Three new dibenzoylmethane derivatives, (E)-3,4-methylenedioxy-2'-methoxy-2'',2''-dimethylpyrano-(5'',6'':3',4')-7-methoxychalcone, 2'-hydroxy-5'(3'''',3''''-dimethylallyl)-8-(α,α-dimethylallyl)-furano-(4'',5'':3'4')-dibenzoylmethane and 2'-O-(3'',3''-dimethylallyl)-8-(α,α-dimethylallyl)-furano-(4'',5'':3'4')-dibenzoylmethane, were isolated from a dichloromethane extract from the root bark of Muellera filipes (Benth.) M.J. Silva & A.M.G. Azevedo, along with two dibenzoylmethane derivatives, 2'-methoxy-8-(α,α-dimethylallyl)-furano-(4'',5'':3',4')-dibenzoylmethane and 2'-hydroxy-8-(α,α-dimethylallyl)-2",2"-dimethylpyrano-(5",6":3',4')-dibenzoylmethane; one flavanone, isolonchocarpin and one flavone, pongaglabrone, which had been previously isolated from other sources. The molecular structures of the new dibenzoylmethane derivatives were determined by analysis of their spectral data (1H and 13C nuclear magnetic resonance (NMR), 2D-NMR, NOE (nuclear Overhauser effect) and HRMS (high resolution mass spectrometry). The known compounds were identified using 1D experiments and comparison with spectral data from the literature. 2'-O-(3'',3''-Dimethylallyl)-8-(α,α-dimethylallyl)-furano-(4'',5'':3'4')-dibenzoylmethane displayed strong activity against the human cancer cell line OVCAR-3 (ovarian), and 2'-methoxy-8-(α,α-dimethylallyl)-furano-(4'',5'':3',4')-dibenzoylmethane showed high selectivity for cell lines NCI-H460 (lung) and UACC-62 (melanoma).

A investigação fitoquímica das folhas de Guatteria friesiana (Annonaceae) levou à obtenção de três novos alcaloides isoquinolínicos, 13-hidroxi-discretinina, 6,6a-desidroguateriopsiscina e 9-desidroxi-1-metoxi-diidroguattouregidina, juntamente com oito alcaloides conhecidos, 13-hidroxi-2,3,9,10-tetrametoxiprotoberberina, guateriopsiscina, lisicamina, liriodenina, aterospermidina, lanuginosina, 7,8-diidro-8-hidroxipalmatina e palmatina. 13-Hidroxi-2,3,9,10-tetrametoxiprotoberberina, obtido somente através de síntese, é relatada pela primeira vez como produto natural. As estruturas dos alcaloides isolados foram elucidadas por extensivas análises de ressonância magnética nuclear (RMN 1D e 2D), espectrometria de massas (MS) e comparação com os dados descritos na literatura. A atividade citotóxica in vitro dos alcaloides majoritários foi avaliada frente a linhagens de células tumorais e não tumorais. Considerando a atividade média, de acordo com os critérios do National Cancer Institute (NCI/EUA), todos os alcaloides avaliados foram inativos. Entretanto, o alcaloide palmatina apresentou efeito citostático para as linhagens MCF-7 (mama) e U251 (glioma) com valores de GI50 abaixo de 20,0 µmol L-1 (10,5 e 16,2 µmol L-1, respectivamente), sugerindo uma ação citotóxica seletiva.

Phytochemical investigation of the leaves of Guatteria friesiana (Annonaceae) afforded three new isoquinoline alkaloids, 13-hydroxy-discretinine, 6,6a-dehydroguatteriopsiscine and 9-dehydroxy-1-methoxy-dihydroguattouregidine. Eight known alkaloids were also isolated, 13-hydroxy-2,3,9,10-tetramethoxyprotoberberine, guatteriopsiscine, lysicamine, liriodenine, atherospermidine, lanuginosine, 7,8-dihydro-8-hydroxypalmatine and palmatine. 13-Hydroxy-2,3,9,10-tetramethoxyprotoberberine was only obtained by synthesis and is being reported as a natural product for the first time. The structures of the isolated alkaloids were established by extensive analysis of 1D and 2D nuclear magnetic resonance (NMR) and mass spectrometric (MS) data, as well as by comparison with data reported in the literature. The in vitro cytotoxic activity of the major alkaloids was evaluated against tumor and non-tumor cell lines. All of the alkaloids evaluated were determined to be inactive based on National Cancer Institute (NCI/USA) criteria. However, the alkaloid palmatine exhibited a cytostatic effect on MCF-7 (breast) and U251 (glioma) human tumor cell lines, with GI50 values lower than 20.0 µmol L-1 (10.5 and 16.2 µmol L-1, respectively), suggesting a selective cytotoxic action.