Optimization of artemisinin extraction from Artemisia annua L. with supercritical carbon dioxide + ethanol using response surface methodology

Green Extraction of Volatile Terpenes from Artemisia annua L

In the present study, the extraction of volatile terpenes from A. annua with supercritical CO2 (sc-CO2) was optimized by a full factorial design procedure and compared with conventional distillation. The influence of pressure (100-220 bar) and temperature (40-60 °C) on sc-CO2 extraction was investigated to obtain extracts rich in the desired components while maintaining a high yield. Extraction yields (m/m) varied from 0.62% (130 bar/40 °C) to 1.92% (100 bar/60 °C). Monoterpenes were the most abundant constituents of the sc-CO2 extracts, among which artemisia ketone (16.93-48.49%), camphor (3.29-18.44%) and 1,8-cineole (4.77-11.89%) dominated. Arteannuin B (3.98-10.03%) and β-selinene (1.05-7.42%) were the major sesquiterpenes. Differences were found between the terpene profiles of the sc-CO2 extracts and the essential oils obtained by conventional hydrodistillation and steam distillation, as well as between the distilled essential oils. Our results demonstrate the optimal conditions for the rapid and effective supercritical extraction of certain monoterpenes and sesquiterpenes from A. annua, which have promising antimicrobial, antioxidant, antiviral, anti-inflammatory and antitumor properties.

Enhanced Antimalarial Activity of Extracts of Artemisia annua L. Achieved with Aqueous Solutions of Salicylate Salts and Ionic Liquids

Artemisinin, a drug used to treat malaria, can be chemically synthesized or extracted from Artemisia annua L. However, the extraction method for artemisinin from biomass needs to be more sustainable while maintaining or enhancing its bioactivity. This work investigates the use of aqueous solutions of salts and ionic liquids with hydrotropic properties as alternative solvents for artemisinin extraction from Artemisia annua L. Among the investigated solvents, aqueous solutions of cholinium salicylate and sodium salicylate were found to be the most promising. To optimize the extraction process, a response surface method was further applied, in which the extraction time, hydrotrope concentration, and temperature were optimized. The optimized conditions resulted in extraction yields of up to 6.50 and 6.44 mg·g-1, obtained with aqueous solutions of sodium salicylate and cholinium salicylate, respectively. The extracts obtained were tested for their antimalarial activity, showing a higher efficacy against the Plasmodium falciparum strain compared with pure (synthetic) artemisinin or extracts obtained with conventional organic solvents. Characterization of the extracts revealed the presence of artemisinin together with other compounds, such as artemitin, chrysosplenol D, arteannuin B, and arteannuin J. These compounds act synergistically with artemisinin and enhance the antimalarial activity of the obtained extracts. Given the growing concern about artemisinin resistance, the results here obtained pave the way for the development of sustainable and biobased antimalarial drugs.

Three-Dimensional Printing Parameter Optimization for Salmon Gelatin Gels Using Artificial Neural Networks and Response Surface Methodology: Influence on Physicochemical and Digestibility Properties

This study aimed to optimize the 3D printing parameters of salmon gelatin gels (SGG) using artificial neural networks with the genetic algorithm (ANN-GA) and response surface methodology (RSM). In addition, the influence of the optimal parameters obtained using the two different methodologies was evaluated for the physicochemical and digestibility properties of the printed SGG (PSGG). The ANN-GA had a better fit (R2 = 99.98%) with the experimental conditions of the 3D printing process than the RSM (R2 = 93.99%). The extrusion speed was the most influential parameter according to both methodologies. The optimal values of the printing parameters for the SGG were 0.70 mm for the nozzle diameter, 0.5 mm for the nozzle height, and 24 mm/s for the extrusion speed. Gel thermal properties showed that the optimal 3D printing conditions affected denaturation temperature and enthalpy, improving digestibility from 46.93% (SGG) to 51.52% (PSGG). The secondary gel structures showed that the β-turn structure was the most resistant to enzymatic hydrolysis, while the intermolecular β-sheet was the most labile. This study validated two optimization methodologies to achieve optimal 3D printing parameters of salmon gelatin gels, with improved physicochemical and digestibility properties for use as transporters to incorporate high value nutrients to the body.

