Estudo fitoquímico de espécies de Sinningia: S. gerdtiana, S. macrostachya, S. mauroana e S. reitzii (Gesneriaceae) e avaliação das atividades antimicrobiana, antioxidante e citotóxica

Abstract

O estudo fitoquímico de Sinningia gerdtiana, S. macrostachya, S. mauroana, e S. reitzii (Gesneriaceae) levou ao isolamento de 37 substâncias, sendo duas antraquinonas, onze naftoquinonas, dois cicloexiletanoides, dois feniletanoides, sete triterpenos, dois esteroides, dois flavonoides, sete glicosídeos fenólicos, um sesquiterpeno, e um benzofurano. As substâncias isoladas foram identificadas como: tectoquinona (SN1), 1,6-diidroxitectoquinona (SN2), 6,7-dimetoxi- -dunniona (SN3), 6-hidroxi-7-metoxi- -dunniona (SN4), 7-hidroxi-6-metoxi- -dunniona (SN5), 5- hidroxi-6,7-dimetoxi- -dunniona (SN6), 5,6-diidroxi-7-metoxi- -dunniona (SN7), 6,8- diidroxi-7-metoxi- -dunniona (SN8), 8-hidroxi-6,7-dimetoxi- -dunniona (SN9), 5,6,7- trimetoxidunniona (SN10), 5,6,7-trimetoxidunniol (SN11), 6,8-diidroxi-7-metoxi-2-Ometildunniol (SN12), 6-hidroxi-7-metoxi-2-O-metildunniol (SN13), halleridona (SN14), jacaranona (SN15), 4-hidroxifenilacetato de metila (SN16), 3-hidroxitirosol (SN17), ácido betulínico (SN18), ácido 3-epi-betulínico (SN19), ácido oleanólico (SN20), ácido ursólico (SN21), ácido pomólico (SN22), ácido maslínico (SN23), hederagenina (SN24), sitosterol (SN25), estigmasterol (SN26), luteolina (SN27), 7- glucoluteolina (SN28), calceolariosídeo A (SN29), allo-calceolariosídeo A (SN30), calceolariosídeo B (SN31), plantainosídeo A (SN32), sanangosídeo (SN33), conandrosídeo (SN34), calceolariosídeo C (SN35), cedrol (SN36), e finalmente, sinningial B (SN37). As naftoquinonas SN3, SN10 e SN11, isoladas de S. mauroana, e SN4 e SN5, isoladas de S. reitzii, são inéditas na literatura. Os extratos em acetato de etila (AcOEt) e etanol (EtOH) de S. mauroana apresentaram atividade antimicrobiana moderada (CIM 250 g mL-1) contra bactérias Gram-positivas. Os extratos em AcOEt e EtOH de S. macrostachya e S. mauroana apresentaram elevada atividade antioxidante pelo método ORAC-FL (3028-8808 mol de trolox equivalente por grama de extrato). As naftoquinonas SN4, SN6-SN8, e SN12 também apresentaram atividade antioxidante (1,39-4,84 de trolox equivalente relativo). Os extratos em diclorometano e acetato de etila de S. macrostachya, bem como o extrato em hexano de S. mauroana apresentaram elevada atividade citotóxica contra a linhagem de células tumorais de próstata (PC-3; CI50 < 0,25 g mL-1). O extrato em hexano de S. mauroana também foi ativo contra a linhagem de célula tumoral de melanoma (SKMEL 103; CI50 = 3,07 g mL-1).

Abstract: The phytochemical study of Sinningia gerdtiana, S. macrostachya, S. mauroana, and S. reitzii (Gesneriaceae) led to the isolation of 37 substances, including two anthraquinones, eleven naphthoquinones, two cyclohexyletanoids, two phenylethanoids, seven triterpenes, two steroids, two flavonoids , seven phenolic glycosides, one sesquiterpene, and one benzofuran. The isolated substances were identified as: tectoquinone (SN1), 1,6-dihydroxytectoquinone (SN2), 6,7-dimethoxy- -dunnione (SN3), 6-hydroxy-7-methoxy- -dunnione (SN4), 7 -hydroxy-6-methoxy- - dunnione (SN5), 5-hydroxy-6,7-dimethoxy- -dunnione (SN6), 5,6-dihydroxy-7- methoxy- -dunnione (SN7), 6,8-dihydroxy-7-methoxy- -dunnione (SN8), 8-hydroxy- 6,7-dimethoxy- -dunnione (SN9), 5,6,7-trimethoxydunnione (SN10), 5,6,7- trimethoxydunniol (SN11), 6,8-dihydroxy-7-methoxy-2-O-methyldunniol (SN12), 6- hydroxy-7-methoxy-2-O-methyldunniol (SN13), halleridone (SN14), jacaranone (SN15), Methyl 4-hydroxyphenylacetate (SN16), 3-hydroxytyrosol (SN17), betulinic acid (SN18), 3-epi-betulinic acid (SN19), oleanolic acid (SN20), ursolic acid (SN21), pomolic acid (SN22), maslinic acid (SN23), hederagenin (SN24), sitosterol (SN25), stigmasterol (SN26), luteolin (SN27), 7-glucoluteolin (SN28), calceolarioside A (SN29), allo-calceolarioside A (SN30), calceolarioside B (SN31), plantainoside A (SN32), sanangoside (SN33), conandroside (SN34), calceolarioside C (SN35), cedrol (SN36), and finally, sinningial B (SN37). Naphthoquinones SN3, SN10 and SN11, isolated from S. mauroana, and SN4 and SN5, isolated from S. reitzii, are new in the literature. The ethyl acetate (AcOEt) and ethanol (EtOH) extracts of S. mauroana showed moderate antimicrobial activity (MIC 250 g mL-1) against Gram-positive bacteria. The EtOAc and EtOH extracts of S. macrostachya and S. mauroana showed high antioxidant activity by the ORAC-FL method (3028-8808 mol of trolox equivalent per gram of extract). Naphthoquinones SN4, SN6-SN8, and SN12 also showed antioxidant activity (1.39-4.84 relative equivalent trolox). The dichloromethane and ethyl acetate extracts of S. macrostachya, as well as the hexane extract of S. mauroana showed high cytotoxic activity against the prostate tumor cell line (PC-3; IC50 < 0.25 g mL-1 ). The hexane extract of S. mauroana was also active against the melanoma tumor cell line (SKMEL 103; IC50 = 3.07 g mL-1).