(347) Development of a semi-quantitative plant based drug assay using Mimosa pudica

Objective : Animal-based drug assays are the most common method of new drug preclinical assays, however there are ethical disadvantages associated with animal use. Here we present the development of a plant-based drug assay using the thigmonastic movement response of Mimosa pudica as an alternative drug assay.

Methods: Mimosa pudica plants were grown from seed. Pinnae with uniform response towards mechanical stimuli were harvested from mature plants by severing the stem at the primary pulvinus. Samples were immediately floated in Petri dishes containing different drug solutions. Pinnae all close upon severance. The samples were allowed to open after harvest and the folding response was stimulated with a monofilament. The qualitative response to stimuli and time to recovery (reopening) recorded at various timepoints after harvest.

Results: All Mimosa pudica plants displayed unanimous folding response to touch. Individual pinnae or samples of 4 pinnae were responsive to stimulus but not individual pairs of pinnules. Pinnae in distilled water rapidly lost the folding response. Pinnae exposed to 0.1% DMSO failed to open after harvest. Pinnae exposed to solutions of lysine, arginine, NSAIDs, auxins or control growth solution all displayed thigmonastic closure, and recovery was observed in all solutions. Both NSAIDs and auxins showed diminished responses at 30 and 60 minute timepoints when compared to controls. Samples showed continued responses to stimulus up to 7 days after harvest.

Conclusions: We developed a protocol for an in vivo (but literally in vitro) test of thigmonastic plant response which can detect the effects of drug exposure. This plant assay represents a viable method to assay drugs using a living, non-animal system that avoids the ethical limitations of animal drug testing.