Curcumin analogues are novel antineoplastic agents designed by structural modifications of the natural product curcumin to enhance its therapeutic effects. Various curcumin analogues displayed a significant cytotoxic effect towards different cancer cell lines including leukemia, melanoma, and colon cancer. In order to evaluate the safety, efficiency and metabolism of the new anticancer candidates, sensitive and high throughput analytical methods are needed. Thirteen curcumin analogues with the backbone structure of 3,5-bis(benzylidene)-4-piperidone were tested. The ionization behavior of curcumin analogues was investigated to reveal the possible mechanisms for the unusual formation of the positively charged [M-H]+ ions during single stage positive ion mode MALDI-MS analysis. Different ionization techniques (i.e., ESI, APCI, APPI, and MALDI) were used to evaluate this phenomenon. The results showed that curcumin analogues ionize into [M-H]+ along with the expected [M+H]+ species during MALDI and dopant free APPI-MS. In contrast, ESI, APCI and the dopant mediated APPI showed only the expected [M+H]+ peak. Our experiments revealed that photon energy triggers the ionization of the curcumin analogues even in the absence of any ionization enhancer such as matrix, solvent or dopant. Three proposed mechanisms for the formation of [M-H]+ were evaluated, two of them are probably involved in the [M-H]+ formation: (i) hydrogen transfer from the analyte radical cation and (ii) hydride abstraction. In addition to the ionization behavior, the collision induced dissociation-tandem mass spectrometric (CID-MS/MS) fragmentation behavior of curcumin analogues was evaluated showing similar dissociation pathways that centered on the piperidone ring of the 3,5-bis(benzylidene)-4-piperidone moiety. The presence of different substitutes on that moiety resulted in specific product ions for each curcumin analogue. The fragmentation patterns were established to confirm the chemical structure of the tested compounds and identify the diagnostic product ions of each compound. Twelve common product ions were identified resulting from the breakage of various bonds within the piperidone moiety. There was a tendency for the formation of highly conjugated product ions that are stabilized via resonance. Common product ions were identified allowing for the establishment of a general MS/MS behavior for any curcumin analogue that belongs to the 3,5-bis(benzylidene)-4-piperidone structural family. The fragmentation routes and the genesis of the product ions were confirmed via MS3 and neutral loss analysis. In summary, the ionization of curcumin analogues provided insights into the formation of unique [M-H]+ ions which were linked to photo ionization of such compounds without the need for additives, such as matrix, dopant or solvent. As such, curcumin analogues should be evaluated as MALDI matrices in the future. The CID-MS/MS analysis of curcumin analogues revealed a common fragmentation behavior of the tested compounds. It will be applied, in the future to determine metabolic by-products of the tested compounds as well as to develop targeted liquid chromatography (LC)-MS/MS methods.

Melanoma é o câncer mais agressivo e a mutação BRAF V600E é a mais frequente entre os pacientes. O vemurafenibe foi o primeiro inibidor específico desta mutação aprovado pela Food and Drug Administration. Entretanto, após cerca de seis meses há recidiva e superar os mecanismos de resistência responsáveis por este fenômeno ainda é um desafio. A curcumina é um tumérico com características antitumorais e anti-inflamatórias, entretanto sua baixa biodisponibilidade e estabilidade limitam seu uso e por isso impulsionaram a busca por análogos capazes de serem eficientes e comercializados. O DM-1, é um análogo monocetônico que apresentou efeitos antiumorais in vitro e in vivo em estudos anteriores. O objetivo deste trabalho foi avaliar os efeitos citotóxicos do DM-1 em células de melanoma sensíveis (naive) e resistentes ao vemurafenibe, bem como na modulação de metaloproteinases. As células de melanoma foram tratadas com diferentes concentrações de DM-1, e este composto foi citotóxico para linhagens sensíveis e resistentes ao vemurafenibe, além de induzir parada de ciclo celular em G1/G0 e diminuir o número de colônias, entretanto ele não foi seletivo em ensaios de citotoxicidade realizados com melanócitos e fibroblastos. O tratamento dessas células em doses subtóxicas resultou na modulação de metaloproteinases importantes no processo de invasão celular. O DM-1 reduziu as concentrações das metaloproteinases -1, -2 e -9 (MMP-1, -2 e -9) em um ensaio de quantificação de MMPs e a atividade das MMP-2 e -9 em um ensaio de zimografia de maneira célula dependente. As modulações negativas do inibidor de MMP TIMP-2 e MMP-14 para SKMEL-28 naive foram associadas a diminuição das atividades de MMP-2 e -9, enquanto que as modulações positivas para SKMEL-19 naive foram relacionadas ao aumento de MMP-2. Este composto ainda inibiu a migração das células e a formação de tubos por células endoteliais. / Malignant melanoma is the most aggressive cancer and the BRAF V600E mutation is the most frequent among patients. Vemurafenib was the first specific inhibitor for this mutation approved by Food and Drug Administration. Therefore around six months later there is relapse and overcoming it is still a challenge. Curcumin is a turmeric and it has been deeply researched because of its anti-inflammatory and antitumoral effects. However the low stability limits its use, therefore, encouraged the investigation of analogues capable to be efficient and commercialized. DM-1 is a monoketone curcumin analog and it showed antitumoral effects in vitro and in vivo in previous studies The aim of this project was to evaluate the cytotoxical effects of DM-1 for vemurafenib responsive (naïve) and resistant melanoma cells, as well as metalloproteinases modulation. Melanoma cells were treated with different DM-1 concentrations, and this compound was cytotoxic for responsive and resistant cell lines, besides inducing G1/G0 cell cycle arrest and reducing the number of colonies, nonetheless it was not selective in assays performed with melanocytes and fibroblasts. Subtoxic treatment of those cells modulated important MMPs in the cell invasion process. DM-1 reduced metalloproteinases -1, -2 and -9 (MMP-1,-2 and -9) in a quantification assay, and MMP-2 and -9 activities by zymography in a cell-dependent way. Negative modulations of MMP inhibitor TIMP-2 and MMP-14 for SKMEL-28 naïve were associated with MMP-2 and -9 reduced activities, whereas positive modulations for SKMEL-19 naïve were correlated to MMP-2 increase. Furthermore, this compound reduced migration of those cells and endothelial cell tube formation.

