Alkaloid constituents from flower buds and leaves of sacred lotus (Nelumbo nucifera, Nymphaeaceae) with melanogenesis inhibitory activity in B16 melanoma cells

  • Bioorg Med Chem. 2013 Feb 1;21(3):779-87. doi: 10.1016/j.bmc.2012.11.038.
Seikou Nakamura  1 ,  Souichi Nakashima ,  Genzo Tanabe ,  Yoshimi Oda ,  Nami Yokota ,  Katsuyoshi Fujimoto ,  Takahiro Matsumoto ,  Rika Sakuma ,  Tomoe Ohta ,  Keiko Ogawa ,  Shino Nishida ,  Hisako Miki ,  Hisashi Matsuda ,  Osamu Muraoka ,  Masayuki Yoshikawa
Affiliations
  • 1. Department of Pharmacognosy, Kyoto Pharmaceutical University, Misasagi, Yamashina-ku, Kyoto 607-8412, Japan.
PMID: 23270663 DOI: 10.1016/j.bmc.2012.11.038
Abstract

Methanolic extracts from the flower buds and leaves of sacred lotus (Nelumbo nucifera, Nymphaeaceae) were found to show inhibitory effects on melanogenesis in theophylline-stimulated murine B16 melanoma 4A5 cells. From the methanolic extracts, a new alkaloid, N-methylasimilobine N-oxide, was isolated together with eleven benzylisoquinoline Alkaloids. The absolute stereostructure of the new alkaloid was determined from chemical and physicochemical evidence. Among the constituents isolated, nuciferine, N-methylasimilobine, (-)-lirinidine, and 2-hydroxy-1-methoxy-6a,7-dehydroaporphine showed potent inhibition of melanogenesis. Comparison of the inhibitory activities of synthetic related Alkaloids facilitated characterization of the structure-activity relationships of aporphine- and benzylisoquinoline-type Alkaloids. In addition, 3-30 μM nuciferine and N-methylasimilobine inhibited the expression of Tyrosinase mRNA, 3-30 μM N-methylasimilobine inhibited the expression of TRP-1 mRNA, and 10-30 μM nuciferine inhibited the expression of TRP-2 mRNA.

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