{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T09:06:46Z","timestamp":1789981606646,"version":"4.0.1"},"reference-count":44,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,9,17]],"date-time":"2026-09-17T00:00:00Z","timestamp":1789603200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100004377","name":"Hong Kong Polytechnic University (PolyU) Strategic Scheme\u2019s Presidential Young Scholar Start-up Fund","doi-asserted-by":"publisher","award":["P0053775"],"award-info":[{"award-number":["P0053775"]}],"id":[{"id":"10.13039\/501100004377","id-type":"DOI","asserted-by":"publisher"}]},{"award":["P0053775"],"award-info":[{"award-number":["P0053775"]}],"id":[{"id":"https:\/\/ror.org\/0030zas98","id-type":"ROR","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100004377","name":"PolyU Research Centre for Resources Engineering towards Carbon Neutrality (RCRE) Seed Fund","doi-asserted-by":"publisher","award":["P0063925"],"award-info":[{"award-number":["P0063925"]}],"id":[{"id":"10.13039\/501100004377","id-type":"DOI","asserted-by":"publisher"}]},{"award":["P0063925"],"award-info":[{"award-number":["P0063925"]}],"id":[{"id":"https:\/\/ror.org\/0030zas98","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Antioxidants"],"abstract":"<jats:p>The processing of litchi (Litchi chinensis Sonn.) fruits generates substantial amounts of pericarp and seed by-products, which are candidate sources of antioxidant compounds but are underutilized. This study systematically investigated the total phenolic content (TPC) and in vitro antioxidant capacities (FRAP, ABTS, and DPPH values) of pericarp and seed extracts across eight commercial litchi cultivars. Qualitative LC-MS-based phytochemical profiling was further performed on the representative \u2018Bingli\u2019 cultivar. The results indicated that litchi seeds consistently exhibited significantly higher TPC and antioxidant activities compared to pericarps. Among the tested pericarps, the \u2018Nuomici\u2019 cultivar showed the highest TPC (10.29 \u00b1 0.10 mg GAE\/g dw) and antioxidant capacities. The \u2018Bingli\u2019 cultivar demonstrated the highest overall antioxidant activity among seeds (e.g., TPC of 33.92 \u00b1 1.75 mg GAE\/g dw and FRAP of 373.06 \u00b1 4.64 \u03bcmol Fe(II)\/g dw). LC-MS-based qualitative screening tentatively annotated several hydroxycinnamic acids and A-type procyanidins as putative phenolic constituents of the \u2018Bingli\u2019 litchi pericarp and seed extracts. Subsequent targeted HPLC analysis determined the concentrations of Procyanidin A2, revealing that it had a high concentration in the \u2018Xianjinfeng\u2019 and \u2018Bingli\u2019 seeds (1298.73 \u00b1 54.87 and 1127.81 \u00b1 67.22 \u03bcg\/g dw, respectively). These findings indicate cultivar- and tissue-specific variations in litchi fruit by-products and suggest that the seeds of \u2018Bingli\u2019 and \u2018Xianjinfeng\u2019 are candidate sources of antioxidant phenolics for further investigation, pending validation in food models or biological systems.<\/jats:p>","DOI":"10.3390\/antiox15091187","type":"journal-article","created":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T08:03:47Z","timestamp":1789977827000},"page":"1187","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Discovery and Characterization of Antioxidant Compounds in the Pericarp and Seed Byproducts of Different Litchi (Litchi chinensis Sonn.) Fruits"],"prefix":"10.3390","volume":"15","author":[{"given":"Yike","family":"Huang","sequence":"first","affiliation":[{"name":"Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Hung Hom, Hong Kong SAR, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"methodology","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"resources","vocabulary":"credit"}]},{"given":"Hujie","family":"Lyu","sequence":"additional","affiliation":[{"name":"Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Hung Hom, Hong Kong SAR, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"data-curation","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4162-1511","authenticated-orcid":false,"given":"Ren-You","family":"Gan","sequence":"additional","affiliation":[{"name":"Department of Food Science and Nutrition, The Hong Kong Polytechnic University, Hung Hom, Hong Kong SAR, China"},{"name":"Research Centre for Resources Engineering towards Carbon Neutrality (RCRE), The Hong Kong Polytechnic University, Hung Hom, Hong Kong SAR, China"},{"name":"Research Institute for Future Food, The Hong Kong Polytechnic University, Hung Hom, Hong Kong SAR, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"},{"role":"funding-acquisition","vocabulary":"credit"},{"role":"project-administration","vocabulary":"credit"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"58","DOI":"10.1016\/j.tifs.2020.12.005","article-title":"Litchi (Litchi chinenis) seed: Nutritional profile, bioactivities, and its industrial applications","volume":"108","author":"Punia","year":"2021","journal-title":"Trends Food Sci. Technol."