mTOR is, in layman terms, a cellular intermediate that lays in between a lot of supplements and the genetic signalling of muscle protein synthesis. Stuff that acts on mTOR can induce muscle protein synthesis, and stuff that inhibits or hinders mTOR expression or activity can thus hinder or inhibit muscle protein synthesis.
This mechanism is elucidated in this article on Rapamycin, a pharmaceutical grade mTOR antagonist.
Why this is critical, is because mTOR is also a pathway in carcinogenesis and tumorogenesis. It is anabolic. It can cause growth of many many things. Thus some compounds that are anti-carcinogenic or health protective in nature can act by suppressing mTOR. Caloric restriction does this as well as many modes of longevity.
Resveratrol is probably the most well-known inhibitor of mTOR. And yes, Resveratrol can acutely hinder muscle growth and muscle preservation via mTOR.
So let this be a PSA. There are supplements that reduce muscle growth, and they are the healthy supplements that we take to live longer. Its not necessarily a bad negation that will induce harm, but it is of course like pissing your money away.