Anti-inflammatory, anticholinesterase and antioxidant activity of leaf extracts of twelve plants used traditionally to alleviate pain and inflammation in South Africa

ETHNOPHARMAOLOGICAL RELEVANCE :Oxidative stress and inflammatory conditions are among the pathological features associated with the central nervous system in Alzheimer’s disease. Traditionally, medicinal plants have been used to alleviate inflammation, pains and also other symptoms possibly associated with Alzheimer’s disease. Therefore, the present study was designed to determine the in vitro antiinflammatory, antioxidant and anticholinesterase activity of twelve South African medicinal plants traditionally used to alleviate pain and inflammation. MATERIALS AND METHODS : Nitric oxide (NO) production in LPS-activated RAW 264.7 macrophages and 15-lipoxygenase (LOX) inhibitory assay were used to evaluate the anti-inflammatory activity. Acetylcholinesterase inhibition was assessed by using a modification of the Ellman’s method. Antioxidant activity, total phenolic and total flavonoids contents were determined using standard in vitro methods. RESULTS : The extract of Burkea africana had the highest anti-15-lipoxygenase activity with 85.92% inhibition at 100 μg/mL. All the extracts tested inhibited nitric oxide (NO) production in a dose dependant manner in LPS-stimulated RAW 264.7 macrophages. However, extracts from Leucaena leucocephala, Lippia javanica inhibited the production of NO by 97% at a concentration of 25 μg/mL. In addition, both Leucaena leucocephala and Englerophytum magaliesmontanum had strong activity against acetylcholinesterase with IC50 values of 118 μg/mL and 160 μg/mL respectively. Hight levels of phenolics and flavonoids were found in Leucaena leucocephala, Lippia javanica and Burkea africana. The correlation with antioxidant activities was not strong indicating that other metabolites may also be involved in antioxidant activity. CONCLUSIONS : The results obtained in this study validate the use of leaf extracts of these plants in South African traditional medicine against inflammation. Extracts of these plants species might be of value in the management of various diseases emerging from oxidative stress and related degenerative disorders.National Research Foundation (NRF) and Medical Research Council (MRC).http://www.elsevier.com/locate/jethpharm2016-02-28hb201

In vitro antibacterial, antioxidant and cytotoxic activity of acetone leaf extracts of nine under-investigated Fabaceae tree species leads to potentially useful extracts in animal health and productivity

BACKGROUND: The Fabaceae family is the second largest family of medicinal plants, containing more than 490 species which are being used as traditional medicine. The aim of this study was to determine the antioxidant and antibacterial activity as well as the cytotoxicity of acetone leaf extracts of nine tree species from the Fabaceae family that have not been investigated well previously for possible use in animal health and production. METHODS: The antibacterial activity was determined by a serial microdilution method against three Gram-positive and three Gram-negative bacteria. Antioxidant activity was determined using free-radical scavenging assays. The safety of the extracts was ascertained using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay on Vero African green monkey kidney cells. RESULTS: Six of the nine acetone extracts had significant antibacterial activity against at least one of the six bacterial species with (MIC 20–80 μg/mL). The Crotalaria capensis extract had the highest activity against Salmonella typhimurium, followed by Indigofera cylindrica with MICs of 20 μg/mL and 40 μg/mL respectively. The Dalbergia nitidula extract had free radical scavenging capacity (IC50 of 9.31 ± 2.14 μg/mL) close to that of the positive control Trolox in the DPPH assay. The Xylia torreana extract also had high activity (IC50 of 14.56 ± 3.96 μg/mL) in the ABTS assay. There was a good correlation between antioxidant activity and total phenolic content (R2 values > 0.8). The extracts had weak or no toxicity to Vero cells, compared to the positive control doxorubicin with the LC50 varying from 10.70 ± 3.47 to 131.98 ± 24.87 μg/mL at the concentrations tested. CONCLUSION: Extracts of D. nitidula, X. torreana, C. capensis and I. cylindrica had a low cytotoxicity and high antimicrobial and/or antioxidant activity. These species are therefore promising candidates for the development of useful antimicrobial/antioxidant preparations with a low cytotoxicity that may be useful in promoting animal health and productivity.The University of Pretoria provided a postdoctoral fellowship to JPD. The National Research Foundation (NRF) and Medical Research Council (MRC) provided funding to support this study.http://www.biomedcentral.com/1472-6882/14/147am201

