The synthesis of the naturally occurring kaempferol glycoside SLO1O1-1, as well as analogs thereof, has been accomplished, as has its biochemical evaluation. SLO1O1-1 exhibits selective and potent p90 Rsk inhibitory activity at nanomolar concentrations without inhibiting the function of upstream kinases such as MEK, Raf, or PKC. The synthetic scheme of the invention verified the structural assignment of the natural product and has provided access to material sufficient for detailed biological evaluation.