Anti-cancer Effect of Spinach Glycoglycerolipids as Angiogenesis Inhibitors Based on the Selective Inhibition of DNA Polymerase Activity

Plants contain major glycoglycerolipids, such as monogalactosyl diacylglycerol ( MGDG), digalactosyl diacylglycerol (DGDG) and sulfoquinovosyl diacylglycerol (SQDG), in the chloroplast membrane. The bioactivities of purified MGDG, DGDG and SQDG from spinach have been investigated extensively. MGDG and SQDG have been shown to inhibit the activities of mammalian DNA polymerases, but DGDG has no such inhibitory effect. The effect of these glycoglycerolipids on cancer cells, angiogenesis and solid tumor growth might be mediated via their inhibition of replicative DNA polymerase activities. On the basis of these findings, we discuss the mode of action of plant chloroplast glycoglycerolipids as anti-cancer therapeutic agents.