Complementary activity of an ancient combination of natural ingredients on the dysbiosis symptoms linked to acne.

ETHNOPHARMACOLOGICAL RELEVANCE: Acne is one of the most common dermatologic diseases in the world. It is due to the secretion of a high level of sebum that causes follicular hyperkeratinisation, alterations of the cutaneous microbiota, and inflammatory processes. One of the first-line treatments is still an antibiotic prescription, that inhibits bacterial growth and, as a consequence, lowers some of the other symptoms. Nevertheless, this high level of antibiotic prescription contributes to the increase of antibiotic resistance. Alternatives to antibiotics are thus highly required, as acne does not represent per se an infection. AIM OF THE STUDY: In the frame of the IRGAP (Interdisciplinary Research Group on Ancient Pharmacopeias) consortium, different preparations dedicated to cutaneous ailments have been identified based on ancient traditional uses, dating back to Antiquity or Middle Ages. Among them, the combination of Aloe vera and Myrrh was widely conserved over centuries. Even though this combination is no longer in use, we wondered why this combination was so widely conserved. We considered the use of this combination of ingredients to treat acne, a case study for which both plants are still used, but separately. MATERIALS AND METHODS: The effects of both plant extracts were analyzed on the growth of different bacteria from the skin microbiota, cultivated alone or in co-culture conditions. As the skin is a rather heterologous environment, we further tested the robustness of our study by varying the experimental conditions. We further analyzed any complementary effects of these extracts on the inflammation process linked to acne. RESULTS: We showed that both plant extracts have complementary effects on micro-organisms and on macrophages. Indeed, while Myrrh extracts inhibited the growth of specific skin microbiota bacteria, Aloe vera gel extracts on the opposite, favored the growth of others: the two plants could act in a complementary way to restore a healthy microbiota. Another complementarity was also observed on macrophages: while Myrrh extracts showed an anti-inflammatory effect, Aloe vera gel extracts showed an antioxidant effect. CONCLUSION: Our results highlight the potential of the combination of Myrrh and Aloe vera to address both the dysbiosis of the skin microbiota and the inflammation associated with acne. Thus, this exploration of forgotten combinations from historical pharmacopoeias underscores the importance of revisiting past traditional knowledge as a source of innovation.