Distribution and structural aspects of extrafloral nectaries in leaves of Pyrostegia venusta (Bignoniaceae) / Distribuição e aspectos estruturais de nectários extraflorais em folhas de Pyrostegia venusta (Bignoniaceae)

Pyrostegia venusta (the orange trumpet or commoly called cipó-de-São-João in Brazil), a medicinal plant that grows with other plants, has an ecological importance due to the presence of nectaries on the leaves. The aim of this work was to study structural and histochemical aspects and the distribution of extrafloral nectaries (ENFs) in P. venusta leaves. Young leaves were collected, fixed and processed by usual techniques, and studied under light microscopy and scanning electron microscopy. Analyses showed that the extrafloral nectaries are dispersed throughout the leaf, with concentrations mainly in the basal third section. Nectaries lie in epidermal depressions and can be found in abaxial and adaxial leaf blades. Their morphology may be characterized macroscopically by achlorophyllous halos and microscopically as structures consisting of a short pedicel, oval multicellular head, covered by a thin cuticular layer with a secretory pole. Reducing sugars, neutral polysaccharides, proteins, starch and phenolic compounds were detected in extrafloral nectaries.

Pyrostegia venusta (cipó-de-São-João) é uma planta medicinal que cresce junto a outras plantas e que apresenta também importância ecológica, pela presença de nectários na região dos folíolos. O objetivo deste trabalho foi estudar aspectos estruturais, histoquímicos e da distribuição de nectários extraflorais (NEFs) em folhas de P. venusta. Folhas jovens foram coletadas, fixadas e processadas por técnicas usuais e estudadas sob microscopia de luz e eletrônica de varredura. As análises mostraram que os NEFs estão dispersos por toda a folha, concentrando -se preferencialmente no terço basal. Os nectários estão localizados em depressões epidérmicas e podem ser encontrados nas faces abaxial e adaxial da lâmina foliar. Macroscopicamente, os NEFs podem ser caracterizados como halos aclorofilados e microscopicamente, como estruturas com pedicelo curto, cabeça ovoide pluricelular, recobertos por uma fina camada cuticular e um polo secretor. Nos nectários extraflorais foram detectados açúcares redutores, polissacarídeos neutros, proteínas, amido e compostos fenólicos.

Histochemistry, content and chemical composition of essential oil in different organs of Alpinia zerumbet / Histoquímica, teor e composição química do óleo essencial nos diferentes órgãos de Alpinia zerumbet

Alpinia zerumbet is a medicinal plant from Asian origin used in folk medicine for the treatment of hypertension, which effect is attributed to terpinen-4-ol, the major component of the essential oil. The objective of this work was to identify the essential oil secretory structures in the leaf, flower, root and rhizome of this plant, and analyze the content and the chemical composition of the oil in the different organs of the plant. Sections were subjected to histochemical test with Nadi reagent for in situ localization of secretion. The essential oil extraction was performed by hydrodistillation in a Clevenger apparatus and the compounds were identified in CG-EM/FID. The histochemical test was positive for terpenoids, confirming the presence of essential oil stored in secretory structures named oils cells present in all analyzed organs. The higher essential oil content was found on the leaf (0.30%), while the petal and the rhizome presented content of 0.10% and 0.06%, respectively. It was not possible to determine essential oil content of the root due to the low amount of biomass produced. There were qualitative and quantitative differences in the chemical composition of the essential oil in the different plant organs, but the major constituent in all of them was the terpinen-4-ol, followed by 1,8 cineol in the leaf and by the α-terpineol in the flower and rhizome.

Alpinia zerumbet é uma planta medicinal de origem asiática, utilizada na medicina popular para o tratamento da hipertensão, cujo efeito é atribuído ao constituinte terpinen-4-ol, que está presente majoritariamente no óleo essencial. Objetivou-se com este trabalho identificar as estruturas secretoras de óleo essencial na folha, flor, rizoma e raiz dessa planta e analisar o teor e a composição química do óleo nos diferentes órgãos do vegetal. Para localização in situ da secreção, cortes foram submetidos ao teste histoquímico com reagente de Nadi. A extração do óleo essencial foi realizada por hidrodestilação em aparelho de Clevenger e a identificação dos compostos em CG-EM/FID. O teste histoquímico foi positivo, confirmando a presença de óleo essencial armazenado em estruturas secretoras do tipo células oleíferas em todos os órgãos analisados. O maior teor de óleo essencial foi verificado na folha (0,30%), enquanto a flor e o rizoma apresentaram teor de 0,10% e 0,06%, respectivamente, não sendo possível a determinação na raiz, devido à baixa quantidade de biomassa produzida. Houve diferenças qualitativas e quantitativas na composição química do óleo essencial nos diferentes órgãos da planta, mas o constituinte majoritário em todos eles foi o terpinen-4-ol, acompanhado pelo 1,8 cineol na folha e pelo α-terpineol na flor e rizoma.

Secretory structures of Ipomoea asarifolia: anatomy and histochemistry

Ipomoea asarifolia (Desr.) Roem. & Schult., Convolvulaceae, is a weed that infests agricultural areas and is toxic to cattle. In spite of its toxicity, the leaves of this plant are used in traditional remedies in the state of Bahia, Brazil. The present work describes the leaf anatomy of I. asarifolia and characterizes the exudates of its secretory structures. The leaves have a unistratified epidermis composed of ordinary cells with straight to slightly sinuous anticlinal walls and thin cuticles. Paracytic stomata are found on both surfaces of the leaves at the same level as the ordinary epidermal cells. Trichomes producing polysaccharide secretions occur on the petiole and leaf blade and are considered colleters. The mesophyll is dorsiventral and the vascular bundle of the central vein is bicollateral. Two opposed nectaries occur on the petiole near the leaf blade. Each nectary is composed of a small canal with internal ramifications and numerous secretory trichomes. The laticiferous glands are articulated, not anastomosed, and are composed of large diameter cells with thin cell walls. The secretions of the laticiferous glands are lipidic.

Studies on the Secretory Structure of Hypericum erectum / 中草药

The structures that secrete and store hypericin and volatile oil, the main medicinal com-ponent of Hepericum erectum Thunb. , were studied using Sudan black, 5% NaOH solution and 0.5%methanolic magnesium acetate on semi-thin sections of H. erectum. Results showed that hypericin was pro-duced and stored in the secretory cell nodules, while the volatile oil was produced and stored in its secreto-ry sac and canal. The distribution and denseness of these 3 secretory structures in various organs were de-scribed to provide a scientific basis for the rational utilization of different parts of this medicinal plant.