Microwave assisted extraction of secondary metabolites from plants: Current status and future directions

A green extraction method for agar with improved thermal stability and water holding capacity

The conventional agar extraction method has drawbacks such as high energy consumption, low yield, poor quality, and possible residual harmful factors, which greatly limit its application in high-end fields such as biomedicine and high-end materials. This work explored a new freezing-thawing-high-temperature coupling technique for agar extraction. It increased the yield and the strength of agar by 10.6 % and 13.7 %, respectively, as compared to direct high-temperature extraction of agar (HA). The greater molecular weight and lower sulfate content of agar obtained from freeze-thaw cycles combined with high temperature extraction (FA) may be attributed to the desulfurization effect caused by freeze-thaw cycles and the preservation of the molecular chain structure. The reduction in sulfate content decreases the steric hindrance resistance of the polysaccharide chains, enhances their interactions, and promotes the regularity and density of the agar structure, while also improving its water retention and thermal stability. In conclusion, this research can offer a theoretical basis and guidance for the eco-friendly extraction of agar with improved agar characteristics and expended its applications.

Trends in extracting protein from microalgae Spirulina platensis, using innovative extraction techniques: mechanisms, potentials, and limitations

Microalgal, species are recognized for their high protein content, positioning them as a promising source of this macronutrient. Spirulina platensis, in particular, is noteworthy for its rich protein levels (70 g/100 g dw), which are higher than those of meat and legumes. Incorporating this microalgae into food can provide various benefits to human health due to its diverse chemical composition, encompassing high amount of protein and elevated levels of minerals, phenolics, essential fatty acids, and pigments. Conventional techniques employed for protein extraction from S. platensis have several drawbacks, prompting the exploration of innovative extraction techniques (IETs) to overcome these limitations. Recent advancements in extraction methods include ultrasound-assisted extraction, microwave-assisted extraction, high-pressure-assisted extraction, supercritical fluid extraction, pulse-electric field assisted extraction, ionic liquids assisted extraction, and pressurized liquid extraction. These IETs have demonstrated efficiency in enhancing protein yield of high quality while maximizing biomass utilization. This comprehensive review delves into the mechanisms, applications, and drawbacks associated with implementing IETs in protein extraction from S. platensis. Notably, these innovative methods offer advantages such as increased extractability, minimized protein denaturation, reduced solvent consumption, and lower energy consumption. However, safety considerations and the synergistic effects of combined extraction methods warrant further exploration and investigation of their underlying mechanisms.

Glycolipids biosurfactants production using low-cost substrates for environmental remediation: progress, challenges, and future prospects

The production of renewable materials from alternative sources is becoming increasingly important to reduce the detrimental environmental effects of their non-renewable counterparts and natural resources, while making them more economical and sustainable. Chemical surfactants, which are highly toxic and non-biodegradable, are used in a wide range of industrial and environmental applications harming humans, animals, plants, and other entities. Chemical surfactants can be substituted with biosurfactants (BS), which are produced by microorganisms like bacteria, fungi, and yeast. They have excellent emulsifying, foaming, and dispersing properties, as well as excellent biodegradability, lower toxicity, and the ability to remain stable under severe conditions, making them useful for a variety of industrial and environmental applications. Despite these advantages, BS derived from conventional resources and precursors (such as edible oils and carbohydrates) are expensive, limiting large-scale production of BS. In addition, the use of unconventional substrates such as agro-industrial wastes lowers the BS productivity and drives up production costs. However, overcoming the barriers to commercial-scale production is critical to the widespread adoption of these products. Overcoming these challenges would not only promote the use of environmentally friendly surfactants but also contribute to sustainable waste management and reduce dependence on non-renewable resources. This study explores the efficient use of wastes and other low-cost substrates to produce glycolipids BS, identifies efficient substrates for commercial production, and recommends strategies to improve productivity and use BS in environmental remediation.

Green Method Comparison and Optimization of Anthocyanin Recovery from "Sangiovese" Grape Pomace: A Critical Evaluation of the Design of Experiments Approach

Grape pomace is the main by-product obtained from wine production that is still enriched in bioactive compounds. Within a framework of waste/by-product reuse through a sustainable approach, various green methods were utilized in this work to recover anthocyanins from the pomace resulting from "Sangiovese" grape vinification. Ultrasound- and Microwave-Assisted Extractions (UAE and MAE) were coupled with the use of green solvents, such as acidified water, an ethanol/water mixture, and Natural Deep Eutectic Solvents (NaDES), and their efficacy was compared with that of a conventional method based on a methanol/acidified water mixture. The Total Anthocyanin Index ranged from 36.9 to 75.2 mg/g DW for UAE, and from 54.4 to 99.6 mg/g DW for MAE, while resulting in 47.1 mg/g DW for conventional extraction. A Design of Experiments (DoE) approach was applied to MAE, the most efficient technique. Temperature, time, and the solid-to-liquid ratio were set as X variables, while malvidin-3-O-glucoside content and antioxidant activity were used as response variables, measured by High-Performance Liquid Chromatography with Diode Array Detection (HPLC-DAD) and 2,2-Diphenyl-1-picrylhydrazyl (DPPH) assay, respectively. The correlation between temperature and time and the antioxidant activity of the extract was positive, while it was found to be negative when considering malvidin-3-O-glucoside concentration as a response variable. Thus, the optimal conditions in temperature, time and solid-to-liquid ratio were different depending on the chosen variable. The results underline the importance of selecting an accurate response when using the response surface methodology approach.

Microwave and ultrasound extraction of antioxidant phenolic compounds from Lantana camara Linn. leaves: Optimization, comparative study, and FT-Orbitrap MS analysis

INTRODUCTION

The species Lantana camara is used in folk medicine. The biological activities of this medicinal plant are attributable to the presence of various derivatives of triterpenoids and phenolic compounds present in its preparations, indicating excellent economic potential.

