I came across a compound called octacosanol, that apparently can be found in propolis – but it also occurs in other foods and compounds like wheat germ oil and sugar cane. It was apparently used in the 1968 Mexican Olympics to enhance endurance, increase physical strength, and improve reaction times:
https://www.sciencedirect.com/science/article/abs/pii/S2212429222000918
Whether it really has any good effects is still in question.
This got me wondering about what other obscure compounds were used by teams during various Olympics games over the years, so I asked GPT-5.5-thinking for a list, and came up with Eleuthero / Siberian ginseng, Rhodiola rosea, Schisandra chinensis, Rhaponticum carthamoides / Leuzea / Maral root, Ecdysterone / 20-hydroxyecdysone, Bee pollen, Royal jelly, Inosine / Riboxin, Hypoxen, L-carnitine, Cytoflavin, Meldonium / Mildronate, Gamma oryzanol, and Succinate / succinic acid derivatives.