Morushalunin D, a tri-O-bridged Diels-Alder type adduct from Morus alba var. shalun root cultures and the related precursors

Abstract

Three Diels-Alder type adducts (1-3) along with their precursors, including one 2-arylbenzofuran (4) and one stilbene (5), were isolated from the MeOH extract of M. alba var. shalun root cultures. Among them, 1 is a new Diels-Alder type adduct named morushalunin D. The molecular structures of 1-5 were elucidated based on spectroscopic data and comparison with the literatures. Cytotoxic properties of compounds 1-5 were evaluated against murine leukemia P-388 cells. Morushalunin D (1), mulberrofuran T (2), sorocein A (3), moracin M (4), and oxyresveratrol (5) were active, significantly inhibiting the growth of P-388 cells with IC₅₀ values of 0.5, 1.0, 0.6, 2.0, and 3.3 μg/ml, respectively.

Keywords:

• Root cultures
• Morus
• Morus alba var. shalun
• Diels-Alder adducts
• calculated ECD
• cytotoxicity

The authors gratefully acknowledge the Research Grant of P3MI 2020 from Institut Teknologi Bandung for part of financial support to this research and the Laboratory of the Integrated Chemistry, Faculty of Mathematics and Natural Sciences, ITB, for facilitating the NMR, HRMS, ECD, UV, and optical rotation measurements. We also thank and express deep gratitude to Dr. Atthar Luqman Ivansyah, Master Program in Computational Science, Faculty of Mathematic and Natural Science, Institut Teknologi Bandung for ECD spectra calculation.

Disclosure statement

No potential conflict of interest was reported by the author(s).