Synopsis Objective. Formaldehyde is an effective and popular semipermanent hair straightener, but the severe consequences for human health due to its toxicity have prompted the search for safer alternatives. Different carbonyl compounds, including glyoxylic acid, have recently been proposed as promising candidates. Despite the interest in this topic, there is a lack of information about the interactions between hair keratin and straightener agents. This study addresses this issue to gain new insights useful in the development of new products for safe, semipermanent hair deformation. MethodsThe possible reactions occurring between carbonyl groups and nucleophilic sites on amino acid residues belonging to the keratin were investigated using as model compounds some aldehydes and amino acid derivatives. Raman and IR analyses on yak hair subjected to the straightening treatment with glyoxylic acid in different conditions were carried out. Scanning electron microscope (SEM) analyses were carried out on yak and curly human hair after each step of the straightening procedure. ResultsThe reactions between aldehydes and N--acetyl-L-lysine revealed the importance of the carbonyl electrophilicity and temperature to form imines. Raman and IR analyses on yak hair subjected to the straightening treatment evidenced rearrangements in the secondary structure distribution, conformational changes to the disulphide bridges, a decrease of the serine residues and formation of imines. It was also indicated that straightening produced major conformational rearrangements within the hair fibre rather than on the cuticle. ConclusionThis investigation revealed the role played by the electrophilicity of the carbonyl on the straightener agent and of the temperature, closely related to the dehydration process. Raman and IR studies indicated the involvement of imine bonds and the occurrence of a sequence of conformational modifications during the straightening procedure. SEM analyses showed the effectiveness of the treatment at the cuticular level. Resume ObjectifLe formaldehyde est un agent defrisant semi-permanent pour cheveux efficace et populaire, defriser mais les graves consequences de son utilisation sur la sante de l'homme dues a sa toxicite ont stimule la recherche pour de plus sures alternatives. Different composes carbonyles, y compris l'acide glyoxylique, ont ete recemment propose comme candidats prometteurs. Malgre l'interet pour ce sujet, il y a un manque d'information sur les interactions entre la keratine des cheveux et les agents defrisant. Cette etude aborde cette question dans le but d'acquerir de nouvelles connaissances utiles a l'elaboration de produits plus surs qui seront utilisees pour obtenir la deformation semi-permanente des cheveux. MethodesLes possible reactions entre les groupes carbonyles et les sites nucleophiles des residus d'acides amines appartenant a la keratine ont ete etudiees en utilisant pour modeles des aldehydes et des derives d'acides amines. Des analyses Raman et IR sur des poils de yack soumis au traitement de defrisage avec l'acide glyoxylique dans differentes conditions ont ete realisees. Des analyses par microscope electronique a balayage (SEM) ont ete effectuees sur des poils de yak et des cheveux boucles humains apres chaque etape de la procedure de defrisage. ResultatsLes reactions entre des aldehydes et des N--acetyl-lysine ont revele l'importance de l'electrophilicite du carbonyl et de la temperature pour former des imines. Les analyses Raman et IR sur les poils de yak soumis a un traitement de defrisage ont mis en evidence des rearrangements dans la distribution de la structure secondaire, des changements conformationnels de ponts disulfures, une diminution des residus de serine et la formation d'imines. Il a egalement ete indique que le defrisage produit des rearrangements conformationnels majeurs au sein de la fibre capillaire plutot que sur la cuticule. ConclusionCette etude a revele le role joue par l'electrophilicite du groupe carbonyle sur l'agent defrisant et par la temperature, etroitement lie au processus de deshydratation. Etudes Raman et IR ont indique l'implication des liaisons imines et la presence d'une sequence de les modifications conformationelles au cours de la procedure de defrisage. Les analyses SEM ont montre l'efficacite du traitement au niveau de la cuticule.

