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porphyrins containing mono- and di-six-membered ring systems.
a. R-| = OMe, R2 = H; b. R^ = H, R2 = Me, c. Rj = H, R2 =OMe
Pandey and Zheng
Scheme 89. The heme biosynthetic pathway.
Coproporphyrin I Uroporphyrin I
Scheme 90. Cationic dyes as photosensitizers.
0.5-3.5mg/kg NPe6 followed 4 hours later by 50-100J/ cm2 at 664 nm light.
PDT using NPe6 caused no significant toxicity with the exception of
temporary generalized skin photosensitivity. In all cases, light
treatment caused immediate tissue blanching followed by a marked necrosis
of the tumor mass. Regression of tumor occurred over the course of 24 to
48 hours after the light treatment and was followed by the formation of a
heavy eschar over the tumor site. These data demonstrate that NPe6 is
both an effective and safe photosensitizer for use in PDT.
Lutetium texaphyrin PCI-0123 Lu(Tex) is a water-soluble
photosensitizer with a broad absorption peak centered at 732 nm and
fluorescence emission at 750 nm. Thirty-five patients with cancers
metastatic to the skin or
43 / Porphyrins as Photosensitizers in Photodynamic Therapy
Scheme 91. A simple approach for the formation of cationic porphyrins and
Scheme 92. Cationic porphyrins and benzochlorins.
V-NH N4 (i) NH2CH2CH2N(CH3)2
)= N HN"i. (ii) CH3I
v N+ I / \ Me Me
Pandey and Zheng
Scheme 93. Glycosylated cationic porphyrins.
455 R = Glc OAc
Glc = (OH
= Me, R = GlcAc = i-Pr, R = GlcAc = n-Oct, R = GlcAc = Me, R = Glc = i-
Pr, R = Glc = n-Oct, R = Glc
Scheme 94. Cationic phthalocyanines and naphthalocyanines.
466 X and Y = OPy or H
467 R = GlucOAc, R' = Me
468 R = MaltOAc, R' = Me
469 R = LactOAc, R' = Me
470 R = GlucOAc, R' = bPr
471 R = GlucOAc, R' = n-Oct
43/Porphyrins as Photosensitizers in Photodynamic Therapy
Scheme 95. Some novel phthalocyanines and naphthalocyanines.
M = H M = Zn
474 R = Cl
475 R = OH
476 R = OSi(CH3)2C(CH3)3
477 R = OSi(CH3)2C(CH3)2CH(CH3)2
478 R = OSi(CeH13)3
479 R = OSi(CH3)2C18H37
Table 1. Selected Photosensitizers: Advantages and Disadvantages
Disadvantages Developed by
Photofrin 1. Easy to synthesize 1. Complex
mixture QLT Pharmaceuticals
(porphyrin 2. Easy to formulate 2.
Absorption: 630 nm Vancouver, Canada
Oligomers) 3. Approved worldwide 3. Skin
m-THPC 1. Easy to synthesize 1. Skin
phototoxicity Scotia Pharmaceuticals
(a chlorin) 2. Very effective Photosensitizer 2. Light
treatment 7-9 Guildford, England
3. Long-wavelength absorption (650 nm) days after
BPD 1. Long-wavelength absorption (690 nm) 1.
Difficult to synthesize QLT Pharmaceutical
(a chlorin) 2. No skin phototoxicity 2. Clears
rapidly, effective only if the tumors Vancouver, Canada
treated with light 3 h post inj. of the drug
NPe6 1. Easy to synthesize 1. Rapidly
cleared from the circulation; Nippon, Japan
(a chlorin) 2. No skin phototoxicity successful
treatment depends on
3. Easy to formulate the
presence of the drug levels in the plasma; levels in