Novel bioconjugates of aminolevulinic acid with vitamins

Chemical approaches for the enhancement of 5-aminolevulinic acid-based photodynamic therapy and photodiagnosis

The development of photodynamic therapy and photodiagnosis with 5-aminolevulinic acid presents a number of challenges that can be addressed by applying chemical insight and a range of novel prodrug strategies.

8-Amino-5,6,7,8-tetrahydroquinoline in iridium(iii) biotinylated Cp* complex as artificial imine reductase

The imine reductase formed by the (R)-CAMPY ligand bound to the S112M Sav mutant showed an 83% ee in the asymmetric transfer hydrogenation of 6,7-dimethoxy-1-methyl-3,4-dihydroisoquinoline.

Synthesis of Bioconjugate Sesterterpenoids with Phospholipids and Polyunsaturated Fatty Acids

A series of sesterterpenoid bioconjugates with phospholipids and polyunsaturated fatty acids (PUFAs) have been synthesized for biological activity testing as antiproliferative agents in several cancer cell lines. Different substitution analogues of the original lipidic ether edelfosine (1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine) are obtained varying the sesterterpenoid in position 1 or 2 of the glycerol or a phosphocholine or PUFA unit in position 3. Simple bioconjugates of sesterterpenoids and eicosapentaenoic acid (EPA) have been obtained too. All synthetic derivatives were tested against the human tumour cell lines HeLa (cervix) and MCF-7 (breast). Some compounds showed good IC₅₀ (0.3 and 0.2 μM) values against these cell lines.

A versatile δ-aminolevulinic acid (ΑLA)-cyclodextrin bimodal conjugate-prodrug for PDT applications with the help of intracellular chemistry

Grafting of δ-aminolevulinic acid (1) moieties on the narrow periphery of a β-cyclodextrin (β-CD) derivative through hydrolysable bonds was implemented, in order to generate a water-soluble, molecular/drug carrier with the capacity to undergo intracellular transformation into protoporphyrin IX (PpIX), an endogenous powerful photosensitizer for photodynamic therapy (PDT). The water-soluble derivative 2 was prepared by esterifying δ-azidolevulinic acid with heptakis(6-hydroxyethylamino-6-deoxy)-β-cyclodextrin, with an average degree of substitution, DS = 3. Delivery of water-soluble, colorless 2 to cells resulted in intense red fluorescence registered by confocal microscopy, evidently due to the engagement of the intracellular machinery towards formation of PpIX. Conjugate 2 was further complexed with a fluorescein-labeled model guest molecule which was successfully transported into the cells, thereby demonstrating the bimodal action of the derivative. The present work shows the versatility of CDs in smart applications and constitutes advancement to our previously shown PpIX-β-CD conjugation both in terms of water solubility and lack of aggregation.

New hydrophilic/lipophilic tetra-α-(4-carboxyphenoxy) phthalocyanine zinc-mediated photodynamic therapy inhibits the proliferation of human hepatocellular carcinoma Bel-7402 cells by triggering apoptosis and arresting cell cycle

Photodynamic therapy (PDT) is a novel and promising antitumor treatment. Phthalocyanine-mediated PDT has shown antitumor activity in some tumor cells, but the effect of new hydrophilic/lipophilic tetra-α-(4-carboxyphenoxy)phthalocyanine zinc (TαPcZn)-mediated PDT (TαPcZn-PDT) on human hepatocellular carcinoma Bel-7402 cells and underlying mechanisms have not been clarified. In the present study, therefore, the ultraviolet-visible (UV-vis) absorption spectrum and cellular localization of TαPcZn, and effect of TαPcZn-PDT on the proliferation, apoptosis, cell cycle, Bcl-2 and Fas in Bel-7402 cells were investigated by spectrophotometry, inverted microscope, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay, electron microscopy, annexinV-FITC/propidium iodide double staining, DNA content and immunoblot assay, respectively. We found that an intense absorption in UV-vis absorption spectrum of TαPcZn was in the red visible region at 650–680 nm, where light penetration in tissue is efficient, that green TαPcZn localized to both plasma membrane and nuclear membrane of Bel-7402 cells, signifying that there was a selective uptake of TαPcZn in Bel-7402 cells and TαPcZn-PDT would be expected to directly damage DNA, and that TαPcZn-PDT significantly resulted in the proliferation inhibition, apoptosis induction, S cell cycle arrest, and down-regulation of Bcl-2 and Fas. Taken together, we conclude that TαPcZn-PDT inhibits the proliferation of Bel-7402 cells by triggering apoptosis and arresting the cell cycle.