Origanum heracleoticum Essential Oils: Chemical Composition, Phytotoxic and Alpha-Amylase Inhibitory Activities

Many studies have demonstrated the herbicidal effects of several essential oils and their possible use as substitutes for chemical herbicides. Several enzymes play a very significant role in seed germination: among these, alpha-amylase could be involved in essential oil phytotoxic processes. The aims of this study were to compare the chemical composition of the essential oils of two ecotypes of O. heracleoticum growing in Cilento (Southern Italy) and to study their possible use as natural herbicide using Raphanus sativus, Sinapis arvensis and Lolium multiflorum seeds. Moreover, a possible inhibitory activity on the alpha-amylase enzyme extracted from germinating seeds was evaluated as a possible mechanism of action. Both oils, characterized by GC-MS, belonged to a carvacrol chemotype. The alpha-amylase activity was determined using DNSA (dinitrosalicylic acid) assay quantifying the reducing sugar produced. Furthermore, the essential oils demonstrated phytotoxicity at the highest dose tested, and an inhibitory effect on alpha-amylase, probably correlated with the phytotoxic effects, was registered. The oils showed interesting phytotoxic and alpha-amylase inhibitory activities, which deserve to be further investigated.

Automated summary

Many studies have shown that certain essential oils have herbicidal effects and can be used as alternatives to chemical herbicides. In this study, the chemical composition of essential oils from two ecotypes of O. heracleoticum in Southern Italy was compared and their potential as natural herbicides was investigated using seeds of Raphanus sativus, Sinapis arvensis, and Lolium multiflorum. The study also evaluated the inhibitory activity of the essential oils on the alpha-amylase enzyme, which is involved in seed germination. The results showed that the essential oils exhibited herbicidal and alpha-amylase inhibitory activities, suggesting their potential for further exploration.