INTRODUCTION: The genus Psychotria is the largest in Rubiaceae family and it is very promising in biosynthesis of bioactive alkaloids that grant anti-inflammatory, antitumor and antimicrobial activities. The specie Psychotria schelechtendaliana has been studied at our search group and the alkaloidal fractions has stimulated the inhibition of proliferation lung and leukemia tumor cell line. Thus, this work presents the isolation and elucidation of alkaloids in P. schelechtendaliana1.

METODOLOGY: The aerial parts of P. schelechtendaliana were collected, dried, crushed and totalized 273 g what enabled the attainment of crude extract (PSCE – 44.52 g) by MeOH exhaustive maceration. A part of PSCE (19.60 g) was submitted an acid-base extraction with HCl 10% and NH4OH, and extractor solvents were CHCl3, CHCl3:MeOH (1:1) and AcOEt. This process provided the acid-chloroform (FCHCl3H – 6.02 g), base-chloroform (FCHCl3OH – 88.4 mg), chloromethanolic (FCHCl3:MeOH - 346.9 mg), ethyl acetate (FAcOEtOH – 11.6 mg) and aqueous (FH2O – 10.0 g) fractions. The FCHCl3OH fraction was submitted to a preparative thin layer chromatography (PTLC) and was obtained the alkaloid PS-1 (3.0 mg). The aqueous fraction was partitioned with AcOEt (FH2O-AcOEt – 95.0 mg) and n-BuOH (FH2O-BuOH – 275.7 mg), and from butanolic fraction the alkaloid PS-2 (6.0 mg) was isolated with Sephadex LH-20 filtration.

DISCUSSION: The alkaloid PS-1 was encoded as indolic alkaloid 1-methyl-β-carbolinic (harmane), because the six aromatic hydrogens in δH 8.23 (d; 8.0 Hz; H-9), 8.20 (d; 5.0 Hz; H-5), 8.12 (d; 5.0 Hz; H-6), 7.32 (ddd; 2.0 e 6.0 e 8.0 Hz; H-10), 7.60-7.66 (m; H-11 e H-12e) and the singlet in δH 2.90 (s) attributed for methyl group in the structure. Through HSQC and HMBC correlation map was possible to identify what hydrogen is bounded in each carbon, making possible to close structure. Among the main proven pharmacological activities for this alkaloid detaching: antimicrobial, antifungal, intestinal and hepatic monoamine oxidase isoenzyme inhibitor2,3. The alkaloid PS-3 was determined as the monoterpene indolic alkaloid strictosidine acid. The 1H NMR spectra presented typical signals of tetrahydro-β-carboline system with two dublets in δH 7.35 (d; 7.99 Hz) e 7.21 (d; J = 8.35 Hz) and two triplets of dublets in δH 6.93 (td; 7.63 e 0.64 Hz; H-10) e 7.03 (td; 7.72 e 1.02 Hz; H-11) allocated to aromatics hydrogens, as well as methylene hydrogens in δH 6.62 (m; H-5) e 2.97 (m; H-6). The dublet in δH 4.72 (d; 7.92 Hz) was determined to anomeric hydrogen H-1’ of D-β-glucose and indicates that hydrogen is in axial position, and the singlet in δH 7.52 (s; H-17) corresponding a typical signal of carbomethoxi-α,β-unsaturated group. Was also observed the signals in δH 5.21 (d; 16.85 Hz; H-18b), 5.11 (d; 10.4 Hz; H-18a) e 5.75 (ddd; 10.4 Hz, 7.60 Hz e 13.3 Hz; H- 19) which corresponding to olefinic hydrogens of secologanin unit. The 13C NMR spectra enabled to attribute the chemical displacement of carbons and it was compared with literature4.

CONCLUSIONS: With the phytochemical study of aerial parts of P. schelechtendaliana was possible to isolate the indolic alkaloid harmane and the monoterpene indolic alkaloid strictosidine acid from the alkaloidal fractions of the specie. These alkaloids and other compounds can be the ones responsible of the biological activities in these fractions that should be studied to isolate more secondary metabolites.

REFERENCES: 1 CALIXTO, N. O. et al. The genus Psychotria: phytochemistry, chemotaxonomy, ethnopharmacology and biological properties. JBCS, v. 27, n. 8, p. 1355-1378, 2016. 2 SEKI, H. et al. The 1H- and 13C- nuclear magnetic resonance spectra of Harman. Reinvestigation of the assigments by 1D and 2D methods. Chem. Pharm. Bulletin, v. 41, n. 6, p. 1169-1172, 1993. 3 BOEIRA, J. M. et al. Genotoxic Effects of the Alkaloids Harman and Harmine Assessed by Comet Assay and Chromosome Aberration Test in Mammalian Cells in Vitro, Pharmacol. Toxicol. 89 (6), 287-294. 12. 2001. 4 SIMÕES-PIRES, C. A. et al. Indole monoterpenes with antichemotactic activity from Psychotria myriantha: Chemotaxonomic significance. Nat. Prod. Com., v. 1, n. 12, p 1101-1106, 2006.