Optimization of pressure-enhanced solid-liquid extraction of flavonoids from Flos Sophorae and evaluation of their antioxidant activity

Bioactivity-Guided Isolation of Secondary Metabolites with Antioxidant and Antimicrobial Activities from Camellia fascicularis

Camellia fascicularis has important ornamental, medicinal, and food values, which also have tremendous potential for exploiting bioactivities. We performed the bioactivity-guided (antioxidant and antimicrobial) screening of eight fractions obtained from the ethyl acetate phase of C. fascicularis. The antioxidant activity was measured by DPPH, ABTS, and FRAP, and the antibacterial activity was measured by the minimum inhibitory concentration (MIC) of Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus. The results of bioactivity-guided isolation indicated that the major antioxidant compounds in the ethanolic extracts of C. fascicularis may be present in fractions (Fr.) (A-G, obtained after silica gel column chromatography). Fr. (D-I, obtained after silica gel column chromatography) is a fraction of C. fascicularis with antimicrobial activity. The structures of compounds were determined by spectral analysis and nuclear magnetic resonance (NMR) combined with the available literature on secondary metabolites of C. fascicularis leaves. In this study, 17 compounds were identified, including four phenolics (1, 3-4, and 14), a phenylpropane (2), five terpenoids (5-7, 12, and 15), four flavonoids and flavonoid glycosides (8-10 and 16), and two lignins (13 and 17). Compounds 4-7, 13-15, and 17 were isolated from the genus Camellia for first time. The remaining compounds were also isolated from C. fascicularis for first time. The evaluation of antioxidant and antimicrobial activities revealed that compounds 1, 3, 9, 11, and 17 exhibited higher antioxidant activity than the positive control drug (ascorbic acid), and compounds 4, 8, 10, and 13 showed similar activity to ascorbic acid. The other compounds had weaker or no significant antioxidant activities. The MIC of antibacterial activity for compounds 4, 7, and 11-13 against P. aeruginosa was comparable to that of the positive control drug tetracycline at 125 µg/mL, and other secondary metabolites inhibited E. coli and S. aureus at 250-500 µg/mL. This is also the first report of antioxidant and antimicrobial activities of compounds 5-7, 13-15, and 17. The results of the study enriched the variety of secondary metabolites of C. fascicularis and laid the foundation for further research on the pharmacological efficacy and biological activity of this plant.

Secondary Metabolites with Antioxidant and Antimicrobial Activities from Camellia fascicularis

Camellia fascicularis has important ornamental, medicinal, and food value. It also has tremendous potential for exploiting bioactivities. However, the bioactivities of secondary metabolites in C. fascicularis have not been reported. The structures of compounds were determined by spectral analysis and nuclear magnetic resonance (NMR) combined with the available literature on secondary metabolites of C. fascicularis leaves. In this study, 15 compounds were identified, including 5 flavonoids (1-5), a galactosylglycerol derivative (6), a terpenoid (7), 4 lignans (8-11), and 4 phenolic acids (12-15). Compounds 6-7 and 9-12 were isolated from the genus Camellia for the first time. The remaining compounds were also isolated from C. fascicularis for the first time. Evaluation of antioxidant and antimicrobial activities revealed that compounds 5 and 8-11 exhibited stronger antioxidant activity than the positive drug ascorbic acid, while compounds 7, 13, and 15 showed similar activity to ascorbic acid. The minimum inhibitory concentration (MIC) of antibacterial activity for compounds 5, 7, 9, 11, and 13 against Pseudomonas aeruginosa was comparable to that of the positive control drug tetracycline at a concentration of 62.50 µg/mL; other secondary metabolites inhibited Escherichia coli and Staphylococcus aureus at concentrations ranging from 125-250 µg/mL.

