Citrus EOs is an economic, eco-friendly and natural alternatives to chemical preservatives and other synthetic antioxidants, such as sodium nitrites, nitrates or benzoates, commonly utilized in food ...preservation. Citrus based EOs is obtained mainly from the peels of citrus fruits which are largely discarded as wastes and cause environmental problems. The extraction of citrus oils from the waste peels not only saves environment but can be used in various applications including food preservation. The present article presents elaborated viewpoints on the nature and chemical composition of different EOs present in main citrus varieties widely grown across the globe; extraction, characterization and authentication techniques/methods of the citrus EOs; and reviews the recent advances in the application of citrus EOs for the preservation of fruits, vegetables, meat, fish and processed food stuffs. The probable reaction mechanism of the EOs based thin films formation with biodegradable polymers is presented. Other formulation, viz., EOs microencapsulation incorporating biodegradable polymers, nanoemulsion coatings, spray applications and antibacterial action mechanism of the active compounds present in the EOs have been elaborated. Extensive research is required on overcoming the challenges regarding allergies and obtaining safer dosage limits. Shift towards greener technologies indicate optimistic future towards safer utilization of citrus based EOs in food preservation.
The current study aimed to investigate the efficacy of dietary thyme essential oil (TEO),
Nigella sativa
essential oil (NSEO), thyme essential oil nano-emulsion (TEO-NE), and
Nigella sativa
essential ...oil nano-emulsion (NSEO-NE) in reducing total ammonia nitrogen (TAN), improving immune response, mitigating stress, and acting as anti-inflammatory agents as well as preventing streptococcosis infection in
Oreochromis niloticus
(
O. niloticus)
. Fish (
N
= 330, 14 ± 2 g) were divided into 10 groups of 11 fish each, with three replicates in each group. The negative and positive controls were fed a control diet, while the third group was given 1% TEO. Moreover, the fourth group of fish was given 2% TEO. The fifth and sixth groups were fed 1% TEO-NE and 2% TEO-NE, respectively. The seventh, eighth, ninth, and tenth groups were fed 1% NSEO, 2% NSEO, 1% NSEO-NE, and 2% NSEO-NE, respectively. After dietary intake of TEO, NSEO, and their nano-emulsions for 28 days, the mean values of TAN levels in the water of fish aquaria had a significant reduction in the group fed 2% TEO-NE compared to the control group. On the contrary, NSEO-NE at the same concentration had no significant effect on TAN levels. The levels of lysozyme, complement 5, and IgM increased in all feeding groups compared to the control group. Concerning cortisol level as a stress indicator, it was decreased in all feeding groups compared to the control. Also, the current experiment overall showed a significant decrease in the expression level of pro-inflammatory tumor necrosis factor (TNF-α) gene in the gills of fish groups fed TEO, TEO-NE, NS, and NS-NE relative to the β-actin gene. Oppositely, there was an increase in the expression level of the anti-inflammatory transforming growth factor (TGF-β). In the current study, TEO-NE and NSEO-NE showed a better effect on preventing streptococcosis in
O. niloticus
with no mortality than 1% TEO and NSEO, respectively. Furthermore, there was a 12.5% mortality rate and an 84.99 RPS in the group fed 1% TEO and injected with
Streptococcus inae
. On the other hand, the groups fed 1 and 2% NSEO showed 37.5 and 25% mortality rate, respectively and 54.99 and 69.99 RPS. In conclusion, the nano-emulsion either TEO or NSEO had the superior effect. For bulk status, the TEO had superior effect than NSEO. The study needs more investigations for ammonia, either on the mode of action or over a longer period.
Tea tree oil (TTO) is a volatile essential oil obtained by distillation, mainly from the Australian native plant Melaleuca alternifolia (Maiden & Betche) Cheel (Myrtaceae). In this study, a ...comparative analysis of the chemical constituents of seven tea tree oils (M. alternifolia) and four other Melaleuca spp. oils (M. cajuputi, (Msub.Ca), two chemotypes of M. quinquenervia, (Msub.Ne and Msub.Ni), and M. ericifolia (Msub.Ro)) was carried out using gas chromatography–mass spectrometry (GC-MS) and high-performance thin-layer chromatography (HPTLC). Among the seven TTOs, terpinen-4-ol (37.66–44.28%), γ-terpinene (16.42–20.75%), α-terpinene (3.47–12.62%), α-terpineol (3.11–4.66%), and terpinolene (2.75–4.19%) were the most abundant compounds. On the other hand, the most abundant compounds of the other Melaleuca oils varied, such as 1,8-cineole (64.63%) in Msub.Ca oil, (E)-nerolidol (48.40%) and linalool (33.30%) in Msub.Ne oil, 1,8-cineole (52.20%) in Msub.Ni oil, and linalool (38.19%) and 1,8-cineole (27.57%) in Msub.Ro oil. HPTLC fingerprinting of Melaleuca oils enabled the discrimination of TTO oils from other Melaleuca spp. oils. Variation was observed in the profile of the Rsub.f values among EOs. The present study shows that HPTLC is one of the best ways to identify and evaluate the quality control in authenticating TTOs, other Melaleuca EOs, or EOs from other species within the Myrtaceae.
