title: Straightforward preparation of organic colloidal particles by harnessing spontaneous non-covalent interactions of active molecules from natural origin.
abstract: We demonstrate a straightforward method to prepare organic colloidal particles based on the spontaneous molecular interactions between small molecular weight actives of natural origin. Representative reactive natural actives from three of the most researched classes of phytochemicals including berberine (isoquinoline alkaloid), tannic acid (polyphenol) and glycyrrhizin (olenane type saponin) were chosen for the study. Binding parameters (association constant, binding enthalpy and entropy) obtained from isothermal titration calorimetry indicated that berberine strongly interacted with tannic acid to form insoluble colloidal complex which could be stabilised in the presence of glycyrrhizin (due to its interaction with both berberine and tannic acid and also due to its amphiphilic nature). Working on this principle, the mutual interactions of these three natural actives were exploited to obtain stable spherical particles with a mean diameter of less than 100 nm (77 nm) simply by mixing the aqueous solutions of berberine:tannic acid:glycyrrhizin at molar ratio of 2:1:1. The involvement of aromatic chromophore (π-π*) system and charged N atom of berberine in the spontaneous interaction between berberine and tannic acid was confirmed from spectral analysis. X-ray diffraction study suggested formation of amorphous organic colloidal particles, and the spherical shape of colloidal particles was confirmed by transmission electron microscopy.
authors.affiliation: Unilever R&D, Olivier van Noortlaan 120, 3133 AC Vlaardingen, The Netherlands. Ashok.Patel@Unilever.com
authors.forename: Ashok R
authors.initials: AR
authors.lastname: Patel
authors.forename: Jack
authors.initials: J
authors.lastname: Seijen-ten-Hoorn
authors.forename: Patricia C M
authors.initials: PC
authors.lastname: Heussen
authors.forename: Ellen
authors.initials: E
authors.lastname: Drost
authors.forename: Johan
authors.initials: J
authors.lastname: Hazekamp
authors.forename: Krassimir P
authors.initials: KP
authors.lastname: Velikov
mesh_terms: D001599:Berberine / Q000737:chemistry*; D002151:Calorimetry; D003102:Colloids / Q000737:chemistry*; D004337:Drug Carriers / Q000737:chemistry*; D004347:Drug Interactions; D019695:Glycyrrhizic Acid / Q000737:chemistry*; D007700:Kinetics; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles; D010316:Particle Size; D013634:Tannins / Q000737:chemistry*; D013816:Thermodynamics; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D003102:Colloids; D004337:Drug Carriers; D013634:Tannins; D014867:Water; D001599:Berberine; D019695:Glycyrrhizic Acid