Antibacterial activities of the methanol extracts, fractions and compounds from Fagara tessmannii

Disruption of Biofilm Formation and Quorum Sensing in Pathogenic Bacteria by Compounds from Zanthoxylum Gilletti (De Wild) P.G. Waterman

Microbial resistance is facilitated by biofilm formation and quorum-sensing mediated processes. In this work, the stem bark (ZM) and fruit extracts (ZMFT) of Zanthoxylum gilletii were subjected to column chromatography and afforded lupeol (1), 2,3-epoxy-6,7-methylenedioxyconiferyl alcohol (3), nitidine chloride (4), nitidine (7), sucrose (6) and sitosterol-β-D-glucopyranoside (2). The compounds were characterized using MS and NMR spectral data. The samples were evaluated for antimicrobial, antibiofilm and anti-quorum sensing activities. Highest antimicrobial activity was exhibited by compounds 3, 4 and 7 against Staphylococcus aureus (MIC 200 µg/mL), compounds 3 and 4 against Escherichia coli (MIC = 100 µg/mL) and compounds 4 and 7 against Candida albicans (MIC = 50 µg/mL). At MIC and sub-MIC concentrations, all samples inhibited biofilm formation by pathogens and violacein production in C. violaceum CV12472 except compound 6. Good disruption of QS-sensing in C. violaceum revealed by inhibition zone diameters were exhibited by compounds 3 (11.5 ± 0.5 mm), 4 (12.5 ± 1.5 mm), 5 (15.0 ± 0.8 mm), 7 (12.0 ± 1.5 mm) as well as the crude extracts from stem barks (16.5 ± 1.2 mm) and seeds (13.0 ± 1.4 mm). The profound inhibition of quorum sensing mediated processes in test pathogens by compounds 3, 4, 5 and 7 suggests the methylenedioxy- group that these compounds possess as the possible pharmacophore.

Ethnopharmacological Study of the Medicinal Plants Used in the Treatment of Sickle Cell Anemia in the West Region of Cameroon

Background

Sickle cell anemia (SCA) or sickle cell disease (SCD) is a genetic disease associated with increased morbidity and mortality in Africa and other developing nations. Therefore, modern and traditional remedies are being introduced for use in the treatment and management of this disease. This is because safe, effective, and inexpensive therapeutic agents are urgently needed for the treatment of this disease in Africa and other developing nations.

Objective

The purpose of this study is to identify medicinal plant species commonly used by traditional healers in the treatment of sickle cell patients across some localities in the west region of Cameroon. Material and Methods. The ethnopharmacological survey was carried out in several districts within some localities of the western region of Cameroon. The survey was based on a semistructured questionnaire that was administered to 17 traditional healers and 62 sickle cell patients. It took place between November 2018 and March 2019. Personal information of participants and plant therapy data were gathered. Plants were identified at the National Herbarium of Cameroon. Literature review determined pharmacological effects and phytochemical compounds of the identified plants. Data were generally analysed using Epi Info 7 software for Windows.

Results

Twelve medicinal plant species belonging to 10 families are being used in the treatment of sickle cell anemia across the study sites. Euphorbiaceae is the dominant family with three plant species. Bark (39.3%) and seeds (35.7%) are the most used plant parts, which get administered through maceration, decoction, and chewing in water. According to the literature review, the identified plants have pharmacological effects and phytochemical compounds (especially polyphenols and alkaloids) that signify the presence of antioxidant compounds, which may possess an antisickling activity. There is therefore a need to conduct another study to scientifically validate (in vitro) antisickling properties of these plants.

Conclusion

This study has revealed promising medicinal plants that are currently applied in the traditional treatment of sickle cell anemia. Although still inconclusive, the association of pharmacological effects and phytochemical compounds with these medicinal plants justifies their use in traditional pharmacopoeia.

Zanthoxylum Species: A Comprehensive Review of Traditional Uses, Phytochemistry, Pharmacological and Nutraceutical Applications

Zanthoxylum species (Syn. Fagara species) of the Rutaceae family are widely used in many countries as food and in trado-medicinal practice due to their wide geographical distribution and medicinal properties. Peer reviewed journal articles and ethnobotanical records that reported the traditional knowledge, phytoconstituents, biological activities and toxicological profiles of Z. species with a focus on metabolic and neuronal health were reviewed. It was observed that many of the plant species are used as food ingredients and in treating inflammation, pain, hypertension and brain diseases. Over 500 compounds have been isolated from Z. species, and the biological activities of both the plant extracts and their phytoconstituents, including their mechanisms of action, are discussed. The phytochemicals responsible for the biological activities of some of the species are yet to be identified. Similarly, biological activities of some isolated compounds remain unknown. Taken together, the Z. species extracts and compounds possess promising biological activities and should be further explored as potential sources of new nutraceuticals and drugs.