Melanoma é o câncer mais agressivo e a mutação BRAF V600E é a mais frequente entre os pacientes. O vemurafenibe foi o primeiro inibidor específico desta mutação aprovado pela Food and Drug Administration. Entretanto, após cerca de seis meses há recidiva e superar os mecanismos de resistência responsáveis por este fenômeno ainda é um desafio. A curcumina é um tumérico com características antitumorais e anti-inflamatórias, entretanto sua baixa biodisponibilidade e estabilidade limitam seu uso e por isso impulsionaram a busca por análogos capazes de serem eficientes e comercializados. O DM-1, é um análogo monocetônico que apresentou efeitos antiumorais in vitro e in vivo em estudos anteriores. O objetivo deste trabalho foi avaliar os efeitos citotóxicos do DM-1 em células de melanoma sensíveis (naive) e resistentes ao vemurafenibe, bem como na modulação de metaloproteinases. As células de melanoma foram tratadas com diferentes concentrações de DM-1, e este composto foi citotóxico para linhagens sensíveis e resistentes ao vemurafenibe, além de induzir parada de ciclo celular em G1/G0 e diminuir o número de colônias, entretanto ele não foi seletivo em ensaios de citotoxicidade realizados com melanócitos e fibroblastos. O tratamento dessas células em doses subtóxicas resultou na modulação de metaloproteinases importantes no processo de invasão celular. O DM-1 reduziu as concentrações das metaloproteinases -1, -2 e -9 (MMP-1, -2 e -9) em um ensaio de quantificação de MMPs e a atividade das MMP-2 e -9 em um ensaio de zimografia de maneira célula dependente. As modulações negativas do inibidor de MMP TIMP-2 e MMP-14 para SKMEL-28 naive foram associadas a diminuição das atividades de MMP-2 e -9, enquanto que as modulações positivas para SKMEL-19 naive foram relacionadas ao aumento de MMP-2. Este composto ainda inibiu a migração das células e a formação de tubos por células endoteliais. / Malignant melanoma is the most aggressive cancer and the BRAF V600E mutation is the most frequent among patients. Vemurafenib was the first specific inhibitor for this mutation approved by Food and Drug Administration. Therefore around six months later there is relapse and overcoming it is still a challenge. Curcumin is a turmeric and it has been deeply researched because of its anti-inflammatory and antitumoral effects. However the low stability limits its use, therefore, encouraged the investigation of analogues capable to be efficient and commercialized. DM-1 is a monoketone curcumin analog and it showed antitumoral effects in vitro and in vivo in previous studies The aim of this project was to evaluate the cytotoxical effects of DM-1 for vemurafenib responsive (naïve) and resistant melanoma cells, as well as metalloproteinases modulation. Melanoma cells were treated with different DM-1 concentrations, and this compound was cytotoxic for responsive and resistant cell lines, besides inducing G1/G0 cell cycle arrest and reducing the number of colonies, nonetheless it was not selective in assays performed with melanocytes and fibroblasts. Subtoxic treatment of those cells modulated important MMPs in the cell invasion process. DM-1 reduced metalloproteinases -1, -2 and -9 (MMP-1,-2 and -9) in a quantification assay, and MMP-2 and -9 activities by zymography in a cell-dependent way. Negative modulations of MMP inhibitor TIMP-2 and MMP-14 for SKMEL-28 naïve were associated with MMP-2 and -9 reduced activities, whereas positive modulations for SKMEL-19 naïve were correlated to MMP-2 increase. Furthermore, this compound reduced migration of those cells and endothelial cell tube formation.