OBJECTIVE

In this study, the operational conditions of ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) were optimized using Box-Behnken design to improve the total phenolic content (TPC) recovered in hydroethanolic extracts of L. camara leaves.

MATERIAL AND METHODS

The TPC, total flavonoid content (TFC), and antioxidant activities of the hydroalcoholic extracts of L. camara, prepared by UAE and MAE under the optimized extraction conditions, were compared with those of the extracts obtained by conventional extraction methods.

RESULTS

Under the optimal conditions, the extracts obtained by UAE (35% ethanol, 25 min, and a solvent-to-solid ratio of 60:1 mL/g) and by MAE (53% ethanol, 15 min, and 300 W) provided high yields of 32.50% and 38.61% and TPC values of 102.89 and 109.83 mg GAE/g DW, respectively. The MAE extract showed the best results with respect to TPC, TFC, and antioxidant activities, followed by extracts obtained by UAE, Soxhlet extraction, decoction, maceration, and infusion, in that order.

CONCLUSION

The results obtained indicate that L. camara may be used as an important source of antioxidant phenolic compounds to obtain products with high biological and economic potential, especially when the extraction process is performed under appropriate conditions using MAE and/or UAE, employing environmentally friendly solvents such as water and ethanol.

Polysaccharides from Platycodon grandiflorum: A review of their extraction, structures, modifications, and bioactivities

Platycodon grandiflorum (P. grandiflorum) has long been used as a food and traditional herbal medicine. As a food, P. grandiflorum is often transformed into pickles for consumption, and as a traditional Chinese medicine, P. grandiflorum clears the lung, nourishes the pharynx, dispels phlegm, and discharges pus. Polysaccharides are among the main active components of P. grandiflorum. Recent literature has described the preparation, identification, and pharmacological activity of these polysaccharides. Studies have shown that these polysaccharides exhibit a variety of significant biological effects in vitro and in vivo, such as immune stimulation and antioxidant, anti-liver injury, anti-apoptosis and antitumour effects. However, there is no systematic summary of the related research articles on P. grandiflorum polysaccharide, which undoubtedly brings some difficulties to the future research. The purpose of this review is to comprehensively describe research progress on the extraction, purification, structural characterization, modification, and biological activity of P. grandiflorum polysaccharides. The shortcomings of recent research are summarized, further research on their biological activity is proposed to provide new reference value for the application of P. grandiflorum polysaccharides in drugs and health products in the future.

Supplementation with Moringa oleifera Lam leaf and seed flour during the pregnancy and lactation period of Wistar rats: Maternal evaluation of initial and adult neurobehavioral development of the rat progeny

ETHNOPHARMACOLOGICAL RELEVANCE

Moringa oleifera Lam. (M. oleifera) is a tree species of Indian origin popularly known as the "tree of life". In various cultures, it is used by pregnant women to increase milk production, yet studies on its effects during pregnancy and lactation are lacking.

AIM OF THE STUDY

To evaluate the nutraceutical aspects of flours produced from the leaves and seeds of M. oleifera, and to evaluate the effect of supplementation of pregnant Wistar rats during the gestation and lactation period, with the aim of studying the weight gain and neonatal parameters of the pregnant rats, as well as effects on the neurobehavioral development and memory in their offspring.

MATERIALS AND METHODS

The flour supplementation was conducted at a concentration of 100 mg per kg of animal body weight. For the memory tests, the Open Field Habituation test was performed and repeated after seven days. The Object Recognition test was conducted with the animal exposed to the open field in short and long familiarization sessions. The data obtained were analyzed using Kruskal-Wallis tests for non-parametric data and one-way and two-way ANOVA for parametric data.

RESULTS

Flour produced from both the leaf and seed of M. oleifera was found to contain significant amounts of nutrients (protein, fibre, carbohydrates, etc.), making them suitable for supplementation. The exposure of pregnant rats to M. oleifera leaf and seed flours did not affect weight gain, did not have harmful effects on the birth of offspring, and did not result in abortions or mutations in the offspring. Regarding the supplemented group's offspring, early maturation of the senses in the offspring compared to the control group was observed in all tests were conducted; indicating that supplementation positively impacted cognitive development. Further, the offspring of the supplemented rats presented reduced locomotion and greater exploration of new objects compared to the control group offspring, indicating positive effects on learning.

CONCLUSION

This study describes for the first time the beneficial effects on pregnant Wistar rats and their offspring of maternal supplementation with flour products from the leaves and seeds of M. oleifera.

Innovative Bioactive Products with Medicinal Value from Microalgae and Their Overall Process Optimization through the Implementation of Life Cycle Analysis-An Overview

Microalgae are being recognized as valuable sources of bioactive chemicals with important medical properties, attracting interest from multiple industries, such as food, feed, cosmetics, and medicines. This review study explores the extensive research on identifying important bioactive chemicals from microalgae, and choosing the best strains for nutraceutical manufacturing. It explores the most recent developments in recovery and formulation strategies for creating stable, high-purity, and quality end products for various industrial uses. This paper stresses the significance of using Life Cycle Analysis (LCA) as a strategic tool with which to improve the entire process. By incorporating LCA into decision-making processes, researchers and industry stakeholders can assess the environmental impact, cost-effectiveness, and sustainability of raw materials of several approaches. This comprehensive strategy will allow for the choosing of the most effective techniques, which in turn will promote sustainable practices for developing microalgae-based products. This review offers a detailed analysis of the bioactive compounds, strain selection methods, advanced processing techniques, and the incorporation of LCA. It will serve as a valuable resource for researchers and industry experts interested in utilizing microalgae for producing bioactive products with medicinal properties.

