Parameters affecting microwave-assisted extraction of withanolides

Green approach for the recovery of secondary metabolites from the roots of Nardostachys Jatamansi (D. Don) DC using microwave radiations: Process optimization and anti-alzheimer evaluation

Nardostachys jatamansi (D. Don) DC is a highly valued medicinal herb that has been used in traditional medicinal systems for its remedial effects. Owing to the over-exploitation and unethical trade of N. jatamansi, the accelerating global demand of herbal products from this plant cannot be satisfied by the conventional extraction approach. In view of the progressive demand and incredible biological potential of herb, the present research was designed to optimize various extraction parameters for microwave-assisted extraction (MAE). The extracts obtained from the traditional and green approach were also assessed for the recovery of secondary metabolites and anti-Alzheimer's potential. Various parameters like microwave power, temperature, and time of irradiation were optimized for MAE using Box Behkhen Design (BBD) The scanning electron microscopy of different plant samples was also done to observe the effect of microwave radiations. Further, the metabolite profiling of different extracts was also done by gas chromatography-mass spectrometry (GC-MS) analysis. Also the different behavioral and biochemical parameters along with acetylcholinesterase (AChE) inhibitory potential were assessed to evaluate the anti-Alzheimer's potential. Optimized parameters for MAE were found to be as microwave power 187.04 W, temperature 90°C, and irradiation time 20 min. The extract yield in MAE was significantly enhanced as compared to the conventional method. Also, the total phenolic content and total flavonoid content (TFC) were improved pointedly from 32.13 ± 0.55 to 72.83 ± 1.1 mg of GAE/g of extract and 21.7 ± 0.85 to 39.21 ± 0.7 mg of RUE/g of extract respectively. Later, the GC-MS analysis of various extracts confirmed the enhancement in the concentration of various sesquiterpenes like jatamansone, spirojatamol, valerenal, valeric acid, globulol, nootkatone and steroidal compounds such as sitosterol, ergosterol, stigmastanone, etc. in the optimized extract. A significant improvement in anti-Alzheimer's potential was also observed owing to the better concentration of secondary metabolites in the optimized microwave extract. From the current findings, it could be concluded that the MAE could be a successful and green alternative for the extraction and recovery of secondary metabolites from the selected medicinal herb.

High-Quality Bioethanol and Vinegar Production from Saudi Arabia Dates: Characterization and Evaluation of Their Value and Antioxidant Efficiency

Dates are very rich in various nutritious compounds, especially reducing sugars. Sugars ensure both anaerobic and aerobic fermentation, carried out respectively for the production of bioethanol and vinegar. Currently, the world production of dates is constantly increasing owing to the significant improvement in production conditions following the continuous scientific and technological development of this field. The Kingdom of Saudi Arabia is one of the most important world producers of dates, occupying the second place by producing 17% of the total world production. This is why it has become a national priority to find new ways to exploit and further valorize dates and palm waste in the development of new and sustainable products. The present study was designed to explore the possible study of a variety of date palm by-products in the production of bioethanol and vinegar via Saccharomyces cerevisiae. Different parameters of bioethanol and vinegar production, including pH, time, fermentation temperature, and yeast concentration, were studied and optimized. Chemical, physicochemical, purity behavior, and antioxidant performance were carried out via NMR, FTIR, and antioxidant activity essays (TPC, DPPH, FRAP, and β-carotene bleaching test) with the aim to evaluate the potential of the bioethanol and vinegar samples extracted from date palm by-products. Khalas date vinegar revealed significantly more phenolic content (5.81 mg GAE/mL) (p < 0.05) than the different kinds of vinegar tested (Deglet Nour and Black dates; 2.3 and 1.67 mg GAE/mL, respectively) and the commercial vinegar (1.12 mg GAE/mL). The Khalas date vinegar generally showed a higher carotenoid value and better antioxidant activity than the other vinegars extracted from other date varieties and commercially available vinegar. The results confirmed the high quality of the bioethanol and vinegar products, and the efficiency of the developed production processes.