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Kumar, M., Kumar, V., Varma, A., and Prasad, R. (2017). Lychee biology and biotechnology. The Lychee Biotechnology, Springer.","DOI":"10.1007\/978-981-10-3644-6"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"124684","DOI":"10.1016\/j.biortech.2021.124684","article-title":"Sustainable processing of food waste for production of bio-based products for circular bioeconomy","volume":"325","author":"Sharma","year":"2021","journal-title":"Bioresour. Technol."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"e13352","DOI":"10.1111\/1541-4337.13352","article-title":"A-type proanthocyanidins: Sources, structure, bioactivity, processing, nutrition, and potential applications","volume":"23","author":"Zeng","year":"2024","journal-title":"Compr. Rev. Food Sci. Food Saf."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"563","DOI":"10.1016\/j.foodchem.2012.08.089","article-title":"Identification of a novel phenolic compound in litchi (Litchi chinensis Sonn.) pericarp and bioactivity evaluation","volume":"136","author":"Jiang","year":"2013","journal-title":"Food Chem."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1081","DOI":"10.1016\/j.foodchem.2010.11.133","article-title":"Chemical constituents with antioxidant activities from litchi (Litchi chinensis Sonn.) seeds","volume":"126","author":"Wang","year":"2011","journal-title":"Food Chem."},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Guo, Z., Zhang, L., Liu, J., and Yang, Z. (2025). Lychee peel extract ameliorates hyperuricemia by regulating uric acid production and excretion in mice. Curr. Issues Mol. Biol., 47.","DOI":"10.3390\/cimb47020076"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Yang, Z., Zhang, L., Wu, Y.-H., Li, D.-P., and Li, W. (2022). Evaluation of chemical constituents of litchi pericarp extracts and its antioxidant activity in mice. Food, 11.","DOI":"10.3390\/foods11233837"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"11667","DOI":"10.1021\/jf1033202","article-title":"A-type proanthocyanidins from lychee seeds and their antioxidant and antiviral activities","volume":"58","author":"Xu","year":"2010","journal-title":"J. Agric. Food Chem."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.foodchem.2009.01.079","article-title":"Identification of phenolic compounds and appraisal of antioxidant and antityrosinase activities from litchi (Litchi sinensis Sonn.) seeds","volume":"116","author":"Prasad","year":"2009","journal-title":"Food Chem."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"145175","DOI":"10.1016\/j.foodchem.2025.145175","article-title":"Full-spectrum utilization of litchi waste: Composition, bioactivity of pericarp and seed, and their development and application in the food industry and beyond","volume":"491","author":"Zhou","year":"2025","journal-title":"Food Chem."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"e13997","DOI":"10.1111\/jfbc.13997","article-title":"A review on the medicinal potential, toxicology, and phytochemistry of litchi fruit peel and seed","volume":"45","author":"Chukwuma","year":"2021","journal-title":"J. Food Biochem."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Louren\u00e7o, S.C., Mold\u00e3o-Martins, M., and Alves, V.D. (2019). Antioxidants of natural plant origins: From sources to food industry applications. Molecules, 24.","DOI":"10.3390\/molecules24224132"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"391","DOI":"10.1016\/j.foodres.2010.10.001","article-title":"Total phenolic content and antioxidant capacity of extracts obtained from six important fruit residues","volume":"44","author":"Babbar","year":"2011","journal-title":"Food Res. Int."