Interspecific variation, antioxidant and allelopathic activity of the essential oil from three Launaea species growing naturally in heterogeneous habitats in Egypt

Abstract

Essential oils (EOs) from the aerial parts of three Launaea species collected from two different habitats were extracted [Launaea mucronata collected from coastal desert (LMC) and from inland desert (LMD), Launaea nudicaulis collected from coastal desert (LNC) and from inland desert (LND), Launaea spinosa (LS)]. The EOs were analysed by gas chromatography mass spectrometry (GC‐MS) and tested for antioxidant activity as well for allelopathic activity against purslane. A total of 117 compounds were identified from all samples, including 64 from LS, 50 from LMC, 39 from LMD, 24 from LNC, and 20 from LND, representing 100% of the total oil mass. The oxygenated sesquiterpenes were the major compounds of the EOs from LS, LMC, LMD, LNC, and LND, representing 62.73, 61.02, 58.35, 43.22, and 48.33%, respectively, whereas the monoterpene hydrocarbons were minor compounds in all samples. α‐Acorenol (31.42%), trans‐longipinocarveol (12.04%), and γ‐eudesmol (6.31%) represented the major compounds of the EO from LS, whereas hexahydrofarnesyl acetone and n‐heneicosane represented the major compounds from LMC, LMD, LNC, and LND. Correlations between the EOs of the five samples were studied via principal component analysis and agglomerative hierarchical clustering, based on the chemical composition of the EOs. There was a significant variation between Launaea species regarding both the quality and the quantity of EO composition, whereas no significant difference was observed based on the habitats (coastal and inland deserts). The EOs of the five Launaea samples exhibited meaningful antioxidant activities, as follows: LND > LNC > LMD > LMC > LS. Moreover, the EOs of the five Lanaea samples exhibited significant allelopathic activity against purslane weed in a concentration‐dependent manner. LMD and LMC showed the highest effect, with germination inhibition of 96.1 and 87.9% at 250 μL L−1, and radicle growth inhibition of 92.6 and 89.7%, but LS was the least effective extract. Our results showed that the variation in the quality and quantity of EO composition is mainly species specific, with a slight correlation with habitats.

Sesquiterpenes-Rich Essential Oil from Above Ground Parts of Pulicaria somalensis Exhibited Antioxidant Activity and Allelopathic Effect on Weeds

“…Our previous work on Xanthium strumarium L. (cocklebur), Symphyotrichum squamatum (Spreng.) Nesom (bushy starwort), and Launaea (Morrar) species indicated that a variation of the chemical composition of the EO was found to be strongly correlated with variation in the habitats [42,43].…”

Profiling of essential oil chemical composition of some Lamiaceae species extracted using conventional and microwave‐assisted hydrodistillation extraction methods via chemometrics tools

“…The unique mechanism offered by microwave radiation as a non‐conventional heat source, can accelerate the delivery of energy and facilitate the penetration of solvent inside the plant matrix, and consequently can shorten the extraction time from hours to minutes. Since the quality of the EO could be measured by the high percentages of the oxygenated compounds present, therefore MAHD technique for the extraction of EOs offers higher quality yields of the extracted EOs in shorter time …”

“…In general, the PCA results showed that there is significant variation between species in the quality and quantity of EO composition; however, no significant difference is observed based on the extraction method used (HD and MAHD). Accordingly, the variation could be ascribed to differences in the environmental and microclimatic conditions as well as the genetic relationship …”

“…Accordingly, the variation could be ascribed to differences in the environmental and microclimatic conditions as well as the genetic relationship. 35,36…”

“…The obtained data also showed a strong correlation between O syriacum and T vulgaris ( Figure 3A; Table 3 and 5). 34,35 In general, the PCA results showed that there is significant variation between species in the quality and quantity of EO composition; however, no significant difference is observed based on the extraction method used (HD and MAHD).…”