Let's start with a layman's definition of MOA (from Wikipedia): "In pharmacology, the term mechanism of action (MOA) refers to the specific biochemical interaction through which a drug substance produces its pharmacological effect. A mechanism of action usually includes mention of the specific molecular targets to which the drug binds, such as an enzyme or receptor."
What’s unique about Anavex 2-73? Simple. In both murines (numerous published studies) and in human applications (preliminary, small-n Australian study), the molecule has shown a) safety and b) efficacy against various CNS diseases.
If you refer to the definition above, you will see that comments related to safety and efficacy do not address the MOA in any way (deferring for now comment regarding highly dubious claims of efficacy). One should not conflate efficacy, what is needed for approval, and what is MOA. They are all separate and it is possible for a drug to be efficacious and be approved when the MOA is completely unknown (there are many examples). Thus, if you would like to claim that 2-73's MOA is via S1R agonism (and you have) then, given that there are many known and marketed S1R agonists, you need to show how 2-73's agonism is unique in a way that produces its pharmacological effect advantageously over these other S1R agonists. THIS, IMO you have not done...if you disagree then once more I ask you to point out where your post mentions it (...and if you can't don't feel bad because no one, including Missling, has ever done so).
Tell us, if you will, an existing drug that matches or exceeds murine results with Rett, Parkinson’s, or Alzheimer’s (not just Alzheimer's).
As has been discussed before, donepezil (and a number of other S1R agonists) match or exceed 2-73 in every measure so assessed in one study measuring effects on oxidative stress*. However, I don't know why you are asking me for references...if you are going to make a claim YOU should show AT LEAST ONE study where 2-73 shows some advantage over another compound with the same MOA. Do you have ANY evidence to support your claim?
*Sigma-1 Receptor Agonists Induce Oxidative Stress inMitochondria and Enhance Complex I Activity in Physiological Condition but Protect Against Pathological Oxidative Stress Nino Goguadze1,2 & Elene Zhuravliova2 & Didier Morin3 & Davit Mikeladze2 & Tangui Maurice1 Neurotox Res https://doi.org/10.1007/s12640-017-9838-2 2017