Synthesis and biological evaluation of trifluoromethyl-containing auxin derivatives

This study focused on the chemical synthesis of auxin analogs, wherein a trifluoromethyl group was introduced near the carboxyl group in the side chain of natural and synthetic auxins, including IAA, NAA, IBA, 2,4-D, and 4-Cl-IAA. The effects of these synthetic compounds and natural auxins on plant growth regulation and callus growth were evaluated. In experiments with black gram, CF₃-IAA and 4-Cl-CF₃-IAA exhibited comparable effects to the parent compound, IAA. Meanwhile, CF₃-NAA, CF₃-2,4-D, CF₃-IBA-1, and CF₃-IBA-2 displayed effects that differed considerably from those of their respective parent auxins. In experiments with lettuce, CF₃-IAA, 4-Cl-CF₃-IAA, CF₃-NAA, CF₃-2,4-D, and CF₃-IBA-1 showed effects comparable to the corresponding parent auxins. However, at low concentrations, these analogs induced hypocotyl and root elongations, a response distinct from that observed with their parent compounds. Furthermore, CF₃-IBA-2 considerably promoted hypocotyl and root elongations across all concentrations relative to the control. The addition of synthetic compounds to callus cultures revealed that CF₃-IAA, 4-Cl-CF₃-IAA, CF₃-NAA, and CF₃-2,4-D promoted callus proliferation, whereas CF₃-IBA-1 and CF₃-IBA-2 did not enhance callus growth.