Authentication of Propolis: Integrating Chemical Profiling, Data Analysis and International Standardization—A Review

Propolis is an apicultural product known for its antioxidant, antimicrobial and anti-inflammatory properties. However, its composition varies with botanical sources, geography, season and bee species, complicating quality control and creating opportunities for adulteration, such as the addition of poplar bud extracts or non-propolis resins. This review synthesizes the latest primary studies and reviews addressing chemical markers identified through analytical platforms, such as TLC, HPTLC, HPLC, LC-MS, GC-MS, NMR, FTIR and ICP, often integrated with chemometrics and machine learning for authentication and standardization. Marker panels are linked to regional chemotypes, including poplar-type, Brazilian green, red and brown, Cuban variants, and stingless bee propolis. Fraud detection strategies using marker-based screening and spectral pattern recognition are also summarized. Multi-marker and chemometric approaches consistently differentiate botanical types, origins and commercial extracts. Common marker families include flavonoids (pinocembrin, chrysin, galangin), phenolic esters (CAPE, benzyl/allyl caffeates), prenylated cinnamates like artepillin C, lignans, and volatile terpenoids or benzenoids. Rapid screening by ATR-FTIR and NMR is often complemented with LC-MS for confirmatory quantitation. Propolis quality control is moving toward harmonized workflows combining FTIR/NMR/HPTLC screening with LC-MS verification and optional elemental or volatile profiling, paving the way for shared marker sets and international standards similar to those for honey.