The increasing problem of antimicrobial resistance highlights the need for new antibacterial agents. Plant kingdom provides a rich source of bioactive compounds and is therefore of interest in the search for novel antimicrobial substances. In the pharmacognosy course (3FN400) for the pharmacy program at the Biomedical Center of Uppsala University, students performed laboratory experiments, testing various plant extracts for antimicrobial activity against the non-pathogenic strain of Escherichia coli bacteria ATCC 25922. Some plant extracts showed indications of antibacterial activity. As laboratory work may be affected by experimental variability, these findings require validation. The aim of this project was to validate the previously reported antibacterial activity by repeating the same laboratory experiments performed during earlier courses since the academic term of autumn, 2022. The overall aim is to assess the potential of these plant extracts as novel antimicrobial candidates with possible pharmaceutical applications. Overall these semesters, more than 300 plant extracts and 1500 fractions were tested. In this project, 13 of the reported active plant extracts and 65 fractions were selected to be tested using the same methods, primarily zone of inhibition agar diffusion assays and microbroth dilution assays. In the repeated experiments, no antibacterial activity was observed for most plant extracts. However, antibacterial activity was confirmed by microbroth dilution for two previously reported fractions from Syzygium wilsonii and Syngonium auritum. This study demonstrates the importance of validating preliminary findings of laboratory work and encourages further investigation of selected plant fractions.