lecaniodiscus genus of the subfamily of Sapindoideae of Sapindaceae family, known to be a rich source of farnesol glycosides., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

A series of novel substituted 1- O -alkylglycerols (AKGs) containing methoxy ( 8 ), gem -difluoro ( 9 ), azide ( 10 ) and hydroxy ( 11 ) group at 12 position in the alkyl chain were synthesized from commercially available ricinoleic acid ( 12 ). The structures of these new synthesized AKGs were established by NMR experiments as well as from the HRMS and elementary analysis data. The antimicrobial activities of the studied AKGs 8 - 11 were evaluated, respectively, and all compounds exhibited antimicrobial activity to different extents alone and also when combined with some commonly used antibiotics (gentamicin, tetracycline, ciprofloxacin and ampicillin). AKG 11 was viewed as a lead compound for this series as it exhibited significantly higher antimicrobial activity than compounds 8 - 10 .

One new acacic acid-type saponin, named lebbeckoside C ( 1 ), was isolated from the stem barks of Albizia lebbeck. Its structure was established on the basis of extensive analysis of 1D and 2D NMR ( 1 H, 13 C NMR, DEPT, COSY, TOCSY, ROESY, HSQC and HMBC) experiments, HRESIMS studies, and by chemical evidence as 3- O -[ β -d-xylopyranosyl-(l→2)- β -d-fucopyranosyl-(1→6)-[ β -d-glucopyranosyl(1→2)]- β -d-glucopyranosyl]-21- O -{(2 E ,6 S )-6- O -{4- O -[(2 E ,6 S )-2,6-dimethyl-6- O -( β -d-quinovopyranosyl)octa-2,7-dienoyl]-4- O -[(2 E ,6 S )-2,6-dimethyl-6- O -( β -d-quinovopyranosyl)octa-2,7-dienoyl]- β -d-quinovopyranosyl}-2,6-dimethylocta-2,7-dienoyl}acacic acid 28 O -[ β -d-quinovopyranosyl-(l→3)-[ α -l-arabinofuranosyl-(l→4)]- α -l-rhamnopyranosyl-(l→2)- β -d-glucopyranosyl] ester. The isolated saponin ( 1 ) displayed significant cytotoxic activity against the human glioblastoma cell line U-87 MG and TG1 stem-like glioma cells isolated from a patient tumor with IC 50 values of 1.69 and 1.44 μM, respectively.

As a continuation of our interest in the study of triterpenoid saponins from Albizia zygia, phytochemical investigation of its stem barks led to the isolation of two new oleanane-type saponins, named zygiaosides C-D (1-2). Their structures were established on the basis of extensive analysis of 1D and 2D NMR (1H-, 13C NMR, DEPT, COSY, TOCSY, ROESY, HSQC and HMBC) experiments, HRESIMS studies, and by chemical evidence as, 3-O-[ β-d-glucopyranosyl-(1→2)-[α-l-arabinopyranosyl-(1→6)]-β-d-glucopyranosyl]-21-O-[(2E,6S)-2,6-dimethyl-6-O-(β-d-quinovopyranosyl) octa-2,7-dienoyl]acacic acid 28-O-α-l-arabinofuranosyl-(1→4)-[β-d-glucopyranosyl-(1→3)]-α-l-rhamnopyranosyl-(1→2)-β-d-glucopyranosyl ester (1) and 3- O-[β-d-glucopyranosyl-(1→2) -[ β-d-fucopyranosyl-(1→6)]-β-d-glucopyranosyl]-21-O-[(2E,6S)-2,6-dimethyl-6-O-(β-D-quinovopyranosyl) octa-2,7-dienoyl]acacic acid 28-O-α-l-arabinofuranosyl-(1→4)-[β-d-glucopyranosyl-(1→3)]-α-l-rhamnopyranosyl-(1→2)-β-d-glucopyranosyl ester (2).

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.