Formaldehyde replacement with glyoxylic acid in semipermanent hair straightening: a new and multidisciplinary investigation

BOGA, CARLA;TADDEI, PAOLA;MICHELETTI, GABRIELE;BALLARIN, BARBARA;
2014

Abstract

Synopsis Objective. Formaldehyde is an effective and popular semipermanent hair straightener, but the severe consequences for human health due to its toxicity have prompted the search for safer alternatives. Different carbonyl compounds, including glyoxylic acid, have recently been proposed as promising candidates. Despite the interest in this topic, there is a lack of information about the interactions between hair keratin and straightener agents. This study addresses this issue to gain new insights useful in the development of new products for safe, semipermanent hair deformation. MethodsThe possible reactions occurring between carbonyl groups and nucleophilic sites on amino acid residues belonging to the keratin were investigated using as model compounds some aldehydes and amino acid derivatives. Raman and IR analyses on yak hair subjected to the straightening treatment with glyoxylic acid in different conditions were carried out. Scanning electron microscope (SEM) analyses were carried out on yak and curly human hair after each step of the straightening procedure. ResultsThe reactions between aldehydes and N--acetyl-L-lysine revealed the importance of the carbonyl electrophilicity and temperature to form imines. Raman and IR analyses on yak hair subjected to the straightening treatment evidenced rearrangements in the secondary structure distribution, conformational changes to the disulphide bridges, a decrease of the serine residues and formation of imines. It was also indicated that straightening produced major conformational rearrangements within the hair fibre rather than on the cuticle. ConclusionThis investigation revealed the role played by the electrophilicity of the carbonyl on the straightener agent and of the temperature, closely related to the dehydration process. Raman and IR studies indicated the involvement of imine bonds and the occurrence of a sequence of conformational modifications during the straightening procedure. SEM analyses showed the effectiveness of the treatment at the cuticular level. Resume ObjectifLe formaldehyde est un agent defrisant semi-permanent pour cheveux efficace et populaire, defriser mais les graves consequences de son utilisation sur la sante de l'homme dues a sa toxicite ont stimule la recherche pour de plus sures alternatives. Different composes carbonyles, y compris l'acide glyoxylique, ont ete recemment propose comme candidats prometteurs. Malgre l'interet pour ce sujet, il y a un manque d'information sur les interactions entre la keratine des cheveux et les agents defrisant. Cette etude aborde cette question dans le but d'acquerir de nouvelles connaissances utiles a l'elaboration de produits plus surs qui seront utilisees pour obtenir la deformation semi-permanente des cheveux. MethodesLes possible reactions entre les groupes carbonyles et les sites nucleophiles des residus d'acides amines appartenant a la keratine ont ete etudiees en utilisant pour modeles des aldehydes et des derives d'acides amines. Des analyses Raman et IR sur des poils de yack soumis au traitement de defrisage avec l'acide glyoxylique dans differentes conditions ont ete realisees. Des analyses par microscope electronique a balayage (SEM) ont ete effectuees sur des poils de yak et des cheveux boucles humains apres chaque etape de la procedure de defrisage. ResultatsLes reactions entre des aldehydes et des N--acetyl-lysine ont revele l'importance de l'electrophilicite du carbonyl et de la temperature pour former des imines. Les analyses Raman et IR sur les poils de yak soumis a un traitement de defrisage ont mis en evidence des rearrangements dans la distribution de la structure secondaire, des changements conformationnels de ponts disulfures, une diminution des residus de serine et la formation d'imines. Il a egalement ete indique que le defrisage produit des rearrangements conformationnels majeurs au sein de la fibre capillaire plutot que sur la cuticule. ConclusionCette etude a revele le role joue par l'electrophilicite du groupe carbonyle sur l'agent defrisant et par la temperature, etroitement lie au processus de deshydratation. Etudes Raman et IR ont indique l'implication des liaisons imines et la presence d'une sequence de les modifications conformationelles au cours de la procedure de defrisage. Les analyses SEM ont montre l'efficacite du traitement au niveau de la cuticule.
INTERNATIONAL JOURNAL OF COSMETIC SCIENCE
C. Boga; P. Taddei; G. Micheletti; F. Ascari; B. Ballarin; M. Morigi; S. Galli
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11585/334915
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