Limonoids and Flavonoids from the Flowers of Azadirachta indica var. siamensis,and Their Melanogenesis‐Inhibitory and Cytotoxic Activities |
| |
| Authors: | Worapong Kitdamrongtham Kenta Ishii Kodai Ebina Jie Zhang Motohiko Ukiya Kazuo Koike Hiroyuki Akazawa Aranya Manosroi Jiradej Manosroi Toshihiro Akihisa |
| |
| Institution: | 1. Faculty of Pharmacy, Chiang Mai University, Chiang Mai 50200, Thailand (phone: +66‐53‐944338;2. fax: +66‐53‐894169);3. College of Science and Technology, Nihon University, 1‐8‐14 Kanda Surugadai, Chiyoda‐ku, Tokyo 101‐8308, Japan (fax: +81‐3‐3293‐7572);4. School of Pharmaceutical Sciences, Toho University, Miyama, Funabashi‐shi, Chiba 274‐8510, Japan;5. Akihisa Medical Clinic, 1086‐3 Kamo, Sanda‐shi, Hyogo 669‐1311, Japan (fax: +81‐79‐567‐1980) |
| |
| Abstract: | A new limonoid, 7‐O‐acetyl‐7‐O‐debenzoyl‐22‐hydroxy‐21‐methoxylimocinin ( 2 ), and two new flavonoids, 3′‐(3‐hydroxy‐3‐methylbutyl)naringenin ( 7 ) and 4′‐O‐methyllespedezaflavanone C ( 9 ), along with nine known compounds, including two limonoids, 1 and 3 , and seven flavonoids, 4 – 6, 8 , and 10 – 12 , were isolated from a MeOH extract of the flowers of Azadirachta indica A.Juss. var. siamensis Valeton (Siamese neem tree; Meliaceae). The structures of new compounds were elucidated on the basis of extensive spectroscopic analysis and comparison with literature data. All of these compounds were evaluated for their melanogenesis‐inhibitory activities in B16 melanoma cells induced with α‐melanocyte‐stimulating hormone (α‐MSH). Compound 2 (16.9% melanin content at 30 μM ), 6‐deacetylnimbin ( 3 ; 49.6% melanin content at 100 μM ), and kaempferide ( 10 ; 41.7% melanin content at 10 μM ) exhibited inhibitory effects with no, or almost no, toxicity to the cells (81.0–111.7% cell viability). In addition, evaluation of their cytotoxic activities against HL60, A549, AZ521, and SK‐BR‐3 human cancer cell lines, isoazadironolide ( 1 ), 4′‐O‐methyl‐8‐prenylnaringenin ( 5 ), euchrestaflavanone A ( 8 ), 9 , and 3‐methoxy‐3′‐prenylnaringenin ( 12 ) revealed potent cytotoxicities against one or more cell lines with IC50 values in the range of 4.5–9.9 μM . |
| |
| Keywords: | Azadirachta indica var siamensis Siamese neem tree Limonoids Flavonoids Melanogenesis‐inhibitory activity Cytotoxic activity |
|
|
