Carboxylated psilocybin derivatives and methods of using

A method for treating a psychiatric disorder, the method comprising administering to a subject in need thereof a pharmaceutical formulation comprising a chemical compound having the formula (I):

• wherein, at least one of R2, R5, R6, or R7 is a carboxyl group or a carboxylic acid derivative, and wherein each non-carboxylated R2, R5, R6, or R7 is a hydrogen atom, an alkyl group, or O-alkyl group, wherein R4 is an O-alkyl group, an O-acyl group, a hydroxy group, a phosphate group, a glycosyloxy group, or a hydrogen atom and wherein R3A and R3B are each independently a hydrogen atom, an alkyl group, acyl group or an aryl group, wherein the pharmaceutical formulation is administered in an effective amount to treat the psychiatric disorder in the subject.