ABSTRACT
Many species of Myrtaceae, including Plinia edulis (Vell.) Sobral (cambucá), have pharmacological properties and are used as hypoglycemiants and therapeutic agents against stomach problems and throat infections. Samples were collected from Tijuca Forest in Rio de Janeiro, and the morpho-anatomical data were compared with other specimens obtained from Trindade, Paraty, found in the literature. Variations in leaf anatomy were observed, and the possible causes for these effects are discussed. The plant material collected from Tijuca Forest was analyzed using scanning electron and optical microscopy. Histochemical tests were applied to identify starch, lipids, phenolic compounds and lignin. The epidermal cells exhibit straight or slightly sinuous anticlinal walls covered by a smooth cuticle with granules of wax. Simple trichomes are restricted to the midrib region, and paracytic stomata are only observed on the abaxial leaf surface. The mesophyll is dorsiventral, with conspicuous intercellular spaces in the spongy parenchyma. Intercalated columns of crystalliferous cells and subepidermal secretory cavities are observed in the single layer of palisade parenchyma. The samples obtained from Trindade, Paraty, show larger leaves, anomocytic stomata and trichomes scattered throughout the leaf surface. This plasticity might reflect leaf adaptations to environmental factors or different stages of leaf development.
ABSTRACT
Plinia edulis (Myrtaceae), espécie arbórea popularmente conhecida como cambucá, é nativa da Mata Atlântica brasileira. Apesar do emprego na medicina tradicional em diversas moléstias, incluindo distúrbios gástricos, não existem estudos relacionando as atividades biológicas e os constituintes químicos da espécie. Esta tese relata a avaliação da gastroproteção, da atividade antioxidante, da citotoxicidade e da mutagenicidade do extrato etanol/água de folhas de P. edulis e das frações. Com o objetivo de correlacionar os metabólitos secundários com a eficácia da droga vegetal na medicina tradicional, o extrato foi submetido à partição e posterior fracionamento cromatográfico. O extrato apresentou atividade gastroprotetora significativa em modelo de indução de úlceras por etanol acidificado em ratos em doses de 100, 200 e 400 mg/kg via oral, sendo mais ativo que o fármaco de referência lansoprazol. Entre as frações, a hexânica (100 mg/kg p.o.) foi a mais eficaz, mas apresentou menor atividade do que o extrato bruto. A gastroproteção do ácido ursólico também foi avaliada, mas embora outros triterpenos sejam conhecidos como gastroprotetores, o ácido ursólico (50 mg/kg p.o.) reduziu a área lesionada, mas não apresentou atividade significativa no modelo empregado. O extrato não evidenciou mutagenicidade na concentração de 20 mg/placa no Ensaio de Ames e apresentou atividade antioxidante pronunciada, com CE50 de 5,75 µg/mL no ensaio com DPPH e valor de ORAC de 3.948 µmol de Trolox/g de extrato. O extrato e as frações foram avaliados quanto à citotoxicidade em linhagens de células tumorais humanas de UACC62 (melanoma), MCF-7 (mama), NCI 460 (pulmão), OVCAR03 (ovário), PC-03 (próstata), HT-29 (cólon), 786-0 (rins), NCI-ADR (mama com fenótipo de resistência a múltiplos fármacos) e linhagem de células normais de ovário de hamster chinês (CHO) in vitro. O extrato e as frações apresentaram citotoxicidade seletiva dose-dependente em células cancerígenas e atividade proliferativa em células normais. A partir das frações de hexano e acetato de etila foram identificados ß-amirina, lupeol, ß-sitosterol, ácido oleanólico, ácido ursólico, ácido maslínico, ácido corosólico, galato de etila, ácido gálico, quercitrina, miricitrina e quercetina por meio de análises espectrométricas. Estes resultados dão suporte à utilização popular desta espécie e estão provavelmente associados à presença dos flavonóides e triterpenos identificados no extrato
Plinia edulis (Myrtaceae), an arboreous species popularly known as cambucá, is native in Brazilian Atlantic Rain Forest. Despite its traditional uses in many diseases, which include gastric disorders, no reports are available on the relationship between the biological activities of its extract and its chemical constituents. This thesis reports the evaluations of the the aqueous ethanol extract of leaves of P. edulis and its fractions on gastroprotective effect, antioxidant capacity, cytotoxicity and mutagenicity of. In order to correlate the secondary metabolites and the efficacy of the crude drug in traditional medicine, the extract was submitted to solvent partition followed by chromatographic fractionation. The extract exhibited significant gastroprotective effect on HCl/ethanol-induced ulcers in rats at doses of 100, 200 and 400 mg/kg p.o., even more active than the reference drug lansoprazole. Among the fractions, the hexane fraction (100 mg/kg p.o.) was the most effective, but showed lower activity than the crude extract. In addition, the gastroprotective effect of ursolic acid was evaluated. Although others triterpenes are well known as gastroprotective agents, ursolic acid (50 mg/kg p.o.) reduced the lesion area, but did not show significant activity on this model. The extract did not show mutagenicity at the concentration of 20 mg/plate in the Ames test and exhibited high antioxidant activity, with EC50 of 5.75 µg/mL on the DPPH assay and ORAC value of 3948 µmol Trolox/g of extract. The extract and its fractions were evaluated for cytotoxic activity against human tumour cell lines as UACC62 (melanoma), MCF-7 (breast), NCI 460 (lung, non-small cells), OVCAR03 (ovarian), PC-03 (prostate), HT-29 (colon), 786-0 (renal), NCI-ADR (breast expressing phenotype multiple drugs resistance) and CHO (Chinese Hamster Ovary) normal cell line in vitro. The extract and its fractions showed selectively dose-dependent cytotoxicity against cancer cells and proliferative activity in normal cells. The hexane and ethyl acetate fractions yielded ß-amyrin, lupeol, ß-sitosterol, oleanolic acid, ursolic acid, maslinic acid, corosolic acid, ethyl gallate, gallic acid, quercitrin, myricitrin and quercetin, which were identified based on spectrometric analyses. These results provide scientific support to the traditional use of this species, which are probably associated with the flavonoids and triterpenoids identified in the extract