Books
in black and white
Main menu
Share a book About us Home
Books
Biology Business Chemistry Computers Culture Economics Fiction Games Guide History Management Mathematical Medicine Mental Fitnes Physics Psychology Scince Sport Technics
Ads

The porphyrin handbook - Kadish K.M.

Kadish K.M. The porphyrin handbook - Academic press, 2000. - 368 p.
Download (direct link): kadishsmishgulilard2000.djvu
Previous << 1 .. 96 97 98 99 100 101 < 102 > 103 104 105 106 107 108 .. 240 >> Next

B. Vinylogous
Porphyrins...............................................................
............................. 205
X. Miscellaneous Porphyrins and
Chlorins.................................................................
.............. 205
A. Glycosylated Porphyrins and
Chlorins.................................................................
............ 205
B. Barbituric Acid Functionalized Porphyrins and
Chlorins........................................................... 206
C. Nucleoside Adducts of Porphyrins and
Chlorins.................................................................
... 206
D. Porphyrins Containing Six-Membered
Rings....................................................................
..... 207
XI. Endogenous Porphyrins from
ALA......................................................................
............. 208
A. Cationic
Photosensitizers.........................................................
............................... 209
XII. Cationic Porphyrins, Chlorins and
Phthalocyanines..........................................................
...... 209
XIII. Phthalocyanines and
Naphthalocyanines........................................................
.................... 211
XIV. Current Status of Photosensitizers Under Clinical
Trials......................................................... 214
A. Advantages and Disadvantages of Some Selected
Photosensitizers................................................... 224
XV.
Conclusions..............................................................
........................................ 224

References...............................................................
........................................... 225
I. Introduction
A. A BRIEF HISTORY OF PHOTODYNAMIC THERAPY
The first observation of chemical sensitization of tissue by light was
reported in 1900 by Raab.1 The basic concept of photodynamic therapy
(PDT) dates from 1903, when Tappeiner and Jesionek used topically applied
eosin and sunlight to treat skin cancer patients.2 Ten years later,
Meyer-Betz injected himself with 200 mg of hematopor-phyrin and suffered
no ill effects until he exposed himself to sunlight, whereupon he
suffered extreme swelling and remained photosensitive for several
months.3 Auler and Banzer reported the affinity of hematoporphyrin for
neoplastic tissues,4 which was confirmed by Figge et al. using the
fluorescence of the accumulated porphyrins under a Wood's lamp.5 In the
mid-1950s Schwartz et al. proposed that the selective fluorescence of
malignant tissues after in vivo administration of hematoporphyrin (Hp) in
mice might be due to an impurity in the crude preparation rather than to
hematoporphyrin itself.6 This awareness led Lipson and his
coworkers,7-9 to develop a derivative of hematoporphyrin that enhanced
the amount of tumor-localizing component in the clinically used drug.
Hematoporphyrin derivative (Hpd) was prepared by first reacting
hematoporphyrin with acetic acid/sulfuric acid (9:1) and then treating
the intermediate mixture containing the corresponding mono-, diacetylated
analogues and the related dehydration products with aqueous sodium
hydroxide. In this reaction, in addition to the Hp and its dehydration
analogues, a completely unexpected product is formed in about 50% yield,
which was named Hpd. Lipson demonstrated that Hpd was taken up and
retained in experimental rodent tumors to a much greater extent than was
pure Hp.10 While the importance of porphyrins and in particular HpD in
cancer diagnosis was becoming accepted, it only became apparent in the
late 1960s and early 1970s that the role of the drug would go beyond that
of a diagnostic agent. During the early and mid-1970s, several groups
including Diamond etal.,11 Kelly and Snell,12 and Dougherty et al.13
realized that together HpD and light had a potential capability for tumor
destruction, and so they began to conduct in vitro and in vivo studies to
43 / Porphyrins as Photosensitizers in Photodynamic Therapy
159
Type I reaction
1. Absorption 2. Nonradiative Decay; 3. Fluorescence;
4. Intersystem Crossing; 5. Phosphorescence; 6. Energy Transfer
Figure 1. Modified Jablonski diagram.
determine the response of tumors to this combined approach. In 1978,
after extensive preclinical studies, Dougherty reported on a series of 25
patients, showing a partial or complete response in 111 of 113 tumors
treated by Hpd following photodynamic therapy.14 However, it was not
until about 1980 that the Hpd was purified and partially identified.
Additional studies since then have demonstrated that this "active"
fraction of Hpd (Photofrin) is a mixture of dimers and higher oligomers
in which the porphyrin units are joined by ether, ester and carbon-carbon
bonds (see Section V.III.A). Since then, a rekindled interest worldwide
Previous << 1 .. 96 97 98 99 100 101 < 102 > 103 104 105 106 107 108 .. 240 >> Next