Table 1.

Screening of Selected Kratom Alkaloids at Adrenergic and Opioid Receptors

binding site	percent displacement of bound radioligand
	corynantheidine		9-hydroxycorynanthei-dine		mitragynine		7-hydroxymitragynine		speciociliatine
	100 nM	10,000 nM	100 nM	10,000 nM	100 nM	10,000 nM 100 nM		10,000 nM	100 nM	10,000 nM
adrenergic α1A	45.9	100.5	16.4	62.3	13.2	83.5	10.1	3.5	16.8	81.1
adrenergic α1B	19.6	91.0	−4.4	29.0	−12.5	40.3	5.9	−4.8	25.2	95.6
adrenergic α1D	73.5	101.2	12.4	66.3	−2.1	57.9	−1.9	13.5	6.3	70.5
adrenergic a2A	27.2	95.1	−10.2	20.0	−8.0	40.4	−6.7	−5.4	7.0	73.1
adrenergic α2B	8.5	79.9	−5.7	14.6	−16.0	25.1	−9.9	1.1	0.0	67.2
opioid δ	8.6	31.4	3.4	25.3	0.4	18.3	19.6	93.7	0.6	69.2
opioid κ	16.7	59.4	6.7	39.5	25.2	88.3	41.0	97.8	61.9	98.5
opioid μ	39.6	96.8	29.3	95.4	29.0	93.7	81.8	100.7	64.7	98.0
nociceptin NOP (ORL1)	−1.3	27.0	−2.9	28.9	4.3	40.8	−1.6	3.4	−14.9	31.8