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B-ring methoxy substitution modulates flavokawain membrane interactions and cytotoxicity
Paulina Strugała-Danak1, Ewa Dejnaka2, Paweł Chlipała3
1Wrocław University of Environmental and Life Sciences, Department of Physics and Biophysics, Norwida 25, 50-375 Wrocław, Poland. paulina.strugala@upwr.edu.pl.
Organic & Biomolecular Chemistry
|August 5, 2026
Summary
Five flavokawain derivatives from Piper methysticum were studied for their biological and physicochemical properties. B-ring methoxy substitution significantly impacts membrane interactions, albumin binding, and cytotoxicity, guiding future drug design.
Area of Science:
- Natural Products Chemistry
- Pharmacology
- Medicinal Chemistry
Background:
- Flavokawains are chalcone derivatives from Piper methysticum with potential pharmacological activities.
- Structure-activity relationships of flavokawain derivatives are not fully understood.
Purpose of the Study:
- To investigate the biological and physicochemical characteristics of five flavokawain derivatives (A1-A5).
- To elucidate the structure-activity relationships based on B-ring methoxy substitution patterns.
Main Methods:
- Hemolytic activity assays
- Fluorescent probe-based membrane interaction studies
- Dynamic light scattering (DLS) for liposome analysis
- Human serum albumin (HSA) binding assays
- Cytotoxicity assays on canine cell lines (CLB70, CLBL-1)
Main Results:
- All derivatives showed low hemolytic activity.
- Flavokawains preferentially partitioned into hydrophobic membrane cores, causing rigidification, with effects varying by methoxy substitution.
- Di-methoxy derivatives (A4, A5) increased liposome size and polydispersity more than mono-methoxy derivatives (A1-A3).
- HSA binding affinity was strongly dependent on B-ring methoxy patterns.
- Flavokawain B (A1) and 2-methoxy-flavokawain B (A2) exhibited potent cytotoxicity (IC50 ≈ 8-16 μM) but lacked selectivity.
Conclusions:
- B-ring methoxy substitution is a critical factor influencing flavokawain membrane interactions, HSA binding, and cellular effects.
- These findings provide a foundation for optimizing flavokawain derivatives for enhanced selectivity and therapeutic potential.
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