Phyllis Addo

Application of real-time PCR in Ghana, a Buruli ulcer-endemic country, confirms the presence of Mycobacterium ulcerans in the environment

This study reports the first successful application of real-time PCR for the detection of Mycobacterium ulcerans, the causative agent of Buruli ulcer (BU), in Ghana, a BU-endemic country. Environmental samples and organs of small mammals were analyzed. The real-time PCR assays confirmed the presence of M. ulcerans in a water sample collected in a BU-endemic village in the Ashanti Region.

Toxicity potentials of the nutraceutical Moringa oleifera at supra-supplementation levels.

Moringa oleifera Lam. (order -Moringales, family -Moringaceae and genus -Moringa) is a well known nutraceutical used in the treatment of hypercholesterolemia and hyperglycemia, and also, as a nutritional supplementation. Its popularity use raises the question of possible toxicity at supra-supplementation levels. The objective of the study was to ascertain possible acute toxicity with supra-supplementation using Sprague-Dawley (S-D) rats. In experiment 1, human peripheral blood mononuclear cells were given graded doses of Moringa oleifera aqueous leaf extract to induce cytotoxicity. In experiment 2, two groups of rats received low and high dose (LD and HD, respectively) levels (1,000 and 3,000 mg/kgb.wt, respectively) per o.s. alongside negative and positive control rats (0.9% saline and 10mg/mL N-ethyl-N-nitrosourea - administered i.m., respectively). Each group consisted of five rats. Rats were killed after 48 h and the femur bone marrow aspirate examined for polychromatic micronucleated erythrocytes (PCEMN)/normochromatic micronucleated erythrocytes (NCEMN) ratios after Giemsa/Leishman staining. In experiment 3, control, LD and HD groups were established. The LD and HD extracts were administered per o.s. to the respective groups and observed for 14 days. Each group consisted of five rats. Blood was sampled after 48 h and 14 days and examined biochemically and haematologically for acute toxicity. Experiment 1 showed that Moringa oleifera was cytotoxic at 20mg/mL. In experiment 2, PCEMN/NCEMN ratios were: negative control=2.087; LD=1.849; HD=1.397; positive control=1.257. Statistically, LD and HD ratios were significant (p=0.020). Experiment 3 showed that hepatonephro-toxicity was nil with no abnormal haematology results. Genotoxicity results have hitherto not been shown. Moringa oleifera is genotoxic at supra-supplementation levels of 3,000 mg/kg b.wt. However, intake is safe at levels ≤ 1,000 mg/kg b.wt.

Acute toxicity studies of aqueous leaf extract of Phyllanthus niruri

Acute toxicity studies of aqueous leaf extract of Phyllanthus niruri Phyllanthus niruri is a plant with medicinal properties. It is often used to treat mild malaria and the elimination of renal stones. However, studies on its toxicity are scarce. The study was carried out to determine if the aqueous leaf extract of P. niruri administered to female Sprague-Dawley rats would illicit evidence of toxicity. Fifteen female rats weighing 150-200 g were divided into 3 groups. Rats in Group 1 were given a single low dose (LD) of 2 000 mg/kg b.w. of the extract by oral gavage within 24 hrs. Rats in Group 2 were given a single high dose (HD) of 5 000 mg/kg b.w. of the extract by oral gavage within 24 hrs. Rats in Group 3 were not given any extract but drinking water and served as the control group (C). All the rats were observed for signs of toxidromes for 14 days. On the 15th day, all the rats were sacrificed. Body organs were harvested for macroscopic examination. Urine and blood samples were drawn and analyzed. Hematological tests performed included full blood count and hemoglobin. Biochemical examinations included bilirubin, alanine aminotransferase (ALT), aspartate aminotransferase (AST), total protein, albumin, globulin, alkaline phosphatse (ALP), γ-glutamyltranspeptidase (GGT), urea, and creatinine. The results of the three groups were not significantly different. Examination of the various body organs did not show any abnormality. Thus no toxicity was observed at the levels administered. The LD50 of the aqueous extract is > 5 000 mg/kg. b.w.

Current perspectives in drug discovery against tuberculosis from natural products

Currently, one third of the worlds population is latently infected with Mycobacterium tuberculosis (MTB), while 8.9-9.9 million new and relapse cases of tuberculosis (TB) are reported yearly. The renewed research interests in natural products in the hope of discovering new and novel antitubercular leads have been driven partly by the increased incidence of multidrug-resistant strains of MTB and the adverse effects associated with the first- and second-line antitubercular drugs. Natural products have been, and will continue to be a rich source of new drugs against many diseases. The depth and breadth of therapeutic agents that have their origins in the secondary metabolites produced by living organisms cannot be compared with any other source of therapeutic agents. Discovery of new chemical molecules against active and latent TB from natural products requires an interdisciplinary approach, which is a major challenge facing scientists in this field. In order to overcome this challenge, cutting edge techniques in mycobacteriology and innovative natural product chemistry tools need to be developed and used in tandem. The present review provides a cross-linkage to the most recent literature in both fields and their potential to impact the early phase of drug discovery against TB if seamlessly combined.

