IC50 and the 95% likelihood values for CYP3A inhibition in CHIM

Three different brands of noninhibitory (black cohosh, elderberry, echinacea) and inhibitory [green tea, horehound, St. John’s wort (SJW), valerian root] HSs and GFJ were evaluated for their inhibitory potential for CYP3A activity in CHIM. The GFJ results were from four replicate plates. The results were derived from nonlinear regression analysis of plots of CYP3A activity (midazolam 1′-hydroxylation) vs. log conc. of each substance using the Graphpad Prism 8.0 software. The different brands are shown in brackets.

Herbal Supplement (Supplier)IC50 (%)IC50 (%) 95% Likelihood
Black cohosh (GNC)>100NA
Black cohosh (Sundance)94.3765.50–183.2
Black cohosh (Nature’s Way)>100NA
Elderberry (Nature’s Way)>100NA
Elderberry (Horbaach)>100NA
Elderberry (NOW)>100NA
Echinacea (GNC)>100NA
Echinacea (Puritan’s Pride)>100NA
Echinacea (Nature’s Bounty))>100NA
Green tea (Nature’s Bounty)32.827.53–39.45
Green tea (Now)27.4822.89–33.11
Green tea (Spring Valley)49.4739.42–64.47
Horehound (Nature’s Answer)16.1413.30–19.59
Horehound (Botanic Choice)70.6550.76–114.6
Horehound (Eclectic Institute)45.3730.09–78.86
SJW (GNC)66.3948.27–104.5
SJW (Sundown Naturals)54.7938.56–85.23
SJW (Nature’s Bounty)86.3469.40–118.7
Valerian (Nature’s Way)4.84.23–5.43
Valerian (Nature’s Bounty)71.2857.71–93.63
Valerian (GNC)36.9630.30–46.13
GFJ-1 (plate 1)8.537.32–9.92
GFJ-2 (plate 2)4.123.36–4.96
GFJ-3 (plate 3)6.165.56–6.82
GFJ-4 (plate 4)6.726.14–7.36
  • NA, not applicable.