André Bigot

Buruli ulcer : a review of in vitro tests to screen natural products for activity against mycobacterium ulcerans

Buruli ulcer (BU), caused by Mycobacterium ulcerans, has recently been recognized by the World Health Organization (WHO) as an important emerging disease. It is largely a problem of the poor in remote rural areas and has emerged as an important cause of human suffering. While antimycobacterial therapy is often effective for the earliest nodular or ulcerative lesions, for advanced ulcerated lesions, surgery is sometimes necessary. Antimycobacterial drugs may also prevent relapses or disseminated infections. Efficient alternatives different from surgery are presently explored because this treatment deals with huge restrictive factors such as the necessity of prolonged hospitalization, its high cost, and the scars after surgery. Traditional treatment remains the first option for poor populations of remote areas who may have problems of accessibility to synthetic products because of their high cost. The search for efficient natural products active on M. ulcerans should then be encouraged because they are part of the natural heritage of these populations; they are affordable financially and can be used at the earliest stage. This review provides a number of tests that will help to evaluate the antimycobacterial activity of natural products against M. ulcerans, which are adapted to its slow growing rate, and lists active extracts published up to now in Medline.

Estimation of Daily Sodium and Potassium Excretion Using Spot Urine and 24‐Hour Urine Samples in a Black Population (Benin)

The 24‐hour urine collection method is considered the gold standard for the estimation of ingested potassium and sodium. Because of the impracticalities of collecting all urine over a 24‐hour period, spot urine is often used for epidemiological investigations. This study aims to assess the agreement between spot urine and 24‐hour urine measurements to determine sodium and potassium intake. A total of 402 participants aged 25 to 64 years were randomly selected in South Benin. Spot urine was taken during the second urination of the day. Twenty‐four‐hour urine was also collected. Samples (2‐mL) were taken and then stored at ‐20°C. The analysis was carried out using potentiometric dosage. The agreement between spot urine and 24‐hour urine measurements was established using Bland‐Altman plots. A total of 354 results were analyzed. Daily sodium chloride and potassium chloride urinary excretion means were 10.2±4.9 g/24 h and 2.9±1.4 g/24 h, respectively. Estimated daily sodium chloride and potassium chloride means from the spot urine were 10.7±7.0 g/24 h and 3.9±2.1 g/24 h, respectively. Concordance coefficients were 0.61 at d=−0.5 g, (d±2SD=−11 g and 10.1 g) for sodium chloride and 0.61 at d=−1 g, (d±2SD=−3.8 g and 1.8 g) for potassium chloride. Spot urine method is acceptable for estimating 24‐hour urinary sodium and potassium excretion to assess sodium and potassium intake in a black population. However, the confidence interval for the mean difference, which is too large, makes the sodium chloride results inadmissible at a clinical level.

Beninese Medicinal Plants as a Source of Antimycobacterial Agents: Bioguided Fractionation and In Vitro Activity of Alkaloids Isolated from Holarrhena floribunda Used in Traditional Treatment of Buruli Ulcer

Buruli ulcer (BU) imposes a serious economic burden on affected households and on health systems that are involved in diagnosing the disease and treating patients. Research is needed to find cost-effective therapies for this costly disease. Plants have always been an important source of new pharmacologically active molecules. Consequently we decided to undertake the study of plants used in traditional treatment of BU in Benin and investigate their antimycobacterial activity as well as their chemical composition. Extracts from forty-four (44) plant species were selected on account of reported traditional uses for the treatment of BU in Benin and were assayed for antimycobacterial activities. Crude hydroethanolic extract from aerial parts of Holarrhena floribunda (G. Don) T. Durand and Schinz was found to have significant antimycobacterial activity against M. ulcerans (MIC = 125 µg/mL). We describe here the identification of four steroidal alkaloids from Mycobacterium ulcerans growth-inhibiting fractions of the alkaloidal extract of the aerial parts of Holarrhena floribunda. Holadysamine was purified in sufficient amount to allow the determination of its MCI (=50 µg/mL). These results give some support to the use of this plant in traditional medicine.