Vaccinium myrtillus L. Leaf Waste as a Source of Biologically Potent Compounds: Optimization of Polyphenol Extractions, Chemical Profile, and Biological Properties of the Extracts

The aims of the present research include (1) optimization of extraction from Vaccinium myrtillus leaf waste via investigation of plant material:medium ratio, extraction medium, and extraction period, employing extractions at room and high temperatures, or using ultrasound and microwaves (M, HAE, UAE, and MAE, respectively), (2) physicochemical characterization, and (3) investigation of extract biological potential. The statistical analysis revealed that optimal levels of parameters for the greatest polyphenolic yield were a proportion of 1:30 g/mL, ethyl alcohol 50% (v/v) during 2 min of microwave irradiation. By LC-MS analysis, 29 phenolic components were detected; HAE showed the highest richness of almost all determined polyphenols, while chlorogenic acid and quercetin 3-O-glucuronide were dominant. All extracts showed a high inhibition of Staphylococcus aureus growth. The effect of different parameters on extracts' antioxidant capacity depended on the used tests. The extracts also showed a stimulative influence on keratinocyte viability and anti-inflammatory activity (proven in cell-based ELISA and erythrocyte stabilization assays). The extraction procedure significantly affected the extraction yield (MAE ≥ maceration ≥ UAE ≥ HAE), whereas conductivity, density, surface tension, and viscosity varied in a narrow range. The presented research provides evidence on the optimal extraction conditions and technique, chemical composition, and antioxidant, antimicrobial, anti-inflammatory, and keratinocyte viability properties of bilberry extracts for potential applications in pharmacy and cosmetics.

Trends in extracting Agro-byproducts' phenolics using non-thermal technologies and their combinative effect: Mechanisms, potentials, drawbacks, and safety evaluation

The agro-food industries generate significant waste with adverse effects. However, these byproducts are rich in polyphenols with diverse bioactivities. Innovative non-thermal extraction (NTE) technologies (Naviglio extractor®, cold plasma (CP), high hydrostatic pressure (HHP), pulse-electric field (PEF), ultrasound-assisted extraction (UAE), etc.) and their combinative effect (integrated UAE + HPPE, integrated PEF + enzyme-assisted extraction, etc.) could improve polyphenolic extraction. Hence, this article comprehensively reviewed the mechanisms, applications, drawbacks, and safety assessment of emerging NTE technologies and their combinative effects in the last 5 years, emphasizing their efficacy in improving agro-byproduct polyphenols' extraction. According to the review, incorporating cutting-edge NTE might promote the extraction ofmore phenolic extractfrom agro-byproducts due to numerous benefits,such as increased extractability,preserved thermo-sensitive phenolics, and low energy consumption. The next five years should investigate combined novel NTE technologies as they increase extractability. Besides, more research must be done on extracting free and bound phenolics, phenolic acids, flavonoids, and lignans from agro by-products. Finally, the safety of the extraction technology on the polyphenolic extract needs a lot of studies (in vivo and in vitro), and their mechanisms need to be explored.

Full-Length Transcriptome Sequencing and Comparative Transcriptomic Analyses Provide Comprehensive Insight into Molecular Mechanisms of Flavonoid Metabolites Biosynthesis in Styphnolobium japonicum

Styphnolobium japonicum L. is a commonly consumed plant in China, known for its medicinal and nutritional benefits. This study focuses on the medicinal properties influenced by flavonoid metabolites, which vary during flower development. Utilizing full-length transcriptome sequencing on S. japonicum flowers, we observed changes in gene expression levels as the flowers progressed through growth stages. During stages S1 and S2, key genes related to flavonoid synthesis (PAL, 4CL, CHS, F3H, etc.) exhibited heightened expression. A weighted gene co-expression network analysis (WGCNA) identified regulatory genes (MYB, bHLH, WRKY) potentially involved in the regulatory network with flavonoid biosynthesis-related genes. Our findings propose a regulatory mechanism for flavonoid synthesis in S. japonicum flowers, elucidating the genetic underpinnings of this process. The identified candidate genes present opportunities for genetic enhancements in S. japonicum, offering insights into potential applications for improving its medicinal attributes.

