Terpenoids with selective cytotoxic activity against HCC70 breast cancer cell line from Leonotis ocymifolia

Triple Negative Breast Cancer (TNBC) is a primary global health concern, especially in sub-Saharan Africa, where treatment options are limited. Medicinal plants, such as those from the genus Leonotis, offer promising therapeutic agents due to their anticancer and anti-inflammatory properties. This study aimed to isolate and characterize labdane diterpenoids and triterpenoids from Leonotis ocymifolia and to evaluate efficacy against breast cancer cells. Compounds from Leonotis ocymifolia were characterised using spectroscopic data such as IR, 1D and 2D NMR, and MS spectrometry and evaluated for cytotoxic activity against triple negative breast cancer (HCC70), hormone receptor-positive breast cancer (MCF-7), and non-tumorigenic mammary epithelial cell lines (MCF-12A). The structural elucidation processes afforded eleven compounds, including two labdane diterpenoids (13S-predubiin and 13S-nepetaefolin) and one unreported tetracyclic triterpenoid (3,10-epoxy-9-epi-cucurbita-24-ene). The isolated labdane diterpenoids exhibited selective activity against HCC70 cells, with 13S-nepetaefolin displaying the most potent cytotoxicity (IC 50 of 24.65 μM), while its isomer, nepetaefolin, showed no significant activity (IC 50 >200 μM) [ 1 ] [ 2 ] [ 3 ]. Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany