Summary We compared para-, meta-and ortho-isomers of meso-tetra(hydroxyphenyl)porphyrin (p-, m-and o-THPP) and the potassium salt of the para compound (K-p-THPP) with haematoporphyrin derivative (HpD) and Photofrin II in their ability to sensitise tumours, skin and brain to light. HpD and Photofrin II induced modest tumour photosensitisation at the cost of substantial skin and brain sensitisation. At doses low enough to keep sensitisation of these normal tissues within acceptable limits, tumour sensitisation was sufficient to give necrosis only 2mm deep after exposure to 1OJcm-2 light.In contrast, doses of p-THPP, K-p-THPP and m-THPP that produced skin and brain sensitivity within acceptable limits sensitised tumours enough to give 4-9mm necrosis after OJCcm-2 light. m-THPP was, on a molar basis, about 25-30 times as potent as HpD and Photofrin II in sensitising tumours. o-THPP was also a potent tumour photosensitiser, but induced a prohibitive degree of skin photosensitivity even at low doses.It is unlikely that these differences in relative selectivity are due to differences in such photophysical parameters as optimum activating wavelength (which would affect tissue penetration by light), or light absorption, and physicochemical factors that determine tissue localisation may be involved.The high tumour sensitising potency and favourable tissue selectivity of m-THPP, p-THPP and K-p-THPP make them promising candidates for clinical tumour phototherapy.
Metal complexes [Al"', Fell', Co", Nil', Cu", Zn", Cd", and Pt"] of various octadecyl ethers of 5,10,15,20-tetrakis(4-hydroxypheny1)porphyrin have been prepared and characterised. The metalloporphyrins are examined for their ability to form layers using the Langmuir technique, and pressure-area isotherms are presented. Multilayers on glass substrates are made in suitable cases using the Langrnuir-Blodgett method. Complexes of the tris(octadecyl) ether generally give films with favourable properties although the aluminium(tti) complex, which is shown to be dimeric, does not. In certain cases where the pure metalloporphyrin gives unsatisfactory results, the film can be improved using a stabiliser such as stearic acid. The absorption maxima of the films are determined before and after exposure to sensor gases (CI,, HCI, NO, ) and after further exposure to hydrazine vapour ('hydrazine reset'), and compared with solution spectra.
A new high-yielding preparation of alkanol propentdyopents is discovered and used to confirm the structure for this system as the valley adduct [e.g. structure (I)].
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