Tissue-specific phenolic profiling of Castanopsis sieboldii: Validated quantification, metabolite annotation, and chemometric discrimination

Authors: BAE, JI-YEONG - University Of Mississippi; AVULA, BHARATHI - University Of Mississippi; TATAPUDI, KIRAN KUMAR - University Of Mississippi; KANG, YE-SOL - Jeju National University; KATRAGUNTA, KUMAR - University Of Mississippi; LEE, SANG HO - Jeju National University; KHAN, IKHLAS - University Of Mississippi

Submitted to: Journal of Pharmaceutical and Biomedical Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/17/2026
Publication Date: 6/18/2026
Citation: Bae, J., Avula, B., Tatapudi, K., Kang, Y., Katragunta, K., Lee, S., Khan, I.A. 2026. Tissue-specific phenolic profiling of Castanopsis sieboldii: Validated quantification, metabolite annotation, and chemometric discrimination. Journal of Pharmaceutical and Biomedical Analysis. 280 (2026) 117621. https://doi.org/10.1016/j.jpba.2026.117621.
DOI: https://doi.org/10.1016/j.jpba.2026.117621

Interpretive Summary: Castanopsis sieboldii is a phenolic-rich evergreen tree native to Korea and Japan with demonstrated antioxidant, anti-inflammatory, and cytoprotective properties, yet no prior study has systematically compared its chemical composition across different plant tissues. This study addressed that gap by combining validated chromatographic quantification with high-resolution mass spectrometry and multivariate statistics to map the phenolic landscape of leaves, stems, fruits, and flowers collected from seven sites across Jeju Island, Republic of Korea. The results revealed a striking tissue-dependent concentration gradient: leaves contained extraordinarily high levels of 3-O-galloylshikimic acid (up to 204 mg/g dry weight), far exceeding those in flowers, stems, and fruits, establishing the leaf as the most promising source tissue for bioactive phenolic extraction. Across all tissues, 185 metabolites spanning tannins, flavonoids, phenolic acids, triterpenoids, and amino acids were identified, and chemometric models classified plant parts with 100% accuracy, confirming that each tissue possesses a distinct chemical fingerprint. These findings provide a practical foundation for selecting the appropriate plant part for pharmaceutical, cosmetic, and nutraceutical development, and the validated analytical method can be directly applied as a quality-control tool for standardizing C. sieboldii-derived botanical products.

Technical Abstract: Castanopsis sieboldii is a phenolic-rich evergreen species in the family Fagaceae, yet comprehensive quantitative and tissue-specific metabolite profiling remains limited. In this study, an integrated analytical flow with UHPLC-PDA quantification, LC-QToF-MS identification, and chemometric analysis was developed to characterize phenolic constituents across leaves, flowers, fruits, and stems. A validated UHPLC-PDA method enabled the simultaneous quantification of six major phenolics, with limits of detection ranging from 0.01 to 0.05 µg/mL and limits of quantification from 0.025 to 0.1 µg/mL. Among all tissues,3-O-galloylshikimic acid (Compound 1) was the predominant metabolite (0.1–204 mg/g), followed by caffeoylquinic acids (Compounds 2–3), ellagic acid (Compound 4), and flavonoid glycosides (Compounds 5–6). LC-QToF-MS analysis facilitated the putative identification of 185 metabolites, including phenolic acids, ellagitannins, galloylshikimic acids, and flavonoid glycosides, based on accurate mass measurements and characteristic MS/MS fragmentation patterns. Chemometric evaluation using principal component analysis (PCA), partial least squares–discriminant analysis (PLS–DA), and hierarchical clustering analysis (HCA) revealed clear tissue-specific clustering, with leaves exhibiting the highest chemical diversity and phenolic abundance, while fruits contained minimal levels. PCA captured 80% of total variance in the first two components, and the PLS–DA model demonstrated excellent predictive performance (R²Y ˜ 1.00; Q² ˜ 0.98). This study provides the first integrated, tissue-resolved phenolic profile of C. sieboldii, establishing a comprehensive chemical foundation for future pharmacological, ecological, and quality-control applications.