Mediterranean Blue Flowers with a Scent of Cannabis

Background The aromatic herb Plectranthus neochilus, known for its cannabis-like scent and widespread use in folk medicine, has become the focus of a study on the essential oils derived from its flowers and leaves. GC-MS analysis revealed a unique composition: the flower oil is predominantly composed of 2-methyl-1-butene, with a concentration exceeding 87%. Results While this finding is unusual, it is known that 2-methyl-1-butene can result from the thermal decompositionof-1, 1-dimethylcyclopropane. Additionally, from a microbiological perspective, it may also be produced through the bacterial reduction of isoprene by a combination of Comamonas sp. and Acetobacterium wieringae. This intriguing phenomenon warrants further investigation, though an initial discussion is provided in this study. Analysis of the leaf oil revealed that α-thujene and α-pinene are the primary constituents, together making up more than 75% of the composition. Conclusion A detailed study of the Plectranthus genus suggests that this species produces volatile metabolites containing cyclopropane and cyclobutane rings. It is hypothesized that these compounds could be the key biologically active substances in this species—or even within the broader Plectranthus genus. Additionally, the biological activity of the main identified compounds in this aromatic plant is discussed.