Apple pomace is a waste product of the apple manufacturing industry that has been in the focus of life sciences as it represents a low-cost source of fruit-derived compounds. High fruit consumption is associated with beneficial health effects, and therefore, apple pomace and its constituents raise therapeutic interest. The present work reviews (i) the chemical constituents of apple pomace, (ii) optimized extraction methods of apple pomace compounds, and (iii) biological activities of apple pomace. Current evidence of apple pomace influence on digestion and metabolism, cholesterol and triglyceride homeostasis, diabetes, and sex hormones is summarized. Furthermore, studies regarding its antioxidative, anti-inflammatory, antiproliferative, antibacterial and antiviral effects are presented. The review concludes that apple pomace is an underutilized waste product of the apple industry with the potential of being processed for its nutritional and pharmaceutical value.

Corydalis Rhizoma is the dried tuber of Corydalis yanhusuo W.T. Wang which is used in traditional Chinese medicine for pain relief and blood activation. Before being used in the clinics, C. yanhusuo is traditionally processed through dry-frying or frying with vinegar, wine or salt. In this study, eleven alkaloids from Corydalis Rhizoma, namely protopine (1), α-allocryptopine (2), tetrahydrocolumbamine (3), coptisine (4), palmatine (5), berberine (6), dehydrocorydaline (7), D,L-tetrahydropalmatine (8), tetrahydroberberine (9), corydaline (10) and tetrahydrocoptisine (11) were simultaneously quantified using a newly developed high performance liquid chromatography-diode array detector (HPLC-DAD) method. The influence of vinegar and wine processing on the content of the main alkaloids of Corydalis Rhizoma was investigated. For this purpose, two common formulations with clinical application, namely the water decoction of Corydalis Rhizoma and its formula Jin Ling Zi San (combination of Corydalis Rhizoma and Toosendan Fructus) were studied. In the two water decoctions, wine and vinegar processing increased the amount of tertiary alkaloids. The differences were more pronounced for Jin Ling Zi San, in which case the content of all tertiary alkaloids (compounds 1, 2, 3, 8, 9, 10, 11) was increased by wine processing.

Pomace is an easy-accessible raw material for the isolation of fruit-derived compounds. Fruit consumption is associated with health-promoting effects, such as the prevention of cardiovascular disease. Increased vascular nitric oxide (NO) bioavailability, for example, due to an enhanced endothelial nitric oxide synthase (eNOS) activity, could be one molecular mechanism mediating this effect. To identify compounds from apple (Malus domestica Borkh.) pomace that have the potential to amplify NO bioavailability via eNOS activation, a bioassay-guided fractionation of the methanol/water (70:30) extract has been performed using the (14)C-L-arginine to (14)C-L-citrulline conversion assay (ACCA) in the human endothelium-derived cell line EA.hy926. Phytochemical characterization of the active fractions was performed using the spectrophotometric assessment of the total phenolic content, as well as TLC, HPLC-DAD-ELSD, and HPLC-MS analyses. Eleven triterpenoic acids, of which one is a newly discovered compound, were identified as the main constituents in the most active fraction, accompanied by only minor contents of phenolic compounds. When tested individually, none of the tested compounds exhibited significant eNOS activation. Nevertheless, cell stimulation with the reconstituted compound mixture restored eNOS activation, validating the potential of apple pomace as a source of bioactive components.

Pomace, the press residue from different fruits accumulating as waste product in food industry, contains high amounts of secondary metabolites that could be utilized for health-related applications. This study aims at evaluating the potential of pomaces of apricot, bilberry, and elderberry to serve as a source for endothelial nitric oxide synthase (eNOS)-activating compounds. Five extracts obtained from the lyophilized pomace of apricot and elderberry with solvents of different polarity were found to enhance A23187-stimulated eNOS activity when tested at 50 μg/mL in an [14C]-l-arginine to [14C]-l-citrulline conversion assay in the human endothelium-derived cell line EA.hy926 (p < 0.05). The bioassay-guided fractionation of the extracts obtained with methanol/water (70:30) led to several active fractions from apricot pomace (p < 0.05) and elderberry pomace (p < 0.01). Liquid chromatography–mass spectrometry-based chemical analysis of the extracts and active fractions pointed mainly to triterpenoic acids as active compounds. One particular dihydroxytriterpenoic acid, characteristic for elderberry, was enriched as the main compound in the two most active fractions and might serve as a promising lead structure for further studies.

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