Effect of Aqueous Nauclea pobeguinii Leaf Extract on Rats Induced with Hepatic Injury

Phenolic rich-extracts from Nauclea latifolia fruit restored Lead acetate-induced liver and kidney damaged in Wistar rats

Liver and kidney diseases are becoming order of the day in both developed and developing countries as a result of environmental pollutants such as lead. Restorative activities of methanol and methanol/acetone phenolic-rich extracts (MPR and MAPR, respectively) of the N. latifolia fruit (NLF) on lead acetate-induced liver and kidney damaged were assessed in Wistar rats. The antioxidant activities of both phenolic-rich extracts of NLF were also carried out using standard methods. Seven groups of Wistar rats comprising of 5 rats each were used for the study and 1000 mg/kg body weight (bw.) of lead acetate solution was administered orally to the 6 groups of animals to induce liver and kidney damage. The high and low dosages of 300 and of 150 mg/kg body weight (bw.) of both MPR and MAPR were administered orally to four groups for 14 days along positive (100 mg/kg bw. of silymarin), negative (treated with the placebo) and naïve control (non-induced). The percentage DPPH radical scavenging activities, ferric reducing antioxidant power and percentage inhibition of lipid peroxidation show high antioxidants activities dose-dependently. Furthermore, administration of lead acetate significantly (p > 0.05) reduces the weight gain and elevates the liver and kidney relative weight as well as their respective damage biomarkers with distortions in their histologies. However, treatment with MPR and MAPR resulted in significant (p < 0.05) improve in the percentage body weight gain, relative liver and kidney weight as well as restoration of the activities of the liver and kidney functions biomarkers of the treated animals. Likewise, lesser hepatic and renal cells injury were also observed in the treated groups with MAPR being more active at high dosage which significantly (p < 0.05) compared well with normal group. Hence, the phenolics content of the N. latifolia fruit can be exploited further for drug development for the management kidney and liver damage arise from lead-induced toxicity.

Traditional uses, phytochemistry and pharmacological properties of African Nauclea species: A review

ETHNOPHARMACOALOGICAL RELEVANCE

The genus Nauclea in Africa comprises seven species. Among them, N. latifolia, N. diderrichii and N. pobeguinii are widely used by the local population in traditional remedies. Preparation from various parts of plants (e.g. roots, bark, leaves) are indicated by traditional healers for a wide range of diseases including malaria, pain, digestive ailments or metabolic diseases.

MATERIALS AND METHODS

A literature search was conducted on African species of the genus Nauclea using scientific databases such as Google Scholar, Pubmed or SciFinder. Every document of ethnopharmacological, phytochemical or pharmacological relevance and written in English or French were analyzed.

RESULTS AND DISCUSSION

The Nauclea genus is used as ethnomedicine all along sub-Saharan Africa. Several local populations consider Nauclea species as a major source of remedies for malaria. In this regard, two improved traditional medicines are currently under development using extracts from N. latifolia and N. pobeguinii. Concerning the chemical composition of the Nauclea genus, indoloquinolizidines alkaloids could be considered as the major class of compounds as they are reported in every analyzed Nauclea species, with numerous structures identified. Based on traditional indications a considerable amount of pharmacological studies were conducted to ensure activity and attempt to link them to the presence of particular compounds in plant extracts.

CONCLUSION

Many experimental studies using plant extracts of the African species of the genus Nauclea validate traditional indications (e.g. malaria and pain). However, bioactive compounds are rarely identified and therefore, there is a clear need for further evaluations as well as for toxicity experiments. The sustainability of these plants, especially of N. diderrichii, a threatened species, should be kept in mind to adapt local uses and preparation modes of traditional remedies.

Potential of Central, Eastern and Western Africa Medicinal Plants for Cancer Therapy: Spotlight on Resistant Cells and Molecular Targets

Cancer remains a major health hurdle worldwide and has moved from the third leading cause of death in the year 1990 to second place after cardiovascular disease since 2013. Chemotherapy is one of the most widely used treatment modes; however, its efficiency is limited due to the resistance of cancer cells to cytotoxic agents. The present overview deals with the potential of the flora of Central, Eastern and Western African (CEWA) regions as resource for anticancer drug discovery. It also reviews the molecular targets of phytochemicals of these plants such as ABC transporters, namely P-glycoprotein (P-gp), multi drug-resistance-related proteins (MRPs), breast cancer resistance protein (BCRP, ABCG2) as well as the epidermal growth factor receptor (EGFR/ErbB-1/HER1), human tumor suppressor protein p53, caspases, mitochondria, angiogenesis, and components of MAP kinase signaling pathways. Plants with the ability to preferentially kills resistant cancer cells were also reported. Data compiled in the present document were retrieved from scientific websites such as PubMed, Scopus, Sciencedirect, Web-of-Science, and Scholar Google. In summary, plant extracts from CEWA and isolated compounds thereof exert cytotoxic effects by several modes of action including caspases activation, alteration of mitochondrial membrane potential (MMP), induction of reactive oxygen species (ROS) in cancer cells and inhibition of angiogenesis. Ten strongest cytotoxic plants from CEWA recorded following in vitro screening assays are: Beilschmiedia acuta Kosterm, Echinops giganteus var. lelyi (C. D. Adams) A. Rich., Erythrina sigmoidea Hua (Fabaceae), Imperata cylindrical Beauv. var. koenigii Durand et Schinz, Nauclea pobeguinii (Pobég. ex Pellegr.) Merr. ex E.M.A., Piper capense L.f., Polyscias fulva (Hiern) Harms., Uapaca togoensis Pax., Vepris soyauxii Engl. and Xylopia aethiopica (Dunal) A. Rich. Prominent antiproliferative compounds include: isoquinoline alkaloid isotetrandrine (51), two benzophenones: guttiferone E (26) and isoxanthochymol (30), the isoflavonoid 6α-hydroxyphaseollidin (9), the naphthyl butenone guieranone A (25), two naphthoquinones: 2-acetylfuro-1,4-naphthoquinone (4) and plumbagin (37) and xanthone V1 (46). However, only few research activities in the African continent focus on cytotoxic drug discovery from botanicals. The present review is expected to stimulate further scientific efforts to better valorize the African flora.

