Phenolic and alkaloid profiling of selected Paracaryum species with chemotaxonomic insights: Antioxidant and enzyme inhibition properties

Paracaryum (Boraginaceae) is a genus characterized by high levels of endemism and a complex taxonomy within the tribe Cynoglosseae, yet its phytochemical profiles remain largely uncharacterized. This study profiled phenolics and pyrrolizidine alkaloids (PAs) in the aerial parts of P. hedgei, P. calycinum, and P. racemosum using UHPLC–MS/MS, alongside evaluations of TPC, TFC, antioxidant and inhibitory activities against acetylcholinesterase, α-glucosidase and α-amylase enzymes. Furthermore, intratribal PA similarity patterns were evaluated using a statistical framework to reveal potential chemotaxonomic cues. Seventy-four metabolites were identified, with P. hedgei concentrating the greatest diversity for both phenolics (28 compounds) and PAs (18 compounds). Hydroxycinnamic acids and flavonoids dominated the phenolic profiles, with rosmarinic acid, kaempferol and quercetin glycosides shared across species. PA profiling revealed diverse unsaturated heliotridine/retronecine and saturated isoretronecanol/trachelanthamidine types in all taxa; however, P. hedgei uniquely contained supinidine and platynecine/turnerforcidine types. P. hedgei and P. calycinum showed superior TPC (39.60-39.99 mg GAE/g of extract), TFC (37.60-39.49 mg RE/g), antioxidant capacity and α-glucosidase inhibitory activity (4.05-4.32 mmol ACAE/g), while P. hedgei showed the strongest acetylcholinesterase inhibition (2.34 mg GALAE/g). Statistical analysis grouped the studied Paracaryum species within Cluster B, aligning them with subtribe Cynoglossinae, as currently circumscribed. P. racemosum and P. calycinum show high similarity in monoester and saturated PA types, while P. hedgei exhibits a more diversified biosynthetic profile. Although still preliminary, these patterns supply crucial hints for subsequent research and establish a comparative reference point for examining how chemical diversity has evolved within these important taxa.