Aldose reductase is a human enzyme that converts aldehydes into alcohols by the addition of hydrogen (H) to to a double bonded oxygen site (C=0 becomes C-OH).
Aldose reductase reduces the aldehyde portion of glucose creating the sugar alcohol sorbitol.
| Glucose | Aldose reductase | Sorbitol |
|---|---|---|
 |
—-> |  |
Effects on Norepinephrine Metabolism
The normal pathway in humans for norepinephrine (NE) is deamination by monoamine oxidase (MAO), forming an aldehyde which is then either metabolized to 3,4-dihydroxy-mandelic acid (DHMA) by aldehyde dehydrogenase or is converted to 3,4-dihydroxyphenylglycol (DHPG) by or aldose reductase.
The same metabolic pathways exists in rats. In vivo tests performed on rats given aldose reductase inhibitors caused a sharp increase in the formation of DHMA and a decrease in the formation of DHPG.[6] Because human metabolism of NE follows the same pathway it can be concluded that inhibition of aldose reductase in humans should produce an increase in DHMA and a decrease in DHPG.
Inhibitors
| Potent Inhibitors | Strength | Dosage | Verified in Man |
|---|---|---|---|
| Cuminaldehyde | IC50 0.00085 mg/mL[1]1 | ? | ? |
| Cinnamaldehyde | IC50 0.003 mg/mL[3]2 | ? | ? |
| Myricitrin [4] | ? | ? | ? |
| Quercetin | IC50 2 mM[2] | ? | ? |
| Quercitrin [4] | ? | ? | ? |
| Rutin | IC50 5 mM[2] | ? | ? |
| Moderate Inhibitors | Strength | Dosage | Verified in Man |
| Black pepper water extract | 0.22 mg/ml[5] | ? | ? |
| Orange fruit water extract | 0.25 mg/ml[5] | ? | ? |