Antibacterial and antibiotic-resistance modifying activity of the extracts and compounds from Nauclea pobeguinii against Gram-negative multi-drug resistant phenotypes

BACKGROUND

Multi-drug resistance of Gram-negative bacteria constitutes a major obstacle in the antibacterial fight worldwide. The discovery of new and effective antimicrobials and/or resistance modulators is necessary to combat the spread of resistance or to reverse the multi-drug resistance. In this study, we investigated the antibacterial and antibiotic-resistance modifying activities against 29 Gram-negative bacteria including multi-drug resistant (MDR) phenotypes of the methanol extracts from Nauclea pobeguiinii leaves (NPL), Nauclea pobeguiinii bark (NPB) and six compounds from the bark extract, identified as 3-acetoxy-11-oxo-urs-12-ene (1), p-coumaric acid (2), citric acid trimethyl ester (3), resveratrol (4), resveratrol β- D -glucopyranoside (5) and strictosamide (6).

METHODS

The broth microdilution method was used to determine the minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) of crude extracts and compounds as well as the antibiotic-resistance modifying effects of MPB and 4.

RESULTS

MIC determinations indicate values ranging from 32-1024 μg/mL for NPB and NPL on 89.7 % and 69.0 % of the tested bacterial strains respectively. MIC values below 100 μg/mL were obtained with NPB against Escherichia coli ATCC10536, AG100 and Enterobacter aerogenes CM64 strains. The lowest MIC value for crude extracts of 32 μg/mL was obtained with NPB against E. coli ATCC10536. Compound 4 was active all tested bacteria, whilst 1, 3 and 6 displayed weak and selective inhibitory effects. The corresponding MIC value (16 μg/mL) was obtained with 4 against Klebsiella pneumoniae KP55 strain. Synergistic effects of the combination of NPB with chloramphenicol (CHL), kanamycin (KAN) as well as that of compound 4 with streptomycin (STR) and ciprofloxacin (CIP) were observed.

CONCLUSION

The present study provides information on the possible use of Nauclea pobeguinii and compound 4 in the control of Gram-negative bacterial infections including MDR phenotypes. It also indicates that NPB and 4 can be used as naturally occurring antibiotic-resistance modulators to tackle MDR bacteria.

Cytotoxicity of selected Cameroonian medicinal plants and Nauclea pobeguinii towards multi-factorial drug-resistant cancer cells

Background

Malignacies are still a major public concern worldwide and despite the intensive search for new chemotherapeutic agents, treatment still remains a challenging issue. This work was designed to assess the cytotoxicity of six selected Cameroonian medicinal plants, including Nauclea pobeguinii and its constituents 3-acetoxy-11-oxo-urs-12-ene (1), p-coumaric acid (2), citric acid trimethyl ester (3), resveratrol (4), resveratrol β-_D-glucopyranoside (5) and strictosamide (6), against 8 drug-sensitive and multidrug-resistant (MDR) cancer cell lines.

Methods

The resazurin reduction assay was used to evaluate the cytotoxicity of the crude extracts and compounds, whilst column chromatography was used to isolate the constituents of Nauclea pobeguinii. Structural characterization of isolated compounds was performed using nuclear magnetic resonance (NMR) spectroscopic data.

Results

Preliminary experiments on leukemia CCRF-CEM cells at 40 μg/mL showed that the leaves and bark extracts from Tragia benthamii, Canarium schweinfurthii, Myrianthus arboreus, Dischistocalyx grandifolius and Fagara macrophylla induced more than 50 % growth of this cell line contrary to the leaves and bark extracts of N. pobeguinii. IC₅₀ values below or around 30 μg/mL were obtained with leaves and bark extracts of N. pobeguinii towards two and five, respectively, of the 8 tested cancer cell lines. The lowest IC₅₀ value was obtained with the bark extract of N. pobeguinii against HCT116 (p53^−/−) colon cancer cells (8.70 μg/mL). Compounds 4 and 6 displayed selective activity on leukemia and carcinoma cells, whilst 1–3 were not active. IC₅₀ values below 100 μM were recorded with compound 5 on all 9 tested cancer cell lines as well as with 4 against 7 out of 8 and 6 against 2 out of 8 cell lines.

Collateral sensitivity was observed in CEM/ADR5000 leukemia cells, MDA-MB-231-BCRP breast adenocarcinoma cells (0.53-fold), HCT116 (p53^+/+) cells, human U87MG.ΔEGFR glioblastome multiforme cells to the methanolic bark extract of N. pobeguinii, as well as in MDA-MB-231-BCRP cells and HCT116 (p53^+/+) cells and U87MG.ΔEGFR cells (0.86-fold) to compound 5.

Conclusions

The results of this study demonstrate the cytotoxicity of six Cameroonian medicinal plants, Canarium schweinfurthii, Dischistocalyx grandifolius, Tragia benthamii, Fagara macrophylla, Myrianthus arboreus and Nauclea pobeguinii. We also demonstrated the antiproliferative potential of Nauclea pobeguinii against drug-resistant cancer cell lines. Resveratrol and its glucoside are the major cytotoxic constituents in the bark of Nauclea pobeguinii.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-015-0841-y) contains supplementary material, which is available to authorized users.