DMAE AND DMAE BITARTRATE IN COSMETICS 277 NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY Nuclear magnetic resonance is one of the most specifi c methods for determining the structure of active principles. The 1H-NMR spectra of DMAE and DMAE bitartrate alone are displayed in Figures 8 and 9 and the corresponding spectral data are given below. Figure 8A shows signals for DMAE at 2.14, 2.4, and 3.61, which were assigned to 2CH3, CH2–N and CH2–O, respectively. Figures 8B and 8C illustrate the same signals for samples of DMAE heated to 40°C and 60°C. Similarly, Figure 9A shows signals for DMAE bitartrate at 2.83 and 3.81, which were assigned to the same hydrogens as in the sample of free-base DMAE. An additional signal at 4.42 was assigned to the CH–COO. Heating the samples to higher temperatures did not affect the pattern of signals (Figures 9B and 9C). When we compared the 1H-NMR spectra for the DMAE alone and in aqueous solu- tion after storage for 30 days (Figures 10,11) we found no differences. Identical results were also obtained in samples heated to 40°C and 60°C. Our 1H-NMR results for DMAE and DMAE bitartrate were similar, and confi rmed the IR spectroscopy and DSC fi ndings. CONCLUSION We observed no changes in any of the physicochemical activities of DMAE and DMAE bitartrate with storage time or temperature. Our results show that both the free base and the bitartrate salt can be used in the preformulation stage to prepare liquid formulas containing this active principle. ACKNOWLEDGMENTS Part of this work was supported by the Junta of Andalucia, Project of Excellence FQM 3993-2008. We thank K. Shashok for translating signifi cant parts of the original manu- script into English. REFERENCES (1) G. C. Singh, M. C. Hankins, A. Dulku, and M. B. Kelly, Psychosocial aspects of botox in aesthetic surgery, Aesthetic Plast. Surg., 30, 71–76 (2006). (2) M. J. Tribo, Razones de ser de la psicodermatología, Piel, 1(2), 51–53 (2006). (3) G. Schneider, G. Driesch, G. Heuft, S. Evers, A. Lugert, and S. Städert, Psychosomatic cofactors and psychiatric comorbidity in patients with chronic itch, Clin. Expl. Dermatol., 31(6), 762–765 (2006). (4) T. Loti, B. Bianchi, and E. Panconesi, Neuropeptides and skin disorders. The new frontiers of neuroen- docrine-cutaneous immunology, Int. J. Dermatol., 38, 673–675 (1999). (5) J. L. Parra and L. Pons, “La piel y sus anejos como sustrato vivo de la cosmetología. El tejido cutáneo. Inervación cutánea,” in Ciencia Cosmética, Bases Fisiológicas y Criterios Prácticos (Consejo General de Colegios Ofi ciales de Farmacéuticos, Madrid, 1995), pp. 149–150. (6) I. Uhoda, N. Faska, and C. Robert, Split face study on the cutaneus tensile effect of 2-dimethylamino- ethanol (deanol) gel, Skin Res. Technol., 8(3), 164–167 (2002).
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