Comparative Study of the Essential Oil and Hydrosol Composition of Sweet Wormwood (Artemisia annua L.) from Serbia

The most abundant volatile compounds of sweet wormwood (Artemisia annua L.) essential oil were artemisia ketone (25.4 %) and trans-caryophyllene (10.2 %), followed by 1,8-cineole, camphor, germacrene D and β-selinene. The major volatile compounds in the hydrosol were camphor (25.1 %), 1,8-cineole (20.5 %) and artemisia ketone (10.7 %), followed by trans-pinocarveol and yomogi alcohol. Tested essential oil was rich in oxygenated monoterpenes and sesquiterpene hydrocarbons, while the former were identified as the major class of volatile compounds in the hydrosol, due to higher water solubility. Classification of all sweet wormwood chemotypes, according to essential oil composition, in available literature (17 studies and 61 accessions) could be done according to four chemotypes: artemisia ketone+artemisia alcohol (most abundant), artemisia ketone, camphor and nonspecific chemotype. According to this classification, essential oil of sweet wormwood from this study belongs to artemisia ketone (content varied between 22.1 and 55.8 %). Bearing in mind that hydrosols are a by-product of industrial production of essential oils, and the fact that sweet wormwood hydrosol has high contents of camphor, 1,8-cineole and artemisia ketone, there is a great potential for the use of this aromatic plant primary processing waste product as a water replacement in cosmetic industry, beverages flavoring, for food preservation, as well as in post-harvest pre-storage treatments in organic agriculture.

Homogenate Extraction of Dihydroartemisinin from Artemisia Hedinii and Its Antifungal Activity

BACKGROUND

Artemisia hedinii is a well-known traditional Chinese medicine. It can be used to extract dihydroartemisinin (DHA).

OBJECTIVE

The purpose of this study was to explore the optimal conditions for the homogenate extraction of DHA from A. hedinii and the antifungal activity of DHA.

METHODS

In this study, single-factor experiments and the response surface method were used to determine the optimal extraction conditions of crude extract and DHA. The method of spore germination was used to study the antifungal activity of DHA on Alternaria alternata.

RESULTS

The optimal conditions were found as follows: ratio of liquid to material 22 mL/g; extraction time 60 s; and soaking time 34 min. Under these conditions, extraction yield of DHA was (1.76 ± 0.04%). When the concentrations of crude extract were 0.5 and 8 mg/mL, the spore germination inhibition rates of A. alternata were (17.00 ± 2.05%) and (92.56 ± 2.01%), which were 3.34 and 1.15 times that of the DHA standard, respectively.

CONCLUSIONS

Homogenate extraction technology is a fast and efficient method for extracting DHA from A. hedinii. The crude extract has significant antifungal activity against A. alternata and is inexpensive, providing possible DHA usage in the prevention and treatment of plant pathogenic fungi.

HIGHLIGHTS

The optimum conditions of the extraction of DHA from A. hedinii by homogenate extraction were obtained. DHA has antifungal activity against A. alternata. Compared with pure DHA, the crude extract has stronger antifungal activity against A. alternata.

Valorization of Tropical Biomass Waste by Supercritical Fluid Extraction Technology

The inception of sustainable and cleaner extraction technology has paved the way for the innovative development of nonconventional extractions, such as supercritical fluid extraction, apart from conventional extraction counterparts. The concept of biomass waste-to-wealth for the conversion of biomass waste or by-products into value-added products for diversified applications had piqued the prominent interest of researchers and industry players, especially with the abundance of biomass resources readily available in tropical regions that have yet to be tapped into to reach their full potential. In this paper, a critical review of the developments of supercritical fluid technology from its initial inception up to commercialized scalability, including its limitations, extraction of potential tropical biomass wastes for various types of applications, such as biopesticides, bio-repellents, phenolics, and lipids for biofuel, and its role in circular bioeconomy and sustainable development approaches, are discussed in detail.

