(R,R)-MK 287  (Synonyms: L-680574)

(R,R)-MK 287 is a tetrahydrofuran derivative that effectively inhibits the binding of [3H]C18-PAF to human platelets, polymorphonuclear leukocytes (PMNs), and lung membranes with K1 values of 6.1 ± 1.5, 3.2 ± 0.7, and 5.49 ± 2.3 nM, respectively. The inhibition is stereospecific and competitive. Its racemate, L-668,750, is less potent, and its enantiomer, L-680574, is only 1/20 as potent as MK 287. MK 287 inhibits the binding of [3H]C18-PAF to human PMN membranes, reducing the affinity of the radioligand without changing the number of receptor sites. The binding of other radioligands (e.g., LTB4, LTC4, C5a, FMLP) to their specific receptors is unchanged at 1-10 microM MK 287. [3H]MK 287 binds to human platelet and PMN membranes with KD values of 2.1 ± 0.6 and 2.9 ± 1.2 nM. When tested on isolated human cells, MK 287 potently and selectively inhibits PAF-induced platelet aggregation (ED50 = 56 ± 38 nM or ED50 = 1.5 ± 0.5 nM for gel-filtered platelets) and elastase release from PMNs (ED50 = 4.4 ± 2.6 nM). In vivo studies, MK 287 inhibited PAF-induced lethality in mice (ED50 = 0.8 mg/kg oral) and PAF-induced bronchospasm in guinea pigs (ED50 = 0.18 mg/kg intraduodenally and 0.19 mg/kg intravenously). The inhibition of PAF-induced bronchospasm was accompanied by a rightward shift in the concentration-response curve for PAF-induced platelet aggregation measured in vitro.

510.60

C₂₅H₃₄O₉S

143490-81-7

Room temperature in continental US; may vary elsewhere.

Please store the product under the recommended conditions in the Certificate of Analysis.

• [1]. MK 287: a potent, specific, and orally active receptor antagonist of platelet-activating factor.