Sustainable utilization of apple pomace and its emerging potential for development of functional foods

Apple pomace, a byproduct of apple processing industry, possesses nutritional components which are of great interests for health aspects. Apple pomace is a good source of dietary fiber, minerals, carbohydrates, phenolic, and antioxidant compounds. These bioactive compounds can be extracted by different extraction techniques which have been comprehensively described in this review article. Furthermore, the incorporation of apple pomace as functional ingredients in different food products like bakery items, extrusion-based snacks, meat, dairy, and confectionary products to improve the commercial value and health benefits has been discussed briefly. This review article can be a helpful tool for industrialists, innovative researchers, and waste management authorities to manage the apple waste in an appropriate and sustainable way.

Microwave-assisted extraction in closed vessel in food analysis

Microwave-assisted extraction (MAE) is an important technique in analytical chemistry. It offers several advantages over traditional extraction methods, such as improved extraction efficiency, shorter extraction times, reduced solvent consumption, and enhanced analyte recovery. Using microwaves, heat is directly applied to the sample, leading to rapid and efficient extraction of target compounds by enhancing the solubility and diffusion of the target compounds, thus requiring lower solvent volume. Therefore, MAE can be considered a more environmentally friendly and cost-effective option facilitating the transition toward greener and more sustainable analytical chemistry workflows. This contribution systematically reviews the application of MAE to a selection of target compounds/compounds classes of relevance for food quality and safety assessment. As inclusion criteria, MAE active temperature control and molecularly-resolved characterization of the extracts were considered. Contents include a brief introduction of the principles of operation, available systems characteristics, and key parameters influencing extraction efficiency and selectivity. The application section covers functional food components (e.g., phenols, diterpenes, and carotenoids), lipids, contaminants (e.g., polycyclic aromatic hydrocarbons and mineral oil hydrocarbons), pesticides, veterinary drug residues, and a selection of process contaminants and xenobiotics of relevance for food safety.

Cold Plasma-Assisted Extraction of Phytochemicals: A Review

In recent years, there has been growing interest in bioactive plant compounds for their beneficial effects on health and for their potential in reducing the risk of developing certain diseases such as cancer, cardiovascular diseases, and neurodegenerative disorders. The extraction techniques conventionally used to obtain these phytocompounds, however, due to the use of toxic solvents and high temperatures, tend to be supplanted by innovative and unconventional techniques, in line with the demand for environmental and economic sustainability of new chemical processes. Among non-thermal technologies, cold plasma (CP), which has been successfully used for some years in the food industry as a treatment to improve food shelf life, seems to be one of the most promising solutions in green extraction processes. CP is characterized by its low environmental impact, low cost, and better extraction yield of phytochemicals, saving time, energy, and solvents compared with other classical extraction processes. In light of these considerations, this review aims to provide an overview of the potential and critical issues related to the use of CP in the extraction of phytochemicals, particularly polyphenols and essential oils. To review the current knowledge status and future insights of CP in this sector, a bibliometric study, providing quantitative information on the research activity based on the available published scientific literature, was carried out by the VOSviewer software (v. 1.6.18). Scientometric analysis has seen an increase in scientific studies over the past two years, underlining the growing interest of the scientific community in this natural substance extraction technique. The literature studies analyzed have shown that, in general, the use of CP was able to increase the yield of essential oil and polyphenols. Furthermore, the composition of the phytoextract obtained with CP would appear to be influenced by process parameters such as intensity (power and voltage), treatment time, and the working gas used. In general, the studies analyzed showed that the best yields in terms of total polyphenols and the antioxidant and antimicrobial properties of the phytoextracts were obtained using mild process conditions and nitrogen as the working gas. The use of CP as a non-conventional extraction technique is very recent, and further studies are needed to better understand the optimal process conditions to be adopted, and above all, in-depth studies are needed to better understand the mechanisms of plasma-plant matrix interaction to verify the possibility of any side reactions that could generate, in a highly oxidative environment, potentially hazardous substances, which would limit the exploitation of this technique at the industrial level.

Advances in extraction and purification of citrus flavonoids

Flavonoids are the representative active substances of citrus with various biological activities and high nutritional value. In order to evaluate and utilize citrus flavonoids, isolation and purification are necessary steps. This manuscript reviewed the research advances in the extraction and purification of citrus flavonoids. The structure classification, the plant and nutritional functions, and the biosynthesis of citrus flavonoids were summarized. The characteristics of citrus flavonoids and the selection of separation strategies were explained. The technical system of extraction and purification of citrus flavonoids was systematically described. Finally, outlook and research directions were proposed.

Ultrasound-Microwave Combined Extraction of Novel Polysaccharide Fractions from Lycium barbarum Leaves and Their In Vitro Hypoglycemic and Antioxidant Activities

Ultrasound-microwave combined extraction (UMCE), gradient ethanol precipitation, chemical characterization, and antioxidant and hypoglycemic activities of Lycium barbarum leaf polysaccharides (LLP) were systematically studied. The optimal conditions for UMCE of LLP achieved by response surface method (RSM) were as follows: microwave time of 16 min, ultrasonic time of 20 min, particle size of 100 mesh, and ratio of liquid to solid of 55:1. Three novel polysaccharide fractions (LLP₃₀, LLP₅₀, LLP₇₀) with different molecular weights were obtained by gradient ethanol precipitation. Polysaccharide samples exhibited scavenging capacities against ABTS and DPPH radicals and inhibitory activities against α-glucosidase and α-amylase. Among the three fractions, LLP₃₀ possessed relatively high antioxidant and hypoglycemic activities in vitro, which showed a potential for becoming a nutraceutical or a phytopharmaceutical for prevention and treatment of hyperglycemia or diabetes.

