NEW MATERIAL:ML-236B derivatives composed of carboxylic acid of formula I (R1 is formula II, formula III; R2, R3 are lower alkyl), its salt, ester or cyclized lactone.

USE: Since it inhibits cholesterol synthesis to lower lipids in blood and so is used as remedy for hyperlipemia or preventive for arterioscrelosis. It is administered orally or parenterally in the form of capsules, tablets or injection solutions. The dose is in general about 0.2W200mg/day/adult in 3 or 4 portions.

PREPARATION: A carboxylic acid of formula IV, or its salt, ester or cyclized lactone is brought into contact with a microorganism capable of causing 3-hydroxylation or 6-hydroxylation to effect enzymatic hydroxylation. Then, the product is subjected to hydrolysis, salt-formation reaction or the like to give the compound of formula I .