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Essential Oils: Extraction Techniques, Pharmaceutical And Therapeutic Potential - A Review

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Background: Essential oils are liquid extracts from aromatic plants, which have numerous applications in multiple industries. There are a variety of methods used for the extraction of essential oils, with each method exhibiting certain advantages and determining the biological and physicochemical properties of the extacted oils. Essential oils from different plant species contain more than 200 constituents which are comprised of volatile and non-volatile components. The application of essential oils as antimicrobial, anticancer, anti-inflammatory and anti-viral agents are due to their effective and efficient properties, inter alia. Methods: Several advanced (supercritical fluid extraction, subcritical extraction liquid, solvent free microwave extraction) and conventional (hydrodistillation, steam distillation, hydrodiffusion, solvent extraction) methods have been discussed for the extraction of essential oils. Advanced methods are considered as the most promising extraction techniques due to less extraction time, low energy consumption, low solvent used and less carbon dioxide emission. Conclusion: This manuscript reviewed the major research studies in the field and discussed several research findings on the chemical composition of essential oils, methods of oil extraction, and application of these oils in pharmaceutical and therapeutic fields. These essential oils can be used as anticancer, antimicrobial, antiviral, and as skin permeation enhancer agents.
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... It's estimated that each oil contains between 20 and 60 chemical components, but some EOs may contain more than 300 . However, typically two or three chemical substances are more frequently concentrated than the others in EOs (Aziz et al., 2018), for instance: basil EO has p-allylanisole as a major component, concentrated at approximately 70 %, and linalool at 18 % (Nuñez et al., 2024); thyme EO, contains thymol concentrated at approximately 47 %, p-cymene at 20 %, and ϒ-terpinene at 9 % (Galgano et al., 2023). In general, the evaluation of the constituents of different EOs is performed using Gas Chromatography-Mass Spectrometry (GCMS) (Aziz et al., 2018). ...
... However, typically two or three chemical substances are more frequently concentrated than the others in EOs (Aziz et al., 2018), for instance: basil EO has p-allylanisole as a major component, concentrated at approximately 70 %, and linalool at 18 % (Nuñez et al., 2024); thyme EO, contains thymol concentrated at approximately 47 %, p-cymene at 20 %, and ϒ-terpinene at 9 % (Galgano et al., 2023). In general, the evaluation of the constituents of different EOs is performed using Gas Chromatography-Mass Spectrometry (GCMS) (Aziz et al., 2018). ...
... Historically, the extraction of these products was first performed by Arabs during the Middle Ages using the hydrodistillation method (Bakkali et al., 2008). The extraction process determines the quality of the product and composition of EOs; improper extraction can interfere with the chemical and pharmacological activity of the respective components (Aziz et al., 2018). Currently, hydrodistillation remains the most widely used method for industrial EO extraction (Ferrentino et al., 2020), though alternative methods such as steam distillation, hydrodiffusion, solvent extraction, and microwave-assisted extraction are also employed (Aziz et al., 2018). ...
... The primary constituents of EOs are terpenoids, which are composed of isoprene units (C5) and often contain oxygen. The smallest group, isoprenoids, consists of a single isoprene unit, whereas monoterpenes (C10) and sesquiterpenes (C15) are more prevalent, with Although the extraction of EOs using solvents varies according to the method employed [24], there is also a need for a separation process to remove the solvent while the presence of trace amounts of the solvent in the final product limits its use, mainly if the solvents employed are toxic and/or harmful to humans, such as acetone, hexane, methanol, petroleum ether, among others [30,31]. For this reason, and to extract the highest amount of compounds while avoiding the loss of those thermolabile volatiles, other green approaches have been developed, such as the replacement of the commonly employed solvents with greener alternatives such as natural deep eutectic solvents (NADES) [32]. ...
... Traditional extraction methods include steam distillation (SD), hydro-distillation (HD), hydro-diffusion (HDF), and solvent extraction (SE) [67]. On the other hand, advanced methods comprise microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), and supercritical fluid extraction (SFE) [24]. The increase in the use of advanced methods for EO extraction is due to the limitations of conventional methods, which include low efficiency, long extraction times, the use of (toxic) organic solvents, and high energy consumption [68,69]. ...
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Essential oils (EOs) are highly valued in the cosmetic and food industries for their diverse properties. However, traditional extraction methods often result in low yields, inconsistent compositions, lengthy extraction times, and the use of potentially harmful solvents. Natural deep eutectic solvents (NADES) have emerged as promising alternatives, offering advantages such as higher efficiency, cost-effectiveness, biodegradability, and tunable properties. This review explores the application of NADES in enhancing EO extraction, focusing on current methodologies, key insights, and practical applications. It examines the factors that influence EO extraction with NADES, including the optimization of their physicochemical properties, extraction techniques, operational conditions, and the role of sample pretreatment in improving efficiency. Additionally, this review covers the chemical characterization and biological activities of EOs extracted using NADES. By providing a comprehensive overview, it highlights the potential of NADES to improve EO extraction and suggests directions for future research in this field.
... Os óleos essenciais (OEs) são concentrações aromáticas extraídas de diferentes espécies de plantas, e sua composição pode variar amplamente de acordo com a fonte vegetal (Aziz et al., 2018). ...
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O uso excessivo de antibióticos nas últimas décadas resultou em um aumento alarmante da resistência antimicrobiana, representando um desafio significativo para a medicina moderna. Nesse contexto, a busca por alternativas eficazes torna-se urgente, especialmente em relação ao desenvolvimento de novos agentes antimicrobianos. Os óleos essenciais, em particular os cítricos, emergem como promissoras opções terapêuticas. Extraídos de frutas como limão e laranja, esses óleos são ricos em compostos bioativos, como limoneno e citral, que demonstram propriedades antimicrobianas contra uma ampla gama de patógenos, incluindo bactérias e fungos. Este trabalho revisa a literatura existente sobre os óleos essenciais cítricos, abordando suas propriedades, mecanismos de ação e possíveis aplicações na prática clínica. Além de suas atividades antimicrobianas, esses óleos apresentam vantagens significativas, como a redução do risco de efeitos adversos e a diminuição da resistência em comparação com antibióticos sintéticos. A exploração dos óleos essenciais cítricos não só oferece uma resposta à crise da resistência antimicrobiana, mas também promove uma abordagem mais sustentável e inovadora no combate a infecções. A pesquisa contínua sobre essas substâncias naturais é essencial para ampliar o arsenal terapêutico e contribuir para a saúde pública.
... They are extracted by methods such as steam distillation, the cold pressing of citrus fruit peels, or solvent extraction, depending on the plant of origin. These oils have predominant applications in aromatherapy, perfumery, and as active ingredients in pharmaceutical and cosmetic products [60,61]. ...
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