Skin irritation test of a microemulsion containing essential oil isolated from Ocimum basilicum

摘要

Thai basil oils have a demonstrated antimicrobial activity against Propionibacterium acnes. An in vitro study revealed that P. acnes was more susceptible to Ocimum basilicum (sweet basil) oil man other Ocimum species. The purpose of this study was to evaluate skin irritation reactions of a 3% O. basilicum microemulsion on human subjects. Thirty healthy human subjects were enrolled in a 3-day cumulative irritancy study. A single application, closed patch epicutaneous technique under semi-occlusion condition was used for testing. Four products were tested along side each other. These were a 3% Ocimum microemulsion (test product), 3% O. basilicum oil in isopropyl myristate (active ingredient), the vehicle alone (placebo), and de-ionized water (control). All products were applied on the upper back of each subject for 1 h, and then removed. After the patch was removed, transepidermal water loss (TEWL), erythema index, scaling, and oedema were evaluated at 0, 1,48, and 72 h. The results showed no clinically observable irritations in all preparations tested at 1, 48, and 72 h after removal of the patch. The TEWL values remained unchanged from baseline (P>0.05) and erythema indices of all tested formulations were lower than baseline (P<0.05). The TEWL values and erythema indices were not significantly different among all preparations tested. We concluded that a 3% Ocimum microemulsion should be considered safe and well tolerated on male human skin.