Abstract A copper‐containing enzyme polyphenol oxidase (other name is tyrosinase) plays crucial role in melanin biosynthesis, as a compound responsible for human pigmentation. Non controlled loss of melanin can cause hypopigmentation disease. The hypopigmentatory disorder can be treated with melanogenesis stimulators. Here, twenty‐four new β‐lactam compounds were synthesized, characterized and in vitro effects of them on banana tyrosinase investigated. The enzyme has been purified from banana by an affinity gel comprised of Sepharose4B−L‐tyrosine‐ p ‐aminobenzoic acid. The results showed that the compounds have an effect on increasing the activity of tyrosinase enzyme. Molecules having a notable tyrosinase activator effects are compound 3 h (79.86) and compound 4 n (61.30). The maximal activation, 131% was determined at 130 μM concentration. These results suggested that compounds 3 h and 4 n might represent a novel approach for an effective therapy for diseases associate with tyrosinase dysfunction, such as vitiligo and hair graying.