On the other hand, the same microbiologist, apparently tested, though it was never verified, the NInC ethyl ester 10, the relatively more stable NInC 33, and NInC 36 for their in vitro enzymatic inhibition. Inasmuch as, the InC moiety of these hybrids is, in point of fact, a potent β-lactamase inhibitor, and some of the cleavable linkers in this work are particularly labile in aqueous media, it did come as a surprise that all of which according to the aforementioned microbiologist showed no in vitro enzymatic inhibition whatsoever.