Protocols for extraction and purification of rutin from leafy by-products of asparagus (Asparagus officinalis) and characterization of the purified product

Valorization of asparagus leafy by-products as a potential source of rutin through selected extraction and purification protocols was investigated. Protocol resulting in the highest extraction yield was first selected. Crude extract was subject to purification via multiple liquid-liquid back extraction using ethanol, methanol or water as a solvent; selection of the most appropriate purification solvent was made based on rutin solubility. The proposed purification protocol yielded yellow-color crystals, which were characterized by fluorescence microscopy, Fourier-transform infrared spectroscopy and liquid chromatography-mass spectrometry to confirm them as rutin. Purity of rutin was confirmed by ultra-performance liquid chromatography at 97.6%; yield of the purified rutin was determined to be 78.2%. The remaining rutin (21.8%) was found in the liquids collected at various stages of purification; such liquids could be recycled using the same purification process. The proposed protocols are simple, yet effective for rutin extraction and purification from asparagus leafy by-products.

From Aloe vera Leaf Waste to the Extracts with Biological Potential: Optimization of the Extractions, Physicochemical Characterization, and Biological Activities

In the study, the optimization of the extraction from Aloe vera leaf waste was performed via varying solid-to-solvent ratio, solvent type, extraction time, and technique (maceration, heat-, ultrasound-, and microwave-assisted extractions-HAE, UAE, and MAE, respectively). The optimal extraction conditions for achieving the highest polyphenol content are a 1:30 ratio, 70% ethanol, and 30 min of HAE. Total flavonoid and protein contents were significantly higher in the extract from MAE, while total condensed tannin content was the highest in HAE. LC-MS analysis quantified 13 anthraquinone and chromone compounds. The variations in the FT-IR spectra of the extracts obtained by different extraction procedures are minor. The influence of extraction conditions on the antioxidant ability of the extracts depended on applied antioxidant assays. The extracts possessed medium inhibition properties against Staphylococcus aureus and weak inhibitory activity against Enterococcus feacalis. The extracts had stimulative effect on HaCaT cell viability. Regarding the extraction yield, there was a significant difference between the used extraction techniques (MAE > HAE > maceration and UAE). The presented study is an initial step in the production of polyphenol-rich extracts from A. vera leaf waste aimed to be used for the potential preparation of pharmaceutical and cosmetic formulations for the skin.

High-Pressure Processing for Sustainable Food Supply

Sustainable food supply has gained considerable consumer concern due to the high percentage of spoilage microorganisms. Food industries need to expand advanced technologies that can maintain the nutritive content of foods, enhance the bio-availability of bioactive compounds, provide environmental and economic sustainability, and fulfill consumers’ requirements of sensory characteristics. Heat treatment negatively affects food samples’ nutritional and sensory properties as bioactives are sensitive to high-temperature processing. The need arises for non-thermal processes to reduce food losses, and sustainable developments in preservation, nutritional security, and food safety are crucial parameters for the upcoming era. Non-thermal processes have been successfully approved because they increase food quality, reduce water utilization, decrease emissions, improve energy efficiency, assure clean labeling, and utilize by-products from waste food. These processes include pulsed electric field (PEF), sonication, high-pressure processing (HPP), cold plasma, and pulsed light. This review describes the use of HPP in various processes for sustainable food processing. The influence of this technique on microbial, physicochemical, and nutritional properties of foods for sustainable food supply is discussed. This approach also emphasizes the limitations of this emerging technique. HPP has been successfully analyzed to meet the global requirements. A limited global food source must have a balanced approach to the raw content, water, energy, and nutrient content. HPP showed positive results in reducing microbial spoilage and, at the same time, retains the nutritional value. HPP technology meets the essential requirements for sustainable and clean labeled food production. It requires limited resources to produce nutritionally suitable foods for consumers’ health.

