Aimé G. Fankam

Antibacterial activities of selected Cameroonian spices and their synergistic effects with antibiotics against multidrug-resistant phenotypes

BackgroundThe emergence of multi-drug resistant (MDR) phenotypes is a major public health problem today in the treatment of bacterial infections. The present study was designed to evaluate the antibacterial activities of the methanol extracts of eleven Cameroonian spices on a panel of twenty nine Gram negative bacteria including MDR strains.MethodsThe phytochemical analysis of the extracts was carried out by standard tests meanwhile the liquid micro-broth dilution was used for all antimicrobial assays.ResultsPhytochemical analysis showed the presence of alkaloids, phenols and tannins in all plants extracts. The results of the antibacterial assays indicated that all tested extracts exert antibacterial activities, with the minimum inhibitory concentration (MIC) values varying from 32 to 1024 μg/ml. The extracts from Dichrostachys glomerata, Beilschmiedia cinnamomea, Aframomum citratum, Piper capense, Echinops giganteus, Fagara xanthoxyloïdes and Olax subscorpioïdea were the most active. In the presence of efflux pump inhibitor, PAßN, the activity of the extract from D. glomerata significantly increased on 69.2% of the tested MDR bacteria. At MIC/5, synergistic effects were noted with the extract of D. glomerata on 75% of the tested bacteria for chloramphenicol (CHL), tetracycline (TET) and norfloxacin (NOR). With B. cinnamomea synergy were observed on 62.5% of the studied MDR bacteria with CHL, cefepime (FEP), NOR and ciprofloxacin (CIP) and 75% with erythromycin (ERY).ConclusionThe overall results provide information for the possible use of the studied extracts of the spices in the control of bacterial infections involving MDR phenotypes.

Antibacterial activity and cytotoxicity of selected Egyptian medicinal plants.

Medicinal plants have been used as a source of remedies since ancient times in Egypt. The present study was designed to investigate the antibacterial activity and the cytotoxicity of the organic extracts from 16 selected medicinal plants of Egypt. The study was also extended to the isolation of the antiproliferative compound jaeschkeanadiol p-hydroxybenzoate (FH-25) from Ferula hermonis. The microbroth dilution was used to determine the minimal inhibitory concentration (MIC) of the samples against twelve bacterial strains belonging to four species, Providencia stuartii, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli, while a resazurin assay was used to assess the cytotoxicity of the extracts on the human pancreatic cancer cell line MiaPaCa-2, breast cancer cell line MCF-7, CCRF-CEM leukemia cells, and their multidrug resistant subline, CEM/ADR5000. The results of the MIC determination indicated that all the studied crude extracts were able to inhibit the growth of at least one of the tested bacterial species, the best activity being recorded with the crude extracts from F. hermonis and Vitis vinifera, whichwere active against 91.7% and 83.3% of the studied bacteria, respectively. The lowest MIC value of 128 μg/mL was recorded against P. stuartii ATCC 29916 and E. coli ATCC 10536 with the extract from V. vinifera and Commiphora molmol, respectively. In the cytotoxicity study, IC50 values below 20 μg/mL were recorded for the crude extract of F. hermonis on all four studied cancer cell lines. FH-25 also showed good cytotoxicity against MCF-7 cells (IC50: 2.47 μg/mL). Finally, the results of the present investigation provided supportive data for the possible use of the plant extracts investigated herein, mostly F. hermonis and V. vinifera in the treatment of bacterial infections and jaeschkeanadiol p-hydroxybenzoate in the control of cancer diseases.

