Inhibition of the Protease Activity of the Light Chain of Type A Botulinum Neurotoxin by Aqueous Extract from Stinging Nettle (Urtica dioica) Leaf

We investigated the inhibitory effect of stinging nettle leaf extract on the protease activity of botulinum neurotoxin type A and B light chains. The nettle leaf infusion was fractionated and HPLC-based enzymatic assays were performed to determine the capacity of each fraction to inhibit the protease activity of botulinum neurotoxin type A and B light chains. Assay results demonstrated that a water-soluble fraction obtained from the nettle leaf infusion inhibited type A, but did not inhibit type B light chain protease activity. The inhibition mode of water soluble fraction against protease activity of type A light chain was analyzed and found to be a non-competitive.