(s)malic acid

(S)-Malic acid ((S)-2-Hydroxysuccinic acid) is a tart-tasting organic dicarboxylic acid found in many sour foods, such as apples, and contributes to the sourness of green apples and tartness of wine, although its concentration decreases with fruit ripeness (wikipedia). In its ionized form, it is called malate, an intermediate in the TCA cycle alongside fumarate, and can be formed from pyruvate through anaplerotic reactions. In humans, malic acid is derived from food sources and synthesized in the body via the citric acid cycle in mitochondria, playing a crucial role in energy production under both aerobic and anaerobic conditions. Under aerobic conditions, malate is oxidized to oxaloacetate, providing reducing equivalents via the malate-aspartate redox shuttle, while during anaerobic conditions, its simultaneous reduction to succinate and oxidation to oxaloacetate removes excess reducing equivalents, reversing hypoxia's inhibition of glycolysis and energy production. Studies on rats have shown that tissue malate depletes following exhaustive physical activity, suggesting that malic acid deficiency may cause physical exhaustion. Administering malic acid to rats has been shown to elevate mitochondrial malate, increasing mitochondrial respiration and energy production.

(S)-Malic acid (Standard) is the standard substance of (S)-Malic acid, and it is applicable for quantitative analysis, quality control, and related research in biochemical experiments. (S)-Malic acid ((S)-2-Hydroxysuccinic acid) is a tart-tasting organic dicarboxylic acid that plays a role in many sour or tart foods. Apples contain malic acid, which contributes to the sourness of a green apple. Malic acid can make a wine taste tart, although the amount decreases with increasing fruit ripeness. (wikipedia). In its ionized form malic acid is called malate. Malate is an intermediate of the TCA cycle along with fumarate. It can also be formed from pyruvate as one of the anaplerotic reactions. In humans, 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. 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 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, malic acid's simultaneous reduction to succinate and oxidation to oxaloacetate is capable of removing the accumulating reducing equivalents. This allows 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. Other key metabolites from the citric acid cycle needed for energy production were found to be unchanged. Because of this, a deficiency of malic acid has been hypothesized to be a major cause of physical exhaustion. Notably, the administration of malic acid to rats has been shown to elevate mitochondrial malate and increase mitochondrial respiration and energy production.