Cytotoxicity and Modes of Action of the Methanol Extracts of Six Cameroonian Medicinal Plants against Multidrug-Resistant Tumor Cells

Introduction. The present study aims at evaluating the cytotoxicity of twelve parts from six Cameroonian medicinal plants on sensitive and drug-resistant cancer cell lines. We also studied the mode of action of the most active plants, Gladiolus quartinianus, Vepris soyauxii, and Anonidium mannii. Methods. The cytotoxicity of the extracts was determined using a resazurin assay. Flow cytometry was used for cell-cycle analysis and detection of apoptosis, analysis of mitochondrial membrane potential (MMP), and measurement of reactive oxygen species (ROS). Results. At 40 g/mL, three extracts showed a growth of CCRF-CEM leukemia cells by less than 50%. This includes the extracts from G. quartinianus (GQW; 25.69%), Vepris soyauxii leaves (VSL; 29.82%), and Anonidium mannii leaves (AML; 31.58%). The lowest IC50 values below 30 μg/mL were obtained with GQW, AML and VSL against 7/9, 8/9, and 9/9 tested cancer cell lines, respectively. The lowest IC50 values for each plant were 4.09 μg/mL, and 9.14 μg/mL (against U87MG.ΔEGFR cells), respectively, for VSL and AML and 10.57 μg/mL (against CCRF-CEM cells) for GQW. GQW induced cell cycle arrest between G0/G1 and S phases, whilst VSL and AML induced arrest in G0/G1. All three extracts induced apoptosis in CCRF-CEM cells by loss of MMP, whilst AML also enhanced production of ROS. Conclusion. The three active plants may be a source for the development of new anticancer drugs.

Antibacterial and antibiotic-potentiation activities of the methanol extract of some cameroonian spices against Gram-negative multi-drug resistant phenotypes

BackgroundThe present work was designed to evaluate the antibacterial properties of the methanol extracts of eleven selected Cameroonian spices on multi-drug resistant bacteria (MDR), and their ability to potentiate the effect of some common antibiotics used in therapy.ResultsThe extract of Cinnamomum zeylanicum against Escherichia coli ATCC 8739 and AG100 strains showed the best activities, with the lowest minimal inhibitory concentration (MIC) of 64 μg/ml. The extract of Dorstenia psilurus was the most active when tested in the presence of an efflux pump inhibitor, phenylalanine Arginine-β- Naphtylamide (PAβN), a synergistic effect being observed in 56.25 % of the tested bacteria when it was combined with Erythromycin (ERY).ConclusionThe present work evidently provides information on the role of some Cameroonian spices in the fight against multi-resistant bacteria.

Flavonoids and Related Compounds from the Medicinal Plants of Africa

Bioactive natural molecules such as flavonoids are considered important for their biological activity. Flavonoids are a group of secondary metabolites derived from the phenylpropanoid pathway. There is strong evidence based on epidemiological studies that correlates consumption of fruits and vegetables with reduced risk in terms of number of cancers. The main flavonoids found in vegetables are quercetin and kaempferol. While plant-based medicines containing phenylpropanoid-derived active components have long been used by humans, the benefits of specific flavonoids and other phenylpropanoid-derived compounds to human health and their potential for long-term health benefits have been recognized only more recently. In this part of the review, we discuss the diversity and biosynthetic origins of phenylpropanoids and particularly of the flavonoid natural products. Flavonoids are one of the classes of heterocyclic natural compounds that are widely distributed in plant as glycosides or as free aglycones. In this chapter, we review the flavonoids isolated in African medicinal plants, their biological properties, and their biosynthesis in plants.

Antibacterial and Antibiotic-Potentiating Activities of Thirteen Cameroonian Edible Plants against Gram-Negative Resistant Phenotypes

This work was designed to investigate the antibacterial activities of methanol extracts from thirteen Cameroonian edible plants and their antibiotic-potentiating effects against Gram-negative multidrug-resistant (MDR) phenotypes. The broth microdilution method was used to evaluate the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the extracts, as well as their antibiotic-potentiating activities. The phytochemical screening of the extracts was carried out according to the standard methods. The results of phytochemical tests revealed the presence of sterols, polyphenols, and tannins in most of the tested extracts, with the other classes of secondary metabolites being selectively distributed. Tested extracts showed variable antibacterial activities with MIC values ranging from 64 to 1024 μg/mL. However, some extracts were significantly active against certain bacterial strains: seeds extract of Theobroma cacao (64 μg/mL) against Escherichia coli AG100Atet and Klebsiella pneumoniae K24, and the bark extract of Uapaca guineensis against E. coli ATCC 8739. The leaves extract of T. cacao displayed the best MBC values (256 μg/mL) against E. aerogenes EA27. Some tested extracts included extracts from the leaves of T. cacao and P. vulgaris, and the seeds of D. edulis and barks A. indica has selectively improved (2- to 64-fold) the antibacterial activities of some of the tested antibiotics, chloramphenicol (CHL), tetracycline (TET), kanamycin (KAN), streptomycin (STR), and erythromycin (ERY), against more than 70% of tested MDR bacteria. The findings of this work showed that tested plant extracts and particularly those from T. cacao and Phaseolus vulgaris can be used alone or in combination with conventional antibiotics in the treatment of infections involving multiresistant bacteria.