Current progress in valorization of food processing waste and by-products for pectin extraction

Food processing waste and by-products such as peel of citrus fruit, melon, mango, pineapple, etc. and fruit pomace can be utilized for manufacturing of several high-value products. Valorization of these waste and by-products for extraction of pectin, can help offset growing environmental concerns, facilitate value-addition of by-products and their sustainable uses. Pectin has many applications in food industries such as gelling, thickening, stabilizing, and emulsifying agent, and as a dietary fibre. This review elaborates on various conventional and advanced, sustainable pectin extraction techniques, and paints a comparative picture between them considering extraction efficiency, quality, and functionality of the pectin. Conventional acid, alkali, and chelating agents-assisted extraction have been profusely used for pectin extraction, but advanced extraction technologies e.g., enzyme, microwave, supercritical water, ultrasonication, pulse electric field and high-pressure extraction are preferred due to less energy consumption, better quality product, higher yield, and minimal or no generation of harmful effluent.

Extraction techniques for bioactive compounds of cannabis

Historically, cannabis has always constituted a component of the civilized world; archaeological discoveries indicate that it is one of the oldest crops, while, up until the 19th century, cannabis fibers were extensively used in a variety of applications, and its seeds comprised a part of human and livestock nutrition. Additional evidence supports its exploitation for medicinal purposes in the ancient world. The cultivation of cannabis gradually declined as hemp fibers gave way to synthetic fibers, while the intoxicating ability of THC eventually overshadowed the extensive potential of cannabis. Nevertheless, the proven value of certain non-intoxicating cannabinoids, such as CBD and CBN, has recently given rise to an entire market which promotes cannabis-based products. An increase in the research for recovery and exploitation of beneficial cannabinoids has also been observed, with more than 10 000 peer-reviewed research articles published annually. In the present review, a brief overview of the history of cannabis is given. A look into the classification approaches of cannabis plants/species as well as the associated nomenclature is provided, followed by a description of their chemical characteristics and their medically valuable components. The application areas could not be absent from the present review. Still, the main focus of the review is the discussion of work conducted in the field of extraction of valuable bioactive compounds from cannabis. We conclude with a summary of the current status and outlook on the topics that future research should address.

Kinetics of Microwave-Assisted Extraction Process Applied on Recovery of Peppermint Polyphenols: Experiments and Modeling

The aim of this work was to investigate the microwave-assisted extraction (MAE) kinetics of polyphenolic compounds from organic peppermint leaves. The phytochemicals of peppermint (Mentha piperita L.) are increasingly used in food technology due to their numerous biological activities. The processing of various plant materials by MAE and the production of high-quality extracts is becoming increasingly important. Therefore, the influence of microwave irradiation power (90, 180, 360, 600, and 800 W) on total extraction yield (Y), total polyphenols yield (TP), and flavonoid yield (TF) were investigated. Common empirical models (first-order, Peleg's hyperbolic, Elovich's logarithmic, and power-law model) were applied to the extraction process. The first-order kinetics model provided the best agreement with the experimental results in terms of statistical parameters (SS_er, R², and AARD). Therefore, the influences of irradiation power on the adjustable model parameters (k and C_eq) were investigated. It was found that irradiation power exerted a significant influence on k, while its influence on the asymptotic value of the response was negligible. The highest experimentally determined k (2.28 min^-1) was obtained at an irradiation power of 600 W, while the optimal irradiation power determined by the maximum fitting curve determination predicted the highest k (2.36 min^-1) at 665 W.

Comprehensive Analysis of Secondary Metabolites of Four Medicinal Thyme Species Used in Folk Medicine and Their Antioxidant Activities In Vitro

Thyme is a colloquial term for number of aromatic species belonging to the genus Thymus L., known for their expressed biological activities and therefore used worldwide for seasoning and in folk medicine. In the present paper, the content of the total polyphenols (TP), total flavonoids (TF), and antioxidant capacity were assessed in the extracts of four traditionally used thyme species. Moreover, a comprehensive metabolomic study of thyme bioactive compounds was performed, and the obtained data were processed using multivariate statistical tests. The results clearly demonstrated the positive correlation between the content of the TP, TF, and antioxidant activity, and TF was more significant than TP. The findings revealed that four selected thyme species contained 528 secondary metabolites, including 289 flavonoids and 146 phenolic acids. Thymus marschallianus had a higher concentration of active ingredients, which improve its antioxidant capacity. Differentially accumulated metabolites were formed by complex pathways such as flavonoid, flavone, flavonol, isoflavonoid, and anthocyanin biosynthesis. Correlation analysis showed that 59 metabolites (including 28 flavonoids, 18 phenolic acids, and 7 terpenoid compounds) were significantly correlated with obtained values of the antioxidant capacity. The results suggested that selected thyme species exhibit a great diversity in antioxidant-related components, whereas flavonoids may be responsible for the high antioxidant capacity of all studied thyme species. The present study greatly expands our understanding of the complex phytochemical profiles and related applications of selected medicinal plants.

Valorization of Fruit Waste for Bioactive Compounds and Their Applications in the Food Industry

The fruit production and processing sectors produce tremendous amounts of by-products and waste that cause significant economic losses and an undesirable impact on the environment. The effective utilization of these fruit wastes can help to reduce the carbon footprint and greenhouse gas emissions, thereby achieving sustainable development goals. These by-products contain a variety of bioactive compounds, such as dietary fiber, flavonoids, phenolic compounds, antioxidants, polysaccharides, and several other health-promoting nutrients and phytochemicals. These bioactive compounds can be extracted and used as value-added products in different industrial applications. The bioactive components extracted can be used in developing nutraceutical products, functional foods, or food additives. This review provides a comprehensive review of the recent developments in fruit waste valorization techniques and their application in food industries. The various extraction techniques, including conventional and emerging methods, have been discussed. The antioxidant and antimicrobial activities of the active compounds extracted and isolated from fruit waste have been described. The most important food industrial application of bioactive compounds extracted from fruit waste (FW) has been provided. Finally, challenges, future direction, and concluding remarks on the topic are summarized.

