New tetracyclo compounds of the formula: ##STR1## in which R.sup.1 is formyl, protected formyl, hydroxymethyl, protected hydroxymethyl, arylaminomethyl, carboxy, protected carboxy or substituted iminomethyl,R.sup.2 is hydroxy, alkoxy or protected hydroxy,R.sup.3 is hydrogen and R.sup.4 is methyl, hydroxymethyl or protected hydroxymethyl, orR.sup.3 and R.sup.4 are combined together to form methylene or oxo,R.sup.5 is hydroxy, alkoxy or protected hydroxy, andR.sup.6 is hydrogen, imino-protective group or alkyl,and pharmaceutically acceptable salts thereof, which have pharmacological activities such as antitumor activity, antimicrobial activity, and the like, and a process for their production and a pharmaceutical composition containing the same.