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, CF-IAA and 4-Cl-CF-IAA exhibited comparable effects to the parent compound, IAA. Meanwhile, CF-NAA, CF-2,4-D, CF-IBA-1, and CF-IBA-2 displayed effects that differed considerably from those of their respective parent auxins. In experiments with lettuce, CF-IAA, 4-Cl-CF-IAA, CF-NAA, CF-2,4-D, and CF-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, CF-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 CF-IAA, 4-Cl-CF-IAA, CF-NAA, and CF-2,4-D promoted callus proliferation, whereas CF-IBA-1 and CF-IBA-2 did not enhance callus growth.