Goldenseal (Hydrastis canadensis)
The root is used medicinally. Goldenseal characteristically contains the isoquinoline alkaloids: berberine, hydrastine, canadine, berberastine, hydrastinine tetrahydroberberastine, and canalidine.(8) A related compound, 8-oxotetrahydrothalifendine, was identified in one study.(9) Berberine behaves as a quaternary base and dissolves slowly in water.(10) Hydrastine is insoluble in water, but freely soluble in alcohol and acetone.(10)
Research into the toxicology and pharmacology of goldenseal has focused on berberine and hydrastine.(11) Berberine is a constituent of the roots of several species of plant though hydrastine is found only in Hydrastis canadensis and Berberis laurina.(10) Berberine is thought to be antimicrobial, antidiarrheal, antiarrhythmic, a positive inotrope, cytotoxic, choleretic, mydriatic, anticarcinogenic, and hypoglycemic.(4) Hydrastine is thought to be choleretic, sedative, antibacterial, and vasoconstrictive.(4) The National Toxicology Program is currently investigating the toxicology of goldenseal root powder.(12,13) To support the effort, Weber et al. has developed a rapid ambient extraction method to assay goldenseal root powder and determine its purity.(8)
No developmental toxicity was noted in rats fed goldenseal powder at up to 7738 mg/kg/day (300 times the standard human dose).(12) In rats fed about 47 times the usual human dose of 26 mg/kg, maternal liver weights increased, but there were no adverse fetal effects.(13) Carcinogenicity studies are ongoing. The oral LD50 for berberine in mice is 329 mg/kg; the subcutaneous LD50 in mice is 18 mg/kg; the intraperitoneal LD50 for berberine sulfate is 24.3 mg/kg in mice and 500mg/kg in rats.(10) The IM LD50 of berberine sulfate in rats is 14.5mg/kg.10 The LD50 of berberine in humans is thought to be 27.5 mg/kg.2 The intraperitoneal LD50 for rats of hydrastine is 104 mg/kg.(10) An LD50 of 1620 mg/kg was reported for goldenseal root extract.(4)
Animal studies suggesting improved cardiac function in rats with induced left ventricular hypertrophy treated with berberine must be interpreted with caution because the dose of berberine was not reported.(14)
Human studies of berberine have revealed evidence of absorption through the skin.(10) In an unknown species, berberine was absorbed slowly orally; it achieved peak plasma concentrations in 4 hours and took 8 hours to clear.(10) Berberine is excreted in the urine.(11) No pharmacokinetic data is available for hydrastine or goldenseal root powder. The following activities are cited for berberine in humans: 1) blocking α1 and α2 receptors in smooth muscle, 2) blocks potassium channels in the heart and reduces ventricular tachycardia, 3) inhibits intestinal ion secretion and toxin formation in the gut and 4) increases bile secretion.(4,11)
Multiple bacteria and fungi, along with selected protozoa and chlamydia are susceptible to berberine in vitro.(4)
A study of healthy volunteers given indinavir with and without goldenseal root powder in a crossover design showed no difference in the peak concentrations of indinavir after a single oral dose and no difference in oral clearance(15). Goldenseal root powder increases IgM production in vivo.(16) Berberine displaced the protein binding of bilirubin a Chinese study using rats.(4) Berberine alone has weak antibiotic activity in vitro since many microorganisms actively export it from the cell. Interestingly, there is some evidence for other berberine-containing species (Berberis fremontii) also synthesizing an efflux pump inhibitor that potentiates the effect of berberine, a case of solid scientific evidence that the herb is superior to the isolated active principle.(17) However, it is not yet known whether goldenseal contains such an efflux pump inhibitor as well.
Herbal properties (whole herb): bitter, hepatic, alterative, anticatarrhal, anti-inflammatory, antimicrobial, laxative, emmenagogue, oxytocic.(18)