Chemical and mineralogical characteristics of French green clays used for healing

Abstract

The worldwide emergence of infectious diseases, together with the increasing incidence of antibioticresistant bacteria, elevate the need to properly detect, prevent, and effectively treat these infections. The overuse and misuse of common antibiotics in recent decades stimulates the need to identify new inhibitory agents. Therefore, natural products like clays, that display antibacterial properties, are of particular interest.The absorptive properties of clay minerals are well documented for healing skin and gastrointestinal ailments. However, the antibacterial properties of clays have received less scientific attention. French green clays have recently been shown to heal Buruli ulcer, a necrotic or 'flesh-eating' infection caused by Mycobacterium ulcerans. Assessing the antibacterial properties of these clays could provide an inexpensive treatment for Buruli ulcer and other skin infections.Antimicrobial testing of the two clays on a broad-spectrum of bacterial pathogens showed that one clay promotes bacterial growth (possibly provoking a response from the natural immune system), while another kills bacteria or significantly inhibits bacterial growth. This paper compares the mineralogy and chemical composition of the two French green clays used in the treatment of Buruli ulcer.Mineralogically, the two clays are dominated by 1Md illite and Fe-smectite. Comparing the chemistry of the clay minerals and exchangeable ions, we conclude that the chemistry of the clay, and the surface properties that affect pH and oxidation state, control the chemistry of the water used to moisten the clay poultices and contribute the critical antibacterial agent(s) that ultimately debilitate the bacteria.

Mineralogical characterization of natural clays from Brazilian Southeast region for industrial applications

“…These clays contained concentrations of these elements higher than some cosmetic clays characterized by Abel [38]. The content of theses oxides was similar to those of two French clays used for healing [39]. These results suggested that the Taubaté and Tremembé clays can also be used for this application.…”

Assessment of three Spanish clays for their use in pelotherapy

“…The concentration of these elements in the peloid will depend on their concentration in the mineralmedicinal water and the solid phase (generally clay) used to prepare the peloid. Several authors have described the presence of essential and/or potentially toxic elements in peloids used in spas (Carretero et al, 2010;Karakaya et al, 2010) and in clays with potential for use in pelotherapy (Cara et al, 2000a(Cara et al, , 2000bGomes and Silva, 2001;Vreca and Dolenec, 2005;Williams et al, 2008). However, when considering a potentially useful clay, the concentration of a particular element in the clay or peloid is not as important as its bioavailability, that is, the concentration of the element which could enter the body of the patient during application of the peloid.…”

Alternatives to antibiotic growth promoters in prevention of diarrhoea in weaned piglets: a review

“…The extent of adsorption is determined by the chemistry of the clay minerals, exchangeable ions, the surface properties (Williams et al, 2008) and the fine structure of clay particles (Hassen et al, 2003). An important role is also played by pH, dosage and exposure time (Brouillard and Rateau, 1989).…”