Enzymatic and Microwave Pretreatments and Supercritical CO2 Extraction for Improving Extraction Efficiency and Quality of Origanum vulgare L. spp. hirtum Extracts

Unlocking the Unique Potential of Thymus pannonicus: Exploring the Efficacy of Supercritical CO2 Extraction, with and Without Pre-Treatments

Since ancient times, many plant species within the Thymus genus have been used due to their numerous health benefits, such as antimicrobial, anti-inflammatory, antiseptic, or diuretic activity. While many of the species within this genus were well known and described, Thymus pannonicus All. or Pannonian thyme remains relatively unexplored despite its unique chemical composition and activity. T. pannonicus is a small shrub, spread over central and eastern Europe, with a diverse, location-dependent chemical composition. Within this study, the citral chemotype of T. pannonicus was used, which up to our knowledge was found and described only in Northern Serbia. Therefore, in order to explore the composition of T. pannonicus low-polar extracts and to present a preliminary insight into their bioactivity, supercritical carbon dioxide (ScCO2) extraction was applied (with and without pre-treatments), followed by GC-MS analysis. Different ScCO2 extraction pressures were tested (100, 150, 200, 250, and 300 bar) in order to determine the most suitable conditions for the extraction of T. pannonicus's low-polar fraction. Additionally, in order to maximize the yield of the extraction, two types of ScCO2 extraction pre-treatments were investigated (enzymatic and microwave). The highest extraction yield obtained from untreated plant material was 3.01% (w/w), and it was obtained at conditions of 150 bar and 40 °C, while the 4% (v/w) enzymatic pre-treatment, with the same conditions, provided a yield of 3.89%. For all of the obtained extracts, the GC-MS analysis showed that oxygenated monoterpenes and sesquiterpenes were the two most dominant groups with principal bioactive compounds such as (E)-citral (18.95-38.17%), (Z)-citral (6.68-14.66%), β-bisabolene (8.2-14.4%), and nerol (6.08-9.67%). The extracts that exhibited the highest concentration of principal bioactive compounds ((Z)-citral, and (E)-citral) were further analyzed for anticancer potential, using short- and long-term cell viability observations on liver cancer cells.

A new green approach for Lavandula stoechas aroma recovery and stabilization coupling supercritical CO2 and natural deep eutectic solvents

This work investigated a green approach to obtain and stabilize Lavandula stoechas L. volatile organic compounds with sensory aroma characteristics by using alternative solvents, namely supercritical carbon dioxide (scCO₂) and deep eutectic solvents (DES). The CO₂ extracts were dispersed in different DES mixtures (betaine:ethylene glycol (1:3), betaine:glycerol (1:2), and glycerol:glucose (4:1)) and their stability was monitored during 6 months of storage at room temperature by monitoring the headspace (HS) profile. The CO₂ extract was used as the control. It was initially determined that there was a dominant presence of oxygenated monoterpenes (67.33-77.50%) in the extracts. During storage, significant changes occurred in the samples' HS, such as the decrease in terpene hydrocarbons which also affected the presence of oxygenated terpenes, which increased in certain cases. Moreover, the highest formation of new components was recorded in the control which could be an indicator of decreased stability. The DESs-CO₂ were more stable than the CO₂ control and among them, betaine:ethylene glycol stood out as the most adequate systems for maintaining the stability of L. stoechas HS components. For the visual estimation of similarities and dissimilarities among the samples, chemometric pattern recognition approaches were applied including the hierarchical cluster analysis, principal component analysis, and sum of ranking differences.

Extraction and purification of α-pinene; a comprehensive review

Extensive use of α-pinene in cosmetics, and medicine, especially for its antioxidant/antibacterial, and anti-cancer properties, and also as a flavoring agent, has made it a versatile product. α-Pinene (one of the two pinene isomers) is the most abundant terpene in nature. When extracting α-pinene from plants and, to a lesser extent, fruits, given that its purity is essential, purification methods should also be used as described in this study. Also, an attempt has been made to describe the extraction techniques of α-pinene, carried out by conventional and novel methods. Some disadvantages of conventional methods (such as hydrodistillation or solvent extraction) are being time consuming, low capacity per batch and being labor intensive and the requirement of trained operators. Most novel methods, such as supercritical fluid extraction and microwave-assisted extraction, can reduce the extraction time, cost, and energy compared to conventional methods, and, in fact, the extraction and preservation efficiency of α-pinene in these methods is higher than conventional methods. Although the above-mentioned extraction methods are effective, they still require rather long extraction times. In fact, advanced methods such as green and solvent-free ultrasonic-microwave-assisted extraction are much more efficient than microwave-assisted extraction and ultrasound-assisted extraction because the extraction efficiency and separation of α-pinene in these methods are higher; furthermore, no solvent consumption and maximum extraction efficiency are some crucial advantages of these techniques. However, the application of some novel methods, such as ultrasound-assisted extraction, in industry scale is still problematic because of their intricate design data.

Fingerprinting based on gas chromatography-Orbitrap high-resolution mass spectrometry and chemometrics to reveal geographical origin, processing, and volatile markers for thyme authentication

Thyme is an aromatic herb traditionally used for food purposes due to its organoleptic characteristics and medicinal properties, which is highly susceptible to food fraud. In this study, GC-HRMS-based fingerprinting was applied for the first time to determine the geographical traceability of thyme based on different origins (Spain, Poland, and Morocco), as well as to assess its processing by comparing sterilized vs. non-sterilized thyme. Unsupervised chemometric methods (PCA and HCA) revealed a predominant influence of the geographical origin on thyme fingerprints rather than processing effects. Supervised PLS-DA and OPLS-DA were used for discrimination purposes, revealing high predictive ability for further samples (100%), and allowing the identification of differential compounds (markers). A total of 24 markers were putatively identified (13 metabolites were confirmed) belonging to different classes: monoterpenoids, diterpenoids, sesquiterpenoids, alkenylbenzenes, and other miscellaneous compounds. This study outlines the potential of combining untargeted analysis by GC-HRMS with chemometrics for thyme authenticity and traceability.

Supercritical CO2 Extract from Microalga Tetradesmus obliquus: The Effect of High-Pressure Pre-Treatment

High-pressure pre-treatment followed by supercritical carbon dioxide (ScCO₂) extraction (300 bar, 40 °C) was applied for the attainment of the lipophilic fraction of microalga Tetradesmus obliquus. The chemical profile of supercritical extracts of T. obliquus was analyzed by ultra-high-performance liquid chromatography-high-resolution mass spectrometry with electrospray ionization (UHPLC-ESI-HRMS). Moreover, the impact of ScCO₂ on the microbiological and metal profile of the biomass was monitored. The application of the pre-treatment increased the extraction yield approximately three-fold compared to the control. In the obtained extracts (control and pre-treated extracts), the identified components belonged to triacylglyceroles, fatty acid derivatives, diacylglycerophosphocholines and diacylglycerophosphoserines, pigments, terpenes, and steroids. Triacylglycerols (65%) were the most dominant group of compounds in the control extract. The pre-treatment decreased the percentage of triacylglycerols to 2%, while the abundance of fatty acid derivatives was significantly increased (82%). In addition, the pre-treatment led to an increase in the percentages of carotenoids, terpenoids, and steroids. Furthermore, it was determined that ScCO₂ extraction reduced the number of microorganisms in the biomass. Considering its microbiological and metal profiles, the biomass after ScCO₂ can potentially be used as a safe and important source of organic compounds.