Ethnobotany and the Role of Plant Natural Products in Antibiotic Drug Discovery

The crisis of antibiotic resistance necessitates creative and innovative approaches, from chemical identification and analysis to the assessment of bioactivity. Plant natural products (NPs) represent a promising source of antibacterial lead compounds that could help fill the drug discovery pipeline in response to the growing antibiotic resistance crisis. The major strength of plant NPs lies in their rich and unique chemodiversity, their worldwide distribution and ease of access, their various antibacterial modes of action, and the proven clinical effectiveness of plant extracts from which they are isolated. While many studies have tried to summarize NPs with antibacterial activities, a comprehensive review with rigorous selection criteria has never been performed. In this work, the literature from 2012 to 2019 was systematically reviewed to highlight plant-derived compounds with antibacterial activity by focusing on their growth inhibitory activity. A total of 459 compounds are included in this Review, of which 50.8% are phenolic derivatives, 26.6% are terpenoids, 5.7% are alkaloids, and 17% are classified as other metabolites. A selection of 183 compounds is further discussed regarding their antibacterial activity, biosynthesis, structure-activity relationship, mechanism of action, and potential as antibiotics. Emerging trends in the field of antibacterial drug discovery from plants are also discussed. This Review brings to the forefront key findings on the antibacterial potential of plant NPs for consideration in future antibiotic discovery and development efforts.

Plants in the management of male infertility

This review attempts to collate existing data and provide the perspectives for future studies on the effects of plants on the male gonads. For many of these medicinal plants such as Lepidium meyenii, Rupus coreanus, Tribulus terrestres, Panax ginseng, Petasites japonicas, Apium graveolens, Eurycoma longifólia, Pedalium murex, Corchorus depressus, Mucuna pruriens, Astragalus membranaceus, Nigella sativa, Crataegus monogyna, Fagara tessmannii, Phaleria macrocarpa, Anacyclus pyrethrum, Cynomorium songaricum and Morinda officinalis, the mechanism of actions of their active principles and crude extracts has been shown in both laboratory animals, in vitro, and human studies, and includes their antioxidant, anti-inflammatory, spermatogenesis-inducing, aphrodisiac, smooth muscle relaxing and androgenic properties. Several active chemical leads including glucosinolates, anthocyanins, protodioscin, ginsenosides, sesquiterpenes, phyto-oestrogens, quassinoids, diosgenin, thymoquinone, proanthocyanidins and bajijiasu isolated from these plants are known to have target effects on the testis, but efforts have been limited in their application at the clinical level. There still appear to be many more extracts of medicinal plants that have not been characterised to determine the phytochemicals unique to them that have target effects on the gonads. Further, collaborative efforts at isolating pro-drug candidates from medicinal plants for studies at the molecular, cellular and clinical level towards elucidating their mechanisms of action on the testes are therefore warranted in the light of the current male fertility crisis.

Cytotoxicity of the crude extract and constituents of the bark of Fagara tessmannii towards multi-factorial drug resistant cancer cells

ETHNOPHARMACOLOGICAL RELEVANCE

Fagara tessmannii Engl. is an African medicinal plant used in Cameroonian traditional medicine to treat various types of cancers.

AIM OF THE STUDY

This work was designed to determine the cytotoxicity of the crude extract (FTB), fractions (FTBa-d) and compounds isolated from the bark of Fagara tessmannii, namely lupeol (1), fagaramide (2), zanthoxyline (3), hesperidin (4), nitidine chloride (5), fagaridine chloride (6), and β-sitosterol-3-O-β-_D-glucopyranoside (7). The study was extended to the mode of induction of apoptosis by FTB, compounds 5 and 6.

MATERIALS AND METHODS

The resazurin reduction assay was used to evaluate the cytotoxicity of samples. The cell cycle, apoptosis, mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) were measured by flow cytometry. Column chromatography was used for the purification of FTB. Meanwhile, nuclear magnetic resonance (NMR) spectroscopic analysis was applied for structural elucidation.