Optimization of Canolol Production from Canola Meal Using Microwave Digestion as a Pre-Treatment Method

Canola meal, the by-product of canola oil refining, is a rich source of phenolic compounds and protein. The meal, however, is primarily utilized as animal feed but represents an invaluable source of nutraceuticals. Of particular interest are the sinapates, sinapine and sinapic acid, with the decarboxylation of the latter to form canolol. Extracting these phenolics has been carried out using a variety of different methods, although there is an urgent need for environmentally safe and sustainable methods. Microwave-assisted solvent extraction (MAE), as a green extraction method, is receiving considerable interest. Its ease of use makes MAE one of the best methods for studying multiple solvents. The formation of canolol, from sinapine and sinapic acid, is primarily dependent on temperature, which favors the decarboxylation reaction. The application of MAE, using the MultiwaveTM 500 microwave system with green extractants, was undertaken to assess its ability to enhance the yield of sinapates and canolol. This study examined the effects of different pre-treatment temperature-time combinations of 140, 150, 160, and 170 °C for 5, 10, 15, 20, and 30 min on the extraction of canolol and other canola endogenous phenolic compounds. Total phenolic content (TPC), total flavonoid content (TFC), as well as metal ion chelation (MIC) and DPPH radical activity of the different extracts were assessed. The results confirmed that extractability of canolol was optimized with methanol at 151 °C and with ethanol at 170 °C with pre-treatment times of 15.43 min and 19.31 min, respectively. Furthermore, there was a strong positive correlation between TPC and TFC (p < 0.05) and a negative correlation between TFC and DPPH radical activity. Interestingly, no significant correlation was observed between MIC and DPPH. These results confirmed the effectiveness of MAE, using the novel MultiwaveTM 500 microwave instrument, to enhance the yield of canolol. This was accompanied by substantial improvements in the antioxidant activity of the different extracts and further established the efficacy of the current MAE method for isolating important natural phenolic derivatives for utilization by the nutraceutical industry.

A metabolomic platform to identify and quantify polyphenols in coffee and related species using liquid chromatography mass spectrometry

INTRODUCTION

Products of plant secondary metabolism, such as phenolic compounds, flavonoids, alkaloids, and hormones, play an important role in plant growth, development, stress resistance. The plant family Rubiaceae is extremely diverse and abundant in Central America and contains several economically important genera, e.g. Coffea and other medicinal plants. These are known for the production of bioactive polyphenols (e.g. caffeine and quinine), which have had major impacts on human society. The overall goal of this study was to develop a high-throughput workflow to identify and quantify plant polyphenols.

METHODS

First, a method was optimized to extract over 40 families of phytochemicals. Then, a high-throughput metabolomic platform has been developed to identify and quantify 184 polyphenols in 15 min.

RESULTS

The current metabolomics study of secondary metabolites was conducted on leaves from one commercial coffee variety and two wild species that also belong to the Rubiaceae family. Global profiling was performed using liquid chromatography high-resolution time-of-flight mass spectrometry. Features whose abundance was significantly different between coffee species were discriminated using statistical analysis and annotated using spectral databases. The identified features were validated by commercially available standards using our newly developed liquid chromatography tandem mass spectrometry method.

DISCUSSION

Caffeine, trigonelline and theobromine were highly abundant in coffee leaves, as expected. Interestingly, wild Rubiaceae leaves had a higher diversity of phytochemicals in comparison to commercial coffee: defense-related molecules, such as phenylpropanoids (e.g., cinnamic acid), the terpenoid gibberellic acid, and the monolignol sinapaldehyde were found more abundantly in wild Rubiaceae leaves.

Response Surface Methodology Optimization for Analytical Microwave-Assisted Extraction of Resveratrol from Functional Marmalade and Cookies

A novel analytical method based on microwave-assisted extraction has been successfully optimized and validated to determine resveratrol from functional marmalade and cookies. The optimization was performed using a Box−Behnken design with three factors: solvent composition (60−100% and 10−70% methanol in water for marmalade and cookies, respectively), microwave power (250−750 W), and solvent-to-solid ratio (20:5−60:5). The main and quadratic effects of solvent composition significantly contributed to the recovery values (p < 0.005) for both kinds of samples. Additionally, the solvent-to-solid ratio and the quadratic effect of microwave power also influenced the resveratrol recovery from functional marmalade. Hence, the optimum condition for resveratrol extraction from marmalade (80% methanol, 500 W, solvent-to-solid ratio 40:5) and cookies (80% methanol, 250 W, solvent-to-solid ratio 20:5) was proposed. The extraction kinetics (5−30 min) was then studied to clarify the complete recovery of resveratrol from the food matrices resulting in 15 min as the optimum extraction time. The developed method showed a satisfactory precision indicated by the coefficient of variation (CV) lower than 5.70% for both repeatability and intermediate precision. To check the matrix effects, the developed MAE procedures were applied to a number of commercial marmalade and cookies. The high-fat and fiber cookies resulted in overestimated values due to the interfering ingredients. As a final point, the methods successfully measured the stability of naturally present resveratrol in grape-derived products while preparing functional marmalade and cookies.

The recovery from agro-industrial wastes provides different profiles of anti-inflammatory polyphenols for tailored applications

Food and agro-industrial processing produce a great amount of side-stream and waste materials that are excellent sources of functional bioactive molecules such as phenolic compounds that recover them can be beneficial not only for food sustainability but also to human for many industrial applications such as flavor compounds and therapeutic applications such as antimicrobial and anti-inflammatory. The treatments and extraction techniques have major effects on the recovery of bioactive compounds. Along with the conventional extraction methods, numerous innovative techniques have been evolved and have been optimized to facilitate bioactive extraction more efficiently and sustainably. In this work, we have summarized the state-of-the-art technological approaches concerning novel extraction methods applied for five most produced crops in Italy; Grape Pomace (GP), Tomato Pomace (TP), Olive Pomace (OP), Citrus Pomace (CP), and Spent Coffee Grounds (SCG), presenting the extraction yield and the main class of phenolic classes, with the focus on their biological activity as an anti-inflammatory in vitro and in vivo studies via describing their molecular mechanism of action.

