There's a slightly older compound called mitoquinone (MitoQ) which is similar in concept. Seems to be a form of ubuquinol (CoQ10) with lipid solubility modified for mitochondria targeting. I think its an SkQ1. I only mention it because its already showing up in anti-aging skin creams ...
MitoQ and SkQ1 are related mitochondrial-targeted antioxidants. Both use a triphenylphosphonium cation as the mitochondrial targeting agent, and are both quinones. It's a bit of a concern to see it in skin cream, since it can act as a pro-oxidant in the presence of atmospheric oxygen.
It is worth mentioning that there are reports of MitoQ and SkQ1 impairing mitochondrial energetics. SS-31 does NOT have this effect, so that is a very significant differentiator.
Fink BD, Herlein JA, Yorek MA, Fenner AM, Kerns RJ, Sivitz WI: Bioenergetic effects of mitochondrial-targeted coenzyme Q analogs in endothelial cells. J Pharmacol Exp Ther 2012, 342:709–719.
Reily C, Mitchell T, Chacko BK, Benavides G, Murphy MP, Darley-Usmar V: Mitochondrially targeted compounds and their impact on cellular bioenergetics. Redox Biol 2013, 1:86–93. 193. Gane EJ, Weilert F, Orr DW, Keogh GF, Gibso