Supercritical Fluid Chromatography development of a predictive analytical tool to selectively extract bioactive compounds by supercritical fluid extraction and pressurised liquid extraction

Selective extraction is a great concern in the field of natural products. The interest is to apply specific conditions favouring the solubility of targeted secondary metabolites and avoiding the simultaneous extraction of unwanted ones. Different ways exist to reach selective extractions with suited conditions. These conditions can be determined from experimental studies through experimental design, but a full experimental design takes time, energy, and uses plant samples. Prediction from varied solubility models can also be applied allowing a better understanding of the final selected conditions and eventually less experiments. The aim of this work was to develop and use a chromatographic model to determine optimal extraction conditions without the need for numerous extraction experiments. This model would be applied on the selective extraction of the desired antioxidant compounds in rosemary leaves (rosmarinic and carnosic acids) vs chlorophyll pigments to limit the green colour in extracts. This model was achieved with Supercritical Fluid Chromatography (SFC) and then applied to Supercritical Fluid Extraction (SFE) and Pressurised Liquid Extraction (PLE) assays. SFC models predicted low solubility of chlorophylls for low (5%) and high (100%) percentage of solvent in carbon dioxide. Also, low solubility was predicted with acetonitrile solvent compared to methanol or ethanol. This was confirmed with different extractions performed using SFE with different percentages of solvent (5, 30, and 70%) and with the three solvents used in the SFC models (acetonitrile, methanol and ethanol). Also extractions using PLE were carried out using the same neat solvents in order to confirm the SFC models obtained for 100% of solvent. Globally, extractions validated the SFC models. Only some differences were observed between ethanol and methanol showing the complexity of plant extraction due to matrix effect. For all these extracts, the content of carnosic acid and rosmarinic acid was also monitored and selective extraction conditions of bioactive compounds could be determined.

Recent advances of green pretreatment techniques for quality control of natural products

A few advancing technologies for natural product analysis have been widely proposed, which focus on decreasing energy consumption and developing an environmentally sustainable manner. These green sample pretreatment and analysis methods following the green Analytical Chemistry (GAC) criteria have the advantage of improving the strategy of chemical analyses, promoting sustainable development to analytical laboratories, and reducing the negative effects of analysis experiments on the environment. A few minimized extraction methodologies have been proposed for replacing the traditional methods in the quality evaluation of natural products, mainly including solid-phase microextraction (SPME) and liquid phase microextraction (LPME). These procedures not only have no need for large numbers of samples and toxic reagent, but also spend a small amount of extraction and analytical time. This overview aims to list out the main green strategies on the application of quality evaluation and control for natural products in the past 3 years.

A review on the latest advances in extraction and analysis of artemisinin

INTRODUCTION

Artemisinin (1), a well-known natural antimalarial drug, is a sesquiterpene lactone that contains a unique peroxide bridge. Since its discovery, the amount of research into the analysis of artemisinin has increased considerably, and it has been further intensified since the Noble Prize win by Tu Youyou in the year 2015 for the discovery of artemisinin.

OBJECTIVE

To review literature on the extraction and analysis of artemisinin, published during 2017-present, and to present an appraisal of those methods.

METHODOLOGY

Extensive literature search was carried out which involved, but not limited to, the use of, various databases, like Web of Knowledge, PubMed and Google Scholar, and relevant published materials including published books. The keywords used, in various combinations, with artemisinin being present in all combinations, in the search were artemisinin, Artemisia annua, analysis, extraction, quantitative, qualitative and quality control.

RESULTS

During the period covered in this review, several methods of analysis of artemisinin have been reported, the most of which were liquid chromatography (LC)-based methods. However, the use of new methods like near-infrared analysis, fluorometirc analysis and molecular imprinting, and a significant increase in the use of computational tools have been observed. Mainly several methods involving supercritical fluid extraction and ultrasound-assisted extraction of artemisinin have dominated the extraction area.

CONCLUSIONS

Newer analytical tools, as well as improved protocols for the known analytical tools, for qualitative and quantitative determination of artemisinin (1), have been made available by various researchers during the period covered by this review. Supercritical fluid extraction and ultrasound-assisted extraction are still the methods of choice for extraction of artemisinin.