Proto-porphyrine

ALA-proto-porphyrin IX Levulan (DUSA) 635 (5000) 0.56 60 50-150 500-1500 Skin cancers, dermatological conditions (psoriasis) No skin phototoxicity Can be used topically with blue light for skin disorders (Approved, actinic keratoses)... 

C Atom Deuterio- porphyrin dimethyl ester Deuterio- porphyrin diethyl ester 2,4-Di- acetyl- deuterio- porphyrin dimethyl ester 2.4-Di- propionyl- deuterio- porphyrin dimethyl ester Meso- porphyrin dimethyl ester Proto- porphyrin diethyl ester... 

Clearly, it is a mass-action phenomenon and the only selection that can occur in such a solution is the fit of specific groups to build larger molecules. In this way the bonding orbitals, the direction and strength as well as their sensitivity to competing reactions, cause the buildup of more complex molecules if reaction conditions favor such a development. In Figure 4.5 the concept is illustrated by an actual example of a radiation-driven, nonbiological series of reactions that ends in the formation of proto-porphyrin. 

Mg-proto-porphyrin IX MME hydroxylase Hydroxyl at ion Fe - + MME + Oi Fe ""- Fe " + divinyl protOchlorophyllide Carotenoid and chlorophyll biosynthesis... 

The degree to which the equilibrium (1) lies to the right increases in the order (Acdeut-DME) < (Proto-DME) < (Deut-DME) < (Meso-DME) for (P) ->[14-17]), as expected from the static cis effect of the porphyrin ligands mentioned. 

The small spectral discrimination between CO, 02, and NO in the Fe(P) system as compared with the Ru(P) or Os(P) systems may also be due to the less pronounced 7T-donor ability of the Fe11 ion relative to the Ru11 or Os11 ion in a porphyrin system. The spectral differences between the nitrosyls and the dioxygen complexes are especially small. The a- or (3-bands indicated for these complexes (Series a, c, d, Table 13) fall in the range where the a- or 0-bands of the corresponding Zn11 porphyrins are observed (Xa for Zn(Proto-IX) 586 nm (43) for Zn (TPP) 548 nm, see Table 3). As... 

A remarkable result is the position of (Proto-DME) between (TPP) and (TpivPP) in Series b, Table 15. The vco values originate from various sources and the observed differences between the three porphyrins may thus be meaningless. (Note the enormous solvent dependence of the infrared spectra of various hemes that has been reported recently (29).) Anyway, the three porphyrins have approximately the same ir-acceptor capacity. Therefore, the tetraarylporphyrin moiety, especially in the picket fence hemes, e.g., Fe(TpivPP)LX [33], is comparable with the natural hemes Fe(Proto-DME)LX ([14], M = Fe), and its use as a model porphyrin for the study of hemoprotein properties is well justified, despite the very different substitution pattern. 

The first picosecond and nanosecond time-resoived Raman spectra of photoexcited metaiioporphyrins in coordinating and noncoordinating soivents are presented. Our data demonstrate that resonance Raman spectra can be obtained from transient nickei porphyrin species and confirm the existence of photoinduced iigation changes in nickel proto and octaethyi porphyrin species on a subnanosecond timescale. 

Table 1 provides a fairly comprehensive listing of trivial names still in regular use in the porphyrin and chlorophyll area. The uro-, copro- and etio-porphyrins are examples of primary type isomer systems, while proto-, meso-, deutero- and hemato-porphyrins derive from the situation where 15 isomers exist. Phyllo-, pyrro- and rhodo-porphyrins, all being chlorophyll degradation products, are examples of the situation where there are four different kinds of porphyrin substituent. It transpires that, in biologically important porphyrin derivatives, the isomer chosen by Nature is Type-Ill (for the primary system), Type-IX (with three types of substituent) and Type-XV (with four). As can be seen in Schemes 1 and 2, primary type-III is related to type-IX in Scheme 2, and type-IX is in turn related to type-XV in the yet more complicated four-substituent system. 

Fig. 2. Structure of some porphyrin-iron complexes. Protoheme IX (Proto) R = —CH=CH2 Deuteroheme IX (Deut) R = —H Mesoheme IX (Meso) R =...

Collapse of N-alkylated porphyrins [80] is an alternative to metal insertion into normal porphyrins. Thus, IV-benzylprotoporphyrin IX-dimethylester reacts in refluxing methanol with PdCl2 to yield 92% Pd(Proto-DME) within 10 min. 

Not only has binding of imidazoles and pyridines to Fe protoporphyrin IX been studied, as discussed in Section 4.1.2, but also photodissociation of axial ligands such as pyridines, imidazoles, or piperidines from six-coordinate, low-spin Fe porphyrins, in which the porphyrin is derived from protoporphyrin IX, or proto- or deuteroporphyrin IX dimethyl ester, has been investigated in nonaqueous solvents using picosecond transient absorption spectroscopy (see Photochemistry of Transition Metal Complexes). It has been shown that photodissociation leads to the formation of five-coordinate complexes, that is, only one ligand appears to be released upon excitation of the six-coordinate complex. ... 

VP PBG > ALA Copro III, uroporphyrin from PBG Proto IX > Copro III, X-porphyrin Not increased 624-628 nm... 

We will start with the findings on the free porphyrin ligands, i.e. the proto-nated forms H2Por to learn about the characteristic spectroscopy of pure porphyrin-centred electron transfer (Section 4.2). In the same section... 

Early studies with PDT employed complex mixtures of poorly defined porphyrins known as hemato-porphyrin derivative (photofrin I) or a partially purified mixture known as porfimer sodium (PHOTOFRIN II) that was administered parenterally with subsequent irradiation using polychromatic light sources. The major problem with this approach was the prolonged period (4-6 weeks) of photosensitivity caused by skin retention of the porphyrin formulations. This led to a search for compounds that could be administered topically and that were eliminated more readily from the skin. The porphyrin precursor S-aminolevulinic acid (ALA) is converted to various porphyrins, particularly protoporphyrin (proto), in tissues including the skin (see below). Protoporphyrin subsequently is eliminated rapidly from the body, thereby minimizing the period of skin photosensitivity to a few hours. Topically applied ALA HCl (20% wA>) and, more recently, the methyl ester of ALA have been used successfully for the PDT of various types of nonmelanoma skin cancers and premalignant lesions. 

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