The aim of the present study was to evaluate the bioavailability and associated bioactivity of p-coumaric (p-COA), caffeic (CA), and ferulic (FA) hydroxycinnamic acids (HCAs) isolated from an aqueous extract of plant material. An aqueous extract is more applicable in practice because this form is the most commonly used for oral administration. The p-COA, CA, and FA acids were evaluated for their behavior in the processes of absorption, distribution, metabolism, and excretion (ADME) using modern methods for assessing their functional groups according to Lipinski’s Rule of Five and the Rule of Nines. Given the available data on extensive metabolism of hydroxycinnamic acids during the first pass through the liver, it is necessary to consider an alternative route of administration, namely the sublingual route. Sublingual delivery of exogenous molecules obtained from plant material by extraction may represent a preferable alternative to oral administration, as first-pass hepatic metabolism is bypassed when dosage forms are administered sublingually.