Tristemma hirtum and Five Other Cameroonian Edible Plants with Weak or No Antibacterial Effects Modulate the Activities of Antibiotics against Gram-Negative Multidrug-Resistant Phenotypes

In order to contribute to the fight against infectious diseases, the in vitro antibacterial activity and the antibiotic-potentiating effects of Tristemma hirtum and five other Cameroonian edible plants have been evaluated against Gram-negative multidrug-resistant (MDR) phenotypes. The microdilution method was used to evaluate the bacterial susceptibility of the extracts and their combination to common antibiotics. The phytochemical screening of the extracts was carried out according to standard methods. Phytochemical analysis of the extracts revealed the presence of alkaloids, triterpenes, steroids, and polyphenols, including flavonoids in most of the tested extracts. The entire tested extracts showed moderate (512 μg/mL ≤ MIC ≤ 2048 μg/mL) to weak (MIC > 2048 μg/mL) antibacterial activities against the tested bacteria. Furthermore, extracts of leaf of Tristemma hirtum and pericarps of Raphia hookeri (at their MIC/2 and MIC/4) strongly potentiated the activities of all antibiotics used in the study, especially those of chloramphenicol (CHL), ciprofloxacin (CIP), kanamycin (KAN), and tetracycline (TET) against 70% (7/10) to 100% (10/10) of the tested MDR bacteria, with the modulating factors ranging from 2 to 128. The results of this study suggest that extracts from leaves of Tristemma hirtum and pericarps of Raphia hookeri can be sources of plant-derived products with antibiotic modifying activity.

Guttiferone BL with antibacterial activity from the fruits of Allanblackia gabonensis

Abstract Allanblackia genus, an endless source of bioactive compounds, was investigated for its antibacterial properties. The chemical study of the methanol extract from the fruits of Allanblackia gabonensis resulted in the isolation of the undescribed guttiferone BL (1) along with the known kaempferol (2), morelloflavone (3), morelloflavone 7″-O-β-D-glucopyranoside (4), β-sitosterol 3-O-β-D-glucopyranoside and β-sitosterol. Their structures were determined using spectrometry and spectroscopic techniques. The antibacterial activity was evaluated against five Gram-negative and two Gram-positive strains using a broth micro-dilution method. Compounds displayed low to significant activity against the tested bacterial strains with MICs ranging from 8 to 512 μg/mL. Morelloflavone (3) presented significant activity against E. coli ATCC8739 (MIC = 8 μg/mL) while guttiferone BL (1) exhibited low activity (MICs = 256–512 μg/mL) against all the tested strains. The crude extract also had moderate to significant activity against the tested bacterial strains.

Toxicity and Protective Effects of African Medicinal Plants on the Spleen and Lung

The spleen and lungs are two organs of the upper abdominal cage. They are two minor organs involved in the metabolism of xenobiotics. However, any abnormality in these organs induced by drugs can affect the entire body. In this chapter, a synopsis of available data related to the toxic and protective effects of African medicinal plants on the lung and spleen is provided. We also provide updated literature on the anatomy and physiology of the two organs as well as their roles in the metabolism of xenobiotics. Finally, the chapter brings awareness to the possible hurtful effects of plants such as Digitalis purpurea (Plantaginaceae), Ricinus communis (Euphorbiaceae), and Allium ascalonicum (Liliaceae), even if the documented data were obtained from samples collected outside of Africa.