Waste resulting from edible plants is considered one of the best sources of valuable phytochemicals. A promising approach for using these appreciated wastes is extracting precious medically important constituents, for example, free quercetin. Two new cost-effective and green extraction methods are introduced in the present study: ultrasound-assisted glycerol extraction (UAGE) and microwave-assisted extraction (MAE). These extraction protocols are optimized using factorial design to define the highest yield of extraction, and HPLC-UV at 370 nm was used as a method of yield analysis. Quercetin remained stable during the whole process in both extraction protocols. A standard addition technique was performed to quantify quercetin in different extracts and eliminate the matrix effect. In UAGE and MAE, extraction yields were 16.55 ± 0.81 and 27.20 ± 1.55 mg/1g from red onion scales on a dry base, respectively. The amount of quercetin extracted using MAE was superior to UAGE in terms of time and yield. A greenness assessment of the offered studies compared to previously published relevant extraction methods was performed using the analytical eco-scale assessment method (ESA) and national environmental methods index (NEMI). MAE showed to be a greener method with a higher ESA score and a greener NEMI pictogram.

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Green tea (GT)-derived catechins; epigallocatechin gallate (EGCG) in particular are commonly used nutraceuticals for their free-radical scavenging activity (FRSA). The influence of photodegradation on the protective power of GT nutracenticals against oxidative stress was thoroughly explored. Photodegradation of GT extracts was carried out and monitored using orthogonal stability-indicating testing protocol; in vitro and in vivo assays. Total polyphenol content (TPC) and FRSA were determined spectrophotometrically while EGCG was selectively monitored using SPE-HPLC. In vivo assessment of photodegraded samples was investigated via measuring a number of biomarkers for hepatic oxidative stress and apoptosis (caspase-3, inducible nitric oxide synthase, nitric oxide, mitogen-activated protein kinase, glutathione, thiobarbituric acid reactive substances, nuclear factor kappa beta, and nuclear factor erythroid 2-related factor) as well as liver damage (alanine transaminase and aspartate transaminase) in serum of rats previously subjected to oxidative stress. Results showed complete degradation of EGCG in photodegraded green tea samples with no correlation with either TPC or FRSA. On the other hand, in vivo assay results revealed not only loss of activity but formation of harmful pro-oxidants. Photostability was found crucial for the protective effect of GT extract against lead acetate insult. Results confirmed that careful design of quality control protocols requires correlation of chemical assays to bioassays to verify efficacy, stability, and most importantly safety of nutraceuticals.

Background Extraction is the leading critical stage in the analysis of nutraceuticals. Ginkgo biloba (GB) has gained an interest because of its therapeutic usages. Objectives Development of four cost effective extraction techniques for extraction of quercetin from GB in mixture of nutraceuticals sachet. These techniques are solid phase extraction (SPE), liquid-liquid extraction (LLE), inverted dispersive liquid-liquid microextraction (IDLLME) and QuEChERS. Methods Direct spectrophotometry was used to monitor the recovery of the standard quercetin throughout the optimization steps. HPLC-UV method of analysis was optimized to quantify the yields from the extracts present in the complicated sachets. The presented study was assessed by analytical eco-scale assessment (ESA) and National Environmental Method Index (NEMI) for greenness in comparison with literature. Results Only SPE showed the best cleanup outcomes. ESA and NEMI showed an adequate greenness of proposed extraction protocol. Conclusion Quercetin (marker for GB) extraction from market nutraceutical sachets is considered an exemplary for analysis in quality control of nutraceuticals. Regarding the greenness results, the proposed method of extraction is grander even with adequate greenness as the extraction was one-step, in comparison with multi-steps in previously published protocols. Accordingly, it is recommended to be used in routine extraction and analysis of such kind of nutraceuticals. Highlights Four extraction protocols had been developed. For GB ternary sachets, proper recovery was obtained from C18 SPE. The assessment of greenness of the proposed protocol guaranteed the superiority of the presented study. Safer sorbents and chemicals favor to be used for routine extraction of nutraceuticals.

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