L-cystine is the L-enantiomer of the sulfur-containing amino acid cystine. It has a role as an EC 1.2.1.11 (aspartate-semialdehyde dehydrogenase) inhibitor, a flour treatment agent, a mouse metabolite, a Saccharomyces cerevisiae metabolite and a human metabolite. It is a cystine, a non-proteinogenic L-alpha-amino acid and a L-cysteine derivative. It is a conjugate acid of a L-cystine anion. It is an enantiomer of a D-cystine. It is a tautomer of a L-cystine zwitterion. L-Cystine can improve hyperlipidemia by restoring LPL and HSL activities.L-Cystine protects against the toxicity of PQ by maintaining reduced glutathione levels in the cells. Co-administration of l-cystine and l-theanine before vaccination may enhance the immune response to influenza vaccine in elderly subjects with low serum total protein or hemoglobin.

Succinic acid is an alpha,-dicarboxylic acid resulting from the formal oxidation of each of the terminal methyl groups of butane to the corresponding carboxy group. It is an intermediate metabolite in the citric acid cycle. It has a role as a micronutrient, an anti-ulcer drug, a nutraceutical, a radiation protective agent and a fundamental metabolite. It is an alpha,omega-dicarboxylic acid and a C4-dicarboxylic acid. It is a conjugate acid of a succinate(1-). Succinic acid is a crystalline organic acid which occurs in living tissue as an intermediate in glucose metabolism.

L-Cysteine inhibits insulin release via multiple actions on the insulin secretory process through H(2)S production. L-Cysteine administration limits ischemia-reperfusion injury through a mechanism that appears to be at least partially dependent on H2S synthesis. L-cysteine hydrochloride hydrate is a hydrate that is the monohydrate form of L-cysteine hydrochloride. It has a role as a flour treatment agent, an EC 4.3.1.3 (histidine ammonia-lyase) inhibitor and a human metabolite. It contains a L-cysteine hydrochloride.