3′-Caffeoylquercetin Glycosides and 4′-Caffeoylkaempferol Glycosides—Novel Antioxidant Flavonoids Discovered in the Freesia Yellow Flowers

Shindo, Kazutoshi; Iwamoto, Nozomi; Usami, Mayu; Saito, Ayuna; Sato, Miho; Sugaya, Maho; Miyashita, Nao; Murahama, Minoru; Higashimura, Yasuki; Takemura, Miho; Furihata, Kazuo; Misawa, Norihiko

doi:10.3390/antiox14020158

Open AccessArticle

3′-Caffeoylquercetin Glycosides and 4′-Caffeoylkaempferol Glycosides—Novel Antioxidant Flavonoids Discovered in the Freesia Yellow Flowers

by

Kazutoshi Shindo

^1,*,†

,

Nozomi Iwamoto

¹,

Mayu Usami

¹,

Ayuna Saito

¹,

Miho Sato

¹,

Maho Sugaya

¹,

Nao Miyashita

²,

Minoru Murahama

²,

Yasuki Higashimura

³

,

Miho Takemura

⁴

,

Kazuo Furihata

⁵ and

Norihiko Misawa

^4,*,†,‡

¹

Department of Food and Nutrition, Japan Women’s University, 2-8-1 Mejirodai, Bunkyo-ku, Tokyo 112-8681, Japan

²

Ishikawa Agriculture and Forestry Research Center, 295-1 Saida-machi, Kanazawa 920-3198, Japan

³

Department of Food Science, Ishikawa Prefectural University, 1-308 Suematsu, Nonoichi-shi 921-8836, Japan

⁴

Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, 1-308 Suematsu, Nonoichi-shi 921-8836, Japan

⁵

Division of Agriculture and Agricultural Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan

^*

Authors to whom correspondence should be addressed.

^†

Current address: CaroProTech Corporation, 77 Tsubono-machi, Nomi-shi 923-1213, Japan.

^‡

Current address: Department of Nutrition, Hokuriku Gakuin University, 11 Mitsukoji, Kanazawa 920-1396, Japan.

Antioxidants 2025, 14(2), 158; https://doi.org/10.3390/antiox14020158

Submission received: 17 December 2024 / Revised: 15 January 2025 / Accepted: 24 January 2025 / Published: 28 January 2025

(This article belongs to the Special Issue Antioxidant Capacity of Anthocyanins and Other Vegetal Pigments: Properties, Intake and Health Benefits)

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Abstract

The petals of flowering plants should retain unique antioxidants that have not been found in the fruits, as the petals need to stay open to attract pollinators against photooxidation and devise a solution to avoid eating attacks. We reported that the yellow petals of freesia cultivars (Freesia x hybrida) accumulated original apocarotenoids, mono- and di-neapolitanosyl crocetin. Here, in the yellow petals, we discovered eight novel flavonoids by their structural determination, including four 3′-caffeoylquercetin 3,7-glycosides, one 3′-caffeoylquercetin 3-glycoside, and three 4′-caffeoylkaempferol 3,7-glycosides. The 3-carbon sugar part was a minor hexose dimer [D-glucosyl-D-glucoside or D-glucosyl-L-rhamnoside] with the β1,2-linkage, while the 7-carbon was usually O-glycosylated with D-glucose, L-rhamnose, or D-glucuronic acid. Such caffeoyl-flavonol glycosides were also present in freesia white petals, regardless of the cultivars and wild species. When dihydroflavonols, the last common precursors between flavonols and anthocyanins, switch to the flavonol route, these caffeoyl-flavonol glycosides are likely to be synthesized via quercetin or kaempferol. All the eight flavonoids exerted in vitro antioxidant activities against both lipid peroxidation and radical generation. Specifically, 3′-caffeoylquercetin 3-sophoroside and its 7-glucuronide showed superior antioxidant activity. Freesia yellow and white flowers have been utilized as edible flowers, indicating the importance of evaluating the human benefits and risks of newly identified flavonoids.

Keywords: freesia petals; quercetin glycosides; kaempferol glycosides; caffeic acid; edible flower; antioxidant activity

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MDPI and ACS Style

Shindo, K.; Iwamoto, N.; Usami, M.; Saito, A.; Sato, M.; Sugaya, M.; Miyashita, N.; Murahama, M.; Higashimura, Y.; Takemura, M.; et al. 3′-Caffeoylquercetin Glycosides and 4′-Caffeoylkaempferol Glycosides—Novel Antioxidant Flavonoids Discovered in the Freesia Yellow Flowers. Antioxidants 2025, 14, 158. https://doi.org/10.3390/antiox14020158

AMA Style

Shindo K, Iwamoto N, Usami M, Saito A, Sato M, Sugaya M, Miyashita N, Murahama M, Higashimura Y, Takemura M, et al. 3′-Caffeoylquercetin Glycosides and 4′-Caffeoylkaempferol Glycosides—Novel Antioxidant Flavonoids Discovered in the Freesia Yellow Flowers. Antioxidants. 2025; 14(2):158. https://doi.org/10.3390/antiox14020158

Chicago/Turabian Style

Shindo, Kazutoshi, Nozomi Iwamoto, Mayu Usami, Ayuna Saito, Miho Sato, Maho Sugaya, Nao Miyashita, Minoru Murahama, Yasuki Higashimura, Miho Takemura, and et al. 2025. "3′-Caffeoylquercetin Glycosides and 4′-Caffeoylkaempferol Glycosides—Novel Antioxidant Flavonoids Discovered in the Freesia Yellow Flowers" Antioxidants 14, no. 2: 158. https://doi.org/10.3390/antiox14020158

APA Style

Shindo, K., Iwamoto, N., Usami, M., Saito, A., Sato, M., Sugaya, M., Miyashita, N., Murahama, M., Higashimura, Y., Takemura, M., Furihata, K., & Misawa, N. (2025). 3′-Caffeoylquercetin Glycosides and 4′-Caffeoylkaempferol Glycosides—Novel Antioxidant Flavonoids Discovered in the Freesia Yellow Flowers. Antioxidants, 14(2), 158. https://doi.org/10.3390/antiox14020158

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3′-Caffeoylquercetin Glycosides and 4′-Caffeoylkaempferol Glycosides—Novel Antioxidant Flavonoids Discovered in the Freesia Yellow Flowers

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