As part of our study of the proapoptotic function of saponins from Cameroonian's Albizia genus, phytochemical investigation of the roots of Albizia adianthifolia led to the isolation of three new triterpenoid saponins, named adianthifoliosides GI (13). Their structures were established on the basis of extensive analysis of 1D and 2D NMR ( 1 H-, 13 C NMR, DEPT, COSY, TOCSY, NOESY, HSQC, HSQC-TOCSY and HMBC) and HRESIMS experiments, and by chemical evidence as 3-O-[β-d-glucopyranosyl-(1 → 2)-β-D-fucopyranosyl-(1 → 6)-β-d-glucopyranosyl]-21-O-{(2E,6S)-2-(hydroxymethyl)-6-methyl-6-O-{4-O-[(2E,6S)-2,6-dimethyl-6-O-(β-D-quinovopyranosyl)octa-2,7-dienoyl]-(β-D-quinovopyranosyl)octa-2,7-dienoyl]}acacic acid-28-O-β-d-xylopyranosyl-(1 → 3)-[5-O-acetyl-α-L-arabinofuranosyl-(1 → 4)]-α-L-rhamnopyranosyl-(1 → 2)-β-d-glucopyranosyl ester (1), 3-O-[β-d-glucopyranosyl-(1 → 2)-β-D-fucopyranosyl-(1 → 6)-β-d-glucopyranosyl]-21-O-{(2E,6S)-2-(hydroxymethyl)-6-methyl-6-O-{4-O-[(2E,6S)-2,6-dimethyl-6-O-(β-D-quinovopyranosyl)octa-2,7-dienoyl]-(β-D-quinovopyranosyl)octa-2,7-dienoyl]}acacic acid 28-O-β-d-xylopyranosyl-(1 → 3)-[α-L-arabinofuranosyl-1 → 4)]-α-L-rhamnopyranosyl-(1 → 2)-β-d-glucopyranosyl ester (2), and 3-O-[β-d-glucopyranosyl-(1 → 2)-β-D-fucopyranosyl-(1 → 6)-β-d-glucopyranosyl]-21-O-{(2E,6S)-2-(hydroxymethyl)-6-methyl-6-O-{4-O-[(2E,6S)-2,6-dimethyl-6-O-(β-D-quinovopyranosyl)octa-2,7-dienoyl]-4-O-[(2E,6S)-2,6-dimethyl-6-O-(β-D-quinovopyranosyl)octa-2,7-dienoyl]-β-D-quinovopyranosyl}-2,6-dimethylocta-2,7-dienoyl}acacic acid 28-O-β-d-xylopyranosyl-(1 → 3)-[α-L-arabinofuranosyl-1 → 4)]-α-L-rhamnopyranosyl-(1 → 2)-β-d-glucopyranosyl ester (3). The apoptotic effect of saponins 1-3 was evaluated on the A431 human epidermoid cancer cell. Flow cytometric analyses showed that saponins 1-3 induced apoptosis of human epidermoid cancer cell (A431) in a dose-dependent manner., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Three new alkaloids, janetinine (1a), pleiokomenine A (2), and huncaniterine B (3a), and 13 known compounds, pleiomutinine (3b), huncaniterine A (3c), 1-carbomethoxy-β-carboline (4), evoxanthine (5), deformyltalbotine acid lactone (6), pleiocarpamine (7), N 4 -methyl-10-hydroxygeissoschizol (8), spegatrine (9), neosarpagine (10), aspidofractinine (11), N 1 -methylkopsinin (12), pleiocarpine (13), and N 1 -methylkopsinin- N 4 -oxide (14), were isolated from the stem bark of Pleiocarpa pycnantha. Janetinine (1a) is a carbazole alkaloid; in pleiokomenine A (2), two aspidofractinine-type alkaloids are bridged by a methylene unit in an unprecedented way, and huncaniterine B (3a) is a pleiocarpamine-aspidofractinine-type dimer. The structures and relative configurations of these compounds were elucidated on the basis of NMR and MS analyses. Their absolute configurations were defined by means of experimental and calculated ECD data, and additionally, the structures of 5 and 13 were determined by single crystal X-ray diffraction. Compounds 1a, 2, 3b, 4, 6, 9, and 12 displayed cancer chemopreventive properties through either quinone reductase induction ( CD = 30.7, 30.2, 29.9, 43.5, and 36.7 μM for 1a, 4, 6, 9, and 12, respectively) and/or NF-κB inhibition with IC 50 values of 13.1, 8.4, 9.4, and 8.8 μM for 2, 3b, 6, and 12, respectively.

