Thermal mud maturation: organic matter and biological activity

Synopsis ObjectiveMany of the therapeutic and cosmetic treatments offered in spas are centred on mud therapy, to moisturize the skin and prevent skin ageing and rheumatic diseases. Thermal mud is a complex matrix composed of organic and inorganic elements which contribute to its functions. It is a natural product derived from the long mixing of clay and thermal water. During its maturation, organic substances are provided by the microalgae, which develop characteristic of the composition of thermal water. MethodsThe aim of this study was to identify methods for introducing objective parameters as a basis for characterizing thermal mud and assessing its efficacy. Samples of thermal mud were collected at the Saturnia spa, where there are several sulphureous pools. The maturation of the mud was evaluated by organic component determination using extractive methods and chromatographic analysis (HPLC, GC-MS, SPME). We also studied the radical scavenging activity of mud samples at different stages of maturation, in a homogeneous phase, using several tests (DPPH, ORAC, ABTS). ResultsWe identified several classes of compounds: saturated and unsaturated fatty acids, hydroxyl acids, dicarboxylic acids, ketoacids, alcohols and others. SPME analysis showed the presence of various hydrocarbons compounds (C-11-C-17) and long-chain alcohols (C-12-C-16). Six or seven months seemed appropriate to complete the process of maturation, and the main effect of maturation time was the increase of lipids. Six-month mud showed the highest activity. The hydrophilic extract was more active than the lipophilic extract. ConclusionThe results indicate that maturation of thermal mud can be followed on the basis of the changes in its organic composition and antioxidant properties along the time. They also highlight the need to develop reference standards for thermal muds in relation to assess their use for therapeutic and cosmetic purposes. Resume ObjectifBeaucoup de traitements therapeutiques et cosmetiques offerts dans les spas sont centres sur la therapie de boue, pour hydrater la peau et prevenir le vieillissement de la peau et les maladies rhumatismales. La boue thermale est une matrice complexe composee d'elements organiques et inorganiques qui contribuent a ses fonctions. C'est un produit naturel derive du long melange d'argile et de l'eau thermale. Au cours de sa maturation, des substances organiques sont fournies par les micro-algues qui se developpent, caracteristiques de la composition de l'eau thermale. MethodesL'objectif de cette etude etait d'identifier des methodes pour introduire des parametres objectifs comme base pour caracteriser la boue thermale et d'evaluer son efficacite. Des echantillons de boue thermale ont ete recueillies au spa Saturnia, oU il y a plusieurs piscines sulfureuses. La maturation de la boue a ete evaluee par la determination des composants organiques en utilisant des procedes d'extraction et l'analyse chromatographique (HPLC, GC-MS, SPME). Nous avons egalement etudie l'activite de piegeage des radicaux d'echantillons de boue a differents stades de maturation, dans une phase homogene, en utilisant plusieurs tests (DPPH, ORAC, ABTS). ResultatsNous avons identifie plusieurs classes de composes: acides gras satures et insatures, les acides hydroxyles, les acides carboxyliques, cetoacides, les alcools et autres. L'analyse SPME montre la presence de divers composes hydrocarbures (C-11-C-17) et d'alcools a longue chaine (C-12-C-16). Six ou sept mois semblaient appropries pour terminer le processus de maturation; l'effet principal du temps de maturation a ete l'augmentation des lipides. La boue de six mois a montre la plus forte activite. L'extrait hydrophile etait plus actif que l'extrait lipophile. ConclusionLes resultats indiquent que la maturation de la boue thermale peut etre suivie sur la base de l'evolution de sa composition organique et des proprietes antioxydantes au cours du temps. Ils soulignent egalement la necessite d'elaborer des normes de reference pour les boues thermales par rapport a l'evaluation de leur utilisation a des fins therapeutiques et cosmetiques.