Polygonati Rhizoma: Geographic Distribution, Traditional Use, Component Transformation, Pharmacological Activity, and Clinical Application.

Polygonati Rhizoma (PR), a plant with dual medicinal and edible properties, has been utilized for over two millennia, and is widely distributed across temperate to frigid zones in the Northern Hemisphere. In ancient China, it was revered as the "immortals' surplus grain," and the classical medical text "Ming Yi Bie Lu" documents its health benefits. These benefits include "tonifying the middle jiao, replenishing qi, dispelling rheumatism, and harmonizing the five viscera," which particularly emphasizes the efficacy of PR in both nourishing the liver and kidneys and prolonging lifespan. Modern studies reveal that PR rhizomes are rich in fructans, non-starch polysaccharides, amino acids, and other nutritional components, and their primary active constituents include polysaccharides, saponins, flavonoids, and polyphenols. These compounds exhibit anti-aging, antidepressant, anti-osteoporotic, and neuroprotective activities. Notably, raw PR contains calcium oxalate raphides, which induce an irritating sensation in the throat. However, processing can not only mitigate this irritation but also enhance its anti-oxidant and anti-aging capacities. Although progress has been made toward understanding its polysaccharides and saponins, the mechanisms underlying its other critical components, such as flavonoids, polyphenols, and oligosaccharides, remain underexplored. This review systematically examines the geographic distribution, traditional and modern applications, and pharmacological activities of PR, and the transformation patterns of key bioactive constituents that occur during its processing. Furthermore, it critically addresses research gaps, and particularly addresses both the relative lack of mechanistic studies on functional components and the lack of correlation between processing-induced compositional changes, pharmacological efficacy, and quality control. These insights contribute to advancing PR exploration, promoting sustainable utilization, and establishing scientific evidence-based quality standards.