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"103929","DOI":"10.1016\/j.fochx.2026.103929","article-title":"Impact of drying technologies on bioactive composition of fruit pomace: A critical review and future perspectives","volume":"36","author":"Esatbeyoglu","year":"2026","journal-title":"Food Chem. X"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"95","DOI":"10.1016\/S0021-9673(04)01409-8","article-title":"Extraction and analysis of phenolics in food","volume":"1054","author":"Naczk","year":"2004","journal-title":"J. Chromatogr. A"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1821","DOI":"10.1016\/j.foodchem.2010.12.026","article-title":"A critical review of methods for characterisation of polyphenolic compounds in fruits and vegetables","volume":"126","author":"Ignat","year":"2011","journal-title":"Food Chem."},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Sai-Ut, S., Kingwascharapong, P., Mazumder, M.A.R., and Rawdkuen, S. (2023). Optimization of Ethanolic Extraction of Phenolic Antioxidants from Lychee and Longan Seeds Using Response Surface Methodology. Foods, 12.","DOI":"10.3390\/foods12152827"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"102397","DOI":"10.1016\/j.biteb.2025.102397","article-title":"Ultrasound-assisted extraction of bioactive compounds from Litchi chinesis kernel: Optimization, bioactivity and antimicrobial study","volume":"32","author":"Soni","year":"2025","journal-title":"Bioresour. Technol. Rep."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"152","DOI":"10.1016\/S0076-6879(99)99017-1","article-title":"Analysis of total phenols and other oxidation substrates and antioxidants by means of Folin-Ciocalteu reagent","volume":"299","author":"Singleton","year":"1999","journal-title":"Methods Enzymol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"14954","DOI":"10.3390\/molecules171214954","article-title":"Phenolic profiles and antioxidant activity of litchi (Litchi chinensis Sonn.) fruit pericarp from different commercially available cultivars","volume":"17","author":"Li","year":"2012","journal-title":"Molecules"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"70","DOI":"10.1006\/abio.1996.0292","article-title":"The ferric reducing ability of plasma (FRAP) as a measure of \u201cantioxidant power\u201d: The FRAP assay","volume":"239","author":"Benzie","year":"1996","journal-title":"Anal. Biochem."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1944","DOI":"10.1016\/j.crfs.2022.10.019","article-title":"Green extraction, chemical composition, and in vitro antioxidant activity of theabrownins from Kangzhuan dark tea","volume":"5","author":"Liu","year":"2022","journal-title":"Curr. Res. Food Sci."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1231","DOI":"10.1016\/S0891-5849(98)00315-3","article-title":"Antioxidant activity applying an improved ABTS radical cation decolorization assay","volume":"26","author":"Re","year":"1999","journal-title":"Free Radic. Biol. Med."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Mai, Y.H., Zhuang, Q.G., Li, Q.H., Du, K., Wu, D.T., Li, H.B., Xia, Y., Zhu, F., and Gan, R.Y. (2022). Ultrasound-assisted extraction, identification, and quantification of antioxidants from \u2018Jinfeng\u2019 kiwifruit. Foods, 11.","DOI":"10.3390\/foods11060827"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"25","DOI":"10.1016\/S0023-6438(95)80008-5","article-title":"Use of a free radical method to evaluate antioxidant activity","volume":"28","author":"Cuvelier","year":"1995","journal-title":"LWT Food Sci. Technol."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Yang, Q.-Q., Cheng, L., Long, Z.-Y., Li, H.-B., Gunaratne, A., Gan, R.-Y., and Corke, H. (2019). Comparison of the phenolic profiles of soaked and germinated peanut cultivars via UPLC-QTOF-MS. Antioxidants, 8.","DOI":"10.3390\/antiox8020047"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"539","DOI":"10.1016\/j.foodchem.2005.06.028","article-title":"Identification of the major flavonoids from pericarp tissues of lychee fruit in relation to their antioxidant activities","volume":"98","author":"Zhao","year":"2006","journal-title":"Food Chem."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"784","DOI":"10.1016\/j.scienta.2011.05.042","article-title":"Phenolic compounds and the antioxidant activities in litchi pericarp: Difference among cultivars","volume":"129","author":"Wang","year":"2011","journal-title":"Sci. Hortic."