Three new cardenolides from the fruits of Cascabela thevetia (L.) Lippold and their cytotoxic activities

Abstract

Phytochemical investigations on the fruits of Cascabela thevetia (L.) Lippold led to obtain three new cardenolides (1–3) and five known analogues (4–7). Their structures were elucidated by means of UV, IR, HR-ESI-MS, 1D and 2D NMR spectroscopic data analysis. Compounds 1 and 2 represent the first examples of naturally occurring cardenolides with 19-nor-5(10)-ene group and α-l-3-demethyl-thevetose, respectively. Compound 3 is a rare C-nor-D-homocardenolide in nature. All isolated cardenolides (1–7) were evaluated for their cytotoxic activities against four human cancer cell lines (MCF-7, HCT-116, HeLa and HepG2), and the results indicated the compounds with sugar units (1, 2, 4, and 5) exhibited stronger cytotoxic activities with IC₅₀ values ranging between 0.022 and 0.308 μM.

GRAPHICAL ABSTRACT

Keywords:

• Apocynaceae
• Cascabela thevetia (L.) Lippold
• chemical constituents
• cardenolides
• antitumour activities

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was financially supported by grants from the funds for Medical Scientific Research Foundation of Guangdong Province (A2021218/A2022014), Key Discipline construction project of Guangdong Medical University (4SG22024G/4SG22004G), Guangdong Basic and Applied Basic Research Foundation (2019A1515110386), Traditional Chinese Medicine Bureau of Guangdong Province (20211228), and Science Technology Development Special Fund Competitive Distribution Project of Zhanjiang City (2020A01029).