Table 2.

Actions in the health of the essential oils.

	Essential oil	Health action	Type of study	Study name	Relevant results	Major active compound	Tentative mechanism (how this essential oil has the effect on health)	Reference
1	Lemon	Showed DPPH radical scavenging activity Demonstrated a good inhibitory activity against the pathogenic microorganisms C. albicans, L. monocytogenes and S. aureus.	Cell line model	Waste Citrus limon Leaves as Source of Essential Oil Rich in Limonene and Citral: Chemical Characterization, Antimicrobial and Antioxidant Properties, and Effects on Cancer Cell Viability	It showed DPPH radical scavenging activity (IC50 value = 10.24 mg/mL) and demonstrated a good inhibitory activity against the pathogenic microorganisms C. albicans, L. monocytogenes and S. aureus. Moreover, the treatment with LLEO significantly affected cell viability and morphology from 25 μM in cancer HeLa and A375 cells, with lower effects on normal fibroblasts and keratinocytes.	Limonene (256.7 ± 2.4 mg/mL), Citral (194.5 mg/mL)	The antimicrobial activity against bacterial species tested were strain dependent. The antioxidant activity is given as IC50 value, which indicates the LLEO concentration required to give a 50% inhibition of the DPPH• radical formation LLEO exhibited good antioxidant activity, with an IC50 value of 10.24 ± 2.8 mg/mL.	(14)
2	Lemon	Antioxidant and antimicrobial activities with its preservative effect against Listeria monocytogenes	Inoculated in minced beef meat	Citrus lemon essential oil: chemical composition, antioxidant, and antimicrobial activities with its preservative effect against Listeria monocytogenes inoculated in minced beef meat	The application of ClEO at a 0.06 and 0.312 mg/g, may open new promising opportunities for the prevention of contamination from and growth of pathogenic bacteria, particularly L. monocytogenes, during minced beef meat storage at 4°C. Additionally, during storage period, physicochemical values were higher in control meat than treated meat with ClEO suggesting an efficient antioxidant activity of ClEO.	Limonene (39.74%) and β-Pinene (25.44%).	It is demonstrated, in vitro and in situ, the efficiency of ClEO as a natural antioxidant and antimicrobial agent.	(15)
3	Lemon/ Grapefruit	Antibacterial activity and antioxidant activity	In vitro	The Chemical Composition and Antibacterial and Antioxidant Activities of Five Citrus Essential Oils	The LEO and DLEO demonstrated greater antioxidant activity, measured as DPPH and ABTS free radicals compared with other EOs. The high concentration of d-limonene appeared not to be necessarily associated with high antibacterial and antioxidant activity, suggesting that the antibacterial and antioxidant activities might be related to the active component profiles and possibly their synergism effects.	Monoterpenes (d-limonene and less so sesquiterpenes)	The antibacterial activities of the EOs on three bacteria (Escherichia coli, Salmonella and Lactobacillus acidophilus) were tested by measuring the minimum inhibitory concentration (MIC), minimal bactericidal concentration (MBC) and inhibition zone diameter (IZD).	(16)
4	Orange	The EOP and EOPD showed antioxidant activity by reducing metals, and particularly the EOP by also neutralizing free radicals. They partially affected the bacterial growth while strongly inhibiting the biofilm formation and viability of sessile bacteria living in a pre-existent biofilm (Gram-negative and Gram-positive)	In vitro	Citrus sinensis Essential Oils an Innovative Antioxidant and Antipathogenic Dual Strategy in Food Preservation against Spoliage Bacteria	They could represent natural and safe alternatives to extend the shelf life of food products by preventing oxidation and contamination by pathogens that spoil food, meaning the sweet orange EOs can be considered as an innovative dual strategy for food preservation.	The main monoterpene was limonene (90.41%), myrcene (3.19%)	Could represent natural and safe alternatives to extend the shelf life of food products by preventing oxidation and contamination by food-spoiling pathogens, meaning that sweet orange EOs can be considered as an innovative dual strategy for food preservation.	(17)
5	Orange	Phytoactive chemicals found in Citrus oil can serve as prototypes in the production of new antimicrobial and antiparasitic drugs.	In vitro	Citrus sinensis Peel Oil Extraction and Evaluation as an Antibacterial and Antifungal Agent	The antibacterial potential of oil against bacterial strains, i.e., E. coli, S. aureus and S. agalactiae exhibited that the oil efficiently controls the bacterial growth. The highest zone of inhibition was observed against the strain E. coli. The antifungal potential of oil for pathogenic fungal strains, i.e., A. flavus, A. niger, A. alternata showed that the oil significantly inhibits fungal growth.	β-pinene (0.55%), limonene (96–98%), α-pinene (0.29%), myrcene (1.3–1.45%) and octanol (0.37–0.53%).	The antibacterial potential of the oil against bacterial strains, i.e., E. coli, S. aureus and S. agalactiae, demonstrated that the oil efficiently controls bacterial growth. The diameter of the inhibition zone was maximum against A. flavus. Phytoactive chemicals found in Citrus oil can serve as prototypes in the production of new antimicrobial and antiparasitic drugs.	(18)