Two bisindoline alkaloids, contortarine A, 16-epi-pleiomutinine and a reaction product of pleiomutinine, namely N 4 -chloromethyl-pleiomutinine, were isolated from the roots of Tabernaemontana contorta Stapf. together with five known compounds: pleiomutinine, 1-carbomethoxy-β-carboline, strictosidine lactam, pleiocarpamine, and pleiocarpine. The structures and relative configuration of these alkaloids were determined by extensive 1D and 2D NMR, and MS measurements. The absolute configuration of these compounds was determined by comparison of experimental and calculated ECD spectra. Among the isolated compounds, contortarine A, 1-carbomethoxy-β-carboline and strictosidine lactam presented cancer chemopreventive properties through either quinone reductase (QR) induction with C D values of 16.0 ± 2.5, 30.2 ± 6.1 and 23.1 ± 4.6 μM, respectively, while pleiomutinine and 16-epi-pleiomutinine displayed the inhibition of TNF-α induced NF-κB activity with IC 50 at 11.7 ± 2.6 and 3.4 ± 1.1 μM, respectively., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

As part of our search for new bioactive saponins from Cameroonian medicinal plants, two new oleanane-type saponins, named gummiferaosides D and E (1 and 2), along with one known saponin, julibroside J 8 (3), were isolated from the roots of Albizia gummifera. Their structures were established on the basis of extensive 1D- and 2D-NMR ( 1 H- and 13 C-NMR, DEPT, COSY, TOCSY, NOESY, HSQC, HSQC-TOCSY, and HMBC) and HR-ESI-MS studies, and by chemical evidence. The apoptotic effect of saponins 1 - 3 was evaluated on the A431 human epidermoid cancer cell. Flow cytometric analyses showed that saponins 1 - 3 induced apoptosis of human epidermoid cancer cell (A431) in a dose-dependent manner., (© 2017 Wiley-VHCA AG, Zurich, Switzerland.)

Two new compounds a flavanolignan (1), and an alkane (2) along with four known compounds including two fatty acid esters (3-4) and two isocoumarins (5-6) were isolated from the methanolic extract of the stem bark of Newtonia griffoniana. Their structures were elucidated using spectroscopic methods including extensive 1-D and 2-D NMR experiments.

A total of 14 compounds were isolated from the ethanol bark extract of O. kirkii S. Moore (Fabaceae) by alternating isocratic and step gradient elution high-speed counter-current chromatography (HSCCC) methods, using several solvent systems with reference to the polarity of compounds being purified. The extract was successively fractionated with generic solvent systems including n-hexane-ethanol-water (4:2:2) and ethyl acetate-water (1:1). Resulting fractions were further purified using the following preparative gradient elution consisting of ethyl acetate-n-butanol-water (X:Y:10), (X:Y=9:1 (I); 8:2 (II); 7:3 (III); 6:4 (IV); 5:5 (V); 4:6 (VI) 3:7 (VII) and n-hexane- ethyl acetate-methanol-water (1:X:1:1), X=1, 2, 2.5, 3 solvent systems. Two flavone glycosides, apigenin-6-C-β-d-glucopyranosyl-4'-O-[β-d-glucopyranosyl-(1→5)]-β-d-apiofuranoside (1) and apigenin-6-C-β-d-glucopyranosyl-4'-O-β-d-apiofuranoside (2), and one biflavanone diglycoside 7,7″-di-O-β-d-glucosylliquiritigeninyl-(I-3,II-3)-naringenin (4) were isolated as new compounds along with other 11 known ones. The structures of the isolated compounds were identified by HPLC-UV, ESI-MS, 1D and 2D NMR and comparison with literature data. Thus, over common traditional chromatographic methods, the present study shows that HSCCC is a useful and fast method for natural product research with no losses and lower solvent use., (Copyright © 2016 Elsevier B.V. All rights reserved.)

