Stereochemical assignment of clerodane-type diterpenes from the fruits of
Casearia grewiifolia and their ability to inhibit PCSK9 expression.
PHYTOCHEMISTRY 2023;
216:113864. [PMID:
37748701 DOI:
10.1016/j.phytochem.2023.113864]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2023] [Revised: 09/14/2023] [Accepted: 09/16/2023] [Indexed: 09/27/2023]
Abstract
More than 20 natural products have been reported to modulate PCSK9-mediated cholesterol regulation, and small-molecule-derived proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors continue to be developed and identified. Here, twelve undescribed clerodane-type diterpenes (1-9 and 12-14) and two known compounds were isolated from the chloroform-soluble extract of the dried fruits of Casearia grewiifolia Vent. using a PCSK9 mRNA expression monitoring assay. Among the undescribed compounds, the stereochemistry of two diastereomeric grewiifolins A and B (1 and 2) were extensively elucidated using 2D Nuclear Overhauser Effect Spectroscopy (NOESY) experiments, excitation-sculptured indirect detection experiments (EXSIDE), interproton distance analyses, and computational calculations that included quantum chemical shift calculations combined with DP4+ analysis. All isolates were assessed for their inhibitory activity against PCSK9 and IDOL mRNA expression. Among the compounds tested, compound 3 inhibited PCSK9 and IDOL mRNA expression.
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