Combination of Flos Sophorae and chili pepper as a nitrite alternative improves the antioxidant, microbial communities and quality traits in Chinese sausages

The main issue remains finding a nitrite alternative able to provide its multiple functions. Flos Sophorae exerts antioxidant and prebiotic actions, chili pepper has potent coloring capacity, thus this study investigated whether combination of Flos Sophorae and chili pepper could address the multiple activities of nitrite in Chinese sausages. Dry-fermented sausages were prepared: control and four treatments added with 150 mg/kg sodium nitrite (Nit), 0.2% Flos Sophorae (FS), 1% chili pepper (CP), and combination of 0.2% Flos Sophorae and 1% chili pepper (FS + CP). Results indicated that FS, CP and FS + CP had higher moisture, antioxidant activity and numbers of beneficial Staphylococcus and yeasts Candida, and lower numbers of Escherichia coli and harmful fungi, while FS had lower redness and harder texture than control. Their combination inhibited the declines of capsanthin and antioxidant capacity with ripening time, further improved microbiological communities compared with CP, and resulted in higher redness, similar color score and bacterial community, less lipid oxidation and softer texture compared with Nit. These results suggested that Flos Sophorae in combination with chili pepper could replace the nitrite's contribution to red curing color and microbiological communities, and effectively hinder lipid oxidation in Chinese sausages.

Recent advances in continuous extraction of bioactive ingredients from food-processing wastes by pulsed electric fields

The food processing produces a great amount of wastes that are rich in nutrients. Extraction is the first and most important step in recovery and purification of active ingredients from these wastes. The traditional extraction technologies are known to be laborious and time-consuming, require large volumes of organic solvent, have high temperature and energy costs, and obtain relatively low extraction efficiency. In recent 10 years, a novel, efficient and green extraction method, pulsed electric fields (PEFs) continuous extraction, which is emerging non-thermal food-processing technology, has shown great promise in extracting these food wastes. This work gives an overview of development in the use of PEF continuous extraction for obtaining bioactive ingredients from food-processing wastes. The technology is described in detail with respect to the mechanism, equipment, critical parameters. The protocols and applications of the technology in the extraction of food-processing wastes are comprehensively summarized. Finally, the degradation of bioactive ingredients, industrial applications, problem of novel food, consumer acceptance, and future trends of the technology are discussed. The PEF continuous extraction is considered as the ideal technology of high efficiency and low temperature for natural ingredients extraction. The technology possesses many remarkable potential applications in the food-processing industries compared to the conventional extraction methods.

Optimization of the extraction, preliminary characterization, and anti-inflammatory activity of crude polysaccharides from the stems of Trapa quadrispinosa

A novel method was developed using pressurized-assisted extraction (PAE) to efficiently extract crude Trapa quadrispinosa polysaccharides (TQCPS) from plant stems, and the extraction process was optimized using response surface methodology (RSM). At a water-to-material fixed ratio of 30 mL g⁻¹, the highest yield of 3.72 ± 0.13% was obtained under the optimum conditions of extraction time of 32 min, extraction temperature at 47 °C, and extraction pressure at 1.87 Mpa, which were in agreement with the predicted value of 3.683%. Compared with conventional hot water extraction (HWE), the PAE method remarkably enhanced the extraction yield with the further advantages of short extraction time and low extraction temperature. The preliminary characteristics of TQCPS were analyzed through UV-vis, FT-IR, and chemical composition analysis. In subsequent anti-inflammatory studies, when RAW 264.7 mouse macrophage cells were treated with TQCPS, satisfactory anti-inflammatory activity was observed, and TQCPS significantly suppressed the release of nitric oxide (NO), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) and synchronously restrained the expression levels of inducible nitric oxide synthase (iNOS), TNF-α, and IL-6 mRNA induced by lipopolysaccharide (LPS) in a dose-dependent manner. These results indicate that PAE is a technology that can be used for efficient extraction of polysaccharides from medicinal plants, and TQCPS can be explored as a potential anti-inflammatory agent in medicine.

