Comparison of Secondary Metabolites and Essential Oil Content of Some Origanum Species

Abstract

Origanum genus is one of the most widely used herbs in folk medicine for its biological properties. This study was performed to determine the morphological and phytochemical properties of five species of Origanum including O. majorana, O. onites, O. syriacum, O. vulgare subsp. vulgare and O. vulgare subsp. hirtum as important ethnomedicinal plants. The study was performed at a Research Farm based at Urmia University, Iran. The plants were collected from various places for determining some quantitative properties, antioxidant compounds, and essential contents. The results showed that the highest plant height (86.4 cm) was observed in O. vulgare subsp. hirtum. The highest fresh weight and dry weight were observed in O. onites (826 and 250 g) and O. vulgare subsp. hirtum (727.64 and 230 g) species in comparison to others, respectively. However, the highest essential oil, essential oil yield per plant, and essential oil yield per ha were 5.26%, 1.71 g and 114 kg ha-1 , respectively, which was observed in O. vulgare subsp. hirtum species. The quantitative analysis revealed higher content of total phenol (51.12%), flavonoid (6.93%), 2, 2-diphenyl-1-picrylhydrazyl (DPPH), (54.29%), superoxide (50.04%) and radical scavenging activities in O. vulgare subsp. hirtum species, but the O. onites species showed higher (21.60%) nitric oxide radical scavenging activities compared to other species. The essential oil analysis revealed that the thymol (6.90-59.89%), carvacrol (0.83-48.91%), gamma-terpinene (6.55-18.20%), p-cymene (0.50-20.94%) and alpha-terpinene (2.71-4.28%) were the most prominent compounds in the studied species of the genus Origanum. Cluster analysis showed two main categories and high similarity between O. onites and O. vulgare subsp. hirtum. The findings of the current research indicate that O. vulgare subsp. hirtum was the best species in terms of phytochemical properties.