Structure and activity relationship of monogalactosyl diacylglycerols, which selectively inhibited in vitro mammalian replicative DNA polymerase activity and human cancer cell growth

The glycoglycerolipid, monogalactosyl diacylglycerol (MGDG), containing two α-linolenic acids (C18:3), was isolated from bitter melon as a potent and selective inhibitor of mammalian DNA polymerase (pol) species such as pols α, γ, δ, and ε with IC50 values of 17.6–37.2 μM. This MGDG also suppressed the growth of six human cancer cell lines, although normal human cell lines were not affected. This compound (i.e., MGDG-C18:3-C18:3) was a stronger inhibitor than both MGDG-C18:1-C18:0 and MGDG-C18:0-C18:0. In this study, we discussed the structure–function relationship in the selective inhibition of mammalian replicative pols and human cancer cell proliferation by MGDGs.