Litoarbolide A: an undescribed sesquiterpenoid from the Red Sea soft coral Litophyton arboreum with an in vitro anti-malarial activity evaluation

Abstract

Soft corals distributed across the Red Sea coasts are a rich source of diverse and bioactive natural products. Chemical probing of the Red Sea soft coral Litophyton arboreum led to isolation and structural characterization of an undescribed sesquiterpenoid, litoarbolide A (1), along with 14 previously reported metabolites (2-15). The chemical structures of the isolates were assigned based on NMR as well as high resolution electrospray ionization mass spectrometry (HR-ESI-MS) data. Litoarbolide A is supposed to be the biosynthetic precursor to other sesquiterpenoids, which formed via further post-translational modifications. Furthermore, these metabolites were evaluated for anti-malarial activity, where only the acyclic sesquiterpenoid of a sec-germacrane nucleus (7) showed an activity against chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum with IC₅₀ at 3.7 and 2.2 mg/mL, respectively. Moreover, the isolated metabolites were all non-toxic to the Vero cell line. These findings support the consideration of L. arboreum in further natural anti-malarial studies.

Graphical Abstract

Keywords:

• Soft coral
• Litophyton arboreum
• sesquiterpenoid
• anti-malarial activity

Acknowledgements

We are grateful to the Egyptian Government represented by the Ministry of Higher Education (MoHE) for the financial support. The authors thank Dr. Avula for acquiring the mass spectral data.

Disclosure statement

The authors declare no conflict of interest.

Additional information

Funding

This research was funded by the Egyptian government represented by the Ministry of Higher Education (MoHE).