Shapeshifter

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Rose Bengal is a molecule that has been around for a long time and used in several very different ways. In addition to being an industrial dye and a food dye (i.e., Red Food Dye No. 105), the molecule has a long history as a diagnostic agent with an established safety history. Use as a diagnostic was Rose Bengal's original and first medicinal use (i.e., an intravenous hepatic diagnostic: 131I-radiolabeled Rose Bengal/Robengatope®; a topical ophthalmic diagnostic: Rosettes®, Minims®).

Rose Bengal's second medicinal use is as a therapeutic, which is being advanced by Provectus in both oncology (PV-10) and dermatology (PH-10). There are other halogenated xanthenes the company owns.

Note the concentrations: intralesionally (intratumorally) injected PV-10 for oncology is a 10% solution of Rose Bengal, and topically applied PH-10 for dermatology is a 0.001% to 0.01% gel of the active pharmaceutical ingredient (API) Rose Bengal. PV-10 up-regulates or stimulates, while PH-10 appears to locally down-regulate.

This is a blog page I update from time to time as information is gathered about Rose Bengal's shape changing (transformation) abilities; h/t a shareholder hatter.

For now, first consider Xu et al., "Aggregation of Rose Bengal Molecules in Solution," Journal of Photochemistry and Photobiology, A: Chemistry, 40 (1987) 361-370.

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The authors note (my underlined emphasis):

"Rose bengal is a bis anionic dye and it has been suggested that it also has a tendency to aggregate in solution. It does not follow Beer’s law at concentrations above 10e5 M and the spectra are both of different shape and shifted at higher concentrations. Thus the aggregation phenomena of rose bengal and the other xanthenes have been previously studied in solution by means of absorption spectroscopy 171. The absorption spectrum of rose bengal in dilute solution consists of two peaks separated by about 30 nm. In more concentrated solution the shorter wavelength of these peaks grows and shifts several nanometers toward the blue. We can now assign the longer wavelength band exclusively to the monomer while the shorter-wavelength band derives from a combination of the monomer and the dimer respectively and its size as well as its shape depend on concentration."

There has been some discussion of the pH environment in a tumor cell, and surrounding healthy tissue. There are differences in the nutritional and metabolic environment of cancerous and healthy tissues.

Pathobiology of Cell Membranes, Volume 2, edited by Benjamin F. Trump, Antti U. Arstila (1980), discuss, among other things, the effect of pH, and mechanism:

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Red Cell Shape: Physiology, Pathology, Ultrastructure, edited by M. Bessis, R. I. Weed, P. F. Leblond (1973), note the factors that facilitate shape transformation (sphering) to varying degrees include pH, temperature, ionic composition, and concentration:

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