In vitro Antimycobacterial, Apoptosis-Inducing Potential, and Immunomodulatory Activity of Some Rubiaceae Species

Tuberculosis (TB), a disease caused by microorganisms of the Mycobacterium tuberculosis complex, infects almost one-third of the world’s population. The TB epidemic has been further exacerbated by the emergence of multi, extensively, and totally-drug-resistant (MDR, XDR, and TDRTB) strains. An effective immune response plays a crucial role in determining the establishment of TB infection. Therefore, the modulation of the immune system has been considered as a vital approach for the treatment or control of various immune-related diseases such as TB. In this study, the antimycobacterial, immunomodulatory, and apoptosis-inducing effects of six Rubiaceae species were evaluated. A twofold serial dilution method was used to determine the minimum inhibitory concentration values of the plant extracts. The effect of the extracts on the activity of 15-lipoxygenase was investigated. The levels of six different cytokines, IL-2, IL-4, IL-5, IL-10, IFN-γ, and TNF-α, were measured in LPS-activated U937 cell line while the apoptosis-inducing effect of the extracts was evaluated using an annexin V/PI assay using a flow cytometer. The results obtained revealed that all the six extracts tested had antimycobacterial activity against M. tuberculosis H37Rv, M. tuberculosis ATCC 25177, and Mycobacterium bovis ATCC 27299 strains, with MIC values ranging from 39 to 312 μg/mL. The extracts of Cremaspora triflora and Cephalanthus natalensis were the most active against M. tuberculosis (MIC = 39 μg/mL), followed by Pavetta lanceolata and Psychotria zombamontana against M. bovis (MIC = 78 μg/mL). The extracts of P. zombamontana and Psychotria capensis had remarkable IC50 values of 4.32 and 5.8 μg/mL, respectively, better than that of quercetin. The selected extracts promoted Th1/Th2 balances in an in vitro model at the tested concentration which may suggest the therapeutic value of the plant in diseases where inflammation is a significant factor such as TB. The addition of the crude extracts of C. triflora, P. capensis, and P. zombamontana at the tested concentrations to the cell culture medium induced apoptosis in a time- and dose-dependent manner. This interesting preliminary result generated from this study encourages further investigations of these extracts owing to the LOX-inhibitory effect, immunomodulatory, and apoptotic-inducing properties in addition to their antimycobacterial properties

In vitro antifungal activity of Dorstenia mannii leaf extracts (Moraceae)

The leaves of Dorstenia mannii are used in traditional medicine in Cameroon and other African countries for the treatment of infectious diseases like malaria, skin rashes and stomach disorders. To substantiate this folkloric claim, the crude methanol extract and fractions from the leaves of D. mannii were investigated for their antifungal activity. The crude methanol extract was prepared from powdered dried leaves of the D. mannii. A portion was subjected to flash liquid chromatography on silica gel to afford test fractions. All test samples were screened for major groups of phytochemicals.Test samples and nystatin (reference) were evaluated for antifungal activity on ten yeasts using agar disc diffusion and broth microdilution methods. The qualitative analysis of crude methanol extract and fractions of D. mannii leaves revealed the presence of flavonoids, phenols, steroids and cardiac glycosides. In agar disc diffusion assay, seven of the ten pathogenic fungal strains were sensitive to the crude methanol extract (7/10), n-hexane ethyl-acetate (Hex-EA) (75%) (8/10) and ethyl-acetate (100%) (8/10). The minimum inhibitory concentrations (MICs) for the test samples varied from 80 to 1280 μg/ml. The crude extract and ethyl-acetate (100%) were the most active plant samples with both fungistatic and fungicidal effects (MIC/MFC values from 80 to 640 μg/ml) though not as the reference drug. Candida tropicalis was the least sensitive to the test samples. Some fractions exerted no fungicidal actions on Cryptococcus neoformans, Candida lusitaniae and Candida tropicalis. The present work shows that the crude methanol extract and fractions (n-hexane, ethyl acetate and residue) from the leaves of D. mannii possess growth inhibitory effect on pathogenic yeast. The active ingredients of this plant could be an addition to the antifungal arsenal to opportunistic fungal yeast pathogens.Keywords: Antifungal activity, Dorstenia mannii, yeasts, opportunistic candidiasi

