Aldehyde dehydrogenases (ALDH, EC 1.2.1.3) are a group of enzymes that catalyze the oxidation (dehydrogenation) of aldehydes to carboxylic acids, an action also performed by xanthine oxidase (XO) and aldehyde oxidase (AO).
The aldehyde cinnamaldehyde commonly used as a food flavoring is rapidly oxidized by aldehyde dehydrogenases into the carboxylic acid cinnamic acid.
Cinnamaldehyde | AO | Cinnamic acid |
---|---|---|
![]() |
—-> | ![]() |
Inhibitors and Inducers
Potent Inhibitors | Strength | Dosage | Verified in Man |
---|---|---|---|
Calcium carbimide | ? | ? | ? |
Citral [5] | 55 mM[6]1 | ? | ? |
Daidzein (in Kudzu) | ? | ? | ? |
Daidzin(in Kudzu) | Ineffective in hamsters [3]2 | ? | ? |
Diethyl disulfide (in durian fruit) | 81.5% in vitro[7] | 1.1 ppm | ? |
Disulfiram | ? | ? | Yes |
Durian fruit extract | 70% in vitro[7] | 0.33 ppm | ? |
Gallic Acid | ? | ? | ? |
Phenethyl isothiocyanate (in cabbage) | 70% in rats [1] | ? | ? |
Semicarbazide | ? | ? | ? |
Moderate Inhibitors | Strength | Dosage | Verified in Man |
Caffeine[4] | Moderate | ? | No3 |
Kudzu (contains Daidzin) | ? | ? | ? |
Soy isoflavones (contains Daidzein, similar to Daidzin) | ? | ? | ? |
Theophylline[4] | Moderate | ? | No4 |
Weak Inhibitors | Strength | Dosage | Verified in Man |
Anisaldehyde | ? | ? | ? |
Benzaldehyde | ? | ? | ? |
Glycerin | ? | ? | ? |
Inducers (Unknown Potency) | Strength | Dosage | Verified in Man |
Black pepper | ? | ? | ? |
Capsaicin | ? | ? | ? |
Isosafrole | ? | ? | ? |
Piperine | ? | ? | ? |
Safrole | ? | ? | ? |
ALDH Action Duplicated By P450 Enzymes
Cytochrome P450 enzymes can oxidize certain aldehydes to carboxylic acids, performing an action similar to that of ALDH.[2]
In several tests the aldehyde 4-hydroxynonenal was successfully converted to its carboxylic acid using cytochrome P450 enzymes.[2]
The human cytochrome P450 enzymes enzymes catalyzed the reduction reaction in this order of effectiveness:
CYP2B6 > CYP3A4 > CYP1A2 > CYP2J2 [2]
Human CYP2E1 did not catalyze this reaction. [2]