Background:

Ki = 68 nM

Uniconazole is a cytochrome P450 707As inhibitor.

Plant growth retardants (PGRs) can reduce the shoot growth of plants via inhibiting gibberellin biosynthesis. The inhibitory effects of PGRs on Arabidopsis abscisic acid (ABA) 8'-hydroxylase, a major ABA catabolic enzyme, recently identified as CYP707As, have been reported.

In vitro: In an in-vitro assay with CYP707A3 microsomes expressed in insect cells, uniconazole could inhibit CYP707A3 activity more effectively than paclobutrazol or tetcyclacis, while the other tested PGRs could not significantly inhibit it. In addition, uniconazole was also found to be a strong competitive inhibitor of ABA 8'-hydroxylase [1].

In vivo: Uniconazole-treated Arabidopsis plants displayed enhanced drought tolerance. In uniconazole-treated plants, endogenous ABA levels increased 2-fold as compared with the control, and co-application of GA(4) could not suppress such effects, suggesting that these effects were not because of gibberellin deficiency. Therefore uniconazole could effectively inhibit ABA catabolism in Arabidopsis plants [1].

Clinical trial: So far, no clinical study has been conducted.

Reference:
[1] Saito, S. ,Okamoto, M.,Shinoda, S., et al. A plant growth retardant, uniconazole, is a potent inhibitor of ABA catabolism in Arabidopsis. Bioscience, Biotechnology, and Biochemistry 70(7), 1731-1739 (2006).