EUCALYPTUS EXTRACT-INDUCED HAIR CHANGES 493 from the scalp. We removed the data obtained from the medulla. The amide I band of each spectrum was analyzed using the Sarver method (24). The secondary structure of the protein of the cortex in the new-growth part of the Eucalyptus extract-treated hair and the placebo-treated hair were compared (Figure 11). In the case of the Eucalyptus extract­ treated hair, the level of beta structure appeared to increase compared to that of the placebo-treated hair. DISCUSSION Neither the changes in hair gloss intensity nor in bending stiffness have been found in hair tresses, which were made from cut hairs, after repeated applications of the scalp lotion containing 3% Eucalyptus extract. These results suggest that these changes in the hair fiber properties result from the Eucalyptus extract acting not on the hair fiber itself, but directly on the follicle under the scalp. As shown in Figure 12, the diameter and the ratio of minor/major axes of hair fibers do not change significantly by the use of EL in all cases of the aforementioned panelists. The changes are 0.995 ± 0.026 on average for the hair diameter and 0.985 ± 0.016 for the ratio of minor/major axes of hair fibers and are not statistically significant. These facts, combined with the result of the change in Young's modulus, lead to the hypothesis that the qualitative alteration of the hair fiber occurs by the action of active ingredients contained in the Eucalyptus extract on the hair follicle. As mentioned in the Results section, the efficacy of the increase in bending stiffness depends on the concentration of the Eucalyptus extract in the scalp lotion (Figure 5). In *:p0.05 **:p0.01 t-test 110 108 .□ Placebo 106 ** . ■ Eucalyphls 104 � 102 0100 98 96 94 92 90 a-helix /J-sheet /J-tum random Figure 11. Results of analysis of secondary protein structure in cortex by microscopic IR: 36 points/hair, eight hair fibers of the new-growth part of Eucalyptus-treated hair, and placebo hairs were measured, respectively. Data from the medulla have been removed. The spectrum of the amide I band was analyzed using the Sarver method (24). The highest and lowest data were neglected at t-test. Each result was normalized by placebo data.

494 JOURNAL OF COSMETIC SCIENCE I.OS ---------- - - - --� 1.05 Q,I .. � 1.025 Q,I � """ Q Q 0.975 (a) Maximum Diameter Minimum Diameter N=67 Averaged Diameter � ... '9 1.025 Q,l � � """ Q Q 0.975 ·­ 0.95 (b) N=67 Ratio of Min/Miax Diameter Figure 12. Relative values of hair diameters (a) and the hair diameter index (minimum/maximum) (b) for all panelists after three months of usage of Eucalyptus extract scalp lotions. The baseline is for those using the placebo lotion or before use of the EL. this result, a more remarkable fact 1s the individual rate of change m the bending stiffness. As shown in Figure 5, the number of panelists whose data show improvement after using Eucalyptus extract scalp lotion increases as the concentration of the Eucalyptus extract in the scalp lotion also increases, from 1.0wt% to 3.0wt%, but the change in the bending stiffness for the affected panelists seems to be almost constant. It is described in par­ ticular that improvement was observed for four panelists and that the average increase was 9. 7% for 1 % EL users, while it was observed for nine panelists to be 9.8% for 3% EL users. In the case of using hair-fixative products, the polymer contained in the products adheres to the surface of the hair fiber and forms a film the bending stress of the hair fiber then increases. Under these circumstances, the rate of increase in the bending stiffness in­ creases as the used amount or the polymer concentration of the hair-fixative product increases, because the amount of adhesive polymer on the hair surface has a positive relation to the amount of use or the polymer concentration of the products. For the dose-dependence of the Eucalyptus extract in the scalp lotion, however, the application of more Eucalyptus extract increases the number of panelists who get a higher bending stiffness of hair fiber, but it does not improve the rate of change. Comparing the results of the concentration of Eucalyptus extract in the scalp lotion of 0. 5wt% and 1.0wt%, the effect of Eucalyptus extract is not continuous but has a threshold. This study suggests that the active ingredient contained in the Eucalyptus extract does not act on the hair components (intermediate filaments, keratin-associated proteins, lipids, etc.) directly, but controls the physical properties of the hair fiber by a biological mechanism. From the fact that the effect of Eucalyptus extract appears independent of gender, the active ingredient of Eucalyptus extract does not seem to relate to sex hor­ mone-related compounds, though details are unclear at this time. As mentioned in the Introduction and Results sections, Eucalyptus extract induces an increase in the amount of ceramides in skin, but the changes in hair components, such as lipids, by Eucalyptus extract are not yet known.