1. Flavonoid 8-O-Glucuronides from the Aerial Parts of Malva verticillata and Their Recovery Effects on Alloxan-Induced Pancreatic Islets in Zebrafish.
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Ko, Jung-Hwan, Nam, Youn Hee, Joo, Sun-Woo, Kim, Hyoung-Geun, Lee, Yeong-Geun, Kang, Tong Ho, Baek, Nam-In, and Ferreira, Isabel C. F. R.
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EDIBLE greens ,HERBAL teas ,HERBAL medicine ,FLAVONOIDS ,FUNCTIONAL groups ,ANTIOXIDANTS - Abstract
Malva verticillata (Cluster mallow), a leafy vegetable that has been popular in East Asia for a long time, has also been used in herbal teas and medicines. The aqueous fraction of the aerial parts ofMalva verticillata , exhibiting a very high quantity of flavonoids compared to the EtOAc andn -BuOH fractions, exhibited significant recovery effects on pancreatic islets damaged by alloxan in zebrafish larvae. Thus, the bioactive components responsible for this anti-diabetic activity were investigated. A new flavonoid glucuronide (1) and five known flavonoids were isolated from the aqueous fraction. Based on several spectroscopic methods, compound1 was identified to be nortangeretin-8-O -β-d-glucuronide, and was named malvaflavone A. The A-ring of compound1 had a 5,6,7,8-tetrahydroxy moiety, which rarely occurs in plant systems. Also 8-O -glucuronide attached to the flavonoid moiety was rarely occurred in plant system. Compounds1 ,3 ,4 , and6 significantly improved the pancreatic islet size in zebrafish at 0.1 μM, and compounds1 and6 were found to block β-cell K+ channels in experiments with diazoxide. In ABTS, ORAC, and SOD assays, compounds1 –5 exhibited high anti-oxidant activities compared with quercetin and BHA (positive controls), indicating that the 8-O -glucuronide attached to the flavonoid moiety is a key structure for the expression of anti-oxidant activity. This is the first report of the isolation of compounds1 –6 fromM. verticillata as well evaluated for anti-diabetic and anti-oxidant ativities. [ABSTRACT FROM AUTHOR]- Published
- 2018
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