title: Massive Bioaccumulation and Self-Assembly of Phenazine Compounds in Live Cells.
abstract: Clofazimine is an orally administered, FDA-approved drug that massively bioaccumulates in macrophages, forming membrane-bound intracellular structures possessing nanoscale supramolecular features. Here, a library of phenazine compounds derived from clofazimine was synthesized and tested for their ability to accumulate and form ordered molecular aggregates inside cells. Regardless of chemical structure or physicochemical properties, bioaccumulation was consistently greater in macrophages than in epithelial cells. Microscopically, some self-assembled structures exhibited a pronounced, diattenuation anisotropy signal, evident by the differential absorption of linearly polarized light, at the peak absorbance wavelength of the phenazine core. The measured anisotropy was well above the background anisotropy of endogenous cellular components, reflecting the self-assembly of condensed, insoluble complexes of ordered phenazine molecules. Chemical variations introduced at the R-imino position of the phenazine core led to idiosyncratic effects on the compounds' bioaccumulation behavior, as well as on the morphology and organization of the resulting intracellular structures. Beyond clofazimine, these results demonstrate how the self-assembly of membrane-permeant, orally-bioavailable small molecule building blocks can endow cells with unnatural structural elements possessing chemical, physical and functional characteristics unlike those of other natural cellular components.
authors.affiliation: Department of Pharmaceutical Sciences, University of Michigan College of Pharmacy, 428 Church St, Ann Arbor, MI 48109.
authors.forename: Kyoung Ah
authors.initials: KA
authors.lastname: Min
authors.affiliation: Department of Medicinal Chemistry, University of Michigan College of Pharmacy, 428 Church St, Ann Arbor, MI 48109, Ann Arbor, MI 48109.
authors.forename: Walajapet G
authors.initials: WG
authors.lastname: Rajeswaran
authors.affiliation: Marine Biological Laboratories, Woods Hole, MA 02543.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Oldenbourg
authors.affiliation: Marine Biological Laboratories, Woods Hole, MA 02543.
authors.forename: Grant
authors.initials: G
authors.lastname: Harris
authors.affiliation: Department of Pharmaceutical Sciences, University of Michigan College of Pharmacy, 428 Church St, Ann Arbor, MI 48109.
authors.forename: Rahul K
authors.initials: RK
authors.lastname: Keswani
authors.affiliation: Department of Pharmaceutical Sciences, University of Michigan College of Pharmacy, 428 Church St, Ann Arbor, MI 48109.
authors.forename: Mason
authors.initials: M
authors.lastname: Chiang
authors.affiliation: Department of Pharmaceutical Sciences, University of Michigan College of Pharmacy, 428 Church St, Ann Arbor, MI 48109.
authors.forename: Phillip
authors.initials: P
authors.lastname: Rzeczycki
authors.affiliation: Department of Pharmaceutical Sciences, University of Michigan College of Pharmacy, 428 Church St, Ann Arbor, MI 48109.
authors.forename: Arjang
authors.initials: A
authors.lastname: Talattof
authors.affiliation: Department of Pharmaceutical Sciences, University of Michigan College of Pharmacy, 428 Church St, Ann Arbor, MI 48109.
authors.forename: Mahwish
authors.initials: M
authors.lastname: Hafeez
authors.affiliation: School of Life Sciences, The University of Glasgow, University Avenue, Glasgow G12 8QQ, Scotland UK.
authors.forename: Richard W
authors.initials: RW
authors.lastname: Horobin
authors.affiliation: Department of Medicinal Chemistry, University of Michigan College of Pharmacy, 428 Church St, Ann Arbor, MI 48109, Ann Arbor, MI 48109.
authors.forename: Scott D
authors.initials: SD
authors.lastname: Larsen
authors.affiliation: Department of Clinical, Social and Administrative Sciences, University of Michigan College of Pharmacy, Ann Arbor, MI 48109.
authors.forename: Kathleen A
authors.initials: KA
authors.lastname: Stringer
authors.affiliation: Department of Pharmaceutical Sciences, University of Michigan College of Pharmacy, 428 Church St, Ann Arbor, MI 48109.
authors.forename: Gus R
authors.initials: GR
authors.lastname: Rosania
keywords: Medicinal chemistry; aggregation; biocrystals; chromophores; clofazimine; imaging; polarization