[(3R)-1-[(2R,3R,4R,5S,6R)-2-[[(2R,3S,4R,5R,6R)-3-hydroxy-4-[(3R)-3-hydroxydecoxy]-5-(3-oxotetradecanoylamino)-6-phosphonooxyoxan-2-yl]methoxy]-6-(methoxymethyl)-3-(3-oxotetradecanoylamino)-5-phosphonooxyoxan-4-yl]oxydecan-3-yl] (Z)-dodec-5-enoate
E5531 is an endotoxin antagonist.