Effects of glycolipids from spinach on mammalian DNA polymerases.
We purified the major glycolipids in the class of monogalactosyl diacylglycerol (MGDG), digalactosyl diacylglycerol (DGDG) and sulfoquinovosyl diacylglycerol (SQDG) from a green vegetable, spinach (Spinacia oleracea L.). MGDG was an inhibitor of the growth of NUGC-3 human gastric cancer cells, but DGDG and SQDG had no such cytotoxic effect. Therefore, we studied MGDG and its monoacyglycerol-form, monogalactosyl monoacylglycerol (MGMG), in detail. MGMG with one fatty acid molecule was obtained from MGDG with two fatty acid molecules by hydrolyzing with a pancreatic lipase. MGMG was also found to prevent the cancer cell growth. MGDG was a potent inhibitor of replicative DNA polymerases such as alpha, delta and epsilon. MGMG inhibited the activities of all mammalian DNA polymerases including repair-related DNA polymerase beta with IC(50) values of 8.5-36 microg/mL, and the inhibition by MGMG was stronger than that by MGDG. Both MGDG and MGMG could halt the cell cycle at the G1 phase, and subsequently induced severe apoptosis. The relationship between the DNA polymerase inhibition and the cell growth effect by these glycolipids is discussed.
Murakami
Chikako
C
Laboratory of Food and Nutritional Sciences, Department of Nutritional Science, Kobe-Gakuin University, Nishi-ku, Kobe, Hyogo 651-2180, Japan.
Kumagai
Taeko
T
Hada
Takahiko
T
Kanekazu
Ui
U
Nakazawa
Satoshi
S
Kamisuki
Shinji
S
Maeda
Naoki
N
Xu
Xianai
X
Yoshida
Hiromi
H
Sugawara
Fumio
F
Sakaguchi
Kengo
K
Mizushina
Yoshiyuki
Y
D000818:Animals; D017209:Apoptosis; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D004247:DNA / Q000187:drug effects / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000187:drug effects / Q000378:metabolism*; D038983:Galactolipids / Q000378:metabolism / Q000494:pharmacology*; D006017:Glycolipids / Q000378:metabolism / Q000494:pharmacology; D006868:Hydrolysis; D008049:Lipase / Q000378:metabolism; D008322:Mammals; D018724:Spinacia oleracea / Q000737:chemistry*; D014407:Tumor Cells, Cultured
D038983:Galactolipids; D006017:Glycolipids; C008543:galactosylglyceride; C009909:monogalactosyldiacylglycerol; D004247:DNA; D004259:DNA-Directed DNA Polymerase; D008049:Lipase