The 15-lipoxygenase inhibitory, antioxidant, antimycobacterial activity and cytotoxicity of fourteen ethnomedicinally used African spices and culinary herbs

ETHNOPHARMACOLOGICAL RELEVANCE : Culinary herbs and spices are widely used ethnomedically across Africa. They are traditionally employed in the treatment of several ailments including inflammation disorders, pain alleviation and infectious diseases. Pharmacological studies are necessary to provide a scientific basis to substantiate their traditional use and safety. In this study, the 15-lipoxygenase inhibitory, antioxidant, antimycobacterial and the cytotoxic activities, total phenolic and flavonoid contents of fourteen edible plants were investigated. MATERIALS AND METHODS : The 15-lipoxygenase inhibitory activity was evaluated by the ferrous oxidation-xylenol orange (FOX) assay method. The antioxidant activity was determined using free-radical scavenging assays. The antimycobacterial activity was determined by a broth microdilution method against three species of mycobacteria: Mycobacterium smegmatis, Mycobacterium aurum and Mycobacterium fortuitum using tetrazolium violet as growth indicator. The cytotoxicity was assessed by the 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide (MTT) assay on Vero monkey kidney cells. RESULTS : All the extracts tested had some 15-lipoxygenase inhibitory activity ranging from 32.9-78.64%. Adansonia digitata (fruit) had the highest antioxidant capacity (IC50 values of 8.15 μg/mL and 9.16 μg/mL in the DPPH and ABTS assays respectively; TEAC of 0.75 in the FRAP assay) along with the highest amount of total phenolics (237.68 mg GAE/g) and total flavonoids (16.14 mg QE/g). There were good correlations between DPPH and ABTS values (R2 0.98) and between total phenolics and total flavonoids (R2 0.94). Tamarindus indica had significant antimycobacterial activity against M. aurum (MIC 78 μg/mL). As could be expected with edible plants, all the extracts had a relatively low cytotoxicity with LC50 values higher than 102 μg/mL with the exception of the two Aframomum species (33 and 74 μg/mL).CONCLUSIONS : This study provides scientific support for some of the the traditional uses and the pharmacological activities of the culinary herbs and spices investigated. The results suggest that increasing intake of some of these herbs may be useful in preventing or reducing the progression of lifestyle-related diseases. The diversity of the pharmacological activities of the extract from the fruit of Adansonia digitata suggested that this plant might be valuable for application in human and animal health.The University of Pretoria.The Medical Research Council and the National Research Foundation (Grant 77228) in South Africa.http://www.elsevier.com/locate/jep2015-10-31hb201

In Vitro Antifungal Susceptibility of Environmental Isolates of Cryptococcus spp. from the West Region of Cameroon

BACKGROUND: Cryptococcus neoformans is responsible of cryptococcosis, a life-threatening infection that affects healthy and immunocompromised individuals. It is the first cause of adult acute meningitis in some sub-Saharan African countries with a mortality rate of about 100% in cases of inappropriate therapy. This study aimed at examining the occurrence and the antifungal patterns of Cryptococcus isolates from pigeon droppings and bat guanos in the west region of Cameroon.METHODS: A total of 350 samples were randomly collected from three selected localities of west region of Cameroon. The identification was performed based on capsule production assessed by Indian ink preparation. Additional tests performed were urea broth, glycine and tryptophan assimilation tests. The antifungal susceptibility test was performed by the broth microdilution method.RESULTS: Mycological analysis led to the identification of 98 isolates, of which 57 isolates of C. neoformans var. gattii and 41 isolates of C. neoformans var. neoformans. All the isolates showed resistance to antifungals tested except nystatin which showed MIC mean values ranging between 0.5 μg/mL and 0.65 μg/mL.CONCLUSION: The prevalence of C. neoformans in pigeons and bats excreta in the west region of Cameroon is 28.57 %. C. neoformans var. gattii and C. neoformans var. neoformans are the main serotypes. Isolates found to be resistant to fluconazole and ketoconazole. Our results emphasize the need for further study on the molecular epidemiology in comparison with clinical isolates.KEYWORDS: Cryptococcus neoformans, bird excreta, antifungal susceptibilit

Anti-bacterial, free radical scavenging activity and cytotoxicity of acetone extracts of Grewia flava .

