Quantitative Analysis and Simultaneous Characterization of Triterpenoids and Phenolics in Inonotus obliquus (Chaga) Using LC-PDA-ELSD and LC-DAD-QToF

Abstract Inonotus obliquus is widely recognized as the Chaga mushroom. Chaga contains various bioactive compounds, including polysaccharides, triterpenoids, polyphenols, and melanin. To address the characterization and quantitative analysis of triterpenoids and phenolics in Chaga, a multi-analytical approach has been developed combining LC-PDA-ELSD and LC-DAD-QToF. These methods were designed to quantify 11 compounds, comprising seven triterpenoids and four fatty acids, using LC-PDA-ELSD, and four phenolics using the LC-DAD-QToF method. Calibration curves for these compounds demonstrated excellent linearity within the tested range. The methods exhibited high precision, with intra- and inter-day relative standard deviations below 3% and recoveries ranged from 91% to 104%. The validated methods were applied to analyze eleven sclerotia samples, one mycelium sample, three grain-based samples, and eighteen dietary supplements. Results revealed that eight of the eighteen supplements (44%) contained ground mycelium, which primarily showed the presence of fatty acids but lacks detectable levels of triterpenoid and phenolic markers characteristic of Chaga. Triterpenoids and hispidin, identified as key bioactive compounds, were detected in eight (44%) of the eighteen supplements; however, these products also contained fatty acids and/or betulin. Two (11%) of the 18 supplements showed the presence of phenolic compounds only; no triterpenoids were detected. Additionally, untargeted metabolomic screening using LC-DAD-QToF tentatively identified 103 compounds from diverse chemical groups, including nine reference compounds. These findings provide valuable insights for the quality assessment of dietary or food supplements marketed as containing Chaga.