Deep eutectic solvent-based ultrasound extraction of bioactive flavonoids from Coreopsis tinctoria Nutt.: Process optimization, HPLC analysis, and preliminary bioactivity evaluation

In the present work, the ultrasonic-assisted extraction (UAE) of total flavonoids (TF) from Pteris cretica L. was optimized by response surface methodology (RSM) on the basis of a single-factor experiment. The optimized UAE parameters were as follows: Ethanol concentration 56.74%, extraction time 45.94 min, extraction temperature 74.27 °C, and liquid/solid ratio 33.69 mL/g. Under the optimized conditions, the total flavonoids yield (TFY) was 4.71 ± 0.04%, which was higher than that obtained by heat reflux extraction (HRE). The extracts were further analyzed by HPLC, and five major flavonoids, including rutin, quercitrin, luteolin, apigenin, and luteolin-7-O-glucoside, were identified and quantified. Furthermore, the results of the antioxidant test showed that the TF extract obtained under optimized UAE conditions exhibited good 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS+•), nitric oxide radical (NO•) scavenging activities, and ferrous ion (Fe2+) chelating capacity, with IC50 values of 74.49, 82.92, 89.12, and 713.41 µg/mL, respectively. Results indicated that the UAE technique developed in this work was an efficient, rapid, and simple approach for the extraction of flavonoids with antioxidant activity from P. cretica.

A novel microwave-assisted steam distillation approach for separation of essential oil from tree peony (Paeonia suffruticosa Andrews) petals: Optimization, kinetic, chemical composition and antioxidant activity

Characterization of flavonoids from Dryopteris erythrosora and evaluation of their antioxidant, anticancer and acetylcholinesterase inhibition activities

Tartary buckwheat flavonoids have a variety of effects on anti‐inflammatory, anti‐oxidation, as well as anti‐tumor and are valuable for academic research and industrial application. Helicobacter pylori (H. pylori) infection is associated with various gastrointestinal diseases in humans, and an increase in its resistance has led to the failure of many drugs. In this study, we quantified the main monomers of tartary buckwheat (Fagopyrum Tataricum (L.) Gaertn.) bran flavonoids extract through HPLC analysis. Then, we investigated the anti‐H. pylori activity and the effect on cell inflammation of tartary buckwheat flavonoids extract and its four main flavonoid monomers (rutin, quercetin, kaempferol, and nicotiflorin). The results showed that tartary buckwheat flavonoids extract and its four flavonoid monomers could inhibit the growth of H. pylori and down‐regulate the expression of proinflammatory factors IL‐6, IL‐8, and CXCL‐1 in H. pylori‐induced GES‐1 cells. Moreover, we also confirmed that tartary buckwheat flavonoids extract could reduce the expression of virulence factor gene of H. pylori. In summary, tartary buckwheat can alleviate the cell inflammation induced by H. pylori, which provides a theoretical basis for the development of tartary buckwheat healthcare products.

Total flavonoids were extracted from Ziziphi Spinosae Semen (ZSS) by applying microwave-assisted extraction with low eutectic solvent (DES) as the extractant. This study investigated the effect of 21 different components of DES on the yield of total flavonoids in ZSS. The results revealed that the DES system, which consists of choline chloride and lactic acid with a molar ratio of 2:1, achieved the best flavonoid extraction efficiency. Based on the single-factor test, response surface methodology was used to optimize and determine the optimal process conditions for the extraction of total flavonoids from ZSS with deep eutectic solvent. The maximum flavonoids yields were achieved at 36.24 mg/g within the 50% DES water content, a microwave power of 600 W, a microwave time of 60 s, a liquid-solid ratio of 1:28 mg/mL, an extraction time of 66 min, and an extraction temperature of 93 °C. The macroporous resin was used to recover flavonoids from extracts. The DM130 resin showed higher adsorption/desorption performance. The total flavonoids of ZSS were extracted using the recovered DES with a yield of 32.58 mg/g and a high reusability of 89.9%.

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

Hydrogen incorporation into solvents can improve the extraction of phenolics, flavonoids, anthocyanins, and antioxidants: A case-study using red beetroot

Psidium guajava leaves are rich in health-promoting flavonoids compounds. For better utilization of the resource, the ultrasound-assisted aqueous extraction was investigated using Box-Behnken design under response surface methodology. A high coefficient of determination (R2 = 97.8%) indicated good agreement between the experimental and predicted values of flavonoids yield. The optimal extraction parameters to obtain the highest total flavonoids yield were ultrasonic power of 407.41 W, extraction time of 35.15 min, and extraction temperature of 72.69 °C. The average extraction rate of flavonoids could reach 5.12% under the optimum conditions. Besides, HPLC analysis and field emission scanning electron microscopy indicated that the ultrasonic treatment did not change the main component of flavonoids during extraction process and the higher flavonoids content was attributed by the disruption of the cell walls of guava particles. Thus, the extraction method could be applied successfully for large-scale extraction of total flavonoids from guava leaves.

Xanthoceras sorbifolium Bunge leaves (XLs) are valuable resources rich in phytochemicals, especially in flavonoids, but they are rarely exploited and utilized. The purpose of this paper is to reduce the waste of XLs resources (usually used as agricultural waste) and extract the high added value of active ingredients from XLs. The extraction of flavonoids from XLs using ultrasonic-assisted extraction (UAE) was reported. Response surface methodology (RSM) was used to adopt different ultrasonic conditions such as ethanol concentration, liquid:solid ratio, and ultrasonic power. In addition, the chemical structures were identified using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and HPLC. Response surface analysis indicated the optimal level of ethanol concentration, liquid:solid ratio, and ultrasonic power as 71.49%, 13.87 mL/g, and 157.49 W respectively for the maximum response of total flavonoids (5.52 ± 0.23%), which fitted well with the predicted value (5.68 ± 0.17%). In addition, the extracts from XLs exhibited potent antioxidant activity using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) ammonium salt (ABTS). The potent antioxidant activity of flavonoids from XLs is beneficial for their application in the food and drug industry, which will facilitate the rise of the added value of the flavonoids from XLs. Myricetin, rutin, and epicatechin, which may be responsible for the antioxidant activity of the extracts from XLs, were confirmed by UPLC-MS/MS and HPLC analysis. The extracted flavonoids can be used as a natural antioxidant additive to food products.