The high-yield TQCPS extracted by PAE presented good anti-inflammatory activity.

Identification and Antioxidant Activity of Flavonoids Extracted from Xinjiang Jujube (Ziziphus jujube Mill.) Leaves with Ultra-High Pressure Extraction Technology

In this study, the ultra-high pressure extraction (UHPE) conditions for obtaining the maximum flavonoid yield from Xinjiang jujube (Ziziphus jujuba Mill.) leaves (XJL) were optimized by response surface methodology (RSM). Box–Behnken design (BBD) was applied to evaluate the effects of four variables (extraction temperature, pressure, time and liquid-to-solid ratio) on flavonoid yield. The results showed that the optimal flavonoid yield (25.45 ± 0.21 mg/g) was derived at 50.0 °C, 342.39 MPa, 11.56 min, and a liquid-to-solid ratio of 43.95 mL/g. Eight compounds were tentatively identified and quantified as kaempferol and quercetin glycosides with UPLC-ESI-MS. Compared to ultrasound-assisted extraction (UAE), UHPE can obtain higher concentrations of total flavonoids and stronger DPPH and ABTS radical-scavenging activities in a much shorter time. Therefore, UHPE is an alternative to UAE for obtaining flavonoids from XJL, which may be an optional method for large-scale industrial flavonoid extraction from XJL.

Isolation and Purification of Two Isoflavones from Hericium erinaceum Mycelium by High-Speed Counter-Current Chromatography

High-speed counter-current chromatography (HSCCC) was used to separate and purify two isoflavones for the first time from Hericium erinaceum (H. erinaceum) mycelium using a two-phase solvent system composed of chloroform-dichloromethane-methanol-water (4:2:3:2, v/v/v/v). These two isoflavones were identified as genistein (4′,5,7-trihydroxyisoflavone, C₁₅H₁₀O₅) and daidzein (4′,7-dihydroxyisoflavone, C₁₅H₁₀O₄), using infrared spectroscopy (IR), electro-spary ionisation mass (ESI-MS), ¹H-nuclear magnetic resonance (NMR) and ¹³C-NMR spectra. About 23 mg genistein with 95.7% purity and 18 mg daidzein with 97.3% purity were isolated from 150 mg ethanolic extract of H. erinaceum mycelium. The results demonstrated that HSCCC was a feasible method to separate and purify genistein and daidzein from H. erinaceum mycelium.

Continuous high voltage electrical discharge extraction of flavonoids from peanut shells based on "annular gap type" treatment chamber

A continuous high voltage electric discharge (HVED) extraction system with "annular gap type" treatment chamber was for the first time designed and optimized for flavonoids extraction from peanut shells, and a comparison with the HVED system with the "converged electric field type" treatment chamber and warm maceration was carried out. The optimal conditions for the "annular gap type" design were: 25% ethanol concentration as solvent, 30:1 mL/g liquid to solid ratio, 13 kV peak pulse voltage and 60 mL/min flow rate of material. Under these conditions, the maximum yield of flavonoids was 0.948 ± 0.014%. Compared with the "converged electric field type" design and warm maceration, the "annular gap type" design possessed shorter duration and higher efficiency for the flavonoids extraction, and had no effects on the composition of extracted flavonoids. The results showed that the "annular gap type" design was a promising alternative method in extracting flavonoids from peanut shells.

