The interaction of alpha-chlorohydrin with glycerol kinase

A re-appraisal of the post-testicular action and toxicity of chlorinated antifertility compounds

Some 30 years ago, alpha-chlorohydrin and some analogues were considered as close to the ideal contraceptive which acted rapidly and reversibly on the post-testicular maturation of spermatozoa. Despite their early promise, research funding was withdrawn only 5 years later because of what were considered to be unacceptable side-effects in primates. The literature on the toxic effects of these contraceptive agents was reviewed and was found to be wanting in respect to the rigour of scientific methods applied (impure compounds were used, inappropriate target populations were studied, excessive doses were employed, abstracts were cited from which no full publications subsequently arose). These compounds remain the closest approach yet to non-hormonal contraceptives for males and have led to the synthesis of related compounds which have a similar antifertility action but with much diminished toxicity. If toxicity remains a problem, a range of other compounds now known to have a similar antifertility action, should be investigated.

Genomic scanning for expressed sequences in Xp21 identifies the glycerol kinase gene

Rapid genomic scanning methods are required to identify expressed sequences and we report an efficient, sensitive and specific approach which relies upon hybridization of an amplified, labeled cDNA library to digested cosmid DNA. We identified expressed sequences within a cosmid in the glycerol kinase (GK) "critical region" of Xp21 that had impressive similarity to prokaryotic GKs. We used this genomic sequence information to clone the human hepatic GK cDNA. Independent confirmation of the identity of this gene was obtained by functional complementation of GK deficient E. coli mutants with a construct containing the complete human X-linked GK coding sequence.

1-Thioglycerol: inhibitor of glycerol kinase activity in vitro and in situ

The infantile form of glycerol kinase (GK) deficiency (McKusick No. 30703) (1) is characterized by adrenal cortical insufficiency, adrenal hypoplasia and developmental delay. The underlying biochemical mechanism(s) responsible for the observed clinical presentations are undetermined. Pursuant to our examination of the molecular pathogenesis of this enzyme deficiency, we have endeavored to develop a model for this disorder. 1-thioglycerol (1-TG) was investigated as a potential GK inhibitor in adrenal gland, an organ consistently affected, and in cultured fibroblasts, available from affected individuals. In 105,000 g bovine adrenal supernatant the Ki for 1-TG was 1.9 mM. In human fibroblast 105,000 g supernatant, the Ki for 1-TG was 3.4 mM. In both tissues the inhibition was purely competitive with respect to glycerol. Using incorporation of [14C(U)]-glycerol into protein as an index of GK activity in situ in human skin fibroblasts, GK deficient fibroblasts incorporate less than 10% of that observed in normal fibroblasts. Addition of 1-TG to normal fibroblasts resulted in inhibited incorporation rates. The specificity of these effects in situ was examined. Our findings indicate that 1-TG may be a suitable inhibitor of GK activity for the development of a model for glycerol kinase deficiency.

Inhibition of glycolysis in boar sperm by alpha-chlorohydrin

The effect of alpha-chlorohydrin (3-chloropropan-1,2-diol) on the metabolism of D-[U-14C]-fructose and L-[U-14C]-lactate by washed boar sperm has been investigated. Whereas alpha-chlorohydrin at concentrations as low as 0.1 mM inhibited the metabolism of fructose and led to an increase in the utilization of endogenous lactate, amounts up to 500 mM had no effect on the oxidation of added lactate. Low levels of alpha-chlorohydrin increased the cellular concentrations of fructose-1,6-bisphosphate and the triosephosphates, an effect consistent with the inhibition of glyceraldehyde-3-phosphate dehydrogenase. Although [U-14C]-glycerol was rapidly oxidized by boar sperm, [U-14C]-alpha-chlorohydrin was not metabolized to 14CO2, showing that it is not converted to glycerol. Extracts obtained by sonication of boar sperm after incubation with [3-36C1]-alpha-chlorohydrin, did not contain [3-36C1]-alpha-chlorohydrin-1-phosphate. This is contrary to the postulate that this phosphorylated compound is the inhibitory metabolite of alpha-chlorohydrin.

Antifertility and toxicological studies with aromatic esters of alpha-chlorohydrin in male rats

Due to the drawbacks in the potential use of alpha-chlorohydrin itself as a male oral contraceptive, two novel crystalline derivatives, alpha-chlorohydrin-bis-m-nitrobenzoate and alpha-chlorohyrdin-mono-p-acetamidobenzoate, were synthesized and tested for antifertility activity in male rats. In addition, the nephrotoxic effects of alpha-chlorohydrin itself and of the two aromatic esters were investigated by the use of diuretic experiments, plasma biochemical analyses and kidney histology. Both esters were found to be of comparable molar potency to alpha-chlorohydrin in inducing temporary infertility following daily oral administration. The nephrotoxic effects following high oral doses of alpha-chlorohydrin were largely eliminated by the use of either ester. These derivatives have several advantages over alpha-chlorohydrin, being crystalline compounds of definable purity. Although potency was retained, acute oral toxicity was greatly reduced, due to a combination of factors - the esters were poorly absorbed in high dosage whilst relatively slow breakdown permitted effective levels to be attained on epididymal spermatozoa.