It still has not been scientifically proven that ANY compound known exhibits "neuroprotective" properties IN VIVO. There are compounds on the market that are in use with the blessing of the FDA for use in alzheimers disease, but their effects are mainly attributed to their anticholinergic activity. We worked for years barking up the "neuroprotective" tree and found that all we ever came up with just showed certain human cell lines aged a bit slower in media treated with some of the compounds we had made. Nothing that the FDA would buy, so we dropped all research in this area.
But I would never discourage any researcher from keeping on trying, and maybe, just maybe something will come up in the future. And just as a footnote, "neuroprotective" agents are all the rage in Japan, where rules for allowing drugs on the market are more lax. In other words you can claim neuroprotection without ever proving it, as long as your compound is pretty well "dead" as far as having any other possibly detrimental physiological effects.