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.

The Disposition of Bioactive Compounds from Fruit Waste, Their Extraction, and Analysis Using Novel Technologies: A Review

Fruit waste contains several bioactive components such as polyphenols, polysaccharides, and numerous other phytochemicals, including pigments. Furthermore, new financial opportunities are created by using fruit ‘leftovers’ as a basis for bioactivities that may serve as new foods or food ingredients, strengthening the circular economy’s properties. From a technical standpoint, organic phenolic substances have become more appealing to industry, in addition to their application as nutritional supplements or functional meals. Several extraction methods for recovering phenolic compounds from fruit waste have already been published, most of which involve using different organic solvents. However, there is a growing demand for eco-friendly and sustainable techniques that result in phenolic-rich extracts with little ecological impact. Utilizing these new and advanced green extraction techniques will reduce the global crisis caused by fruit waste management. Using modern techniques, fruit residue is degraded to sub-zero scales, yielding bio-based commodities such as bioactive elements. This review highlights the most favorable and creative methods of separating bioactive materials from fruit residue. Extraction techniques based on environmentally friendly technologies such as bioreactors, enzyme-assisted extraction, ultrasound-assisted extraction, and their combination are specifically covered.

Chemical Structure, Hypoglycemic Activity, and Mechanism of Action of Selenium Polysaccharides

Selenium polysaccharides (Se-polysaccharides) are one of important forms of organic Se, in which selenium (Se) and polysaccharides are joined by covalent bonds. In the present review, recent progress in chemical structure and hypoglycemic activity of Se-polysaccharides is summarized. In particular, the mechanism underlying hypoglycemic capacity of Se-polysaccharides is discussed, and the relationship between hypoglycemic activity and chemical structure is analyzed. Besides, strategies for further research into chemical structure and hypoglycemic activity of Se-polysaccharides are proposed. Hypoglycemic activity of Se-polysaccharides is closely related to their inhibitory effect on α-amylase and α-glucosidase, influence on insulin signal pathway especially IRS-PI3K-Akt signaling pathway, and protection capacity against oxidative stress.

Edible Polymers and Secondary Bioactive Compounds for Food Packaging Applications: Antimicrobial, Mechanical, and Gas Barrier Properties

Edible polymers such as polysaccharides, proteins, and lipids are biodegradable and biocompatible materials applied as a thin layer to the surface of food or inside the package. They enhance food quality by prolonging its shelf-life and avoiding the deterioration phenomena caused by oxidation, humidity, and microbial activity. In order to improve the biopolymer performance, antimicrobial agents and plasticizers are also included in the formulation of the main compounds utilized for edible coating packages. Secondary natural compounds (SC) are molecules not essential for growth produced by some plants, fungi, and microorganisms. SC derived from plants and fungi have attracted much attention in the food packaging industry because of their natural antimicrobial and antioxidant activities and their effect on the biofilm’s mechanical properties. The antimicrobial and antioxidant activities inhibit pathogenic microorganism growth and protect food from oxidation. Furthermore, based on the biopolymer and SC used in the formulation, their specific mass ratio, the peculiar physical interaction occurring between their functional groups, and the experimental procedure adopted for edible coating preparation, the final properties as mechanical resistance and gas barrier properties can be opportunely modulated. This review summarizes the investigations on the antimicrobial, mechanical, and barrier properties of the secondary natural compounds employed in edible biopolymer-based systems used for food packaging materials.

Application of Green Technologies in Design-Based Extraction of Celastrus paniculatus (Jyotishmati) Seeds, SEM, GC-MS Analysis, and Evaluation for Memory Enhancing Potential

Background

The Celastrus paniculatus (CP), commonly known as Jyotishmati, is considered as “elixir of life” by Indian people for the prevention or management of many ailments. The seed powder and its extract have widely used commercially for the preparation of various Ayurvedic formulations for the improvement of memory. CP seeds were generally extracted by conventional extraction methods (CEMs) which are assumed to impact environment burden and also produce low extract yield. Green extraction with possible improvement in extract yield has always been the need of hour for selected medicinal plant.

Objective

In the present research, we aimed to optimize the different extraction factors in microwave and ultrasound-based extraction. The various extracts obtained in conventional and green methods are also evaluated for the possible improvement in memory enhancing potential.

Materials and Methods

The selected medicinal herb was extracted by CEM (maceration and percolation). In green methods such microwave-assisted extraction (MAE) and ultrasound assisted-extraction (UAE), various parameters were optimized using Box-Behnken design coupled with response surface methodology. The scanning electron microscopy (SEM) and gas chromatography–mass spectroscopy (GC-MS) analyses were also done to confirm the possible improvement in concentration of plant actives. The Swiss albino mice were used to evaluate memory enhancing potential of different extracts.

Results

At the optimized conditions MAE and UAE the extraction yield, total phenolic content (TPC) and Total flavonoid content (TFC) are significantly improved. The GC-MS analysis further confirms the improvement in concentration of certain fatty acid esters, pilocarpine, and steroidal compounds in optimized extracts. The optimized extracts also exhibited the significant improvement in behavioral parameters, oxidative stress-induced parameters, and acetylcholinesterase inhibitory potential.

Discussion and Conclusion

From the results, we can say that the application of green technologies in design-based extraction of selected herb not only significantly reduces the extraction time but also improves the extract yield and concentration of plant actives. In nutshell, it can be concluded that the green approaches for extraction of seeds of Celastrus paniculatus could be scale up at a commercial level to meet the rising demand for herbal extract.

