Larrea ameghinoi Speg. (Zygophyllaceae) "Jarilla Rastrera": UHPLC-ESI-QTOF-MS Analysis, Antioxidant, Antimicrobial Properties, and Inhibition of Enzymes of Interest to Human Health.

Larrea ameghinoi Speg., an endemic species of Argentine Patagonia traditionally used in folk medicine to treat fever, stomach disorders, respiratory conditions, back pain, and as an emmenagogue, among others, still remains chemically and biologically underexplored compared to the other four members of the genus. This study aimed to perform a comprehensive metabolomic characterization of methanolic extracts from two populations (EMLaSAO and EMLaMAQ) using ultra-high-resolution liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry (UHPLC-ESI-QTOF-MS) and to evaluate their antioxidant, antimicrobial, and enzyme-inhibitory activities of relevance to human health. Thirty-three compounds were tentatively identified by extensive UHPLC-MS analysis, including flavones, two major lignans, and oleanane-type triterpenes. Both extracts exhibited high phenolic content (215-239 mg of gallic acid equivalents (GAE)/g extract) and strong free radical scavenging activity, as evidenced by 2,2-diphenyl-1-picrylhydrazyl (DPPH, EC50 ≈ 10 μg/mL), ferric-reducing antioxidant power (FRAP), and Trolox equivalent antioxidant activity (TEAC) assays. In addition, significant inhibition of butyrylcholinesterase (IC50 ≈ 50 μg extract/mL) and α-glucosidase, together with selective antibacterial activity against methicillin-sensitive and resistant Staphylococcus aureus (MIC = 125 μg extract/mL), were recorded. These findings suggest that L. ameghinoi possesses a distinctive phytochemical composition conferring multitarget bioactivity, differing from other Larrea species dominated by lignans such as nordihydroguaiaretic acid (NDGA) and its derivatives. Overall, this work supports the potential of L. ameghinoi as a novel source of bioactive metabolites for managing oxidative stress-related disorders and opportunistic infections. This warrants future in vivo studies investigating biological activities associated with oxidative stress and their relevance to human health.