Glycosidic Inhibitors of Melanogenesis from Leaves of Momordica charantia

• Published in: Chemistry & biodiversity 2012-07, Vol.9 (7), p.1221-1230
• Main Authors: Kikuchi, Takashi, Zhang, Jie, Huang, Yan, Watanabe, Kensuke, Ishii, Kenta, Yamamoto, Ayako, Fukatsu, Makoto, Tanaka, Reiko, Akihisa, Toshihiro
• Format: Article
• Language: English
• Subjects: Animals; Antineoplastic Agents - chemistry; Antineoplastic Agents - pharmacology; Cell Line, Tumor; Cell Survival - drug effects; Glycosides; Glycosides - chemistry; Glycosides - pharmacology; Inhibitors; Magnetic Resonance Spectroscopy; Melanins - antagonists & inhibitors; Melanins - metabolism; Melanogenesis; Mice; Momordica charantia; Momordica charantia - chemistry; Plant Leaves - chemistry
• ISSN: 1612-1872; 1612-1880
• DOI: 10.1002/cbdv.201100350

Eight glycosidic compounds, 1–8, including two new compounds, (4ξ)‐α‐terpineol 8‐O‐[α‐L‐arabinopyranosyl‐(1→6)‐β‐D‐glucopyranoside] (5) and myrtenol 10‐O‐[β‐D‐apiofuranosyl‐(1→6)‐β‐D‐glucopyranoside] (7), were isolated from the BuOH‐soluble fraction of a MeOH extract of Momordica charantia leaves. The structures of the new compounds were elucidated on the basis of extensive spectroscopic analyses and comparison with literature. Upon evaluation of compounds 1–8 on the melanogenesis in B16 melanoma cells induced with α‐melanocyte‐stimulating hormone (α‐MSH), these compounds were found to exhibit inhibitory activities with 7.1–27.0% and 23.6–46.4% reduction of melanin content at 30 μM and 100 μM, respectively, with no or almost no toxicity to the cells (80.0–103.5% of cell viability at 100 μM). Western blot analysis showed that compound 7 reduced the protein levels of MITF, tyrosinase, TRP‐1, and TRP‐2 mostly in a concentration‐dependent manner, suggesting that this compound inhibits melanogenesis on the α‐MSH‐stimulated B16 melanoma cells by, at least in part, inhibiting the expression of MITF, followed by decreasing the expression of tyrosinase, TRP‐1, and TRP‐2.