Unveiling the Cytotoxic and NO Inhibitory Potential of Heliotropium dolosum Extracts from Türkiye: A First Insight Into Its Phenolic Profile.

Heliotropium dolosum (Boraginaceae) is traditionally used for its choleretic, antipyretic, and cicatrizing properties. Despite some reports on its traditional uses, this species' cytotoxic and nitric oxide (NO) inhibitory potential and its polyphenolic compounds have not been previously investigated. This study aims to evaluate the antioxidant, cytotoxic, and NO inhibitory activities of H. dolosum extracts and to identify polyphenolic compounds that could be contributing to these effects. The antioxidant activity of H. dolosum extracts (ethanol, methanol, chloroform, water) was assessed using six in vitro models. Total phenolics, flavonoids, and saponins were quantified via colorimetric assays, while phenolic compounds were identified using HPLC. Cytotoxicity was evaluated through brine shrimp lethality and cancer cell assays, and NO inhibitory activity was measured in LPS-induced cancer cells. The methanol extract displayed the highest antioxidant activity, with major phenolic compounds identified as caffeic acid, 2,5-dihydroxybenzoic acid, and ellagic acid with 12.307, 5.710 and 5.061 mg/g, respectively. It showed notable cytotoxicity (LC₅₀ = 18.1 µg/mL) and concentration-dependent effects on cancer cells. The highest NO inhibition was observed in HCC78 cells (15.56 µM nitrite). H. dolosum demonstrates potential as a wild plant source of bioactive compounds with antioxidant, cytotoxic, and NO inhibitory properties, highlighting its promise for functional food development and nutraceutical applications.