Antimicrobial Properties of Bacterial Cellulose Films Enriched with Bioactive Herbal Extracts Obtained by Microwave-Assisted Extraction

The use of bacterial cellulose (BC) as scaffold for active biofilms is one of the most interesting applications, especially for the biomedical and food industries. However, there are currently few studies evaluating the potential of incorporating herbal extracts into various biomaterials, including BC. Thus, the aim of this study is to report a screening of the total phenolic content and antioxidant and antimicrobial activity of ethanolic extracts of oregano, rosemary, parsley, and lovage. At the same time, the bioactive potential of BC enriched with the four ethanolic extracts is described. Microwave-assisted extraction was used to extract bioactive compounds from the four selected herbs. The physical, mechanical, structural, and chemical properties of BC were also assessed. Next, BC was enriched with the extracts, and their effect against Escherichia coli, Staphylococcus aureus, and Candida albicans was evaluated. The results showed that the bioactivity of the herbs varied significantly, with rosemary extract being the most bioactive. The BC films possessed good mechanical properties, and a three-dimensional network fibrillar structure appropriate for ethanolic-extract incorporation. The BC samples enriched with rosemary extracts had the highest antibacterial activity against S. aureus, while E. coli. and C. albicans seemed to be resistant to all extracts, regardless of herbs.

Grape Pomace Valorization by Extraction of Phenolic Polymeric Pigments: A Review

In recent years there has been a growing concern about environmental pollution linked to the generation of agroindustrial waste. The wine industry generates approximately 8.49 million tons of grape pomace per year worldwide; this residue can be used to obtain compounds with biological activity. Grape pomace is a source of anthocyanins, pigments that have antioxidant properties and help prevent cardiovascular disease. The development of sustainable extraction, purification and identification techniques constitutes an important step in adding value to this waste. Therefore, the present research has focused on presenting a review of works carried out in the last years.

Oleanolic Acid: Extraction, Characterization and Biological Activity

Oleanolic acid, a pentacyclic triterpenoid ubiquitously present in the plant kingdom, is receiving outstanding attention from the scientific community due to its biological activity against multiple diseases. Oleanolic acid is endowed with a wide range of biological activities with therapeutic potential by means of complex and multifactorial mechanisms. There is evidence suggesting that oleanolic acid might be effective against dyslipidemia, diabetes and metabolic syndrome, through enhancing insulin response, preserving the functionality and survival of β-cells and protecting against diabetes complications. In addition, several other functions have been proposed, including antiviral, anti-HIV, antibacterial, antifungal, anticarcinogenic, anti-inflammatory, hepatoprotective, gastroprotective, hypolipidemic and anti-atherosclerotic activities, as well as interfering in several stages of the development of different types of cancer; however, due to its hydrophobic nature, oleanolic acid is almost insoluble in water, which has led to a number of approaches to enhance its biopharmaceutical properties. In this scenario, the present review aimed to summarize the current knowledge and the research progress made in the last years on the extraction and characterization of oleanolic acid and its biological activities and the underlying mechanisms of action.

Influence of the extraction method on the recovery of bioactive phenolic compounds from food industry by-products

Agro-foodindustries generate colossal amounts of non-edible waste and by-products, easily accessible as raw materials for up-cycling active phytochemicals. Phenolic compounds are particularly relevant in this field given their abundance in plant residues and the market interest of their functionalities (e.g. natural antioxidant activity) as part of nutraceutical, cosmetological and biomedical formulations. In "bench-to-bedside" achievements, sample extraction is essential because valorization benefits from matrix desorption and solubilization of targeted phytocompounds. Specifically, the composition and polarity of the extractant, the optimal sample particle size and sample:solvent ratio, as well as pH, pressure and temperature are strategic for the release and stability of mobilized species. On the other hand, current green chemistry environmental rules require extraction approaches that eliminate polluting consumables and reduce energy needs. Thus, the following pages provide an update on advanced technologies for the sustainable and efficient recovery of phenolics from plant matrices.

Bioactive compounds of mango (Mangifera indica): a review of extraction technologies and chemical constituents

Mango (Mangifera indica) has been recognized as a rich source of bioactive compounds with potential pharmaceutical and nutraceutical applications and has attracted increasing interest from research. Phytochemistry studies have demonstrated that phenolic compounds are one of the most important biologically active components of M. indica extracts. Ultrasound- and microwave-assisted extractions and supercritical fluids have been employed to obtain bioactive molecules, such as phenolic acids, terpenoids, carotenoids, and fatty acids. These phytochemicals exhibit antioxidant, antimicrobial, anti-inflammatory, and anticancer activity, and depending on the source (bark, leaves, seeds, flowers, or peel) and extraction method there will be differences in the structure and bioactivity. This review examines the bioactive compounds, extraction techniques, and biological function of different parts of M. indica of great importance as nutraceuticals and functional compounds with potential application as therapeutic agents and functional foods. © 2021 Society of Chemical Industry.

Comprehensive Analysis of Secondary Metabolites in the Extracts from Different Lily Bulbs and Their Antioxidant Ability

The genus Lilium contains more than 100 wild species and numerous hybrid varieties. Some species of them have been used as medicine and food since ancient times. However, the research on the active components and the medical properties of lilies has only focused on a few species. In this study, the total phenolic acid content (TPC), total flavonoid content (TFC), and antioxidant capacity of 22 representative lilies were systematically investigated. The results showed that the TPC, TFC and antioxidant activity were highly variable among different lilies, but they were significantly positively correlated. Hierarchical cluster analysis indicated that L. henryi and L. regale were arranged in one group characterized by the highest TPC, TFC and antioxidant capacity, followed by Oriental hybrids and Trumpet and Oriental hybrids. The traditional edible and medicinal lilies were clustered in low TPC, TFC and antioxidant capacity group. A total of 577 secondary metabolites, including 201 flavonoids, 153 phenolic acids, were identified in the five species with great differences in antioxidant capacity by extensive targeted metabonomics. Differentially accumulated metabolites (DAMs) analysis reviewed that the DAMs were mainly enriched in secondary metabolic pathways such as isoflavonoid, folate, flavonoid, flavone, flavonol, phenylpropanoid, isoquinoline alkaloid biosynthesis, nicotinate and nicotinamide metabolism and so on. Correlation analysis identified that 64 metabolites were significantly positively correlated with antioxidant capacity (r ≥ 0.9 and p < 0.0001). These results suggested that the genus Lilium has great biodiversity in bioactive components. The data obtained greatly expand our knowledge of the bioactive constituents of Lilium spp. Additionally, it also highlights the potential application of Lilium plants as antioxidants, functional ingredients, cosmetic products and nutraceuticals.