As part of our search of new bioactive saponins from Cameroonian medicinal plants, phytochemical investigation of the roots of Albizia glaberrima led to the isolation of three new oleanane-type saponins, named glaberrimosides A-C (1-3). Their structures were established by direct interpretation of their spectral data, mainly HRESIMS, 1D NMR (1H, 13C NMR, and DEPT) and 2D NMR (COSY, ROESY, HSQC and HMBC) as 3-O-[α-L-arabinopyranosyl-(1 → 6)-[β-D-glucopyranosyl-(1 → 2)]-β-D-glucopyranosyl]-28-O-[β-D-glucopyranosyl-(1 → 6)-[β-d-glucopyranosyl-(1 → 2)]-β-D-glucopyranosyl]-oleanolic acid (1), 3-O-[α-L-arabinopyranosyl-(1 → 6)-[β-D-glucopyranosyl-(1 → 2)]-β-D-glucopyranosyl]-28-O-[β-D-glucopyranosyl-(1 → 6)-β-D-glucopyranosyl]-oleanolic acid (2), and 3-O-[β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl]-28-O-[β-D-glucopyranosyl-(1 → 6)-[β-D-fucopyranosyl-(1 → 2)]-β-D-glucopyranosyl]-oleanolic acid (3). The pro-apoptotic effect of the three saponins was evaluated on three human cell lines (pancreatic carcinoma AsPC-1, hematopoietic monocytic THP-1, and human fibroblast cell line BJ). Saponins 1-3 specifically induced apoptosis of pancreatic carcinoma cell (AsPC-1) in a dose-dependent manner. More interestingly, there were inactive on monocytic (THP-1) and normal human fibroblast (BJ) cell lines., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Background: Newtonia griffoniana (Mimosaceae) is a Central African rain forest tree, whose bark extracts are used in Cameroonian folk medicine for the treatment of anxiety and sleep disorders., Methods: We evaluated the anxiolytic effects of N. griffoniana stem bark methanol extract and its major isolated constituent 2,3,4-trihydroxybutylpentatriacontanoate (newtonoate) on the elevated plus maze., Results: Significant increases in the percentage of entries into open arms were induced by both N. griffoniana extract (100 and 150 mg/kg BW; p<0.01) and newtonoate (doses of 3 and 15 mg/kg BW; p<0.05). Conversely, decreases in the percentage of entries into closed arms were observed at the same doses. In addition, N. griffoniana methanol extract (100 mg/kg) and the isolated newtonoate (30 mg/kg) induced significant (p<0.01 and p<0.05, respectively) increases in the time spent in the open arms, while inducing a decrease in the time spent in the closed arms. Newtonoate treatment also decreased head dipping number at doses of 3 and 15 mg/kg, while N. griffoniana methanol extract induced the same effect at 200 mg/kg., Conclusions: These results suggest that N. griffoniana bark extract has anxiolytic properties, which justify its use in folk medicine. Such effects are at least partly mediated by newtonoate.

As part of our search of new bioactive triterpenoid saponins from Cameroonian Mimosaceae plants, phytochemical investigation of the roots of Albizia lebbeck led to the isolation of two new oleanane-type saponins, named lebbeckosides A-B (1-2). Their structures were established on the basis of extensive 1D and 2D NMR ((1)H, (13)C NMR, DEPT, COSY, TOCSY, ROESY, HSQC, and HMBC) and HRESIMS studies, and by chemical evidence. Compounds 1-2 were evaluated for their inhibitory effect on the metabolism of high grade human brain tumor cells, the human glioblastoma U-87 MG cell lines and the glioblastoma stem-like TG1 cells isolated from a patient tumor, and known to be particularly resistant to standard therapies. The isolated saponins showed significant cytotoxic activity against U-87 MG and TG1 cancer cells with IC50 values of 3.46 μM and 1.36 μM for 1, and 2.10 μM and 2.24 μM for 2, respectively., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

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.

Two new flavone glycosides, 3″-O-acetyl-7-O-methylvitexin (1) and 6″-α-rhamnopyranosyl-7-O-methylvitexin (2), along with nine known compounds (3-11) were isolated from the leaves of Rhabdophyllum arnoldianum (Ochnaceae). The structures of the new compounds were established by detailed spectroscopic studies and mass spectrometry, while known compounds were characterised by direct comparison of their reported NMR data with those found in the literature. All these compounds were the first reported from Rhabdophyllum genus. The biological assays on crude extracts and compounds of this plant demonstrated that the crude extracts possess significant antimicrobial activity against Gram-positive bacteria.

Phytochemical investigation of the leaves of Sorindeia juglandifolia A. Rich. led to the isolation and identification of a new C-glucosylflavone, 2",6"-di-O-acetyl-7-O-methyl vitexin (1), together with seven known compounds, 2"-O-acetyl-7-O-methyl vitexin (2), mearnsitrin (3), robustaflavone (4), 3-O-galloyl catechin (5), tachioside (2-methoxy-benzene-1,4-diol-1-O-beta-glucopyranoside) (6), 3beta-O-D-glucopyranosyl-beta-stigmasterol (7), and methyl gallate (8). The structures of 1 and the known compounds were established by IR, UV, MS, 1D, and 2D NMR spectra and by comparison with those of related compounds.

