J. Cosmet. Sci., 64, 287–296 ( July/August 2013) 287 Cosmetic and amino acid analysis of the effects of lye and no-lye relaxer treatment on adult black female South African hair THABISILE MAMABOLO, NANA M. AGYEI, and BEVERLEY SUMMERS, Department of Pharmacology and Therapeutics, University of Limpopo, (T.M.), Department of Chemistry, University of Limpopo, (N.M.A.), and Department of Pharmacy, University of Limpopo, (B.S.), Medunsa 0204, South Africa. Accepted for publication January 14, 2013 Synopsis Surveys indicate that many South African women use relaxers to straighten their hair for cosmetic reasons, which can damage the hair and scalp. The objective of this study was to assess the effects of treating hair with two types of relaxers: Product A (a lye relaxer, sodium hydroxide base) and Product B (a no-lye relaxer, guanidine hydroxide base). Five adult black female South African subjects were used for the study that was divided into two parts. The fi rst part used a half-head study design in a clinical study in which the re- searcher and the subjects visually assessed various hair quality parameters before and after relaxer treatment. Product B was assessed to perform better (p = 0.032) than Product A in terms of hair straightening. The second part of the study involved hair amino acid analysis by reversed-phase high performance liquid chro- matography. There was a decrease in the amount of cystine [Median (range) g/100 g hair] after treatment with both Product A [7.8 (2.5–9.9), p = 0.086] and Product B [4.0 (2.9–4.8), p = 0.005] compared to be- fore treatment [9.1 (6.4–11.9)] this decrease was greater (p = 0.085) for Product B. Reduction in cystine content was consistent with increased straightness. Product B (the no-lye relaxer) was found to be more ef- fective and safer to use. INTRODUCTION The use of chemical straightening products is said to put African American women in particular at high risk for various “traumatic” alopecia, or hair loss, and other adverse hair and scalp reactions. Due to the characteristic curly nature of African American hair, straightening the hair using chemical treatments allows for greater manageability and fl exibility in styling (1). The most common chemical hair straighteners are termed “relax- ers.” There are two types of relaxers: lye relaxers [sodium hydroxide (Na+OH−) base] and no-lye relaxers [guanidine hydroxide (HNC(NH2)NH3+OH−) base]. The size of the Address all correspondence to Thabisile Mamabolo at Thabisile.Mamabolo@ul.ac.za

JOURNAL OF COSMETIC SCIENCE 288 relaxer market in South Africa, with a predominantly black female clientele, is approxi- mately R400 ($50) million per annum (2). The durability of the shape of hair is attribut- able to cross-linking disulphide bonds (C-S-S-C) in the amino acid cystine (Cys), which makes up to ca. 18% of human hair (3–5) using a relaxer to break these bonds in curly hair allows the hair to be straightened. The Photobiology Laboratory at Medunsa Campus, University of Limpopo, has been in- volved in relaxer effi cacy work with multinationals for the past 10 years, but that work is subject to confi dentiality agreements. According to the Laboratory’s experience (6), South African origin hair in different individuals behaves differently with the same cosmetic treatment, performed at the same time points, using the same procedure. Subjects of the same type of hair (e.g., coarse hair) may be treated with the same cosmetic treatment, e.g., a relaxer, and the results may not be the same. In some subjects, the resultant hair is straighter, shinier, and silkier than in others hence, there is a need to determine the effect of different types of hair relaxers on the surface characteristics of South African origin hair. There appears to be relatively few research publications in scientifi c journals on this type of work. Only one study (7) on the effect of relaxers on South African hair could be found in the scientifi c literature. The study reported changes in amino acid composition but did not study lye and no-lye relaxers separately. There is a need to contribute to the existing body of knowledge on the effect of different types of relaxers on the biochemical composi- tion of South African hair, which may be expected to be not too dissimilar to African American hair. The aim of this study was to elucidate the cosmetic and biochemical ef- fects of lye and no-lye relaxer treatment on African hair by visual assessment and amino acid analysis, respectively. EXPERIMENTAL The study was divided into two parts. The fi rst was a clinical study involving the visual assessment of hair appearance, and the second was the amino acid analysis of hair by reversed-phase liquid chromatography (RP-HPLC). CLINICAL STUDY Subjects, samples, and test products. Five South African subjects were enrolled for the study. They were adult black females with at least 4 cm of virgin hair and in good general health. Ethical clearance for the use of human participants for the study was obtained from the Medunsa Research Ethics Committee of the University of Limpopo. All the subjects voluntarily completed a Health Questionnaire form and signed a Subject Infor- mation and Consent form. Strands of hair were sampled from each subject before and after relaxer treatment. Two types of hair relaxers manufactured by AMKA Products (Pty) Ltd (Pretoria, SA) were tested in the study. These were Product A: “PC Super re- laxer,” a lye relaxer (sodium hydroxide base) and Product B: “PC No-lye relaxer,” a no- lye relaxer (guanidine hydroxide base) both were “Perfect Choice®” (Pretoria, SA) products. A neutralizing shampoo and a normal shampoo from the same manufacturer were also used.