The isolation of water-soluble natural products - challenges, strategies and perspectives

Covering period: up to 2019Water-soluble natural products constitute a relevant group of secondary metabolites notably known for presenting potent biological activities. Examples are aminoglycosides, β-lactam antibiotics, saponins of both terrestrial and marine origin, and marine toxins. Although extensively investigated in the past, particularly during the golden age of antibiotics, hydrophilic fractions have been less scrutinized during the last few decades. This review addresses the possible reasons on why water-soluble metabolites are now under investigated and describes approaches and strategies for the isolation of these natural compounds. It presents examples of several classes of hydrosoluble natural products and how they have been isolated. Novel stationary phases and chromatography techniques are also reviewed, providing a perspective towards a renaissance in the investigation of water-soluble natural products.

Response Surface Optimization of Extraction Conditions and In Vitro Antioxidant and Antidiabetic Evaluation of an Under-Valued Medicinal Weed, Mimosa pudica

Mimosa pudica Linn is a well-known perennial herb and is traditionally used in ayurvedic medicine for the treatment of various illnesses. Despite its abundance in nature, the therapeutic potential of this invasive weed is deemed to be underappreciated in Malaysia. Previous studies have found an abundance of bioactive compounds associated with potent antioxidant properties in all parts of the plant. However, the optimum parameters required for the extraction of antioxidant compounds are still unknown. Therefore, the present study aimed to optimize the solvent extraction parameters of M. pudica using response surface methodology to enrich the accumulation of antioxidant compounds in the extracts. The effects of the optimized M. pudica extracts were then evaluated on the cell viability and glucose uptake ability in a 3T3-L1 adipocyte cell line. The highest total phenolic (91.98 mg of gallic acid equivalent per g of the dry extract) and total flavonoid content (606.31 mg of quercetin equivalent per g of the dry extract) were recorded when using 100% ethanol that was five-fold and three-fold higher, respectively, as compared to using 50% ethanol. The extract concentration required to achieve 50% of antioxidant activity (IC₅₀ value) was 42.0 µg/mL using 100% ethanol as compared to 975.03 µg/mL using 50% ethanol. The results indicated that the use of 100% ethanol solvent had the greatest impact on the accumulation of antioxidant compounds in the extract (p < 0.05). Cell viability assay revealed that all extract concentration treatments recorded a viability level of above 50%. Glucose uptake assay using 2-NBDG analog showed that the cells treated with 50 µg/mL extract combined with insulin were five-fold higher than the control group. Given the high antioxidant and antidiabetic properties of this plant, M. pudica can be easily highlighted as a plant subject of interest, which warrants further investigation for nutraceutical prospects.

Ultrasound extraction optimization for bioactive molecules from Eucalyptus globulus leaves through antioxidant activity

Antioxidant products present a very high added value and are demanded in the market. The optimization of their extraction is a high-stakes matter for both economic and environmental points of view. Ultrasound extraction has been considered one of the most promising methods, so the relative importance of key parameters may have decisive economic significance. For this reason, different parameters that have influence on the extraction capacity such as ultrasound power, time, temperature, pH and % ethanol in water have been studied to know the relationships between the independent parameters and their influence on the extraction from Eucalyptus globulus leaves. An experimental Box-Behnken factorial design and subsequent analysis by neural networks have been used. The relative influence of each parameter varies according to the nature of the extracted compound. In this regard, the higher capacity of extraction of the selected antioxidant compounds by means of the variation of the operation conditions can be facilitated. For all the studied compounds, temperature has been the most important parameter for their extraction. The relative content (%) of bioactive compounds (terpenes) in the optimized Eucalyptus globulus extract has been performed by GC-MS analysis.

Development of edible Thai rice film fortified with ginger extract using microwave-assisted extraction for oral antimicrobial properties

This study aimed to investigate microwave-assisted extraction (MAE) of dried ginger and to develop a rice-based edible film incorporating ginger extract. The optimal MAE conditions of 400 W microwave power and an extraction time of 1 min were determined using a 32 full factorial design. The optimized extract showed total phenolic compounds (TPC, 198.2 ± 0.7 mg gallic acid equivalent/g), antioxidant activity measured by DPPH (91.4 ± 0.6% inhibition), ABTS (106.4 ± 3.1 mg Trolox/g), and FRAP (304.6 ± 5.5 mg Trolox/g), and bioactive compounds including 6-gingerol (71.5 ± 3.6 mg/g), 6-shogaol (12.5 ± 1.0 mg/g), paradol (23.1 ± 1.1 mg/g), and zingerone (5.0 ± 0.3 mg/g). Crude extract of dried ginger showed antimicrobial activity against Streptococcus mutans DMST 18777, with a minimum inhibitory concentration and minimum bactericidal concentration of 0.5 and 31.2 mg/mL, respectively. The rice-based edible film incorporating 3.2% (w/v) ginger extract tested against S. mutans DMST 18777 had a mean zone of inhibition of 12.7 ± 0.1 mm. Four main phenolic compounds, 6-gingerol, 6-shogaol, paradol, and zingerone, and six volatile compounds, α-curcumene, α-zingiberene, γ-muurolene, α-farnesene, β-bisabolene, and β-sesquiphellandrene, were found in rice film fortified with crude ginger extract.