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Article

Enhanced Antioxidant and Anti-Inflammatory Activities of Diospyros lotus Leaf Extract via Enzymatic Conversion of Rutin to Isoquercitrin

1
R&D Center, Ildusanbang Co., Cheongsong 37434, Republic of Korea
2
Department of Wild Plants and Seeds Conservation, Baekdudaegan National Arboretum, Bonghwa 36209, Republic of Korea
3
Department of Bioscience and Biotechnology, Hankuk University of Foreign Studies, Yongin 17035, Republic of Korea
*
Authors to whom correspondence should be addressed.
Antioxidants 2025, 14(8), 950; https://doi.org/10.3390/antiox14080950 (registering DOI)
Submission received: 2 July 2025 / Revised: 1 August 2025 / Accepted: 1 August 2025 / Published: 2 August 2025

Abstract

Isoquercitrin, a monoglucoside form of quercetin, exhibits superior antioxidant, anti-inflammatory, and cardiovascular protective effects in comparison to its precursor, rutin. However, its natural abundance is limited. This study aimed to increase the functional value of Diospyros lotus leaf extract through enzymatic conversion of rutin to isoquercitrin using α-l-rhamnosidase and to evaluate the changes in biological activities after conversion. A sugar-free D. lotus leaf extract was prepared and subjected to enzymatic hydrolysis with α-l-rhamnosidase under optimized conditions (pH 5.5, 55 °C, and 0.6 U/mL). Isoquercitrin production was monitored via high-performance liquid chromatography. Antioxidant and anti-inflammatory activities were assessed using the 2,2-diphenyl-1-picrylhydrazyl radical scavenging and lipoxygenase (LOX) inhibition assays, respectively. The enzymatic reaction resulted in complete conversion of 30 mM rutin into isoquercitrin within 180 min, increasing isoquercitrin content from 9.8 to 39.8 mM. The enzyme-converted extract exhibited significantly enhanced antioxidant activity, with a 48% improvement in IC50 value compared with the untreated extract. Similarly, LOX inhibition increased from 39.2% to 48.3% after enzymatic conversion. Both extracts showed higher inhibition than isoquercitrin alone, indicating synergistic effects of other phytochemicals present in the extract. This study is the first to demonstrate that α-l-rhamnosidase-mediated conversion of rutin to isoquercitrin in D. lotus leaf extract significantly improves its antioxidant and anti-inflammatory activities. The enzymatically enhanced extract shows potential as a functional food or therapeutic ingredient.
Keywords: Diospyros lotus; isoquercitrin; rutin; α-l-rhamnosidase; antioxidant; anti-inflammatory; enzymatic bioconversion Diospyros lotus; isoquercitrin; rutin; α-l-rhamnosidase; antioxidant; anti-inflammatory; enzymatic bioconversion

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MDPI and ACS Style

Kim, Y.-S.; Na, C.S.; Shin, K.-C. Enhanced Antioxidant and Anti-Inflammatory Activities of Diospyros lotus Leaf Extract via Enzymatic Conversion of Rutin to Isoquercitrin. Antioxidants 2025, 14, 950. https://doi.org/10.3390/antiox14080950

AMA Style

Kim Y-S, Na CS, Shin K-C. Enhanced Antioxidant and Anti-Inflammatory Activities of Diospyros lotus Leaf Extract via Enzymatic Conversion of Rutin to Isoquercitrin. Antioxidants. 2025; 14(8):950. https://doi.org/10.3390/antiox14080950

Chicago/Turabian Style

Kim, Yeong-Su, Chae Sun Na, and Kyung-Chul Shin. 2025. "Enhanced Antioxidant and Anti-Inflammatory Activities of Diospyros lotus Leaf Extract via Enzymatic Conversion of Rutin to Isoquercitrin" Antioxidants 14, no. 8: 950. https://doi.org/10.3390/antiox14080950

APA Style

Kim, Y.-S., Na, C. S., & Shin, K.-C. (2025). Enhanced Antioxidant and Anti-Inflammatory Activities of Diospyros lotus Leaf Extract via Enzymatic Conversion of Rutin to Isoquercitrin. Antioxidants, 14(8), 950. https://doi.org/10.3390/antiox14080950

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