Essential oil variation in wild populations of Artemisia saharae (Asteraceae) from Tunisia: chemical composition, antibacterial and antioxidant properties

Artemisia spp. Essential Oils: From Their Ethnobotanical Use to Unraveling the Microbiota Modulation Potential

BACKGROUND

The 2015 Nobel Prize in Medicine, awarded for the discovery of artemisinin in Artemisia annua, reignited interest in aromatic plants, including Artemisia absinthium L. This article delves into the historical, ethnopharmacological and medicinal significance of A. absinthium, examining its bitter taste noted since ancient Greek times and its association with medicinal properties throughout history. Despite being banned in the 20th century due to perceived health risks; recent research has led to the reconsideration of A. absinthium's potential applications. This study focuses on the prebiotic efficacy of essential oils (EOs) from two Artemisia species: A. absinthium and A. annua.

MATERIALS AND METHODS

A broth microdilution test, growth curve test and in vivo models were used to study the impact of low doses (from 0.5% v/v to 0.00048 v/v) of Artemisia spp-EO on the three probiotic strains (Lactobacillus, Lactobacillus casei and Saccharomyces boulardii).

RESULTS

These essential oils, when used in minimal concentrations (lower than 0.06% v/v), are safe and exhibit prebiotic effects on major probiotic strains, supporting the traditional culinary use of Artemisia spp.

CONCLUSION

This research opens avenues for potential applications in the food industry, emphasizing the need for further exploration into the prebiotic properties of Artemisia spp-EOs and their influence on the microbiota.

Volatile Oil Components of Laurel (Laurus nobilis L.) Leaves Obtained from Plants Cultivated under Salinity Stress Conditions

Laurel (Laurus nobilis L.) is a strict endemic species of natural vegetation of the Mediterranean region, which is known for its medicinal, aromatic, forestry, ornamental and culinary properties. This species produces valuable essential oil (EO). The content of EO and its composition depend on different factors, e.g., genetic, cultural practices and environmental conditions. Among these, salt stress is a major limiting factor, which affects almost all plant functions. Similar to essential oils (EOs), biotic and abiotic stresses may stimulate or inhibit the emission of volatile compounds (VCs) in plant materials, suggesting that these substances can be responsible on stress defense strategies. Therefore, an experiment was conducted to assess the effect of different NaCl concentrations (0, 50, 100 and 150 mM) of the irrigation water on VCs of laurel leaves. Our results showed that salt stress affected the volatile metabolites compounds, mainly the major ones. For instance, 1,8-cineole and linalool were negatively affected by high salinity levels, while the opposite was observed for α-terpenyl acetate and methyl eugenol. The proportion of grouped compounds of laurel VCs also differed among the studied treatments. The relative content of oxygenated monoterpenes and monoterpene hydrocarbons, respectively the first and the second largest groups, decreased with increasing NaCl concentration. Differently, the relative amount of sesquiterpene hydrocarbon group increased, especially at 100 mM NaCl. These findings indicate that the cultivation of laurel in marginal lands, characterized by high salinity or low-quality water, must be carefully evaluated because it significantly varies the quality of its products.

Assessment of artemisinin and antioxidant activities of three wild Artemisia species of Algeria

Artemisinin, a natural product, has received considerable attention in the last few years as a potent antimalarial drug.This study reports the presence of Artemisinin in three Algerian wild Artemisia species assessed by HPLC method: A. herba-alba (AH), A. campestris subsp. glutinosa (AC), and A. judaica subsp sahariensis (AJ).The HPLC analysis of the hexane extracts, showed a difference in artemisinin content in studied species with a yield of 0.64%, 0.34% and 0.04% for AC, AH and AJ, respectively. Moreover, the level of artemisinin obtained in A. campestris was better than those found in A. sieberi and A. annua. This rate has been reported for the first time.Furthermore, the antiradical activities of methanolic extracts of plants were also tested. There was a remarkable antioxidant capacity found in all Artemisia methanolic extracts analysed.

Data handling and data analysis in metabolomic studies of essential oils using GC-MS

Gas chromatography electron impact ionization mass spectrometry (GC-EI-MS) has been, and remains, the most widely applied analytical technique for metabolomic studies of essential oils. GC-EI-MS analysis of complex samples, such as essential oils, creates a large volume of data. Creating predictive models for such samples and observing patterns within complex data sets presents a significant challenge and requires application of robust data handling and data analysis methods. Accordingly, a wide variety of software and algorithms has been investigated and developed for this purpose over the years. This review provides an overview and summary of that research effort, and attempts to classify and compare different data handling and data analysis procedures that have been reported to-date in the metabolomic study of essential oils using GC-EI-MS.

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

Oliveria decumbens (Apiaceae) is an aromatic herb traditionally employed in the Persian medicine for the treatment of infectious and gastrointestinal disorders. In the present study, we analyzed the chemical composition of essential oils obtained from different Iranian populations and evaluated their efficacy on a panel of human pathogens (Staphylococcus aureus and Escherichia coli), probiotic (Bacillus subtilis), and phytopathogens (Clavibacter michiganensis, Curtobacterium flaccumfaciens, Xanthomonas citri, and Agrobacterium tumefaciens). The gas chromatographic-mass spectrometry analysis put in evidence four main volatile constituents such as thymol (20.3–36.4%), carvacrol (18.8–33.1%), γ-terpinene (10.6–25.9%), and p-cymene (9.5–17.3%), though with significant variability from an essential oil to another. Notably, the oils from the populations sited in Nourabad Mamasani and Dehdasht showed the highest amount of the phenolic monoterpenes thymol (36.4 and 35.2%, respectively) and carvacrol (33.1 and 30.6%, respectively). The antibacterial activity of O. decumbens essential oils was assessed by the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) methods, showing high activity for the samples from Nourabad Mamasani and Dehdasht populations exhibiting high level of the above phenolics. The obtained MIC and MBC values (mg/ml) were in the ranges 0.0625–2 mg/ml and 1–16 mg/ml, respectively. Noteworthy, in some cases, the antibacterial activity of O. decumbens essential oils was higher than that of chloramphenicol used as positive control. The average MBCs displayed by the O. decumbens samples showed that C. flaccumfaciens had the highest sensitivity to the essential oils. Based on these results, our work shed light on selected O. decumbens populations deserving proper breeding and cultivation strategies in order to warrantee production of bioactive essential oils to be used at pharmaceutical and agricultural level to combat several pathogens.