RESULTS

The crude extract, fractions FTBa, FTBc, FTBd as well as compounds 5 and 6 revealed cytotoxicity towards the 9 tested cancer cell lines. The IC₅₀ values ranged from 17.34 µg/mL (towards U87MG.ΔEGFR glioblastoma cells) to 40.68 µg/mL (against CCRF-CEM leukemia cells) for FTB, from 16.78 µg/mL (towards U87. MGΔEGFR cells) to 37.42 µg/mL (against CEM/ADR5000 leukemia cells) for FTBa, from 19.47 µg/mL (towards U87. MG glioblastoma cells) to 41.62 µg/mL (against CCRF-CEM cells) for FTBc, from 14.17 µg/mL (against HCT116p53^-/- colon adenocarcinoma cells) to 22.28 µg/mL (towards CEM-ADR5000 cells) for FTBd, from 1.75 µM (against CCRF-CEM cells) to 23.52 µM (against U87. MGΔEGFR cells) for compound 5, from 1.69 µM (against CCRF-CEM cells) to 22.06 µM (against HepG2 hepatocarcinoma cells) for compound 6 and from 0.02 µM (against CCRF-CEM cells) to 122.96 µM (against CEM/ADR5000 cells) for doxorubicin. FTB induced apoptosis in CCRF-CEM cells mediated by enhanced ROS production. Compound 5 induced apoptosis through caspases activation and increase ROS production. Meanwhile, 6 induced apoptosis mediated by caspases activation, MMP alteration and enhanced ROS production.

CONCLUSION

Fagara tessmannii as well as its constituents 5 and 6 revealed considerable cytotoxicity and may be suitable candidates deserving to be further explored to develop new anticancer drugs to combat sensitive and resistant phenotypes.

Antibacterial activities of the methanol extracts, fractions and compounds from Harungana madagascariensis Lam. ex Poir. (Hypericaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Harungana madagascariensis Lam. ex Poir. (Hypericaceae) is used in folk medicine to treat a variety of human ailments, mainly antibacterial, antifungal, antiviral and viral infections. In the present study, the methanol extract from the leaves (HML) and bark (HMB) of this plant as well as fractions (HMBa-c), sub-fractions (HMBa1-5) and compounds isolated from HMBa and HMBb namely betulinic acid (1), madagascin (2), ferruginin A (3) and Kaempferol-3-O-β-d-glucopyranoside (4) were tested for their antimicrobial activities against a panel of 28 g-negative bacteria including multidrug resistant (MDR) phenotypes.

MATERIALS AND METHODS

The broth microdilution method was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the above samples; column chromatography was used for the fractionation and purification of the bark extract whilst the chemical structures of compounds were determined using spectroscopic techniques.

RESULTS

Crude extract HMB together with fraction HMBa and sub-fraction HMBa3 were active on the 28 tested bacterial strains. HML as well as fractions HMBb, HMBc and sub-fractions HMBa1, HMBa2, HMBa4 and HMBa5 were selectively active. MIC values below or equal to 1024µg/mL were recorded with these samples on 92.9% (for HML and HMBa 4), 82.1% (for HMBb), 78.6% (for HMBa2), 50.0% (for HMBa5) and 42.9% (for HMBc) tested bacteria. For crude material, the lowest MIC value below 8µg/mL was obtained with HMB against Escherichia coli ATCC10536 and W3110 strains, and with sub-fraction HMBa3 against Klebsiella pneumoniae K2 strains. MIC values below 10µg/mL were recorded with compound 3 against E. coli ATCC10536, Enterobacter aerogenes ATCC13048 and EA294, Pseudomonas aeruginosa PA01, K. pneumoniae K2 and Kp55 and Enterobacter cloacae BM67.

CONCLUSIONS

Harungana madagascariensis is a potential source of antimicrobial drugs to fight against MDR bacteria. The anthranol 3 is the main antibacterial constituents of the bark of the plant. HMB and compound 3 deserve further investigations to develop natural drug to combat Gram-negative bacteria and otherwise MDR phenotypes.

Antimicrobial and antioxidant activity and chemical characterisation of Erythrina stricta Roxb. (Fabaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

The bark of Erythrina stricta Roxb. (Fabaceae) has been used in Indian indigenous systems as a remedy for rheumatism, stomach-ache, asthma, dysentery, contact dermatitis, eczema and skin infections. However, there have been limited phytochemical or biological studies on the bark of E. stricta and there are no studies that align with its traditional medicinal uses.

AIM OF THE STUDY

The aim of this study was to assess the antimicrobial and antioxidant activity of the stem bark of E. stricta to support its topical use in the treatment of contact dermatitis, eczema and skin infections and to isolate and identify any bioactive compounds.

