Comparative Chemical Profiles and Phytotoxic Activity of Essential Oils of Two Ecospecies of Pulicaria undulata (L.) C.A.Mey

Spectroscopic Characterization and Biological Effects of 1-Oxo-bisabolone-rich Pulicaria burchardii Hutch. subsp. burchardii Essential Oil Against Viruses, Bacteria, and Spore Germination

Pulicaria species are used as herbal medicine and in the preparation of decoctions in several Asian and African regions. Among them, the plant Pulicaria burchardii is known for its medicinal properties, but comprehensive studies on its biological activity are still limited. This study examined the properties of the essential oil (EO) extracted by P. burchiardii and collected in Morocco during the flowering period. The focus was on its antimicrobial, anti-germinative, antioxidant, and antiviral activities, with the aim of evaluating its potential use in food preservation and beyond. The EO was subjected to various analyses to determine its chemical composition and biological efficacy. Specifically, GCMS and NMR analyses revealed that the EO is rich in oxygenated sesquiterpenes (72.59%), with 1-oxo-bisabolone being the predominant component (65.09%). The antimicrobial activity was tested against various Gram-positive and Gram-negative bacteria, demonstrating a significant inhibition of bacterial growth, particularly against Bacillus subtilis (MIC value of 0.6 mg/mL). The anti-germinative property was evaluated on spores of B. subtilis and other bacilli, such as Bacillus cereus, revealing a notable ability to prevent germination. For antiviral activity, the EO was tested against several pathogenic viruses including SARS-CoV-2 and HSV-1, showing an effective broad-spectrum reduction in viral replication in vitro. This study demonstrated that P. burchardii essential oil had excellent antibacterial and antiviral capabilities. The future challenge will focus mainly on the principal compound, 1-oxo-bisabolone, to demonstrate its real effectiveness as an antibacterial and/or antiviral.

Chemical Composition, Antioxidant, and Cytotoxic Activity of Essential Oils in the Above-Ground Parts of Sonchus oleraceus L

Sonchus oleraceus L. is a leafy vegetable that is usually consumed in the area of the Mediterranean and is a frequently used traditional herb to treat a variety of ailments. Previous studies deduced the potent antioxidant and cytotoxic functions of the different extracts and isolated compounds from S. oleraceus. The current study represents the first instance of chemical profiling and bioactivities of the extracted essential oil (EO) of S. oleraceus. The present investigation set out to identify the chemical components of this EO by means of Gas Chromatography with Flame Ionization Detector (GC-FID) and Gas Chromatography-Mass Spectrometry (G004-MS) techniques; assess the oil's antioxidant potencies through 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate (ABTS) assays; and evaluate the oil's cytotoxic impact against HepG2 cancer cell lines. The GC-MS chemical profiling revealed the identification of 23 components representing 97.43% of the total oil mass within abundant cyclic ketones (20.15%), nonterpenoidial hydrocarbons (28.77%), and sesquiterpenes (42.19%). The main components were n-nonadecane (28.77%), trans-caryophyllene (23.73%), trans-methyl dihydrojasmonate (19.55%), and cis-cadina-1,4-diene (9.44%). In a dose-dependent manner, this EO demonstrated antioxidant capacities on DPPH and ABTS, with IC50 values of 609.35 and 804.16 µg/mL, respectively, compared to ascorbic acid. Using doxorubicin as a reference therapy, the MTT assay findings revealed that this oil had remarkable inhibitory effects on the proliferation of HepG2 cancer cell lines, with an IC50 of 136.02 µg/mL. More studies were recommended for further investigation of new biological roles for this oil and its main components, along with the construction of action mechanisms based on chemical components.

Essential Oil of Ipomoea carnea: Chemical Profile, Chemometric Analysis, Free Radical Scavenging, and Antibacterial Activities

Essential oils (EOs) have been reported as a promising group of naturally extracted compounds due to their various reported biological activities. Ipomoea carnea is a widely distributed plant with many traditional uses worldwide. However, although the EOs of various Ipomea species have been reported, I. carnea remains poorly studied. Therefore, the present investigation aimed to characterize the chemical profile of the EO of I. carnea growing in Egypt via gas chromatography/mass spectroscopy (GC-MS) and correlate its profile with other reported species via chemometric analysis using agglomerative hierarchical clustering (AHC) and principal component analysis (PCA). In addition, the aim was to determine the antioxidant and antibacterial activities of the extracted EO. Depending on the GC-MS analysis, 31 compounds were identified, mainly terpenes (94.82), with traces of carotenoid and apocarotenoid-derived compounds. The major compounds were tau-cadinol (35.68%), α-cadinol (26.76%), spathulenol (8.11%), and caryophyllene oxide (6.56%), which were assigned as major compounds. The chemometric studies showed that the Egyptian ecospecies of I. carnea differs in chemical profile from those growing in Brazil, as well as those reported for other Ipomea species. The EO showed significant DPPH and ABTS radical scavenging abilities, with IC50 values of 33.69 and 40.86 mg L−1, respectively. Additionally, the I. carnea EO displayed significant inhibition against the growth of all tested bacterial strains, where it showed an MIC range of 82–1442 mg mL−1. Based on the current results, the I. carnea EO, particularly the major identified compounds, could be used as a potential eco-friendly green resource for antioxidant and antimicrobial activities. Therefore, further study is recommended to evaluate the biological significance of the main compounds, either individually or in combination, as well as assess their modes of action and safety.

Plant Essential Oil with Biological Activity

Plant essential oils (PEOs), extracted from many aromatic and medicinal plants, are used in folk medicine and often represent an important part of the traditional pharmacopoeia: they have a long history of use in folk medicine as antimicrobial agents to control several human and phyto-pathogens. Many PEOs have been registered as effective alternatives to chemical and synthetic antimicrobials, and in the last few decades, they have also been effectively used in the food industry as antioxidants and anticarcinogens, thanks to the efforts of many research/medical institutions and pharmaceutical companies. This Special Issue discussed the chemical composition and biological-pharmaceutical activities of some important PEOs and their single constituents. Detailed information has been also covered in this Special Issue regarding the mechanisms, possible modes of action, and factors affecting these activities, such as geographical origins, environmental conditions, nutritional status, and the extraction methods used.

GC-MS and SPME-GC/MS Analysis and Bioactive Potential Evaluation of Essential Oils from Two Viola Species Belonging to the V. calcarata Complex

Viola calcarata L. and Viola dubyana Burnat ex Gremli belong to the V. calcarata complex in Viola section Melanium (Violaceae family). For the first time, the essential oils (EOS) obtained by hydrodistillation from dried flowers, were analyzed by GC/MS and SPME-GC/MS to describe their volatile chemical profile. Differences in the qualitative and quantitative composition between the two violets have been found. A total of 43 compounds were identified among which methyl salicylate was the most abundant (from 45.5 to 68.0%) both in the vapor and liquid phase. The performed bioactivity tests pointed out the greater effect of V. dubyana EO compared to that obtained from V. calcarata. Nevertheless, both EOs proved to be good scavengers, especially toward the ABTS⋅+ radical. They also showed a dose-dependent phytotoxic action against Sinapis alba and Lolium multiflorum. Their seed germination was inhibited up to 100% and 25%, respectively, in response to the highest used dose (100 μL) of each EO. Furthermore, a significant decrease in root and shoot length was observed. The resulting seedling vigor index was reduced by 15–100% and 8–82% for S. alba and by 11–91% and 4–91% for L. multiflorum by V. dubyana and V. calcarata EOS, respectively.