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Limonoids and Flavonoids from the Flowers of Azadirachta indica var. siamensis , and Their Melanogenesis‐Inhibitory and Cytotoxic Activities
Author(s) -
Kitdamrongtham Worapong,
Ishii Kenta,
Ebina Kodai,
Zhang Jie,
Ukiya Motohiko,
Koike Kazuo,
Akazawa Hiroyuki,
Manosroi Aranya,
Manosroi Jiradej,
Akihisa Toshihiro
Publication year - 2014
Publication title -
chemistry and biodiversity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 70
eISSN - 1612-1880
pISSN - 1612-1872
DOI - 10.1002/cbdv.201300266
Subject(s) - azadirachta , limonoid , meliaceae , melanin , chemistry , traditional medicine , stereochemistry , cytotoxic t cell , naringenin , flavonoid , biochemistry , in vitro , antioxidant , medicine
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 μ M ), 6‐deacetylnimbin ( 3 ; 49.6% melanin content at 100 μ M ), and kaempferide ( 10 ; 41.7% melanin content at 10 μ M ) 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 IC 50 values in the range of 4.5–9.9 μ M .