Aims: To evaluate the in vitro antiproliferative, anticholinesterase and anti-phosphodiesterase
activities of the sub-extracts of Uvaria alba (family Annonaceae) and explore putative binding
mechanisms of its chemical constituents in silico.
Main methods: U. alba sub-extracts, obtained by solvent-solvent partition, were subjected to
antiproliferative and cytotoxicity screening against chronic myelogenous leukemia (K-562) and
human cervical cancer (HeLa) cells, respectively. Inhibitory assays against acetylcholinesterase
(AChE) and phosphodiesterase (PDE4 B2) enzymes were also performed. The dichloromethane
sub-extract (UaD) was chemically profiled using LC-HR-ESIMS-QToF to identify secondary
metabolites 1–18. Molecular docking and molecular dynamics simulations were performed to
determine the affinity of the putatively annotated metabolites against PDE4 B2B, AChE, ubiquitin
specific peptidase 14 (USP14), and Kelch-like ECH-associated protein 1 (Keap1). In addition,
DFT calculations were also performed to demonstrate Michael addition reaction between
electrophilic cytotoxic metabolites and Cys151 of the Keap1-BTB domain.
Key findings: UaD showed antiproliferative and cytostatic activities against K-562 and HeLa,
respectively, and inhibitory activities against AChE and PDE4 B2. Meanwhile, its polyphenolic
constituents 3-(3,4-dihydroxybenzyl)-3’,4’,6-trihydroxy-2,4-dimethoxychalcone (8) and
grandifloracin (15) showed favorable binding to AChE and Keap1-BTB domain, respectively. The
most electrophilic and kinetically stable grandifloracin (15), favorably formed a beta-addition
adduct with the Cys151 of Keap1 via Michael addition. The top-ranked ligand-protein complexes
attained dynamic stability at 50-ns simulations with high free energy of binding. The top-ranked
compounds also conferred favorable in silico pharmacokinetic properties.
Significance: The study highlights the role of U. alba secondary metabolites as potential inhibitors
against the aforementioned target proteins in an effort to discover new drug leads for cancer and
InstitutionUniversity of Santo Tomas
ORCID For Submitting Author0000-0002-6055-0886
Declaration of Conflict of InterestThe authors declare that they have no conflict of interests.
Version NotesThis is the first draft of the paper.