Solanum campaniforme: chemical constituents, fragmentation study and dereplication by electrospray mass spectrometry (ESI-MS/MS)

This work describes the phytochemical investigation of Solanum campaniforme (Solanaceae), aiming the isolation and structural elucidation of new bioactive chemical constituents, as well as the study of their fragmentation pattern under electrospray ionization tandem mass spectrometry (ESI-MS/MS) of the isolated alkaloids. The chemical investigation performed with the ethanol extract from leaves of this species by chromatographic methods, including HPLC (reverse phase), resulted in the isolation and identification of nineteen compounds, being four of them phenol derivatives: caffeic acid (SC-1), caffeic acid ethyl ester (SC-2), kaempferol-3-rutinoside (SC-3) and tyramine (SC-4), and fifteen steroidal alkaloids: 22,23-epoxy-solanida-1,4,9-trien-3-one (SC-5), 22,23-epoxy-solanida-1,4-dien-3-one, (SC-6), 3,9-dihydroxy-22,23-epoxy-9(10)-seco-solanida-1,3,5(10)-triene (SC-7), 12-acetoxyl-(25S)-22N-spirosol-4-en-3-one (SC-8), (25S)-22N-spirosol-1,4-dien-3-one (SC-9), (25S)-22-N-spirosol-4-en-3-one (SC-10), 22,23-epoxy-solanida-1,4-dien-3-one (SC-11), 22,23-epoxy-10-epi-solanida-1,4,9-trien-3-one (SC-12), 12-hydroxy-(25S)-22N-spirosol-4-en-3-one (SC-13), 22,23-epoxy-solanida-4-en-3-one (SC-14) and 22,23-epoxy-solanida-4-en-3-one (SC-15), (E)-N-[8’(4-hydroxyphenyl)ethyl]-22,23-epoxy-solanida-1,4,9-trien-3-imine (SC-16), (E)-N-[8’(4-hydroxyphenyl)ethyl]-22,23-epoxy-solanida-1,4-dien-3-imine (SC-17), (Z)-N-[8’(4-hydroxyphenyl)ethyl]-22,23-epoxy-solanida-1,4,9-trien-3-imine (SC-18) and (Z)-N-[8’(4-hydroxyphenyl)ethyl]-22,23-epoxy-solanida-1,4-dien-3-imine (SC-19). Except the alkaloids SC-9 and SC-10, which are being reported as natural products for the first time, all others are unknowns. The structure of all isolated compounds were elucidated by spectral) methods (IR, HR-ESI-MS, 1H and 13C NMR 1D and 2D and by comparison with literature data. The fragmentation pattern of the alkaloids was established based on MS/MS experiments and the data were used for the dereplication these compounds present in the crude ethanol extract from leaves of S. campaniforme. The cytotoxic potencial of the main alkaloids (SC-5 and SC-7) was evaluated against the human tumor cell lines (HCT8, MDA-MB-435, HL6 and SF295), however, no one showed any activity. The antiophidic properties of the same compounds were also investigated against Bothrops pauloensis venom, showing anti-myotoxic, anti-hemorrhagic and anti-necrosis effects. In addition, was evaluated the effect of tyramine on the metabolism of animals with dyslipidemia and obesity, which exhibited therapeutic effect associated to reduction of the cholesterol levelsEste trabalho descreve o estudo fitoquímico de Solanum campaniforme (Solanaceae), visando o isolamento e elucidação estrutural de novos constituintes químicos bioativos, bem como o estudo do padrão de fragmentação por espectrometria de massas seqüencial com ionização por electrospray (IES-EM/EM) dos alcalóides obtidos. A investigação química realizada com o extrato etanólico das folhas da referida espécie, através de métodos cromatográficos, incluindo CLAE (fase reversa), resultou no isolamento e identificação de dezenove substâncias, sendo quatro derivados fenólicos: ácido caféico (SC-1), éster etílico do ácido caféico (SC-2), canferol-3-O-rutinosídeo (SC-3) e tiramina (SC-4), e quinze alcalóides esteroidais: 22,23-epoxi-solanida-1,4,9-trien-3-ona (SC-5), 22,23-epoxi-solanida-1,4-dien-3-ona (SC-6), 3,9-dihidroxi-22,23-epoxi-9,10-seco-solanida-1,3,5(10)-trieno (SC-7), 12-acetiloxi-(25S)-22N-espirosol-4-en-3-ona (SC-8), (25S)-2N-espirosol-1,4-dien-3-ona (SC-9), (25S)-22N-espirosol-4-en-3-ona (SC-10), 22,23-epoxi-solanida-1,4-dien-3-ona (SC-11), 22,23-epoxi-10-epi-solanida-1,4,9-trien-3-ona (SC-12), 12-hidroxi-(25S)-22N-espirosol-4-en-3-ona (SC-13), 22,23-epoxi-solanida-4-en-3-ona (SC-14) e 22,23-epoxi-solanida-4-en-3-ona (SC-15), (E)-N-[8’(4-hidroxifenil)etil]-22,23-epoxi-solanida-1,4,9-trien-3-imina (SC-16), (E)-N-[8’(4-hidroxifenil)etil]-22,23-epoxi-solanida-1,4-dien-3-imina (SC-17), (Z)-N-[8’(4-hidroxifenil)etil]-22,23-epoxi-solanida-1,4,9-trien-3-imina (SC-18) e (Z)-N-[8’(4-hidroxifenil)etil]-22,23-epoxi-solanida-1,4-dien-3-imina (SC-19). Com exceção dos alcalóides SC-9 e SC-10, os quais estão sendo relatados como produtos naturais pela primeira vez, todos os demais são inéditos. As substâncias isoladas tiveram suas estruturas elucidadas por métodos espectrométricos (IV, EM e RMN 1H e 13C 1D e 2D), além de comparação com dados da literatura. O padrão de fragmentação dos alcalóides foi estabelecido com base nos experimentos EM/EM e os dados obtidos foram usados na análise de desreplicação destes compostos no extrato etanólico bruto das folhas da espécie em estudo. O potencial citotóxico dos alcalóides majoritários (SC-5 a SC-7) foi avaliado frente às linhagens de células tumorais humanas: cólon (HCT8), mama (MDA-MB-435), leucemia (HL60) e cérebro (SF295), porém mostraram-se inativos. Estes compostos também foram investigados quanto as suas propriedades antiofídicas frente ao veneno de Bothrops pauloensis, mostrando significativos efeitos anti-miotóxico, anti-hemorrágico e anti-necrosante. Além disso, foi avaliado o efeito da tiramina sobre o metabolismo de animais com dislipidemia e obesidade, a qual apresentou efeito terapêutico relacionado à redução dos níveis de colesterol