Genotoxicity, cytotoxicity and toxicological evaluation of whole plant extracts of the medicinal plant Phyllanthus niruri (Phyllanthaceae).

Phyllanthus niruri is a medicinal plant (commonly known as stone breaker) found in the tropics and other parts of the world. It is known for its capacity to block the formation of calcium oxalate crystals and kidney stone formation in urolithiasis. This plant has been used to treat hyperglycemia, hypertension, pain, and mild cases of malaria. We examined the geno-, cyto- and overall toxicity of P. niruri whole plant ethanolic extract. The extract was administered as a single dose of 30 or 300 mg/kg to laboratory rats by gavage, accompanied by negative (0.9% saline) and positive (10 mg/mL N-ethyl-N-nitrosourea) controls that were injected intramuscularly 48 h after extract administration. The ratio of polychromatic (PCE)/normochromatic erythrocytes (NCE) from femur bone marrow was scored for genotoxicity. Cytotoxicity was determined using descending concentrations (0.2-0.0125 g/mL) of the extract incubated with peripheral blood mononuclear cells. Lactate dehydrogenase release from damaged cells was determined and the CC(50) calculated. Subchronic administration of the extract at 30 or 300 mg/kg was done for 90 days to determine general toxicity. PCE:NCE (%) for the extract and negative control was 63, compared to 168 (positive control). The CC(50) was 26.3 mg/mL and hepato-renal toxicity after subchronic extract administration was nil. We conclude that ethanol extract of P. niruri is not cytotoxic or genotoxic, and is generally non-toxic on subchronic administration.

Medicinal plants used to treat TB in Ghana.

AIMS The current study was designed to document medicinal plant species that are traditionally used to treat tuberculosis (TB) by Ghanaian communities. METHODS The medicinal plants used against TB or its signs and symptoms were selected using library and online published data searches. A guided questionnaire interview was also conducted with a botanist involved in plant collection at the Centre for Scientific Research into Plant Medicine (CSRPM) at Mampong. Data obtained were entered in Excel and summarized into means and frequencies using SPSS 12.0.1 for windows, and expressed as tables and bar graphs. RESULTS A total of 15 medicinal plant species distributed between 13 genera and 13 families were documented. The following medicinal plant species were found to be used against TB in Greater Accra and Eastern parts of Ghana: Azadirachta indica A. Juss. Stem bark (Meliaceae), Hygrophila auriculata Heine, whole plant (Acanthaceae), Chenopodium ambrosioides L. leaves (Amaranthaceae), Coix lacryma-jobi L. glumes (Poaceae), Solanum torvum Sw. unripe fruits (Solanaceae), Solanum torvum Sw. leaves (Solanaceae), Bidens pilosa L. whole plant (Asteraceae), Phyllanthus fraternus G.L. Webster leaves (Phyllanthaceae), Dissotis rotundifolia (Sm.) Triana, leaves (Melastomataceae), Cymbopogon giganteus Chiov. Leaves (Poaceae), Cyperus articulatus L. roots (Cyperaceae), Allium sativum L. bulb (Amaryllidaceae), Zingiber officinale Roscoe, rhizomes (Zingiberaceae), Allium cepa L. bulbs (Amaryllidaceae), Allium cepa L. leaves (Amaryllidaceae), Aloe vera var. barbadensis aqueous extract from leaves (Xanthorrhoeaceae), Aloe vera var. barbadensis organic extract from leaves (Xanthorrhoeaceae), Cocos nucifera Linn, water (Arecaceae) and Cocos nucifera Linn. Husk (Arecaceae). CONCLUSIONS The collected plant species could be a source of a new class of drugs against TB. Bioactivity guided fractionation is recommended to identify lead compounds for antimycobacterial activity. The current paper documents for the first time medicinal plant species used by Ghanaian communities to treat TB. These results are a basis for selection of plants for further pharmacological, toxicological and phytochemical studies in developing new plant-based antimycobacterial drugs.

A quick and cost effective method for the diagnosis of Mycobacterium ulcerans infection

BackgroundBuruli ulcer (BU), a neglected tropical skin disease caused by Mycobacterium ulcerans, has been reported in over 30 countries worldwide and is highly endemic in rural West and Central Africa. The mode of transmission remains unknown and treatment is the only alternative to disease control. Early and effective treatment to prevent the morbid effects of the disease depends on early diagnosis; however, current diagnosis based on clinical presentation and microscopy has to be confirmed by PCR and other tests in reference laboratories. As such confirmed BU diagnosis is either late, inefficient, time consuming or very expensive, and there is the need for an early diagnosis tool at point of care facilities. In this paper we report on a simple, quick and inexpensive diagnostic test that could be used at point of care facilities, in resource-poor settings.MethodsThe methodology employed is based on the loop mediated isothermal amplification (LAMP) technique. Four sets of Primers, targeting the mycolactone encoding plasmid genome sequence of M. ulcerans were designed. The BU-LAMP assay was developed and tested on five M. ulcerans strains from patients in Ghana and two American Type Culture Control (ATCC) reference isolates; Ghana #970321 (D19F9) and Benin #990826 (D27D14). We also tested the assay on other closely related, mycolactone-producing mycobacterial strains; M. marinum 1218, M. marinum DL240490, M. liflandii and M. pseudoshotsii, as well as experimentally infected laboratory animal and clinical samples.ResultsThe results revealed a high specificity of the BU-LAMP assay for selectively detecting M. ulcerans. Compared to the conventional IS-2404 PCR, the new assay is cheaper and simpler and ten times more sensitive. Test results can be obtained within 1 hour.ConclusionsThis study indicates that the BU-LAMP assay could be suitable for early disease diagnosis and application in low-resource health facilities.

