FULLERENOL SUPPRESSES SEBUM AND INHIBITS LIPASE 263 Thus, it may be concluded that fullerenol is a more promising candidate for the treat- ment of acne vulgaris (25). Consequently, we investigated its inhibitory effect on sebo- cyte sebum production resulting from UV irradiation and on P. acnes lipase activity. An in vitro assay of sebum production demonstrated that just 1.5 μM of fullerenol is suffi - cient to reduce sebocyte sebum production induced by UV irradiation. This result indicates that fullerenol is a sebum suppressor specifi cally under oxidative stress, such as UVB expo- sure. On the other hand, our previous study reported that 75 μM of polyvinylpyrrolidone (PVP)-wrapped pristine fullerene (PVP-fullerene) decreased sebum production by 27.4% by using the same method (22) but without UVB irradiation. Thus, fullerenol can be a sebum suppressor more specifi c for oxidative stress, compared with PVP-fullerene. The IC50 value of fullerenol against P. acnes lipase activity was four times higher than that of adapalene. We previously reported that pristine fullerene in olive squalane was effec- tive in the treatment of acne vulgaris in an open clinical study of 11 individuals (22). However, after application for eight weeks, infl ammatory lesions were reduced by only 37.8% this value is lower than that observed for adapalene gel in a previous study (me- dian, 63.7%) (35). It is known that antioxidant activity correlates well with a reduced severity of acne vul- garis (36). Fullerene and fullerenol are potent radical scavengers against ROS by ESR and the β-carotene breaching method (26–28). It is highly likely that fullerene and fullerenol might be effective antioxidants in clinical application. Therefore, we consider it prudent to test the effectiveness of fullerene in the reduction of infl ammatory acne in an open clinical trial. Porphyrins, metabolic products of P. acnes, reportedly stimulate expression of keratinocyte-derived IL-8 in pilosebaceous tissue, resulting in perifollicular infl amma- tion (37). Therefore, there is a need to evaluate the anti-infl ammatory effects of fullerene Figure 2. Dose-dependent inhibition of P. acnes lipase activity by fullerenol and adapalene. P. acnes lipase ac- tivity was determined by its conversion of 4-MUO into (fl uorescent) 4-MU. The inhibitory activities of fullerenol and adapalene were measured at concentrations of 1.9–484.8 μM and 66.5–1050 μM, respectively.

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