Background: Bacterial infections of the gastrointestinal tract (GIT) cause vomiting, diarrhoea and even systemic disease. There is a need for the development of natural products into alternative and safer medicines. Objectives: This study evaluated the anti-microbial activity of extracts prepared from berries, leaves,bark and roots of the edible plant Grewia flava. Methods: The anti-bacterial activity was evaluated by the broth microdilution method. Anti-oxidant activity of the most active extracts was performed by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay. The cytotoxicity of the extracts was determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Results: The acetone extracts of the leaves and roots showed the best activity with MIC values as low as 0.03 mg/mL against Staphylococcus aureus and Salmonella typhimurium and 0.07 mg/mL against Bacillus cereus , Escherichia coli and Staphylococcus aureus. Quantitative analysis of the scavenging ability showed that acetone extracts exhibited good free radical scavenging activity in a dose-dependent manner. The berries extract had the highest LC50 (lowest toxicity) of 551.68 68 \ub5g/mL. Conclusion: Acetone extract of leaves and roots of Grewia flava contain anti-microbial and anti-oxidant compounds and could therefore be used as a natural product with little toxicity to host cells

The efficacy and safety of nine South African medicinal plants in controlling Bacillus anthracis Sterne vaccine strain

BACKGROUND : Anthrax is a zoonotic disease caused by Bacillus anthracis, a Gram-positive spore-forming bacterium. The presence of the bacteria and the toxins in the blood of infected hosts trigger a cascade of pathological events leading to death. Nine medicinal plants with good activities against other bacteria were selected to determine their in vitro antibacterial activity against Bacillus anthracis Sterne strain. The cytotoxicity of the extracts on Vero kidney cells was also determined. RESULTS : The minimum inhibitory concentration (MIC) values of the extracts against Bacillus anthracis Sterne strain ranged from 0.02 to 0.31 mg/ml. Excellent MIC values were observed for the following plant species: Maesa lanceolata (0.02 mg/ml), Bolusanthus speciosus, Hypericum roeperianum, Morus mesozygia (0.04 mg/ml) and Pittosporum viridiflorum (0.08 mg/ml). The total antibacterial activity of the extracts ranged from 92 to 5562 ml/g. Total activity presents the volume to which the extract from 1 g of plant material can be diluted and still inhibit microbial growth. Maesa lanceolata and Hypericum roeperianum had the highest total activity with values of 5562 and 2999 ml/g respectively. The extracts of Calpurnia aurea had the lowest total activity (92 ml/g). The cytotoxicity determined on Vero cells indicated that most of the extracts were relatively non-toxic compared to doxorubicin (LC50 8.3 ± 1.76 μg/ml), except for the extracts of Maesa lanceolata, Elaeodendron croceum and Calpurnia aurea with LC50 values at 2.38 ± 0.25, 5.20 ± 0.24 and 13 ± 2.26 μg/ml respectively. The selectivity index (SI) ranged from 0.02 to 1.66. Hypericum roeperianum had the best selectivity index, (SI = 1.66) and Elaeodendron croceum had lowest value (SI = 0.02). CONCLUSIONS : The crude acetone extracts of the selected plant species had promising antibacterial activity against Bacillus anthracis. Maesa lanceolata extracts could be useful as a disinfectant and Hypericum roeperianum could be useful to protect animals based on its high total activity and selectivity index. Further investigation of these plant extracts may lead to the development of new therapeutic agents to protect humans or animals against anthrax.The National Research Foundation of South Africa (Eloff 95991) and the University of Pretoria.http://www.biomedcentral.com/bmccom/plementalternmedam2016Paraclinical Science

