Dimeric pyrrolidinoindoline-type alkaloids with melanogenesis inhibitory activity in flower buds of Chimonanthus praecox
2014
Morikawa, Toshio | Nakanishi, Yusuke | Ninomiya, Kiyofumi | Matsuda, Hisashi | Nakashima, Souichi | Miki, Hisako | Miyashita, Yu | Yoshikawa, Masayuki | Hayakawa, Takao | Muraoka, Osamu
A methanol extract of the flower buds of Chimonanthus praecox (L.) Link (Calycanthaceae) demonstrated inhibitory effects on melanogenesis in theophylline-stimulated murine B16 melanoma 4A5 cells. From the extract, five dimeric pyrrolidinoindoline alkaloids and four sesquiterpenes were isolated, together with 16 known compounds. Among them, (−)-chimonanthine (1, IC₅₀ = 0.93 μM), (−)-folicanthine (2, 1.4 μM), and (−)-calycanthidine (3, 1.8 μM) showed potent inhibitory effects without notable cytotoxicity at the effective concentrations. The most potent alkaloid (1) inhibited both tyrosinase and tyrosine-related protein-1 mRNA expressions, to which the melanogenesis inhibitory activity would be ascribable.
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