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. 2022 Feb 24;13:805986. doi: 10.3389/fphar.2022.805986

TABLE 3.

Opioid Agonistic Activity of Mitragynine (1), Speciociliatine (3), and Morphine in Electrically Stimulated Guinea-Pig Ileum Preparation.

Compound Structure a pD2 value b Relative potency (%) c Relative inhibitory activity (%)
Mitragynine (1) graphic file with name fphar-13-805986-fx1.jpg 6.95 ± 0.12 26 95
Speciociliatine (3) graphic file with name fphar-13-805986-fx2.jpg 5.40 ± 0.07 2 101
Morphine graphic file with name fphar-13-805986-fx3.jpg 7.17 ± 0.05 100 100
a

pD2 values indicate the potency of agonist, the higher pD2 reflects higher potency of the agonist.

b

Relative potency is shown as a percentage of the pD2 value of the compound against that of morphine.

c

Relative inhibitory activity reflects to the intrinsic activity on opioid receptors, is shown as a percentage of the maximum inhibition by compounds against that by morphine. All data points represent mean ± SEM (µM) of n ≥ 3.