Essential oils (EOs) and their individual volatile organic constituents have been an inherent part of our civilization for thousands of years. They are widely used as fragrances in perfumes and cosmetics and contribute to a healthy diet, but also act as active ingredients of pharmaceutical products. Their antibacterial, antiviral, and anti-inflammatory properties have qualified EOs early on for both, the causal and symptomatic therapy of a number of diseases, but also for prevention. Obtained from natural, mostly plant materials, EOs constitute a typical example of a multicomponent mixture (more than one constituent substances, MOCS) with up to several hundreds of individual compounds, which in a sophisticated composition make up the property of a particular complete EO. The integrative use of EOs as MOCS will play a major role in human and veterinary medicine now and in the future and is already widely used in some cases,e.g., in aromatherapy for the treatment of psychosomatic complaints, for inhalation in the treatment of respiratory diseases, or topically administered to manage adverse skin diseases. The diversity of molecules with different functionalities exhibits a broad range of multiple physical and chemical properties, which are the base of their multi-target activity as opposed to single isolated compounds. Whether and how such a broad-spectrum effect is reflected in natural mixtures and which kind of pharmacological potential they provide will be considered in the context of ONE Health in more detail in this review.

Recent clinical evidence suggests the efficacy of a traditional herbal medicinal product containing myrrh (Commiphora molmol Engl.), coffee charcoal (Coffea arabica L.) and chamomile flower dry extract (Matricaria chamomilla L.) in the therapy of inflammatory bowel diseases (IBD). However, the mechanisms of action in this context have not been entirely elucidated. The present study aimed to evaluate the effects of myrrh, coffee charcoal and chamomile flower extract on the inflammatory cross talk between immune and intestinal epithelial cells together with the resulting intestinal barrier disorders. A complex co-culture cell model consisting of intestinal epithelial cell (IEC) monolayers (Caco-2, HT29-MTX-E12) and macrophages (THP-1) was established for the simultaneous investigation of these two IBD characteristics. The lipopolysaccharide (LPS) activation of the macrophages led to a pro-inflammatory mediator release and thereby an inflammatory stimulation of IECs with chemokine release and reduced barrier function. The effects of the individual plant extracts and a ternary combination on inflammatory mediator release (IL-6, TNF, IL-8, MCP-1, PGE2) was quantified by ELISA. The transepithelial electrical resistance (TEER) of IEC monolayers was measured to evaluate the effects on the barrier function. Budesonide served as a positive control. All three plant extracts exhibited anti-inflammatory properties via the inhibition of the inflammatory mediator release to a varying extent. An intestinal barrier stabilising effect was observed for myrrh and coffee charcoal. Myrrh exerted the most distinct pharmacological activity. Dose reducing and synergistic interactions emerged within the threefold combination. Thus, our results provide a mechanistic basis for the use of the herbal combination of myrrh, coffee charcoal and chamomile flower extract in IBD treatment and underline the potential benefits of the phytotherapeutic multi-component/multi-target approach in this complex pathogenesis.