Bitter Compounds in Medicinal Food Plants Based on Traditional Chinese Medicine: Analysis and Regulation Strategies from Chemical Structure to Perception Mechanisms

Bitter phytochemicals, including alkaloids, terpenoids, and bitter glycosides, are abundant in medicinal food plants and exhibit well-documented anti-inflammatory, hypoglycemic, and other bioactivities relevant to human health. However, the inherent bitterness of these compounds presents a significant sensory barrier to patient compliance and limits their application as functional food ingredients. This review provides a comprehensive and interdisciplinary synthesis of current knowledge on bitter compounds in medicinal food plants, integrating perspectives from phytochemistry, molecular pharmacology, and sensory science. We summarize the major chemical classes of bitter phytochemicals, critically evaluate methods for their isolation and identification—from classical sensory-guided fractionation to modern computational approaches such as molecular docking and metabolomics—and analyze three principal strategies for bitterness regulation: physical removal, biological transformation, and sensory modulation (including molecular inclusion and TAS2R receptor blocking). We also briefly touch upon the extraoral expression of TAS2Rs and there suggested links to local immune responses and metabolic regulation, noting that this may be relevant to the concept of “taste–bioactivity homology.” The review further highlights ongoing challenges, such as the identification of unknown bitter compounds and the lack of standardized sensory evaluation systems, and outlines possible directions for improving bitterness analysis and regulation in medicinal food plants.