Undescribed C-geranylflavonoids isolated from the fruit peel of Paulownia catalpifolia T. Gong ex D.Y. Hong with their protection on human umbilical vein endothelial cells injury induced by hydrogen peroxide

Paulownia C-geranylated flavonoids: their structural variety, biological activity and application prospects

“…3 Noncyclic modified C-geranylflavanones isolated from the Paulownia genus yield furan (between C-3″ and C-6″, 65) or pyran (between C-3″ and C-7″, 66) moieties in Paulownia C-geranylflavonoids. Compound 67 was, to date, a unique C-geranylflavanone with a monocyclic monoterpene side-chain isolated from Paulownia plants up to mow (Wang et al 2019), and its oxygenated cyclogeranyl substituent was similar to that (without the hydroxyl) in some ugonins isolated from Helminthostachys zeylanica (Huang et al 2003;.…”

“…To date, only four C-geranylated flavones (73-76, Fig. 6) were obtained from the fruits of P. catalpifolia (Wang et al , 2019. The variety of their geranyl substituents was minimal, with only hydroxylation at C-7″ to form a 7-hydroxy-3,7dimethyl-2(E)-octenyl substituent (74-76).…”

“…Regarding cellular biological activities (anti-inflammatory and cytotoxic effects), antibacterial and antiparasitic activities, and enzymatic inhibitions, an ortho-dihydroxy arrangement at C-3′,4′ of the B-ring was considered an essential group but also enhanced the cytotoxic risk. Hydroxylation at C-3 in ring C and 4′-methoxy substitution of ring B might cause a loss of bioactive potency (Šmejkal et al 2008a;Wang et al 2019). In addition, the unmodified geranyl group at the C-6 position seemed to be crucial for these various biological effects in vitro and in vivo (Vochyánová et al 2015) of C-geranylated flavonoids, however, hydroxylation on the distal end of the geranyl substituent decreased the biological activities revealed by different research (Alcaráz et al 2000;Š mejkal et al 2010;Hanáková et al 2017;Ryu et al 2017).…”

“…Phytochemical research demonstrated that Paulownia species are natural resources of C-geranylated flavonoids with varied geranyl substituents. There might be another C-geranylated flavonoid constituent with more attractive geranyl variations, such as the cyclic monoterpene side-chain in paucatalinone F (67, Wang et al 2019), metabolized in Paulownia species. Theirfore, it is worthwhile to carry out further investigations on Paulownia species for more novel C-geranylated flavonoids on the phytochemical view.…”

“…a UV spectrum of diplacone(2)as a C-geranylated flavanone with a main maximum absorption at approximately λ 290 nm, a shoulder peak at approximately λ 230 nm and a weak absorption at approximately λ 340 nm. b UV spectrum of paucatalinone C (73) as a C-geranylated flavone with two main maximum UV absorption at approximately λ 270 nm and λ 350 nm Phytochem Rev (2019) 18:549-570 559and compounds 2, 25, 26, 34 and 67 caused improved proliferative activity at 10 µM, however, at 20 µM or higher, diplacone (2) expressed cytotoxic activity to HUVECs and reduced its proliferative activity(Chen et al 2017b;Wang et al 2019).…”