Alessia Salvador

Synthesis of a new class of pyrrolo[3,4-h]quinazolines with antimitotic activity

A new series of pyrrolo[3,4-h]quinazolines was conveniently prepared with a broad substitution pattern. A large number of derivatives was obtained and the cellular cytotoxicity was evaluated in vitro against 5 different human tumor cell lines with GI₅₀ values reaching the low micromolar level (1.3-19.8 μM). These compounds were able to induce cell death mainly by apoptosis through a mitochondrial dependent pathway. Selected compounds showed antimitotic activity and a reduction of tubulin polymerization in a concentration-dependent manner. Moreover, they showed anti-angiogenic properties since reduced in vitro endothelial cell migration and disrupted HUVEC capillary-like tube network in Matrigel.

Pyrrolo[3,2-h]quinazolines as photochemotherapeutic agents.

Heteroanalogues of angelicin, pyrrolo[3,2‐h]quinazolines, were synthesized with the aim of obtaining new potent photochemotherapeutic agents. Many derivatives caused a significant decrease in cell proliferation in several human tumor cell lines after irradiation with UVA light (GI50=15.2–0.2 μM). Their phototoxicity effected apoptosis in Jurkat cells with the involvement of mitochondria (as determined by the loss of mitochondrial membrane potential and production of reactive oxygen species) and lysosomes. The phototoxicity of these compounds could be explained by lipid peroxidation.

Pyrrolo[3,4-h]quinolinones a new class of photochemotherapeutic agents

Pyrrolo[3,4-h]quinolin-2-ones were synthesized as nitrogen isosters of the angular furocoumarin angelicin, with the aim of obtaining new photochemotherapeutic agents with increased antiproliferative activity and lower undesired toxic effects. A versatile synthetic pathway was approached to allow the isolation of derivatives of the new ring system with a good substitution pattern on the pyrrole moiety. Photobiological screenings of the new compounds revealed a potent phototoxic effect and a great UVA dose dependence, reaching IC(50) values at submicromolar level. The induced cellular photocytotoxicity was related to apoptosis with the involvement of mitochondria and lysosomes, alteration of cell cycle profile and membrane lipid peroxidation.

Synthesis of pyrrolo[3,2-h]quinolinones with good photochemotherapeutic activity and no DNA damage.

In the search for new photochemotherapeutic agents, a series of derivatives of the ring system pyrrolo[3,2-h]quinoline--bioisosters of the angular furocoumarin angelicin--were synthesized through a four-step synthetic approach, in reasonable overall yields. Eight of the synthesized derivatives showed a remarkable phototoxicity against a panel of four human tumor cell lines and a great dose UV-A dependence, reaching IC₅₀ values at submicromolar level. The mode of cellular death photoinduced by pyrrolo[3,2-h]quinolines was evaluated through a series of flow cytometric analysis and other tests were performed to clarify their mechanism of action.

Pyrano[2,3-e]isoindol-2-ones, new angelicin heteroanalogues.

A convenient synthesis of the pyrano[2,3-e]isoindol-2-one ring system, an heteroanalogue of angelicin, is reported. Our synthetic approach consists of the annelation of the pyran ring on the isoindole moiety using 5-dialkylamino- or 5-hydroxymethylene intermediates as building blocks. The photoantiproliferative activity of the new derivatives was studied. Some of them bearing the benzyl group at the 8 position were active with IC(50) in the micromolar range. Cell cytotoxicity involves apoptosis, alteration of cell cycle profile and membrane photodamage.

