Comparative Phytochemical Profiling, Antioxidant Activity, and Chondrocyte Cytocompatibility of Water and Ethanolic Extracts from Different Organs of Golden Gardenia (Gardinia sootepensis)

Gardenia sootepensis Hutch. (Golden Gardinia) has received limited scientific attention despite the chemical diversity of its specialized metabolites. In this study, aqueous and 70% ethanolic preparations derived from the leaves, peel plus pulp, and seeds were systematically evaluated for extraction efficiency, total phenolic content (TPC), flavonoid content (TFC), ABTS and DPPH radical-scavenging capacity, HPLC–ESI–MS phytochemical profiles, and cytocompatibility with C28/I2 cells and primary human articular chondrocytes. The largest extract recovery was obtained from seed material, whereas the ethanolic leaf preparation contained the greatest TPC (81.08 ± 4.60 mg GAE/g), and TFC (28.36 ± 3.63 mg QE/g), and showed the strongest ABTS antioxidant activity (272.92 ± 10.95 mg TE/g). HPLC–ESI–MS analysis based on nominal-mass measurements enable the provisional annotation of 34 phytochemical features encompassing iridoids and iridoid glycosides, phenolic acids, flavonoids and their glycosides, xanthones, and benzophenone-related constituents. Overall, extraction with aqueous ethanol yielded a wider spectrum of detectable metabolites than extraction with water, while seed-derived preparations displayed the greatest chemical diversity. Under the experimental conditions and concentration range tested, viability of both immortalized C28/I2 cells and primary human articular chondrocytes remained above 80%. Collectively, these findings demonstrate that the botanical tissue selected and the extraction solvent substantially influence the phytochemical composition and antioxidant properties of G. sootepensis. The observed cytocompatibility provides a basis for subsequent mechanistic investigations but does not establish chondroprotective activity. Further confirmation and quantitative characterization of the provisionally annotated metabolites using high-resolution MS/MS and authentic reference standards are warranted.