Phenolic Profile and Biological Evaluation of <i>Salvia ceratophylloides</i> Ard.: A Novel Source of Rosmarinic Acid

Salvia ceratophylloides Ard. (Sc), a rare endemic species from Southern Italy, has been chemically unexplored. We report the first analysis of its polyphenolic profile, antioxidant potential, and preliminary toxicity, compared with the well-studied Salvia officinalis L. (So). Plants were cultivated under identical Mediterranean conditions to minimize variability. Leaf hydroalcoholic extracts were examined for polyphenols (high-performance liquid chromatography with photodiode array detection and electrospray ionization mass spectrometry [HPLC-PDA/ESI-MS]), antioxidant activity (2,2-diphenyl-1-picrylhydrazyl [DPPH], reducing power, Fe²⁺ chelation), and toxicity (Artemia salina lethality bioassay). Although differing qualitatively, both species showed nearly identical total phenolic content (So 274.59 mg/g; Sc 274.27 mg/g). Notably, Sc was rich in rosmarinic acid and consistently exhibited superior antioxidant activity. It was also nontoxic against A. salina, in contrast to So (LC₅₀ = 79.27 ± 11.62 µg/mL). These findings highlight Sc as a promising source of bioactive compounds and warrant further pharmacological and conservation studies.