In Vitro Photoprotective, Anti-Inflammatory, Moisturizing, and Antimelanogenic Effects of a Methanolic Extract of Chrysophyllum lucentifolium Cronquist

UVB exposure causes DNA mutation and ROS generation, which lead to skin photoaging, skin wrinkling, skin sagging, and uneven skin pigmentation. ROS activate the NF-κB and MAPK signaling pathways leading to production of inflammatory molecules such as COX-2, collagen-degrading proteins such as matrix metalloproteinases (MMPs), and moisture-deficiency-related proteins such as hyaluronidases (HYALs). UVB exposure also induces irregular skin pigmentation though melanin overproduction, related to CREB transcription factor activity and transcription of melanogenesis genes. Here, we demonstrate that Chrysophyllum lucentifolium methanol extract (Cl-ME) has antioxidant activity; it dose-dependently decreased the expression of COX-2, MMP-1, MMP-9, HYAL-1, and HYAL-4 by downregulating the NF-κB (IKKα/β, IκBα) and MAPK (ERK, JNK, and p38) pathways and increased the expression of Col1a1, which encodes a protein important for maintaining skin elasticity. Cl-ME also showed promising antimelanogenic activity by decreasing the expression of CREB, a transcription factor, which in turn inhibited the expression of genes encoding tyrosinase, MITF, TYRP1, and TYRP2. In summary, a methanol extract of C. lucentifolium exhibited antiphotoaging and antimelanogenic activity and could be useful in the cosmeceutical industry.

Potential development of non-synthetic food additives from orange processing by-products—a review

Citrus is the largest fruit crop worldwide. Meanwhile, oranges account for 60 per cent of the total, with their main application in juice production. During orange juice production, only about 50 per cent of the fresh orange weight is transformed into juice, with the remaining 50 per cent comprised of residue (peel, pulp, seeds, orange leaves and whole orange fruits that do not reach the quality requirements). With the resulting tons of orange by-products, there has been an initiative to research possible ways to reutilize and revalorize citrus waste. Orange pomace, the by-product from juicing process, is currently used to extract the essential oils for fragrance and flavor, and a majority of the waste is used as cattle feed; however, these applications do not account for all of the waste or capture all of its potential value. Meanwhile, these by-products are put into landfills at the owner’s expense, and contribute to global warming through carbon emissions. On the other hand, orange by-products still contain many useful nutraceutical components, such as dietary fiber and phytochemicals, which could be utilized for value-added ingredients and new product development. Some research approaches in this area include the production of organic fertilizers and biofuels, or the extraction of essential oils, pectins, and antioxidant compounds. There is little information in the literature and in the food industry in terms of utilizing the orange pomace directly or with some simple treatments. Orange pomace may be used for food product development as a ‘clean-label’, non-synthetic preservative, which rationalizes this review.

Recent Advances in Microwave Assisted Extraction of Bioactive Compounds from Complex Herbal Samples: A Review

Microwaves are utilized for extraction of Phytoconstituents from complex herbal sample as a result of incredible research. Conventional extraction strategies are tedious and need more solvents and are no more relevant for thermal sensitive plant components. This review emphasize on the working and significance of microwave extraction technology in herbal research and medical field. The extraction step must be more yielding; quick, particular, not more solvent consuming, ensuring stability of thermolabile components and these features are available with microwave extraction method. In this nonconventional technology heat is created utilizing microwave energy. The important parameters that influence extraction efficiency are solvent properties, volume, duration of exposure, microwave control, system attributes, temperature and application were discussed in this article. The microwave assisted extraction, as green technology is contrasted with other extraction technique. This review is intended to discuss this green extraction technique along with its critical parameters for extracting bioactive compounds from complex plant matrices.

Impact of extraction techniques on antioxidant capacities and phytochemical composition of polyphenol-rich extracts

In this work, impact of extraction methods (maceration, decoction, MAE, and UAE) on TPC, antioxidant activity, and the mass fraction of phenolics in several plant extracts (Punica granatum, Juglans regia, Moringa oleifera, and Cassia fistula) was investigated. The results showed that, despite the nature of matrix, the highest values of TPC in all samples were obtained by MAE as follows: PP (18.92±0.11), ML (15.19±0.11), HL (12.69±0.16), and WS (12.80±0.11) mg GAEg^-1 respectively, and exhibited potent antioxidant activity (from 0.28±0.01 to 5.34±0.02mgGAEg^-1), representing sources of powerful antioxidants. The LC-MS² analysis revealed a wide range of phenolics, highlighting their content in phenolic acids, flavonoids and lignans. The presence of different phenol molecules demonstrated that the extraction method had influence on phytochemical profile. Finally, due to its high extraction efficiency, MAE was the more effective extraction technique.

