Contribuição ao conhecimento químico de plantas medicinais do gênero Plectranthus: Plectranthus amboinicus Lour (Spreng); Plectranthus barbatus Andr.; Plectranthus grandis Cramer (Willense) e Plectranthus omatus Codd

Abstract

This work describes the chemical study of the four species of Plectranthus cultivated in the Medicinal Plants Garden Francisco José of Abreu Matos of the Federal University of Ceará - Plectranthus amboinicus (Lour) Spreng, Plectranthus barbatus Andr.; Plectranthus grandis Cramer (Willense) and Plectranthus omatus Codd.. These species are used as medicinal plants by people in Ceará, in Brazil Northeast under the names malvarigo, malva santa, boldo gambá and boldo grande," respectively. The bibliographic search in Chemical Abstract (1907-2003) refer the presence of several diterpenoids compounds with pharmacological properties. In the study the ethanolic extract of the leaves of P. grandis yield by chrmatographic analysis four abietane diterpenes: barbatusin, 318-hydroxy-3- deoxybarbatusin, cyclobutatusin and 7p-acetil-12-desacetoxicyclobutatusin these being reported for the first time in the literature. It was identified also phytoesteroid p-sitosterol and stigmasterol a mixture, and a mixture with of triterpenes with ursan and oleanan series identified as a - and 16 - amyrin. Chromatographic analysis of the ethanolic extract of P.grandis stems, allowed the isolation of three diterpenoids knew as ferruginol, abietatriene and acetilferruginol obtained from acetilated fraction. The chromatographic study the ethanolic extract of P. omatus leaves, using silica gel and alumina columns, allowed to obtain a flavone knew as cirsimaritin. It was possible also to obtain three diterpenes, reported for the first time in the literature, for which it was proposed the names ornantin A, ornantin B and ornantin C, besides barbatusin. The presence of barbatusin in the tree species P. barbatus, P. grandis and P. ornatus characterize this diterpene as its a marker chemical. The chemical composition of the essential oil of the four species of Plectranthus was studied during a period of one year, variation was also obtained for the oil of Plectranthus species during the day time. The oil were obtained by steam distilation and chemical composition of the essential oils were analyzed by GC/MS, allowing the identification of the majority of the components of each species: For: P. barbatus - a-pinene, p-myrcene, (Z)-p-ocimene; transcaryophyllene; germacrene D and; eremophyllene. For: P. amboinicus p-cymene; /3-phellandrene thymol; carvacrol; trans-caryophyllene; (E)-a- / bergamotene; For: P. grandis - a-copaene; trans-caryophyllene; germacrene D; zingiberene.;. For: P. omatus - 1,4-terpineol; thymol; carvacrol; transcaryophyllene; germacrene D and caryophyllene oxide. The structural identification was accomplished by spectrometric analysis such as infrared, mass espectroscopy, NMR 1H and 130, including techniques type HETCOR, COLOC, HMQC and HMBC .