Introduction: Standard NMR 2D heteronuclear HMBC spectra have a low resolution in the indirect carbon dimension, making it very difficult to assign signals to individual carbons when their chemical shifts are < 0.3 ppm apart., Objective: To establish spectral aliasing for HMBC experiments to improve the resolution in the carbon dimension without increasing the total experimental time and avoiding ambiguities in the observed chemical shifts., Methodology: The NASCA-HMBC (Non-ambiguous Assignment by Superposition of Coupled Aliased HMBC) methodology combines a pair of HMBC spectra recorded with slightly different carbon windows to provide typically one order of magnitude increase in the resolution and unambiguous chemical shifts., Results: The application of this methodology to a biflavonoid found in Ouratea gilgiana resulted in spectra with a sufficiently high resolution to make the assignment straightforward and report, for the first time, the full assignment of agathisflavone., Conclusion: The methodology should find many applications in dimeric and oligomeric compounds such as peptides, carbohydrates, polyketides and other cases where signal clustering is expected., (Copyright © 2011 John Wiley & Sons, Ltd.)

From the leaves and stem bark of Campylospermum flavum (Ochnaceae), three compounds, namely 4‴-O-methylagathisflavone, flavumchalcone, and flavumindole have been isolated together with 10 known compounds, including three flavonoids, two biflavonoids, two alkaloids, two nitrile glucosides, and glucopyranosyl-β-sistosterol. The structures of these compounds and their relative configurations were established by 1D and 2D NMR experiments. The methanolic crude extracts of leaves and stem bark of C. flavum and compounds displayed a significant cytotoxicity towards Artemia salina larvae., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Background: In effort to identify novel bacterial agents, this study was initiated to evaluate the antimicrobial properties of 17 crude extracts from 12 medicinal plants against beta-lactam-resistant bacteria., Methodology: The antimicrobial activities of plant extracts were evaluated against clinically proved beta-lactam-resistant bacteria (Klebsiella pneumoniae, Klebsiella oxytoca, Enterobacter cloacae, Serratia marcescens, Acinetobacter baumannii, Staphylococcus aureus and Enterococcus sp.) and reference strains of bacteria (Escherichia coli ATCC 35218, Enterobacter aerogenes ATCC 29751, E. aerogenes ATCC 13048, Pseudomonas aeruginosa ATCC 27853 and Enterococcus hirae ATCC 9790) by using disc-diffusion and agar-dilution assays., Results: The crude plant extracts demonstrated broad spectrum activity against all bacteria tested with inhibition zones in the range of 8-30 mm. The minimal inhibitory concentration (MIC) values of different plant extracts against the tested bacteria were found to range from or= 10 mg ml(-1). The most active plant extracts were from Dortenia picta and Bridelia micrantha (MIC: 1.25-10 mg ml(-1)) on beta-lactam-resistant Gram-negative bacilli and the extracts from B. micrantha, Mallotus oppositifolius, Garcinia lucida, Garcinia. kola, Campylospermum densiflorum (leaves) and C. zenkeri (root) on beta-lactam-resistant Gram-positive cocci (MIC:

Two new oleanane-type saponins, coriariosides A (1) and B (2), along with a known saponin, gummiferaoside C (3), were isolated from the roots of Albizia coriaria. Their structures were established by extensive analysis of 1D and 2D NMR experiments (COSY, ROESY, TOCSY, HSQC, and HMBC) and mass spectrometry. Compounds 1 and 3 when tested for cytotoxicity against two colorectal human cancer cells showed activity against the HCT 116 (IC50 4.2 microM for 1 and 2.7 microM for 3) and HT-29 (IC50 6.7 microM for 1 and 7.9 microM for 3) cell lines.