Comparison of heat and mass transfer of different microwave-assisted extraction methods of essential oil from Citrus limon (Lisbon variety) peel

Dried and fresh peels of Citrus limon were subjected to microwave‐assisted hydrodistillation (MAHD) and solvent‐free microwave extraction (SFME), respectively. A comparison was made between MAHD and SFME with the conventional hydrodistillation (HD) method in terms of extraction kinetic, chemical composition, and antioxidant activity. Higher yield results from higher extraction rates by microwaves and could be due to a synergy of two transfer phenomena: mass and heat acting in the same way. Gas chromatography/mass spectrometry (GC/MS) analysis did not indicate any noticeable differences between the constituents of essential oils obtained by MAHD and SFME, in comparison with HD. Antioxidant analysis of the extracted essential oils indicated that microwave irradiation did not have adverse effects on the radical scavenging activity of the extracted essential oils. The results of this study suggest that MAHD and SFME can be termed as green technologies because of their less energy requirements per ml of essential oil extraction.

Microwave-Assisted Extraction Studies of Target Analyte Artemisinin from Dried Leaves of Artemisia annua L

Artemisia annua L. (Asteraceae) is an annual herb native of Asia. This plant has been used for many centuries in traditional Chinese medicine for the treatment of fever and malaria. Conventional methods for the extraction of artemisinin from A. annua including solvent extraction, Soxhlet extraction, and heat reflux extraction are characterized by long extraction times and the consumption of large volume of solvents. A simple, rapid, and precise microwave-assisted extraction process was optimized for fast sample preparation for the faster quantitative determination of artemisinin, potential new generation antimalarial drug, from dried leaves of Artemisia annua L. A simple experiment was designed for the optimization of the appropriate solvent under same extraction conditions. The selected appropriate solvent was then standardized for various different extraction variables. The major parameters studied showed effects on extraction efficiency including processing time, strength of microwave, moisture content, volume and nature of the solvent. The most favorable conditions were obtained by using plant material of 25 mesh (particle size) extracted with acetone for 120 seconds at 160 W (i.e., 20% of total power). Quantitative analysis was performed using thin-layer chromatography coupled with a densitometer (TLC densitometry). The results showed that MAE can be used as an efficient and rapid method for the extraction of the active components from plants.

Optimisation of a microwave-assisted method for extracting withaferin A from Withania somnifera Dunal. using central composite design

INTRODUCTION

Recently, there have been growing attention on the modification and optimisation of new extraction and quantification methods, caused by the lack of environmentally friendly methodologies for the extraction of phytochemicals from complex matrices. In the case of pharmaceutical compounds, not only the extraction procedure but also the analysis method should be efficient, precise, fast and easy.

OBJECTIVES

The essential pharmaceutical characteristics and trace concentration of withanolides led us to modify and optimise the previously reported extraction and quantification procedure for withaferin A (WA) as a candidate for withanolides.

MATERIAL AND METHODS

The WA from the air-dried aerial part of Withania somnifera Dunal. was extracted using a microwave-assisted extraction (MAE) technique. Four variables affecting the extraction procedure were optimised using the central composite design approach. The method of high-performance thin-layer chromatography assay was validated and applied for the quantification of each experiment.

RESULTS

The optimum values of factors were: extraction time (150 s), extraction temperature (68°C) and 17 mL of methanol : water in the ratio 25 : 75 as extracting solvent. The solvent system consisted of ethyl acetate : toluene : formic acid : 2-propanol (7.0 : 2.0 : 0.5 : 0.5, v/v/v/v), and densitometric scanning at 220 nm was applied for the analysis. The dynamic linear range, LOD, LOQ and recovery with the inter-day, and intra-day RSDs of the developed method indicated the validity of the method.

CONCLUSION

A pressurised MAE method for extracting WA from the plant's aerial part was optimised using factorial-based design. The net effect of time, temperature, solvent volume and its ratio suggests that the yield of WA increases until each factor reaches its optimum value, and decreases with further increase in temperature or solvent ratio.

Natural product isolation

Since the 1990s, interest in natural product research has increased considerably. Following several outstanding developments in the areas of separation methods, spectroscopic techniques, and sensitive bioassays, natural product research has gained new attention for providing novel chemical entities. This updated review deals with sample preparation and purification, recent extraction techniques used for natural product separation, liquid-solid and liquid-liquid isolation techniques, as well as multi-step chromatographic operations. It covers examples of papers published since the NPR review 'Modern separation methods' by Marston and Hostettmann,1 with major emphasis on methods developed and the research undertaken since 2000.

Microwave-assisted extraction of the main phenolic compounds in flaxseed

A microwave-assisted extraction (MAE) method has been applied for the first time to the extraction of the main lignan, secoisolariciresinol diglucoside (SDG), and the two most concentrated hydroxycinnamic acid glucosides in flaxseed. The effects of microwave power, extraction time and alkaline treatment were investigated. It was shown that a 3 min MAE resulted in an SDG content of 16.1+/-0.4 mg/g, a p-coumaric acid glucoside content of 3.7+/-0.2 mg/g and a ferulic acid glucoside content of 4.1+/-0.2 mg/g. These values were compared with those obtained using conventional extraction methods and the results demonstrated that MAE was more effective in terms of both yield and time consumption.