Antimycobacterial and cytotoxic activity of selected medicinal plant extracts

Ethnopharmacological relevance Tuberculosis (TB) caused by Mycobacterium tuberculosis remains an ongoing threat to human health. Several medicinal plants are used traditionally to treat tuberculosis in Ghana. The current study was designed to investigate the antimycobacterial activity and cytotoxicity of crude extracts from five selected medicinal plants. Material and methods The microplate alamar blue assay (MABA) was used for antimycobacterial studies while the CellTiter 96® AQueous Assay, which is composed of solutions of a novel tetrazolium compound [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt; MTS] and an electron coupling reagent (phenazine methosulfate) PMS, was used for cytotoxic studies. Correlation coefficients were used to compare the activity of crude extracts against nonpathogenic strains and the pathogenic Mycobacterium tuberculosis subsp.tuberculosis. Results Results of the MIC determinations indicated that all the crude extracts were active on all the three tested mycobacterial strains. Minimum inhibitory concentration values as low as 156.3 µg/mL against M. tuberculosis; Strain H37Ra (ATCC® 25,177™) were recorded from the leaves of Solanum torvum Sw. (Solanaceae). Cytotoxicity of the extracts varied, and the leaves from S. torvum had the most promising selectivity index. Activity against M. tuberculosis; Strain H37Ra was the best predictor of activity against pathogenic Mycobacterium tuberculosis subsp.tuberculosis (correlation coefficient=0.8). Conclusion The overall results of the present study provide supportive data on the use of some medicinal plants for tuberculosis treatment. The leaves of Solanum torvum are a potential source of anti-TB natural products and deserve further investigations to develop novel anti-TB agents against sensitive and drug resistant strains of M. tuberculosis.

Acute toxicity studies of Croton membranaceus root extract

AIM OF THE STUDY Croton membranaceus root and leaf extracts are used in the Bahamas to aromatize tobacco, in Nigeria to improve digestion, and in Ghana, for benign prostate hyperplasia. Despite claims of success there is paucity of information on its toxicity. The aim of this study was to determine if Croton membranaceus has acute toxicity properties. MATERIALS AND METHODS Roots were air-dried in a solar dryer for one week before milling. The powder was extracted with 96% ethanol, freeze-dried and re-extracted with distilled water and freeze-dried. 15 male Sprague-Dawley rats (180-200 g) were divided equally into 2 treatment groups [low dose (LD) and high dose (HD)], plus a control group (C). LD and HD received 1500 and 3000 mg/kg b.wt. Croton membranaceus aqueous extract, respectively, one time and observed for 14 days. Haematological [Full Blood Count and haemoglobin (Hb)], biochemical [bilirubin, alanine aminotransferase (ALA), aspartate aminotransferase (AST), total protein, albumin, globulin, alkaline phosphatise (ALP), γ-glutamyltranspetidase (GGT), urea, creatinine, creatinine kinase - Muscle and Brain (CK-MB), creatinine kinase - Total (CK-R)] examinations were performed. RESULTS Control groups CK-MB (5444±534 U/L) and LD group CK-MB (4014±1016 U/L) were significantly different (p<0.05). Control and the HD group CK-MB (3955±1135 U/L) were significantly different (p<0.05). Both LD and HD CK-R levels (697±197U/L and 732±203 U/L, respectively), were lower than the control (1139±220 U/L) at 48 h and 14 days (p<0.05, p<0.05, respectively). γ-GT levels of the HD group was 4.8±0.4 U/L compared to the Control group value of 0.9±0.2 U/L (p<0.05). CONCLUSIONS Taking all factors into consideration, Croton membranaceus ingestion does not produce general acute toxicity. However, its creatinine kinase lowering ability could be explored.

Aqueous extract of ocimum canum decreases levels of fasting blood glucose and free radicals and increases antiatherogenic lipid levels in mice

The basis for managing diabetes mellitus with aqueous extract of Ocimum canum Sim (Lamiaceae), in Ghana was investigated in diabetic and normoglycemic mice. In the diabetic mice, fasting blood glucose decreased by 60% compared to 10% in control mice after 13 weeks of extract administration. Body weight, serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) decreased while serum high-density lipoprotein cholesterol (HDL-C) increased in the extract-treated group. In vitro hydroxyl (OH) and superoxide (O2) radical formation, and lipid peroxidation of isolated human LDL and mouse liver homogenates decreased in extract-treated experimental systems. These findings justify the use of O. canum extract as an antidiabetic folk medicine.