The invention discloses and claims a compound of formula (I): ##STR00001## Wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6, R.sub.7, R.sub.8 and R.sub.11 are as defined herein. Further embodiments of the invention include a method of preparation of a compound of formula (I), its pharmaceutical composition and a method of treatment of a disease using a compound of formula (I).