Extract text from between characters multiple instances in one cell

[H-M-P]

Hi

I have an online forms database that, when exported, provides both the field label and value, such that many of the table's columns have redundant data. I would like to eliminate the duplicated info. 

Example: I would like column A to go from:

GMC (GMC), NH4+ (NH4+), NO3- (NO3-), Other (Other)

to

GMC, NH4+, NO3-, Other

I tried =MID(LEFT(A1,FIND(")",A1)-1),FIND("(",A1)+1,LEN(A1)) but that returns only the first instance of text bordered by brackets, and I need every instance output into in a single cell.

[#2]

@H-M-P 

With Excel 365, you could search for parentheses and then use FILTER and the MID function.

= LET(
    k,    SEQUENCE(LEN(text)),
    strt, 1+FILTER(k,MID(text,k,1)="("),
    end,  FILTER(k,MID(text,k,1)=")"),
  TEXTJOIN(", ", , MID(text,strt,end-strt)))