Synthesis of Triazenoazaindoles: a New Class of Triazenes with Antitumor Activity

Despite improvements in the treatment and prevention of cancer, the number of new diagnoses continues to rise; this has fuelled substantial interest in the development of new and effective chemotherapeutic agents. Compounds of the triazene class, such as dacarbazine, have been used in the clinical management of many cancer types including brain, leukemia, and melanoma. A new compound class bearing a triazenoazaindole scaffold was synthesized with the aim of identifying new antiproliferative agents. Compounds 5 a–g and 6 a–c were screened against a panel of human tumor cell lines, and two of them, 5 e and 5 f, showed cytotoxicity (GI50 range: 2.2–8.2 μM) in all cell lines. These two compounds even maintained their cytotoxicity in some multidrug‐resistant cell lines. Flow cytometry analysis demonstrated their ability to induce cell death by apoptosis with involvement of lysosomes.

Pyrazolo[3,4-h]quinolines promising photosensitizing agents in the treatment of cancer

A new series of pyrazolo[3,4-h]quinolines, heteroanalogues of angelicin was conveniently prepared with a broad substitution pattern. A large number of derivatives was obtained and the cellular photocytotoxicity was evaluated in vitro against 5 different human tumor cell lines with GI50 values reaching the nanomolar level (14.52-0.04 μM). Selected compounds were able to photoinduce a massive cell death with the involvement of mitochondria. Their photodamage cellular targets were proteins and lipids and they did not cause any kind of DNA photodamage. This latter event is of considerable importance in the modulation of long term side effects, generally associated with the use of classical furocoumarins.

Photoreactivity of 5-fluorouracil under UVB light: photolysis and cytotoxicity studies.

The photodegradation of the chemotherapeutic agent 5-fluorouracil (5-FU) under UVB light was studied both in aqueous and methanol solutions and in systemic and topical formulations. As monitored by HPLC, photodegradation in solution takes place in a concentration dependent manner; thus, the solution for parenteral administration (10(-1) M) showed negligible loss of the active principle. On the contrary, the commercial cream containing 5% of 5-FU showed low stability under UVB exposure. When dissolved either in water or methanol, 5-FU yields two photoproducts which have been characterized as two isomers coming from the addition of the solvent to the 5,6 double bond of the drug. As a consequence, photomodified 5-FU loses its antiproliferative activity on HCT-15 and HeLa cells. MS analysis showed that photoaddition occurred with nucleophilic amino acids, such as cysteine and serine, while susceptible amino acids (cysteine and methionine) were oxidized. In fact, high production of the superoxide anion under UVB light as well as photooxidation of BSA suggests protein photodamage as a mechanism of photosensitization. Indeed, some phototoxicity was shown in experiments on NCTC keratinocytes and MCF-7 resistant cells irradiated with UVB light. The interactions with these biological targets may contribute to skin phototoxicity and photoallergy induced by 5-FU in vivo.

Photophysical Properties and Photobiological Behavior of Amodiaquine, Primaquine and Chloroquine

This article describes the results of a coupled photophysical and photobiological study aimed at understanding the phototoxicity mechanism of the antimalarial drugs amodiaquine (AQ), primaquine (PQ) and chloroquine (CQ). Photophysical experiments were carried out in aqueous solutions by steady‐state and time‐resolved spectrometric techniques to obtain information on the different decay pathways of the excited states of the drugs and on the transient species formed upon laser irradiation. The results showed that all three drugs possess very low fluorescence quantum yields (10−2–10−4). Laser flash photolysis experiments proved the occurrence of photoionization processes leading to the formation of a radical cation in all three systems. In the case of AQ the lowest triplet state was also detected.

Thiopyrano[2,3-e]indol-2-ones: Angelicin heteroanalogues with potent photoantiproliferative activity

A new class of compounds, the thiopyrano[2,3-e]indol-2-ones, bioisosters of the angular furocoumarin angelicin, was synthesized with the aim of obtaining new photochemotherapeutic agents. In particular 7,8-dimethyl-thiopyranoindolone 6c s showed a remarkable phototoxicity and a great dose UVA dependence reaching IC(50) values at submicromolar level. This latter photoinduced a massive apoptosis and a remarkable photodamage to lipids and proteins. Although it did not intercalate DNA, it was able to cause photooxidation of DNA bases.