In this study, an alkaloid was extracted from LN leaves. The AE was firstly evaluated as AO, by using a DPPH solution, and comparing it with a BHT standard solution. The AE, at 200 mg/mL, showed high efficiency as AO (93%). Furthermore, it was studied as a CI for an Fe alloy in HCl, at 25 °C, with different C (1 to 5 ppm). The AE depicted the highest IE(%) of 92.42%, at 5 ppm. T effect on IE(%), for optimal C (5 ppm), was studied at 35, 45 and 55 °C. The results revealed that the IE(%) decreased with higher T. Additionally, kinetic parameters, such as Ea*, ΔH* and ΔS*, were calculated. © 2023, Sociedade Portuguesa de Electroquimica. All rights reserved.