Folate has recently been proposed as a new antioxidant. Folate supplementation may have a protective effect in counteracting oxidant-induced apoptotic damage. The present studies were undertaken to examine whether there is a direct link between folate levels, antioxidant capability and reduced apoptotic damage. Using an in vitro cellular model of 7-ketocholesterol (KC)-induced apoptosis, U937 cells were pre-cultured with a folate-deficient medium supplemented with various levels of folate (2–1500μmol/l) before treatment with 7-KC. Apoptotic markers, mitochondria-associated death signals and levels of reactive oxygen species were assayed. After treatment with 7-KC for 30h, low and high levels of folate supplementation significantly (P<0.05) reduced nuclear DNA loss. Only high levels of folate supplementation (>1000μmol/l) were effective in counteracting 7-KC-promoted apoptotic membrane phosphatidylserine exposure and DNA laddering. The attenuation of 7-KC-induced apoptotic damage by high-dose folate supplementation coincided with a partial normalization of mitochondria membrane potential dissipation, a suppression of cytochrome c release and an inhibition of procaspase 3 activation. The prevention of mitochondrial dysfunctions and apoptotic processes was associated with antioxidant actions of high-dose folate by a marked scavenging of intracellular superoxide. Collectively, our present results demonstrate that in vitro folate supplementation exerts differentially protective effects against 7-KC-induced damage. High-dose supplementation alleviates oxidative stress, mitochondria-associated death signalling and apoptosis induced by 7-KC. However, the in vivo relevance is not clear and requires further study.

Two studies were conducted to investigate the possibility that pteroylmonoglutamic acid supplementation would alleviate teratogenesis in zinc-deficient rats. Pregnant rats of the Wistar strain were fed on Zn-deficient (< 0.5 mg Zn/kg) or Zn-supplemented (75 or 95 mg Zn/kg) diets from mating until day 18.5 of gestation. The basal level of pteroylmonoglutamic acid added to all diets (0.56 mg/kg) was supplemented with 30–200 mg/kg in selected diets. Dietary Zn deprivation resulted in fetal resorption, fetal growth retardation and reduced concentrations of Zn in fetuses and maternal plasma and tibia. Low maternal body-weight at conception emerged as an important determinant of risk of resorption in Zn-deficient rats. Dietary Zn deficiency resulted in reduced maternal plasma folate concentrations and these values were inversely correlated with litter size or weight in Zn-deficient rats. Pteroylmonoglutamic acid supplementation increased maternal plasma folate concentrations, but did not reduce the high incidence of teratogenesis which occurred in Zn-deficient rats. Supplementation of Zn-deficient rats with pteroylmonoglutamic acid significantly increased the incidence of clubbed foot and tended to increase the incidence of brain or meningeal abnormalities, or both, and cleft palate, but did not reduce maternal or fetal Zn status. Pteroylmonoglutamic acid supplementation also increased the weights of Zn-supplemented control fetuses.