The potential of tobacco waste as a viable source of medicinally important flavonoids like rutin has been investigated. Three flavonoids, apigenin, quercetin and rutin, have been isolated from waste tobacco leaves, and their identities have been confirmed by UV-visible, 1 H-NMR and 13 C-NMR spectroscopy. By using analytical HPLC, the amount of rutin present in the tobacco leaves, before and after fermentation, and also in waste tobacco leaves, has been determined as 1.5, 0.5 and 0.6%, respectively.

Combination of supercritical CO2 and ultrasound for flavonoids extraction from Cosmos sulphureus: Optimization, kinetics, characterization and antioxidant capacity

Givotia rottleriformis has been used in the indigenous systems of medicine for the treatment of inflammatory diseases like rheumatism and psoriasis. In order to evaluate this information, antipsoriatic activity of three flavonoids isolated from the ethanol extract of the bark of Givotia rottleriformis were investigated using in-vitro and in-vivo model, namely Rutin (I), Luteolin-7-O-β-D-Glucuronide (II) and Kaempferol 3-O-[2-O-(6-O-feruloyl)-β-D-glucopyranosyl]-β-D-galactopyranoside (III). The extract was standardized by HPLC using chemical markers. In vitro antiproliferant assay of the ethanol extract and isolated flavonoids were done on HaCaT cell lines. Mouse tail test was used for the evaluation of antipsoriatic activity of ethanol extract (100, 200 and 400 mg/kg b.w.) and bioactive flavonoids (50 mg/kg b.w.) in Swiss albino mice. In the HPLC analysis, 4 flavonoids were identified by comparison with retention time of standard marker viz., Rutin, Quercetin, Kaempferol and Luteolin. Maximum antiproliferant activity was shown by isolated flavonoids II and III (56.50±12.84μg/ml and 76.50±8.60μg/ml). In mouse tail model, a significant reduction in epidermal thickness with respect to control was observed in groups treated with isolated flavonoids II, III and significant orthokeratosis was observed in groups treated with ethanol extract (200 and 400 mg/kg) and isolated flavonoids II, III.

Botanical insecticides that degrade rapidly are safer than persistent synthetic chemical insecticides, less harmful to the environment, decrease production costs and are not likely to cause insecticide resistance among pests. This study aimed to evaluate the effect of five different botanical extracts on the bean aphid, Aphis craccivora and the 2nd larval instar of the green lacewing, Chrysoperla carnea under laboratory conditions. Also, the flavonoids in the methanolic extracts of these tested plants were detected using HPLC analysis. The data from the HPLC analysis indicated that the tested plants differed in their flavonoid components. The total flavonoids were 869.4, 1125.6, 721.4, 1667.8 and 2025.9 mg/kg in Psiadia penninervia, Salvia officinalis, Ochradenus baccatus, Pulicaria crispa and Euryops arabicus, respectively. Moreover, there were many variations among these plants in the amount of each compound. The lethal concentration (LC50) value of P. penninervia extract on aphids was the lowest among all of the plants (128.546 µg/mL) followed by O. baccatus (626.461 µg/mL). Also, the LC50 value of P. penninervia extract on the 2nd larval instar of C. carnea (232.095 µg/mL) was significantly lower than those of all other four plant species extracts, while the other four plants did not show significant differences among them according to relative median potency analyses. Accordingly, O. baccatus extract had a strong effect on aphids and was safest for the predator. This finding suggests that O. baccatus could be exploited and further developed as an effective plant extract-based insecticide to be utilized in integrated pest management (IPM) programs against A. craccivora.

A green approach for multivariate consecutive extraction of essential oils and flavonoids from Citrus aurantium L. var. amara Engl.: Process optimization and mechanistic insights based on machine learning methods

The total flavonoids of Cannabis sativa L. were selected as the research object, and the extraction process of C. sativa L. was optimized on the basis of a single factor experiment utilizing a five-factor, three-level response surface method. Subsequently, the vitro antimicrobial and antioxidant activities of the flavonoids were evaluated. The optimized extraction conditions were as follows: ratio of liquid to solid, 24.69:1 mL/g; soaking time, 102.12 min; extraction time, 165.96 min; ethanol concentration, 46.59%; extraction temperature, 86.87 °C. The extraction rate of C. sativa L. flavonoids (CSF) was found to be 5.51 ± 0.04 mg/g. The extraction of crude flavonoid (i.e., flavonoids extracted under the optimal extraction process) was conducted using four solvents, resulting in five C. sativa L. flavonoid extracts (petroleum ether, CSFp; n-butanol, CSFb; ethyl acetate, CSFe; aqueous phase, CSFw; and crude flavonoid, CSF). CSF contains 10 flavonoid components. In vitro, all five CSF samples demonstrated good total reducing power, effective scavenging capacity against DPPH and ABTS+ radicals, and pronounced inhibitory effects against Escherichia coli, Bacillus subtilis, and Bacillus pumilus. Analytic Hierarchy Process (AHP) was employed to evaluate the five CSF samples in terms of antibacterial and antioxidant activity. The results indicated that petroleum-ether-extracted C. sativa L. flavonoids (CSFp) exhibited the most pronounced antibacterial and antioxidant effects.