Influence of plant matrix on microwave-assisted extraction process. The case of diosgenin extracted from fenugreek (Trigonella foenum-graecum L.)

A focused microwave-assisted extraction method was developed for the extraction of diosgenin from fenugreek (Trigonella foenum-graecum) seeds, air-dried and fresh leaves and air-dried roots. Several experimental parameters were studied, including extraction time, microwave power applied and percentage of 2-propanol in the extraction mixture as well as their interactions, in order to optimize the extraction efficiency. The two latter parameters were found to be the most important. Response surface modelling was used to predict the extraction yield of diosgenin in selected matrices. The analysis of diosgenin in crude extracts was carried out by capillary gas chromatography-mass spectrometry (GC-MS).

Optimization of microwave-assisted solvent extraction for volatile organic acids in tobacco and its comparison with conventional extraction methods

In the present study, a new method using microwave-assisted solvent extraction (MASE) technique followed directly GC analysis was developed for the extraction of volatile organic acids (VOAs) in tobacco. The MASE conditions (heating time, volume of extracting solvent and extraction temperature) were optimized by means of an orthogonal array design (OAD) procedure. The results suggested that extractant, temperature and heating time were statistically the most significant factors. The extracts were directly analyzed with capillary GC operating in splitless-injection mode on an Agilent HP-FFAP capillary column. Under optimum operating conditions, MASE showed significantly better recoveries than those obtained by the conventional extraction method (ultrasonic and reflux extraction), ranging from 90.6% to 103.2%. In addition, a drastic reduction of the extraction time (20 min versus 4h) and solvent consumption (20 mL versus 100 mL) was achieved with an outstanding reproducibility (CV < or =5%).

Solvent effects on focused microwave assisted extraction of polyphenolic acids from Eucommia ulmodies

An open microwave-assisted extraction system was used to extract gallic acid, protocatechuic acid, chlorogenic acid and caffeic acid from Eucommia ulmodies. The effect of extraction variables, especially solvent, on the recoveries of these polyphenolic compounds was investigated using factorial design. As extracting solvent for these compounds, methanol produced a higher recovery than pure water. For straight chain alcohol solvents, the lower the carbon number, the higher the recoveries of the polyphenolic acids. The optimal ratio of methanol:water:glacial acetic acid in the solvent mixture used in microwave-assisted extraction was 2:8:0.3 (v/v) and this solvent could be directly used as the mobile phase in HPLC separation without additional intermittent treatment as reported in literature. The extraction under the condition of 50% microwave power and 30 s irradiation at a solvent:sample ratio of 10 (mL/g) was found to be the most advantageous. The repeatability test of extraction and chromatographic analysis was satisfactory for the analysis of these polyphenolic compounds.

Effects of moisture content in cigar tobacco on nicotine extraction. Similarity between soxhlet and focused open-vessel microwave-assisted techniques

The effects of tobacco moisture on nicotine yield were investigated in this study. Soxhlet and microwave-assisted techniques were used to extract nicotine from cigar fillers of varying moisture contents (5-20%), using a polar (methanol) and a non-polar (isooctane) solvent. The extracts were analyzed by a gas chromatograph equipped with a flame-ionization detector. For both extraction techniques, higher nicotine yields were consistently obtained with methanol than with isooctane from the same samples. Solubility of nicotine salts in methanol but not in isooctane is the major cause of this observation. Moreover, pronounced effects of the tobacco moisture content on extraction efficiency were observed with isooctane but not with methanol. For microwave assisted extraction (MAE) with isooctane, nicotine yield increased from 3 to 70% as the moisture level in tobacco was raised from 3 to 13%, and leveled off thereafter. Similar observations were made with Soxhlet extraction. While MAE results were rationalized by the known cell-rupture process, a mechanism based on the interaction between the solvents and the structural components of the plant cells has been proposed to account for the observations made with Soxhlet extraction.

Recent extraction techniques for natural products: microwave-assisted extraction and pressurised solvent extraction

In the last 10 years there has been an increased interest in using techniques involving microwave-assisted extraction and pressurised solvent extraction in analytical laboratories. This review gives a brief overview of both methods, and reports on their application to the extraction of natural products. The influence of parameters such as the nature of the solvent and volume, temperature, time and particle size of the matrix is discussed. Through numerous examples, it is demonstrated that both techniques allow reduced solvent consumption and shorter extraction times, while the extraction yields of the analytes are equivalent to or even higher than those obtained with conventional methods.