Pyrrolizidine Alkaloids Content and Antioxidant Activity of Two Heliotropium Species from Basrah - Southern Iraq

Abstract

Background: Heliotropium species (Boraginaceae) have long been used in traditional medicine, yet their antioxidant properties remain underexplored. This study investigates and compares the antioxidant activity of two species—H. curassavicum (a newly recorded species in Iraq) and H. crispum—collected from Basrah, Iraq. Methodology: Whole plants of H. curassavicum and H. crispum were collected, shade-dried, and ground into coarse powder. Methanolic maceration was performed over 5 days. The crude extracts were analyzed for PA content using High-Performance Liquid Chromatography (HPLC). Antioxidant activity of the extracts and isolated heliotrine was evaluated using in vitro assays: Total Antioxidant Capacity (TAC), DPPH radical scavenging assay, and Ferric Reducing Antioxidant Power (FRAP). Ascorbic acid served as the standard for comparison. Two-fold serial dilutions (50–800 µg/ml) were used in the antioxidant assays. Results: The TAC of H. crispum (0.413 mg AAE/g) was higher than that of H. curassavicum (0.191 mg AAE/g). Heliotrine exhibited strong antioxidant activity in DPPH (29.36%–62.92%) with an IC₅₀ of 151.40 µg/ml and good reducing capacity in FRAP assays (0.36–3.67 FRP) across concentrations of 50–800 µg/ml, comparable to ascorbic acid (31.52%–77.24%, IC₅₀ = 137.17 µg/ml). Statistical analysis revealed no significant differences between heliotrine and ascorbic acid across all concentrations tested (p < 0.05).

Conclusion: Both H. crispum and H. curassavicum demonstrated notable antioxidant activity, with H. crispum exhibiting higher TAC. Heliotrine displayed strong scavenging and reducing power, comparable to ascorbic acid, supporting the medicinal potential of these species and encouraging further pharmacological exploration.