From the stem bark of Tetrapleura tetraptera, two new oleanane-type saponins, tetrapteroside A 3-O-{6-O-[(2E,6S)-2,6-dimethyl-6-hydroxyocta-2,7-dienoyl]-beta-D-glucopyranosyl-(1 --> 2)-beta-D-glucopyranosyl-(1 --> 3)-beta-D-glucopyranosyl-(1 --> 4)-[beta-D-glucopyranosyl-(1 --> 2)]-beta-D-glucopyranosyl}-3,27-dihydroxyoleanolic acid (1), and tetrapteroside B 3-O-{ beta-D-glucopyranosyl-(1 --> 2)-6-O-[(E)-feruloyl]-beta-D-glucopyranosyl-(1 --> 3)-beta-D-glucopyranosyl-(1 --> 4)-[beta-D-glucopyranosyl-(1 --> 2)]-beta-D-glucopyranosyl}-3,27-dihydroxyoleanolic acid (2), were isolated. Further extractions from the roots led to the isolation of four known oleanane-type saponins. Their structures were elucidated by the combination of mass spectrometry (MS), one and two-dimensional NMR experiments., (2009 John Wiley & Sons, Ltd.)

Two nitrile glucosides (1S,3S,4S,5R)-4-benzoyloxy-2-cyanomethylene-3,5-dihydroxycyclohexyl-1-O-beta-glucopyranoside (campyloside A) and (1S,3S,4S,5R)-5-benzoyloxy-2-cyanomethylene-3-hydroxy-4-(2-pyrrolcarboxyloxy)cyclohexyl-1-O-beta-glucopyranoside (campyloside B) were isolated from the stem roots of Campylospermum glaucum, whereas serotobenine was isolated from Ouratea turnarea. The structure elucidations were based on spectroscopic evidence. The biological assays of compounds and crude extract of plant species showed good antimicrobial activity of crude extracts against Gram-positive cocci.

In efforts to find new bioactive beta-lactamase inhibitors, this study investigated 16 Cameroonian plants belonging to 10 families which were evaluated for anti-beta-lactamase activity. The investigation showed that extracts 2, 6, 3 and 5 of the 16 plants investigated presented interesting in vitro beta-lactamase inhibition (over 90%), respectively, of the beta-lactamases TEM-1, OXA-10, IMP-1 and P99. These extracts were from Mammea africana (all beta-lactamases), Garcinia lucida, G. kola (OXA-10, IMP-1 and P99), Bridelia micrantha (OXA-10, P99), Ochna afzelii (OXA-10, P99), Prunus africana (IMP-1) and Adenia lobata (TEM-1). After elimination of tannins (according to the European Pharmacopoeia) the extracts from B. micrantha, G. lucida and M. africana were tested further for their anti-beta-lactamase activity. The extracts from B. micrantha and G. lucida exhibited potent inhibitory activity, respectively, of beta-lactamase OXA-10 (IC(50) = 0.02 mg/mL) and P99 (IC(50) = 0.01 mg/mL). The anti-beta-lactamase activity of M. africana extract was weak. The isolation and the structural elucidation of the active constituents of G. lucida and B. micrantha will provide useful leads in the development of beta-lactamase inhibitors.

The leaves of Ouratea nigroviolacea (Ochnaceae) afforded two biflavonoids, ouratine A and B together with agathisflavone and stigmasterol. The biflavonoids were characterized as 4'-O-methylated apigeninyl-(I-6, II-8)-4'-O-methylatedapigenin and 4'-O-methylated apigeninyl-(I-6, II-8) apigenin by spectral and chemical transformation studies.

The antimicrobial activities of 10 plant species (Voacanga africana, Crepis cameroonica, Plagiostyles africana, Crotalaria retusa, Mammea africana, Lophira lanceolata, Ochna afzelii, Ouratea elongata, Ou. flava and Ou. sulcata), each of which is currently used in the traditional medicine of Cameroon, were investigated in vitro. The activities of a methanol extract of each plant were tested, in disc-diffusion assays, against 37 reference or laboratory strains of seven species of microorganism (Staphylococcus aureus, S. epidermidis, Enterococcus hirae, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Candida albicans). The minimal inhibitory concentrations of each extract were then estimated, against each of the more susceptible microorganisms (i.e. those giving an inhibition zone measuring at least 9 mm in diameter in the disc-diffusion assays), by agar dilution. Although, in the disc-diffusion assays, each of the 10 methanol extracts investigated displayed some degree of antimicrobial activity against at least one species of microorganism, no activity against the Gram-negative bacteria (Es. coli, K. pneumoniae and Ps. aeruginosa) was observed. The extract with the greatest antimicrobial activity was that of Pl. africana (Euphorbiaceae).