Estriol (E3), also spelled oestriol, is a steroid, a weak agonist of the estrogen receptors ERα and ERβ., and a minor female sex hormone. According to in vitro study, the relative binding affinity (RBA) of estriol for the human ERα and ERβ was 11.3% and 17.6% of that estradiol, respectively, and the relative transactivational capacity of estrone at the ERα and ERβ was 10.6% and 16.6% of that of estradiol, respectively. Estriol is marketed widely in Europe and elsewhere throughout the world under the brand names Ovestin, Ortho-Gynest, and a variety of others. It is available in oral tablet, vaginal cream, and vaginal suppository form, and is used in menopausal hormone therapy for the treatment of menopausal symptoms. Estriol is also available in some countries as estriol succinate (brand name Synapause), a dosage-equivalent ester prodrug of estriol. Estriol and estriol succinate are not approved for use in the United States and Canada, although they have been produced and sold by compounding pharmacies in North America for use as a component of bioidentical hormone therapy. Estriol can be measured in maternal blood or urine and can be used as a marker of fetal health and well-being. If levels of unconjugated estriol (uE3 or free estriol) are abnormally low in a pregnant woman, this may indicate chromosomal or congenital anomalies like Down syndrome or Edward's syndrome. It is included as part of the triple test and quadruple test for antenatal screening for fetal anomalies.

Sodium 2-naphthalenesulfonate is a sodium salt of naphthalene sulfonic acid. Sodium 2-naphthalenesulfonate is a surfactant-hydrotrope used in cosmetics. Use concentrations would be typically below 2%. In clinical studies, Sodium 2-naphthalenesulfonate was neither an irritant (tested up to 2%), cumulative irritant (tested up to 1%), nor a sensitizer (tested up to 1%). Sodium 2-naphthalenesulfonate is considered safe as used in cosmetic formulations intended to be applied to the skin.

L-Malic acid is a tart-tasting organic dicarboxylic acid that plays a role in many sour or tart foods. L-Malic acid is the naturally occurring form, whereas a mixture of L- and D-malic acid is produced synthetically. In humans, L-malic acid is both derived from food sources and synthesized in the body through the citric acid cycle or Krebs cycle which takes place in the mitochondria. L-Malate's importance to the production of energy in the body during both aerobic and anaerobic conditions is well established. Under aerobic conditions, the oxidation of L-malate to oxaloacetate provides reducing equivalents to the mitochondria through the malate-aspartate redox shuttle. During anaerobic conditions, where a buildup of excess of reducing equivalents inhibits glycolysis, L-malic acid's simultaneous reduction to succinate and oxidation to oxaloacetate is capable of removing the accumulating reducing equivalents. This allows L-malic acid to reverse hypoxia's inhibition of glycolysis and energy production. In studies on rats it has been found that only tissue malate is depleted following exhaustive physical activity. Notably, the administration of malic acid to rats has been shown to elevate mitochondrial malate and increase mitochondrial respiration and energy production. L-Malic acid is the source of extreme tartness in United States-produced confectionery, the so-called extreme candy. It is also used with or in place of the less sour citric acid in sour sweets. These sweets are sometimes labeled with a warning stating that excessive consumption can cause irritation of the mouth. The quantitative determination of L-malic acid is especially important in the manufacture of wine, beer, bread, fruit and vegetable products, as well as in cosmetics and pharmaceuticals. It is one of the most important fruit acids, and has the highest concentration of all acids in wine. In the wine industry, the level of L-malic acid is monitored, along with L-lactic acid, during malolactic fermentation. Malic acid is approved for use as a food additive in the EU, US and Australia and New Zealand. Malic acid, when added to food products, is denoted by E number E296.

Methylenetetrahydrofolate reductase (MTHFR) is an enzyme required for the formation of 5-methyltetrahydrofolate (5-MTHF), a form of folate able to cross the blood-brain barrier and which is necessary as a substrate for the remethylation of homocysteine to methionine by methionine synthase. Patients with severe MTHFR deficiency cannot make 5-MTHF and have extremely low levels in the CSF. Only treatment with oral 5-MTHF given as calcium mefolinate resulted in an increase in CSF 5-MTHF.

Estriol (E3), also spelled oestriol, is a steroid, a weak agonist of the estrogen receptors ERα and ERβ., and a minor female sex hormone. According to in vitro study, the relative binding affinity (RBA) of estriol for the human ERα and ERβ was 11.3% and 17.6% of that estradiol, respectively, and the relative transactivational capacity of estrone at the ERα and ERβ was 10.6% and 16.6% of that of estradiol, respectively. Estriol is marketed widely in Europe and elsewhere throughout the world under the brand names Ovestin, Ortho-Gynest, and a variety of others. It is available in oral tablet, vaginal cream, and vaginal suppository form, and is used in menopausal hormone therapy for the treatment of menopausal symptoms. Estriol is also available in some countries as estriol succinate (brand name Synapause), a dosage-equivalent ester prodrug of estriol. Estriol and estriol succinate are not approved for use in the United States and Canada, although they have been produced and sold by compounding pharmacies in North America for use as a component of bioidentical hormone therapy. Estriol can be measured in maternal blood or urine and can be used as a marker of fetal health and well-being. If levels of unconjugated estriol (uE3 or free estriol) are abnormally low in a pregnant woman, this may indicate chromosomal or congenital anomalies like Down syndrome or Edward's syndrome. It is included as part of the triple test and quadruple test for antenatal screening for fetal anomalies.