Anti-acne activities of pulsaquinone, hydropulsaquinone, and structurally related 1, 4-quinone derivatives.
Quinone type compound, pulsaquinone 1, isolated from the aqueous ethanol extract of the roots of Pulsatilla koreana exhibited antimicrobial activities against an anaerobic non-spore-forming gram-positive bacillus, Propionibacterium acnes, which is related with the pathogenesis of the inflamed lesions in a common skin disease, acne vulgaris. Compound 1 was unstable on standing and thus converted to more stable compound 2, namely hydropulsaquinone by hydrogenation, whose activity was comparable to mother compound 1 (MIC for 1 and 2 against P. acnes: 2.0 and 4.0 microg/mL, respectively). Other structurally-related quinone derivatives (3-13) were also tested for structure-activity relationship against anaerobic and aerobic bacteria, and fungi. The antimicrobial activity was fairly good when the quinone moiety was fused with a nonpolar 6- or 7-membered ring on the right side whether or not conjugated (1,4-naphtoquinone derivatives 3-5), while simple quinone compounds 6-9 showed poor activity. It seems that the methoxy groups at the left side of the quinone function deliver no considerable antimicrobial effect.
Nutritional supplementation with omega-6 essential fatty acids (omega-6 EFAs) is of potential interest in the treatment of atopic dermatitis. EFAs play a vital role in skin structure and physiology. EFA deficiency replicates the symptoms of atopic dermatitis, and patients with atopic dermatitis have been reported to have imbalances in EFA levels. Although direct proof is lacking, it has been hypothesized that patients with atopic dermatitis have impaired activity of the delta-6 desaturase enzyme, affecting metabolism of linoleic acid to gamma-linolenic acid (GLA). However, to date, studies of EFA supplementation in atopic dermatitis, most commonly using evening primrose oil, have produced conflicting results. Borage oil is of interest because it contains two to three times more GLA than evening primrose oil. This review identified 12 clinical trials of oral or topical borage oil for treatment of atopic dermatitis and one preventive trial. All studies were controlled and most were randomized and double-blind, but many were small and had other methodological limitations. The results of studies of borage oil for the treatment of atopic dermatitis were highly variable, with the effect reported to be significant in five studies, insignificant in five studies, and mixed in two studies. Borage oil given to at-risk neonates did not prevent development of atopic dermatitis. However, the majority of studies showed at least a small degree of efficacy or were not able to exclude the possibility that the oil produces a small benefit. Overall, the data suggest that nutritional supplementation with borage oil is unlikely to have a major clinical effect but may be useful in some individual patients with less severe atopic dermatitis who are seeking an alternative treatment. Which patients are likely to respond cannot yet be identified. Borage oil is well tolerated in the short term but no long-term tolerability data are available.