In Vitro and Randomized, Double‐Blind, Placebo‐Controlled Trial to Determine the Efficacy and Safety of Nine Antiacne Medicinal Plants

The present in vitro and randomized, double‐blind, placebo‐controlled trial aims to determine the efficacy and safety of nine Mediterranean antiacne medicinal plants. The antimicrobial, antisebum, and anti-inflammatory activities of the plant extracts were evaluated in cells from the immortalized human keratinocytes (HaCaT) and human monocytic cell line (THP-1) as well as in a double-blind, randomized, and placebo‐controlled trial. Most of the extracts showed no significant cytotoxic effects on HaCaT cells up to 250 μg/ml. Inula helenium (IH) and Saponaria officinalis (SO) inhibited sebum production at 90 μg/ml and 30 μg/ml, respectively. The inhibition effect of SO on the growth of Cutibacterium acnes was 1.2 times higher than that of chloramphenicol. IH and SO extracts significantly inhibited the lipopolysaccharide- (LPS-) induced IL-6 and TNF-α production in THP-1 cells reaching the control levels of untreated cells at a concentration of 250 μg/ml. SO, IH, and Solanum nigrum (SN) extracts inhibited the nitric oxide (NO) production in a dose-dependent manner. Based on these results, an antiacne herbal cream (AHC) was prepared from different portions of extracts from SO, IH, and SN, and its efficacy was evaluated in a double-blind, randomized, and controlled efficacy study with 41 acne patients, ages 18–24, who were asked to apply AHC (n = 27) or a placebo (n = 14) two to three times daily for six weeks. Results obtained indicate that the AHC has unique synergistic effects that halt sebum production, combined with highly antiseptic and anti-inflammatory activity, in which 54.95% (t = 19.37 P < 0.001) of acne inflammatory and noninflammatory lesions disappeared after two weeks, 85.3%, after five weeks (t = 14.19 P < 0.001), and 91.4%, at the end of the sixth week of application (t = 5.7 P < 0.001). In conclusion, SO, IH, and SN as single extracts and in combination as AHC showed significant antimicrobial, antisebum, and anti-inflammatory activities in vitro and in a double-blind, randomized, and controlled antiacne efficacy. Therefore, AHC represents an interesting alternative treatment for acne.