School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
Freie Universität Berlin, Department of Dermatology, Venereology and Allergology, Humboldt-Universität zu Berlin, Berlin Institute of Health, Charité - Universitätsmedizin Berlin, Berlin, Germany.
Int J Cosmet Sci. 2022 Feb;44(1):118-130. doi: 10.1111/ics.12761. Epub 2022 Feb 10.
To evaluate the safety and the synergistic effects of tea tree, lavender, eucalyptus and tangerine essential oils in combination on the skin using in vitro, ex vivo and clinical studies.
The phototoxicity was predicted using 3T3 neutral red uptake phototoxicity test (OECD TG 432). Skin penetration was evaluated by confocal Raman microspectroscopy using direct application of essential oils to pig ears. For the clinical studies, 40 participants were enrolled and randomized in three groups: (1) lavender, eucalyptus and tangerine, (2) the same essential oils plus melaleuca and (3) placebo group. The skin was evaluated by noninvasive techniques before and after a 90-day period of topical use.
The essential oils were non-phototoxic, but the tangerine oil showed dose-dependent cytotoxicity (IC50: 33.1 µg/ml), presenting 35% of penetration in the viable epidermis. On the contrary, 17.7 µg/ml in combination was applied per day in the clinical study and the penetration rate for the combinations (10%, 1.77 µg/ml achieving the viable epidermis) guaranteed the safety, since in the clinical study, the application of the four essential oils improved skin barrier and morphologic skin characteristics, as well as increased skin hydration and decreased sebum levels, with no unwanted effects reported.
All essential oils studied were considered non-cytotoxic or non-phototoxic separately except tangerine, which present a dose-dependent cytotoxicity. Finally, the essential oils in combination in an appropriate amount were safe and effective in the improvement of the hydrolipidic balance and morphological properties of the skin.
通过体外、离体和临床研究评估茶树、薰衣草、桉树和橘精油联合使用对皮肤的安全性和协同作用。
使用 3T3 中性红摄取光毒性试验（OECD TG 432）预测光毒性。通过将精油直接应用于猪耳，使用共焦拉曼微光谱法评估皮肤渗透。对于临床研究，招募了 40 名参与者并随机分为三组：（1）薰衣草、桉树和橘；（2）相同的精油加桃金娘；（3）安慰剂组。在 90 天的局部使用前后，使用非侵入性技术评估皮肤。
精油无光毒性，但橘油显示出剂量依赖性细胞毒性（IC50：33.1μg/ml），在活表皮中具有 35%的渗透。相反，在临床研究中，每天应用 17.7μg/ml 的混合物，并且组合的渗透率（10%，达到活表皮的 1.77μg/ml）保证了安全性，因为在临床研究中，四种精油的应用改善了皮肤屏障和形态皮肤特征，以及增加皮肤水分和减少皮脂水平，没有报告不良影响。
除了橘油外，研究的所有精油单独使用均被认为是非细胞毒性或非光毒性的，橘油呈现出剂量依赖性细胞毒性。最后，以适当的量组合使用精油在改善皮肤的水脂平衡和形态特性方面是安全有效的。
