ELOM-080, also known as Myrtol, represents a distillate of a mixture of 4 rectified essential oils: eucalyptus oil, sweet orange oil, myrtle oil, and lemon oil. ELOM-080 is an approved herbal medicinal product for the secretolytic therapy and facilitation of expectoration in acute and chronic bronchitis and for the secretolytic therapy of sinusitis. Its clinical efficacy has been reported by several randomized control trials. Interestingly, in the recent past, a considerable number of clinical studies on the use of ELOM-080 as add-on treatment of different respiratory tract diseases has been conducted and published in China. As these publications were only available in Chinese, the international attention in the literature was limited. Based on the translation of these studies into English, this review aims to provide a brief overview of the studiesʼ major results, which contribute to the knowledge on the efficacy of ELOM-080 in the treatment of respiratory tract diseases: ELOM-080 was shown to be of great value as add-on treatment not only for the well-established indications bronchitis and sinusitis, but also for pharyngitis, asthma, chronic obstructive pulmonary disease, and, most importantly, otitis media. Besides this clinical evidence, this review also summarizes the great progress in deciphering the mode of action of ELOM-080 that has been made by Chinese publications.

The vacuolar-type H+-ATPase (v-ATPase) is the major proton pump that acidifies intracellular compartments of eukaryotic cells. Since the inhibition of v-ATPase resulted in anti-tumor and anti-metastatic effects in different tumor models, this enzyme has emerged as promising strategy against cancer. Here, we used the well-established v-ATPase inhibitor archazolid, a natural product first isolated from the myxobacterium Archangium gephyra, to study the consequences of v-ATPase inhibition in endothelial cells (ECs), in particular on the interaction between ECs and cancer cells, which has been neglected so far. Human endothelial cells treated with archazolid showed an increased adhesion of tumor cells, whereas the transendothelial migration of tumor cells was reduced. The adhesion process was independent from the EC adhesion molecules ICAM-1, VCAM-1, E-selectin and N-cadherin. Instead, the adhesion was mediated by β1-integrins expressed on tumor cells, as blocking of the integrin β1 subunit reversed this process. Tumor cells preferentially adhered to the β1-integrin ligand collagen and archazolid led to an increase in the amount of collagen on the surface of ECs. The accumulation of collagen was accompanied by a strong decrease of the expression and activity of the protease cathepsin B. Overexpression of cathepsin B in ECs prevented the capability of archazolid to increase the adhesion of tumor cells onto ECs. Our study demonstrates that the inhibition of v-ATPase by archazolid induces a pro-adhesive phenotype in endothelial cells that promotes their interaction with cancer cells, whereas the transmigration of tumor cells was reduced. These findings further support archazolid as a promising anti-metastatic compound.

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