MATERIALS AND METHODS

MTT microdilution and disc diffusion assays were used to determine the antimicrobial activities of n-hexane, dichloromethane, ethyl acetate, methanol and water extracts of the bark of E. stricta. Column and preparative thin layer chromatography were used for the purification of the dichloromethane extract. The structures of the compounds isolated were elucidated by extensive 1D and 2D NMR spectroscopic techniques and comparison with published data. The antioxidant activities of the extracts were determined by DPPH free radical scavenging and FRAP assays and the antioxidant activity of the pure compounds by dot-blot and DPPH staining methods.

RESULTS

The dichloromethane, ethyl acetate, and n-hexane extracts showed the most significant activity with MIC values of 7.8µg/mL, 125µg/mL, and 125µg/mL against a sensitive strain of Staphylococcus aureus. The dichloromethane and ethyl acetate extracts also showed significant activity against Candida albicans with MIC values of 125µg/mL and 1mg/mL respectively. GC-MS analysis of the n-hexane extract showed the presence of the antibacterial and antifungal compounds β-caryophyllene, caryophyllene oxide, α-selinene, β-selinene, selin-11-en-4-α-ol, α-copaene and δ-cadenine. Phytochemical studies of the dichloromethane extract led to the isolation of the novel compound erynone (1), together with six known compounds; wighteone (2), alpinum isoflavone (3), luteone (4), obovatin (5), erythrinassinate B (6) and isovanillin (7). Luteone (4) exhibited the most significant antibacterial activity with minimum inhibitory quantity (MIQ) values of 1.88µg, 1.88µg and 3.75µg, respectively, against sensitive (MSSA) and resistant strains (MRSA and MDRSA) of S. aureus using a TLC bioautography assay. Erynone (1) exhibited the greatest DPPH free radical scavenging activity.

CONCLUSIONS

Seven compounds, including a new chromanone, were isolated from the antimicrobial dichloromethane extract of the stem bark of E. stricta. Six of the seven compounds showed antibacterial and/or antioxidant activities. These findings provide support for the customary (traditional and contemporary) use of E. stricta bark for the treatment of skin and wound infections.

Antibacterial activities of the methanol extracts of Albizia adianthifolia, Alchornea laxiflora, Laportea ovalifolia and three other Cameroonian plants against multi-drug resistant Gram-negative bacteria

In the last 10 years, resistance in Gram-negative bacteria has been increasing. The present study was designed to evaluate the in vitro antibacterial activities of the methanol extracts of six Cameroonian medicinal plants Albizia adianthifolia, Alchornea laxiflora, Boerhavia diffusa, Combretum hispidum, Laportea ovalifolia and Scoparia dulcis against a panel of 15 multidrug resistant Gram-negative bacterial strains. The broth microdilution was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the extracts. The preliminary phytochemical screening of the extracts was conducted according to the reference qualitative phytochemical methods. Results showed that all extracts contained compounds belonging to the classes of polyphenols and triterpenes, other classes of chemicals being selectively distributed. The best antibacterial activities were recorded with bark and root extracts of A. adianthifolia as well as with L. ovalifolia extract, with MIC values ranging from 64 to 1024 μg/mL on 93.3% of the fifteen tested bacteria. The lowest MIC value of 64 μg/mL was recorded with A. laxiflora bark extract against Enterobacter aerogenes EA289.

Finally, the results of this study provide evidence of the antibacterial activity of the tested plants and suggest their possible use in the control of multidrug resistant phenotypes.

Antibacterial activities of Fagara macrophylla, Canarium schweinfurthii, Myrianthus arboreus, Dischistocalyx grandifolius and Tragia benthamii against multi-drug resistant Gram-negative bacteria

Bacterial infections caused by multidrug resistant phenotypes constitute a worldwide health concern. The present study was designed to evaluate the in vitro antibacterial activities of the methanol extracts of five medicinal plants: Fagara macrophylla, Canarium schweinfurthii, Myrianthus arboreus, Dischistocalyx grandifolius and Tragia benthamii against a panel of 28 multidrug resistant Gram-negative bacterial strains. The liquid broth microdilution was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the extracts. The best activity was recorded with Canarium schweinfurthii bark extract, MIC values ranging from 32 to 1024 µg/mL being recorded against 85.7 % tested bacteria. Broad spectra of antibacterial activities were also obtained with both bark and leaf extracts from Myrianthus arboreus (78.6 %) as well as the bark extract from Fagara macrophylla (75.0 %). The lowest MIC value of 32 µg/mL was obtained with Canarium schweinfurthii bark extract against Klebsiella pneumoniae KP63 strain. The results of this work provide baseline information for the use of the studied plants, and mostly Fagara macrophylla, Canarium schweinfurthii and Myrianthus arboreus in the treatment of bacterial infections including multidrug resistant phenotypes.