Contribuição ao conhecimento químico de plantas do nordeste do Brasil: monitorado por ensaios de atividade anticolinesterásica de Kalanchoe brasiliensis Camb.; Senna siamea (Lam.) Irwin & Barneby (Sin. Cassia siamea Lamarck) e Anacardium occidentale L.

Abstract

This work describes a phytochemical study, monitored by essays, for the verification of inhibiting activity of acetylcolinesterase (AChE) of the following plants: Kalanchoe brasiliensis Camb. (courama branca), Senna siamea (Lam.) Irwin & Bameby (Sin. Cassia siamea Lamarck) (cássia do sião) and Anacardiurn occidentale L. (cajueiro). Studies were also carried out to investigate the antioxidant and insecticide activities of these plants. The extracts ethyl acetate (AcOEt) and methanolic (MeOH) from the leaves of Kalanchoe brasiliensis (Crassulaceae) show inhibition of the enzyme AChE at 100%, in the concentration of 2 mg/mL. From the fraction n-hexanic, positive for the inhibition of AChE, nine compounds were identified: two monoterpenes -- neral (18,41%) and geranial (55,25%) — and seven sesquiterpenes -- p-cubebene (7,41%); elemol (8,47%); a-cubebene (0,84%); a-zingiberene (1,12%); cubebol (0,64%); nerolidol (1,14%) and valerianol (0,67%). There were also a mixture of the active flavonoids: 8-metoxiquercetine 3-O-a-Lraminopiranosil-7-O-a.-L-raminopiranoside e 8-metoxicanferol 3-0-raminosídeo-7-0-a-L-raminopiranoside. This extract also supplied the following non-active flavonoids: 8-metoxiquercetine; 3', 4', 5, 7-tetrahidroxi-8- metoxiflavone 3-O-a-L-raminopiranoside e 8-metoxiquercetine 7-O-a-L-raminopiranoside, being all of inedit description in the gener Kalanchoe. From the combination of the fraction dicloromethane and the hexanic extract, the fi-sitosterol stcroi and its glicoside were isolated. Larvae from the mosquito Aedes aegvpti were utilized for the verification of the insecticide activity. The following results were obtained: Extract AcOEt from Kalanchoe brasiliensis (DL50< 250 ppm) and nhexanic extracts (DL50 269.15). The isolated flavonoids from Kalanchoe brasiliensis were tested in the concentration of 50 ppm and did not present insecticide effect The n-hexanic extracts from the leaves, trunk and roots from Senna siamea (Leguminosae) showed positive results in CCD in relation to the inhibition of the enzyme AChE. From the n-hexanic extracts from the trunk and root, the following were isolated: I, 8-dihidroxi-3-metilantraquinone (crisofanol) e o triterpene lupeol. From the ethanolic extract of the root, the biantraquinones 1,1',6,8,8' pentahidroxi-3,3'-dimetyl[2,2'- biantracene]-9,9',10,10'-tetrone (cassiamin A) and 1 ,1 ' ,6 ,6 ' ,8 ,8 ' -hexahidroxi-3 ,3' -dimetyl [2,2 ' -biantracene] - 9,9',10,10' -tetrone (cassiamin B) proved to be non-active compounds. The cashew nut shell liquid (CNSL), Anacardium occidentale (Anacardiaceae), provided the anacardic, monoene and diene acids. During the tests, these acids demonstrated to be active for the inhibition of the AChF in CCD and against the larva from Aedes aegypti, in the concentration of 15 ppm. Antioxidant activities were also observed being CI50 of 0.56 mM with monoene acid and, CI50 of 0.77 mM, with the diene acid. The identification of the structure of the isolated chemical constituents was performed with the aid of spectroscopic analyses, as follows: infrared region spectroscopy, RMN 'H, RMN13C and EM, including bidimensional techniques of type 'H, 'H-COSY and 'H, 13C-COSY (°J, n = 1,2,3), with normal and inverse detections. In addition to the spectroscopic analyses, a comparison study between the data from the tests and literature was carried out.