Essential Oil Chemical Variability in Oliveria decumbens (Apiaceae) from Different Regions of Iran and Its Relationship with Environmental Factors

Abstract

Oliveria decumbens Vent. (Apiaceae) is an annual herb resistant to harsh environmental conditions, which has got numerous pharmacological, food and feed, and cosmetic applications. In the present study, the variation in the essential oil (EO) content and composition of twelve O. decumbens populations growing wild in several habitats of Iran was studied. The EO contents varied from 2.71% (Darab) to 8.52% (Behbahan) on a dry matter basis, where the latter population revealed to be the highest source of essential oil reported so far in this species. Gas chromatography (GC-FID) and gas chromatography-mass spectrometry (GC-MS) analysis revealed that carvacrol (18.8–51.8%), thymol (20.3–38.7%), γ-terpinene (0.9–28.8%), p-cymene (1.6–21.3%) and myristicin (0.8–9.9%) were the major volatile compounds in all the investigated populations. The EO content had a strong and significant positive correlation with temperature (r = 0.62) and sand content (r = 0.73), but a strong and significant negative correlation with altitude (r = −0.61). On the other hand, the rising altitude led to an increase in thymol content. Cluster and principal component analyses placed the samples from different regions into two main groups based on the main EO components, including thymol/carvacrol type and γ-terpinene/thymol/carvacrol/p-cymene type. This study provides valuable information for identifying chemotypes in O. decumbens as well as insight into planning a domestication and cultivation program.

The Variability of Thymol and Carvacrol Contents Reveals the Level of Antibacterial Activity of the Essential Oils from Different Accessions of Oliveria decumbens

“…γ-Terpinene, which is related to the biosynthesis of the phenolic monoterpenes [42], showed an inverse trend, with the highest percentage (25.9%) in the essential oil from the Kahnoyeh population, and the lowest one in that from Nourabad Mamasani (13%). A similar trend was observed for p-cymene, with the oil from Behbahan population containing the highest percentage (17.3%), and that from Nourabad Mamasani showing the lowest value (9.5%) [33].…”

“…A number of various factors, including genetics, soil, geographic, and climatic conditions affect the essential oil content [40]. In addition, some factors like altitude have been reported to affect the essential oil content [33,40,41]. In our study, the highest content was found in the essential oil from Behbahan population growing at the lowest altitude (394 m), followed by that from Kahnoyeh and Dehdasht populations located at 758 and 971 m a.s.l., respectively.…”

“…The essential oil content differed among the various O. decumbens populations and ranged from 3.34 to 8.52% (w/w) [33]. On the other hand, the values reported in previous reports varied from 0.1 to 8.1% [2,15,16,18,30,38,39].…”

“…Our recent study showed that the number and relative percentages of essential oil compounds changed at variance with the geographic origin of O. decumbens populations [33]. A total of 18, 17, 16, and 11 compounds were identified in the populations from Nourabad Mamasani, Kahnoyeh, Behbahan, and Dehdasht, respectively [33].…”

“…Our recent study showed that the number and relative percentages of essential oil compounds changed at variance with the geographic origin of O. decumbens populations [33]. A total of 18, 17, 16, and 11 compounds were identified in the populations from Nourabad Mamasani, Kahnoyeh, Behbahan, and Dehdasht, respectively [33]. The number of identified compounds in the investigated populations was partly in accordance with those reported in previous papers, that ranged from 8 to 35 [2,7,9,[14][15][16][17][18]30,38].…”