OXYRADICALS FROM PHOTOIRRADIATED HAIR 173 Keratin x8• • White H air x80 • _•..••'•-•• Bleached Hair x80 10G Black Hair xl Red Hair x5 Brown Hair xl Figure 1. Intrinsic ESR signals for milled wool keratin and human hair. Spectrometer settings: modulation amplitude, 4G receiver gain, 1.25 x 104 microwave power, 20 row. Each was 0.03 g in a 2-ram I.D. quartz tube. time. Figure 5 shows the effects of azide and ethanol on HTA production from irradiated bleached hair. ESR spectra are displayed in Figure 6 for the trapped radical adduct from bleached, red, and brown hair irradiated in the presence of DMPO. The spectra are characterized by hyperfine coupling constants of a N = 14.9 G, aH • = 14.9 G, showing that the radical is the DMPO-OH adduct (29,30), and confirming that oxyradicals are produced during irradiation. For both the fluorescence and the ESR experiments, bleached hair and red hair give much larger signals than brown hair. When cinnamic acid is present, no DMPO-OH adduct is observed. Figure 7 gives the result from red hair other hair types show similar results. Since at the wavelengths (k -- 320 nm) and concentrations of our experiments, cinnamic acid does not have a significant absorption, it seems also to be competing for oxyradicals. This is not unex- pected given its aromatic ring and unsaturated side chain. (We note that parallel fluorescence measurements could not be performed because of high background fluo- rescence of cinnamic acid.)

174 JOURNAL OF COSMETIC SCIENCE Figure 2. Kinetics of the buildup and decay of hair melanin radicals from human hair. a. Red hair. b. Brown hair. Arrows •' and ,• indicate light on and light off. Other conditions as in Figure 1. Eumelanin and pheomelanin respond differently to photoirradiation, and this difference is reflected in the melanins extracted from hair. Conclusions of earlier workers (31) that irradiated red hair melanin produces more oxyradicals than black hair melanin are consistent with our results using ESR spin trapping and HTA fluorescence on sepia and on melanin isolated from red and brown hair (25). These results parallel those of the present study for red and brown hair. As with oxyradical production, we also found that the intrinsic ESR signals of red and brown hair melanin respond differently to irradiation above 320 nm. However, in contrast to oxyradical production, stimulation of the in- trinsic ESR signal for red hair or melanin isolated from red hair is less than that for brown