Jean-de-Dieu Tamokou

Mutagenicity and Carcinogenicity of African Medicinal Plants

Several medicinal plants are known to act as mutagenic, cocarcinogenic, and/or carcinogenic agents. Prevention of cancer and other related diseases can be pursued by avoiding exposure to these agents. This chapter reports scientific progress in detecting mutagenic and carcinogenic plants used in African traditional medicine. Over 400 African medicinal plants were screened mainly in South Africa, Nigeria, and Tunisia, for their mutagenicity and carcinogenicity for the period of 2003–2013 by in vitro and in vivo methods. The results showed that at least 64 plant species used in African traditional medicine are potentially mutagenic/carcinogenic based on their ability to induce genetic changes. Although plants used medicinally are widely assumed to be safe, the issue of quality control may, in the interim, be addressed. This chapter aims: (i) to report African medicinal plants with mutagenic/carcinogenic effects and (ii) to highlight the advanced in the methods used to detect these mutagenic/carcinogenic plants. Most of the extracts reported in this chapter were prepared from plant species with recognized toxicity, but widely used in African traditional medicine. Such plant extracts should consequently be examined carefully for their safety perspective and caution to their use should be taken.

Electrochemical behavior and in-vitro antimicrobial screening of some thienylazoaryls dyes

BackgroundA series of recently reported phenolic azo dyes 7a–e were prepared by coupling the thienyl diazonium sulfate of 3-Amino-4H-benzo[f]thieno[3,4-c](2H)chromen-4-one with selected diversely substituted phenolic and naphtholic derivatives. These compounds were evaluated for their antibacterial and antifungal activities. Furthermore their voltammetric behavior was compared at a glassy carbon electrode.ResultsThe voltammetric behavior of the five recently reported azo dyes has been compared at a glassy carbon electrode. It is shown that the azo dyes 7a–e with a hydroxyl group in the ortho position with respect to the azo bridge give rise to well defined, irreversible peaks for the oxidation and reduction process within a pH range of 2–7. The mechanisms of electrochemical oxidation of compound 7a–c and 7e are proposed. For the hydroxyl-substituted dyes, re-oxidation peaks were obtained in the subsequent scan. The antimicrobial activities of the reported compounds 7a–e along with the entire precursors 1–4 and 6a–e were performed against selected bacterial and fungal species and their activities compared to those of nystatin, griseofulvin and ciprofloxacin used as reference drugs.ConclusionsThe present study showed significant antimicrobial activity of compounds 6d, 7a and 7c,e against the tested microorganisms; this result confirms the antimicrobial potency of azo compounds and some of their precursors.

The assessment of risk factors, lipid profile, uric acid and alanine aminotransferase in Helicobacter pylori-positive subjects

Background: Helicobacter pylori infection is associated with gastro duodenal ulcer, chronic gastric, MALT lymphoma and gastric cancer but also to coronary heart diseases, ischemic diseases and metabolic diseases like diabetes. The colonization of the stomach by H. pylori causes persistent inflammation of the stomach wall which can influence some biochemical parameters in the patient. The aim of this study was to investigate risk factors, uric acid and alanine aminotransferase along with lipid parameters in H. pylori-positive and -negative patients at Dschang District Hospital in Cameroon. Methods: A cross-sectional study was carried out on 160 consenting patients of average age 53.91±13.36 years attending the hospital for medical check-up or admitted in the hospital. The determination of anti-H. pylori IgG by the indirect enzyme-linked immunosorbent assay (ELISA) technique, enabled us to distinguish two groups of patients. A questionnaire survey was administered to study participants and potential risk factors for H. pylori exposure sought. Measurements of total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides, uric acid and activity of alanine aminotransferase were carried out in serum by methods resulting from commercial kits. Results: The habits of not washing hands after the toilets (OR = 3.33; p = 0.036) and giving of chewed food by the parents to children (OR = 2.26; p = 0.029) were independent risk factors of H. pylori infection. H. pylori infected patients had increased levels of uric acid (p = 0.017), total cholesterol (p = 0.001), LDL-cholesterol (p = 0.021) and total cholesterol/HDL-cholesterol ratio (p = 0.046) compared to the uninfected group. Conclusions: Our study therefore suggests that H. pylori infection can cause modifications of lipid parameters and uremia that are considered as risk factors for cardiovascular diseases and gout.

Synthesis, Characterization, and Antimicrobial Activity of a Novel Trisazo Dye from 3-Amino-4H-thieno[3,4-c][1]benzopyran-4-one

A new trisazo dye has been synthesized by coupling the diazonium ion of 3-amino-4H thieno[3,4-c][1]benzopyran-4-one with 2-tert-butyl-4-methoxyphenol. The newly prepared trisazo dye was characterized by its physical, elemental, and spectroscopic data. 2D-NMR (COSY, HSQC, and HMBC) techniques were used to secure the structural assignments. The new trisazo dye (compound 7) along with precursors 3, 4, and 6 was screened by microdilution susceptibility assay for antibacterial and antifungal activities towards eight bacterial strains and three yeasts selected on the basis of their relevance as human pathogens. The results showed that compound 7 (MIC = 2–128 μg/mL) was the most active as compared with its precursors. The most resistant microorganisms were V. cholerae NB2 and V. cholerae SG24, whereas the most sensitive microorganism was C. neoformans. The overall results of this study indicated that compound 7 had the greatest potential value against both yeasts and multidrug-resistant bacteria, so further investigation is warranted.

Toxic Plants Used in African Traditional Medicine

Toxic medicinal plants can be defined as any plant that in one or more of its organs contains toxin that can induce adverse side effects in animal/humans upon consumption or administration for therapeutic purposes. The use of plants in African traditional medicine (ATM) is currently not regulated in most countries of the continent, resulting in a serious danger of misadministration of toxic plants. The potential toxic effects following prolonged use of some of the popular medicinal plants are to be scientifically investigated. Of the 120 African medicinal plants screened for their toxic effects and examined in this chapter, 49 of them were potentially toxic. Toxic symptoms mainly included neurological, hepatic, renal, gastrointestinal, and cardiovascular signs. The issues related to the use of toxic plants in ATM should now be addressed and taken as a priority in all African countries. This chapter aims: (i) to report toxic or potentially toxic plants used in ATM based on the LD50 values, physical and biochemical changes; (ii) to highlight the advanced in the methods used to detect these toxic plants; (iii) to provide baseline information in order to warn healer and patient on the side effects of some commonly used herbal drugs. Most of the plants mentioned in this chapter are used in ATM for treatment of several diseases in humans and it is essential to be aware of their toxic effects.