The present study evaluated the housefly repellency of single-component formulations and combinations of lemongrass and star anise essential oils (EOs) and their main constituents. The efficacies of ...the combinations were compared against those of single-component formulations and DEET. Safety bioassays of all formulations and DEET on non-target species-guppy, molly, dwarf honeybee, and stingless bee-were conducted. GC-MS analysis showed that the main constituent of lemongrass EO was geranial (46.83%) and that of star anise EO was
-anethole (92.88%). All combinations were highly synergistic compared to single-component formulations, with an increased repellent value (IR) of 34.6 to 51.2%. The greatest synergistic effect was achieved by 1.0% lemongrass EO + 1.0%
-anethole combination, with an IR of 51.2%. The strongest, 100% repellent rate at 6 h was achieved by 1.0% geranial + 1.0%
-anethole. They were twice as effective as DEET and caused obvious damage to housefly antennae under microscopic observation. All single-component formulations and combinations were benign to the four tested non-target species. In contrast, DEET was highly toxic to them. The synergistic repellency and biosafety of these two combinations are compellingly strong support for developing them into an effective green repellent.
Carvacrol (CV) is a phenolic monoterpenoid found in essential oils of oregano (Origanum vulgare), thyme (Thymus vulgaris), pepperwort (Lepidium flavum), wild bergamot (Citrus aurantium bergamia), and ...other plants. Carvacrol possesses a wide range of bioactivities putatively useful for clinical applications such antimicrobial, antioxidant, and anticancer activities. Carvacrol antimicrobial activity is higher than that of other volatile compounds present in essential oils due to the presence of the free hydroxyl group, hydrophobicity, and the phenol moiety. The present review illustrates the state‐of‐the‐art studies on the antimicrobial, antioxidant, and anticancer properties of CV. It is particularly effective against food‐borne pathogens, including Escherichia coli, Salmonella, and Bacillus cereus. Carvacrol has high antioxidant activity and has been successfully used, mainly associated with thymol, as dietary phytoadditive to improve animal antioxidant status. The anticancer properties of CV have been reported in preclinical models of breast, liver, and lung carcinomas, acting on proapoptotic processes. Besides the interesting properties of CV and the toxicological profile becoming definite, to date, human trials on CV are still lacking, and this largely impedes any conclusions of clinical relevance.
Thymol is a naturally occurring phenol monoterpene derivative of cymene and isomer of carvacrol. Thymol (10–64%) is one of the major constituent of essential oils of thyme (Thymus vulgaris L., ...Lamiaceae), a medicinal plant with several therapeutic properties. This plant, native to Mediterranean regions, is commonly used as a culinary herb and also with a long history of use for different medicinal purposes. Nowadays, thymol and thyme present a wide range of functional possibilities in pharmacy, food, and cosmetic industry. The interest in the formulation of pharmaceuticals, nutraceuticals, and cosmeceuticals based on thymol is due to several studies that have evaluated the potential therapeutic uses of this compound for the treatment of disorders affecting the respiratory, nervous, and cardiovascular systems. Moreover, this compound also exhibits antimicrobial, antioxidant, anticarcinogenesis, anti‐inflammatory, and antispasmodic activities, as well as a potential as a growth enhancer and immunomodulator. In the present review, these bioactivities have been covered because some of them can contribute to explain the ethnopharmacology of thymol and its main source, T. vulgaris. Other important aspects about thymol are discussed: its toxicity and bioavailability, metabolism, and distribution in animals and humans.
The antimicrobial activity of essential oils has been reported in hundreds of studies, however, the great majority of these studies attribute the activity to the most prevalent compounds without ...analyzing them independently. Therefore, the aim was to investigate the antibacterial activity of 33 free terpenes commonly found in essential oils and evaluate the cellular ultrastructure to verify possible damage to the cellular membrane.
Screening was performed to select substances with possible antimicrobial activity, then the minimal inhibitory concentrations, bactericidal activity and 24-h time-kill curve studies were evaluated by standard protocols. In addition, the ultrastructure of control and death bacteria were evaluated by scanning electron microscopy.
Only 16 of the 33 compounds had antimicrobial activity at the initial screening. Eugenol exhibited rapid bactericidal action against
serovar Typhimurium (2 h). Terpineol showed excellent bactericidal activity against
strains. Carveol, citronellol and geraniol presented a rapid bactericidal effect against
.
The higher antimicrobial activity was related to the presence of hydroxyl groups (phenolic and alcohol compounds), whereas hydrocarbons resulted in less activity. The first group, such as carvacrol, l-carveol, eugenol,
-geraniol, and thymol, showed higher activity when compared to sulfanilamide. Images obtained by scanning electron microscopy indicate that the mechanism causing the cell death of the evaluated bacteria is based on the loss of cellular membrane integrity of function. The present study brings detailed knowledge about the antimicrobial activity of the individual compounds present in essential oils, that can provide a greater understanding for the future researches.
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