Anti-biofilm, antibacterial, and anti-quorum sensing activities of selected South African plants traditionally used to treat diarrhoea

DATA AVAILABILITY : The original data can be obtained from the corresponding author upon request.The development of resistance of microorganisms to conventional antibiotics is a major global health concern; hence, there is an increasing interest in medicinal plants as a therapeutic option. This study aimed to evaluate the antibacterial, anti-biofilm, and anti-quorum activities of crude extracts prepared using various solvents of nine indigenous South African plants used locally for the treatment of diarrhoea. The minimum inhibitory concentration (MIC) was determined using the broth microdilution method and the crystal violet assay was used to test the anti-biofilm activity of the extracts against a panel of bacteria. Anti-quorum sensing activity of the extracts was assessed via inhibition of violacein production in Chromobacterium violaceum ATCC 12472. Preliminary screening of extracts against E. coli ATCC 25922 revealed that the acetone extracts had significant activity, with MIC values ranging from 0.04 to 0.63 mg/mL. Further screening against a panel of bacterial pathogens showed that the acetone extract of Bauhinia bowkeri was the most active with MIC of 0.01 mg/mL against Salmonella enteritidis, followed by Searsia lancea with MIC of 0.03 mg/mL against Bacillus cereus. All the plant extracts prevented the attachment of biofilms by more than 50% against at least one of the tested bacteria. However, only the mature biofilm of B. cereus was susceptible to the extracts, with 98.22% eradication by Searsia pendulina extract. The minimum quorum sensing inhibitory concentration of the extracts ranged from 0.08 to 0.32 mg/mL with S. lancea having the most significant activity. The extract of S. lancea had the best violacein production inhibitory activity with IC50 value of 0.17 mg/mL. Overall, the results obtained indicate that acetone extracts of S. leptodictya, S. lancea, S. batophylla, S. pendulina, B. galpinii, and B. bowkeri possess antibacterial and anti-biofilm activities and can modulate quorum sensing through the inhibition of violacein production. Therefore, these results signify the potential of the selected plant extracts in treating diarrhoea through inhibition of bacterial growth, biofilm formation inhibition, and quorum sensing antagonism, supporting their medicinal use.The World Academy of Science (NRFTWAS), South Africa, the University of Pretoria, the DAAD and the National Research Foundation (South Africa).http://www.hindawi.com/journals/ecamam2023Paraclinical Science

Anti-inflammatory and anticholinesterase activity of six flavonoids isolated from Polygonum and Dorstenia species

This study was aimed at investigating the anti-inflammatory and anticholinesterase activity of six naturally occurring flavonoids: (-) pinostrobin (1), 2’,4’-dihydroxy-3’,6’-dimethoxychalcone (2), 6-8-diprenyleriodictyol (3), isobavachalcone (4), 4-hydroxylonchocarpin (5) and 6- prenylapigenin (6). These compounds were isolated from Dorstenia and Polygonum species used traditionally to treat pain. The anti-inflammatory activity was determined by using the Griess assay and the 15-lipoxygenase inhibitory activity was determined with the ferrous oxidationxylenol orange assay. Acetylcholinesterase (AChE) inhibition was determined by the Ellman’s method. At the lowest concentration tested (3.12 μg/mL), compounds 2, 3 and 4 had significant NO inhibitory activity with 90.71%, 84.65 and 79.57% inhibition respectively compared to the positive control quercetin (67.93%). At this concentration there was no significant cytotoxicity against macrophages with 91.67%, 72.86 and 70.86% cell viability respectively, compared to 73.1% for quercetin. Compound 4 had the most potent lipoxygenase inhibitory activity (IC50 of 25.92 μg/mL). With the exception of (-) pinostrobin (1), all the flavonoids had selective anticholinesterase activity with IC50 values ranging between 5.93 and 8.76 μg/mL compared to the IC50 4.94 μg/mL of eserine the positive control. These results indicate that the studied flavonoids especially isobavachalcone are potential anti-inflammatory natural products that may have the potential to be developed as therapeutic agents against inflammatory conditions and even Alzheimer’s disease.National Research Foundation (NRF) and Medical Research Council (MRC).http://link.springer.com/journal/122722016-05-08hb201