Plant-derived phenolic acids in Shilajit: a comparative HPLC–MS/MS analysis across five regions

Shilajit, a resinous exudate traditionally used in Asian medicine, is thought to originate from the decomposition of plant material, yet direct chemical evidence for this hypothesis has remained limited. Here, we report the first comprehensive quantification of phenolic acids, as the key plant-derived antioxidants, in eleven Shilajit samples from Iran, India, Nepal, Russia, and Kyrgyzstan using HPLC-MS/MS. Nine phenolic acids (gallic, vanillic, syringic, caffeic, p-coumaric, ferulic, sinapic, chlorogenic, and rosmarinic acids) were identified and quantified. Most samples had more hydroxybenzoic acids (gallic, vanillic, syringic) than hydroxycinnamic acids. Gallic acid was the most abundant compound, reaching up to 2839.28 µg g^{- 1} in Iranian Shilajit, whereas rosmarinic acid displayed exceptionally high levels (216.26 µg g^{- 1}) in one Iranian sample. The pronounced geographical variation in phenolic acid composition suggests a strong environmental and botanical influence on Shilajit formation. These findings provide molecular evidence supporting its plant-based origin and highlight phenolic acids as contributors to Shilajit's well-documented antioxidant and therapeutic effects. The study also establishes a robust analytical platform for future standardization and quality assessment of Shilajit as a natural medicinal product.