Sequential Combination of Microwave- and Ultrasound-Assisted Extraction of Total Flavonoids from Osmanthus fragrans Lour. Flowers

Microwave-assisted and ultrasound-assisted extraction assays were used to isolate total flavonoids (TF) from Osmanthus fragrans flowers. The effects of the solid-liquid ratio, ethanol concentration, microwave power, microwave extraction time, ultrasonic power and ultrasonic extraction time on the yield of TF were studied. A sequential combination of microwave- and ultrasound-assisted extraction (SC-MUAE) methods was developed, which was subsequently optimized by Box-Behnken design-response surface methodology (BBD-RSM). The interaction effects of the ethanol concentration (40-60%), microwave extraction time (5-7 min), ultrasonic extraction time (8-12 min) and ultrasonic power (210-430 W) on the yield of TF were investigated. The optimum operating parameters for the extraction of TF were determined to be as follows: ethanol concentration (48.15%), microwave extraction time (6.43 min), ultrasonic extraction time (10.09 min) and ultrasonic power (370.9 W). Under these conditions, the extraction yield of TF was 7.86 mg/g.

Response Surface Optimized Infrared-Assisted Extraction and UHPLC Determination of Flavonoid Types from Flos Sophorae

Single-factor experiment and Box-Behnken design were applied to optimize the infrared-assisted extraction (IRAE) of rutin, quercetin, kaempferol, and isorhamnetin from Flos sophorae. Four factors (extract solvent, solid-liquid ration, extraction time, infrared power) affecting the extraction yield of flavonoids were studied. Under optimized conditions the extraction yield was 33.199 ± 0.24 mg/g, which substantially improved, compared with heating reflux extraction (HRE) and ultrasonic-assisted extraction (UAE), while extraction time was only 9 min. The eluents were rich in 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azobis (2-methyl-propionamidine) dihydrochloride radical scavenging potential (IC₅₀ of DPPH: 53.44 ± 0.01 μg/mL, oxygen radical absorbance capacity (ORAC): 3785.83 ± 52 μmol/g) than the extracts obtained by HRE and UAE. In addition, an ultra-high performance liquid chromatography method was optimized for the identification and quantification of the tested flavonoids, and the method was validated based on its correlation coefficient (r), reproducibility (RSD, n = 5), and recovery values, which were 0.9994–0.9998, 0.74–1.83%, and 97.78–102.94%, respectively. These results confirmed that high extraction yield of flavonoids results in stronger antioxidant values and response surface methodology optimization of IRAE is a promising alternative to traditional extraction techniques for flavonoids from medicinal plants.

Baccaurea angulata fruit juice ameliorates altered hematological and biochemical biomarkers in diet-induced hypercholesterolemic rabbits

Hypercholesterolemia is an important risk factor linked to the alteration of blood hematology and clinical chemistry associated with the development and progression of atherosclerosis. Previous studies have demonstrated the safety and potential health benefits of Baccaurea angulata (BA) fruit. We hypothesized that the oral administration of BA fruit juice could ameliorate the alteration in the hematological and biochemical biomarkers of diet-induced hypercholesterolemic rabbits. The aim of this study was to investigate the effects of different doses of BA juice on the hematological and biochemical biomarkers in normo- and hypercholesterolemic rabbits. Thirty-five healthy adult New Zealand White rabbits were assigned to seven different groups for 90days of diet intervention. Four atherogenic groups were fed a 1% cholesterol diet and 0, 0.5, 1.0, and 1.5mL of BA juice per kg of rabbit daily. The other three normal groups were fed a commercial rabbit pellet diet and 0, 0.5, and 1.0mL of BA juice per kg of rabbit daily. Baseline and final blood samples after 90days of repeated administration BA juice were analyzed for hematological parameters while serum, aortic and hepatic lysates were analyzed for lipid profiles and other biochemical biomarkers. The alteration of the hemopoietic system, physiological changes in serum and tissues lipid profiles and other biochemicals resulting from the consumption of a high-cholesterol diet were significantly (P<.05) ameliorated by the administration of BA juice. Improvements of the biomarkers in rabbits were dose-dependent, markedly enhanced at the highest dose of juice (1.5mL/kg/day). The results suggest potential health benefits of the antioxidant-rich BA fruit juice against hypercholesterolemia-associated hematological and biochemical alterations in the rabbit.