6	Cinnamon	Significant decrease in fasting blood glucose, plasma C-peptide, serum triglyceride, total cholesterol, and blood urea nitrogen levels, with significant increase in high-density lipoprotein after 35 days. Glucose tolerance was improved and pancreatic islet β-cells showed increased immunoreactivity.	In vivo (Rat), STZ	Encapsulation of cinnamon oil in whey protein counteracts the disturbances in biochemical parameters, gene expression, and histological picture of the liver and pancreas of diabetic rats	Both doses improved glucose, insulin, SOD, GSH, amylase, lipid profile and hepatic MDA levels. Gene expression was modulated to favor antidiabetic results. Positive histological changes are observed in the liver and pancreas.	More than 86% of these volatiles: cinnamaldehyde (88.7%), 1,8 cineole (2.02%), acetic acid, 1,7,7 trimethylbicyclo [2.2.1] hept2yl ester (1.79%), α-Pinene (1.45%), and α-Terpineol (0.92%)	The protective role of COE against disturbance in biochemical parameters, antioxidant capacity, gene expression, and histological changes in the liver and pancreas in STZ-treated rats was evaluated. It was reported that STZ has a rapid action on pancreatic β cells and induces a massive reduction of these cells in islets of Langerhans resulting in hyperglycemia and the ROS generation in β cells following the increasing of ROS in other organs	(19)
7	Cinnamon	Cinnamomum zeylanicum Blume offers novel approach to chemotherapy treatment	in vitro	Optimization of Cinnamon (Cinnamomum zeylanicum Blume) Essential Oil Extraction: Evaluation of Antioxidant and Antiproliferative Effects	Cinnamon essential oil was able to remove hydrogen peroxide depending on the amount, 0.7 mg/mL of cinnamon essential oil exhibited 50% hydrogen peroxide removing activity.	cinnamaldehyde (77.34%), transcinnamyl acetate (4.98%), benzenedicarboxylic acid (3.55%), α-pinene (2.6%) and coumaric acid (1.79%)	Essential oils seem to be useful as possible antitumor agents. This work studied the effect of different concentrations of Cinnamomum zeylanicum Blume essential oil against HeLa (0.0625 to 4 μ g/mL) and Raji (0.375 to 12 μ g/mL) cell lines. mL	(20)
8	Coriander	The coriander oil and linalool combinations conferred a synergistic anthelmintic effect	In vitro	Nematocidal Effects of a Coriander Essential Oil and Five Pure Principles on the Infective Larvae of Major Ovine Gastrointestinal Nematodes In Vitro	The coriander oil and linalool showed the most inhibitory effects against L3s. Combined treatment using coriander oil enhanced with additional linalool offered more synergistic effect on larval motility indicated by the extensive cuticular damage of treated L3s.	linalool (68.03%), α-tinene (9.71%), γ-terpinene (10.48%) and camphor (11.76%)	The mode of action of coriander oil and linalool is related to disruption of membrane function	(21)
9	Coriander	Inhibition of 65 essential oils and 21 essential oil mixtures against several species/clinical strains of dermatophytes of two main genera, Microsporum and Trichophyton	In vitro	Activity of various essential oils against clinical dermatophytes of Microsporum and Trichophyton	All genera/species tested were completely inhibited for 21 days after a single application	The exact content of the individual components of each oil was not tested or evaluated	Inhibition of strain growth for a long time	(22)
10	Parsley	Parsley presented the best antioxidant profile	In vitro	Chemical Composition, Antioxidant and Antimicrobial Activity of Essential Oils from Organic Fennel, Parsley, and Lavender from Spain	Parsley had the highest phenolic content. Overall, parsley presented the best antioxidant profile, given its highest % of inhibition of DPPH radical (64.28%) and FRAP (0.93 mmol/L Trolox), but had a pro-oxidative behavior by TBARS.	myristicin (36.15%), apiole (20.97%), α-pinene (15.47%), and β-pinene (10.43%).	The antioxidant activity of organic fennel, parsley, and lavender EOs was assessed by evaluating hydrogen donating ability, or radical scavenging activity, using the stable radical DPPH.	(13)
11	Rosemary	Evaluation of Their Chemical Composition, Genotoxicity, Antimicrobial, Antiviral, and Antioxidant Properties	In vitro	Rosemary Extract and Essential Oil as Drink Ingredients: An Evaluation of Their Chemical Composition, Genotoxicity, Antimicrobial, Antiviral, and Antioxidant Properties	The essential oil in dilutions of up to 5% and the extract in the range of 25–90% are not genotoxic, and confer antiviral, antifungal, and antioxidant properties; the extract also confers important antibacterial properties, whereas the essential oil is mainly effective against S. aureus.	Monoterpenes (95.57%), sesquiterpenes amounted only to 4.24%	The antioxidant activity was evaluated by the DPPH radical method, the Ferric reducing antioxidant power (FRAP) assay and the ABTS assay and the radical scavenging activity among rosemary essential oils is mainly due to the different amounts of major compounds in the essential oils	(23)
12	Thyme	To determine the bioactive compounds, present in thyme essential oil and utilize the nanoemulsion technique to enhance its protective capacity against oxidative stress, genotoxicity, and DNA damage caused by biosynthesized titanium dioxide nanoparticles.	in vivo	Improvement of the antioxidant activity of thyme essential oil against biosynthesized titanium dioxide nanoparticles-induced oxidative stress, DNA damage, and disturbances in gene expression in vivo	The TEO nanoemulsion enhances the biological activity of the oil, improves its antioxidant properties, and provides protection against oxidative damage and genotoxicity induced by TiO2-NP.	The successful identification of 17 bioactive compounds was achieved in thyme essential oil (TEO), with thymol and carvacrol being the main components present in this essential oil.	Sixty male Sprague–Dawley rats were divided into six groups and orally treated for a period of 21 days. These groups included the control group, the TEO-treated group, the TEON-treated groups, the TiO2-NP-treated group, and those groups that received both TiO2-NP and TEO. Blood and tissue samples were collected for various analyses.	(24)