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Platzer, M., Kiese, S., Herfellner, T., Schweiggert-Weisz, U., and Eisner, P. (2021). How Does the Phenol Structure Influence the Results of the Folin-Ciocalteu Assay?. Antioxidants, 10.","DOI":"10.3390\/antiox10050811"},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Chen, Q., Wang, D., Tan, C., Hu, Y., Sundararajan, B., and Zhou, Z. (2020). Profiling of flavonoid and antioxidant activity of fruit tissues from 27 Chinese local citrus cultivars. Plants, 9.","DOI":"10.3390\/plants9020196"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"411","DOI":"10.1016\/j.foodchem.2004.02.003","article-title":"Antioxidant activity and phenolic content of selected fruit seeds","volume":"88","author":"Soong","year":"2004","journal-title":"Food Chem."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"4290","DOI":"10.1021\/jf0502698","article-title":"Standardized methods for the determination of antioxidant capacity and phenolics in foods and dietary supplements","volume":"53","author":"Prior","year":"2005","journal-title":"J. Agric. Food Chem."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"1446","DOI":"10.1016\/j.foodchem.2007.05.022","article-title":"A-type procyanidins from Litchi chinensis pericarp with antioxidant activity","volume":"105","author":"Liu","year":"2007","journal-title":"Food Chem."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"197","DOI":"10.1007\/s13765-017-0269-9","article-title":"Anti-diabetic functional food with wasted litchi seed and standard of quality control","volume":"60","author":"Choi","year":"2017","journal-title":"Appl. Biol. Chem."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"5995","DOI":"10.1021\/jf000815r","article-title":"Phenolic composition of litchi fruit pericarp","volume":"48","author":"Lozano","year":"2000","journal-title":"J. Agric. Food Chem."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"820","DOI":"10.1016\/j.jff.2015.06.018","article-title":"Phenolics and polyphenolics in foods, beverages and spices: Antioxidant activity and health effects-A review","volume":"18","author":"Shahidi","year":"2015","journal-title":"J. Funct. Foods"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"284","DOI":"10.1016\/j.tifs.2015.06.007","article-title":"Natural food additives: Quo vadis?","volume":"45","author":"Carocho","year":"2015","journal-title":"Trends Food Sci. Technol."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.tifs.2016.03.009","article-title":"Food colorants: Challenges, opportunities and current desires of agro-industries to ensure consumer expectations and regulatory practices","volume":"52","author":"Martins","year":"2016","journal-title":"Trends Food Sci. Technol."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"512","DOI":"10.1111\/1541-4337.12330","article-title":"Fruit and vegetable waste: Bioactive compounds, their extraction, and possible utilization","volume":"17","author":"Sagar","year":"2018","journal-title":"Compr. Rev. Food Sci. Food Saf."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"68","DOI":"10.1016\/j.tifs.2012.03.003","article-title":"Recovery of high added-value components from food wastes: Conventional, emerging technologies and commercialized applications","volume":"26","author":"Galanakis","year":"2012","journal-title":"Trends Food Sci. Technol."},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Cano-G\u00f3mez, C.I., Alonso-Castro, A.J., Carranza-Alvarez, C., and Wong-Paz, J.E. (2024). Advancements in Litchi chinensis peel processing: A scientific review of drying, extraction, and isolation of its bioactive compounds. Foods, 13.","DOI":"10.3390\/foods13101461"},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Zeng, Q., Xu, Z., Dai, M., Cao, X., Xiong, X., and He, S. (2019). Effects of simulated digestion on the phenolic composition and antioxidant activity of different cultivars of lychee pericarp. BMC Chem., 13.","DOI":"10.1186\/s13065-019-0544-4"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"510","DOI":"10.1016\/j.tifs.2010.08.003","article-title":"Encapsulation of polyphenols\u2014A review","volume":"21","author":"Fang","year":"2010","journal-title":"Trends Food Sci. Technol."}],"container-title":["Antioxidants"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-3921\/15\/9\/1187\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T08:47:01Z","timestamp":1789980421000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-3921\/15\/9\/1187"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,9,17]]},"references-count":44,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2026,9]]}},"alternative-id":["antiox15091187"],"URL":"https:\/\/doi.org\/10.3390\/antiox15091187","relation":{},"ISSN":["2076-3921"],"issn-type":[{"value":"2076-3921","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,9,17]]}}}