Hancornia speciosa Gomes (Apocynaceae) as a potential anti-diabetic drug.

ETHNOPHARMACOLOGICAL RELEVANCE: The leaves of Hancornia speciosa Gomes are traditionally used to treat diabetes in Brazil. The aim of the study is to evaluate the potential anti-diabetic effect of Hancornia speciosa extract and derived fractions. MATERIALS AND METHODS: The ethanolic extract from Hancornia speciosa leaves and chromatographic fractions thereof were evaluated on α-glucosidase assay, on hyperglycemic effect and glucose uptake. The chemical composition of the extract and its most active fraction was investigated by ESI-LC-MS. RESULTS: The ethanolic extract and derived fractions inhibited α-glucosidase in vitro. However, only the crude extract and the dichloromethane fraction inhibited the hyperglycemic effect induced by starch or glucose. Both the extract and dichloromethane fraction were also able to increase glucose uptake in adipocytes. Bornesitol, quinic acid, and chorogenic acid were identified in the extract, along with flavonoid glycosides, whereas the dichloromethane fraction is majorly composed by esters of lupeol and/or α/ß-amirin. CONCLUSIONS: Hancornia speciosa has a potential anti-diabetic effect through a mechanism dependent on inhibition of α-glucosidase and increase on glucose uptake. These results give support to the use on traditional medicine of this medicinal plant.

Seasonal variation on the contents of coumarin and kaurane-type diterpenes in Mikania laevigata and M. glomerata leaves under different shade levels.

Coumarin (1) and kaurane-type diterpenes are considered the bioactive constituents of Mikania glomerata and M. laevigata, used in Brazil to treat respiratory affective disorders. The seasonal variation of 1, ortho-coumaric acid (2), benzoylgrandifloric acid (3), cinnamoylgrandifloric acid (4), and kaurenoic acid (5) in leaves of both species, cultivated in full sunlight and under shade levels of 40 and 80%, was quantified by HPLC. Compound 2 was detected solely in M. laevigata in concentrations below the limit of quantification. Coumarin was not found in M. glomerata, whereas its concentration reached 0.94±0.24% (w/w) in M. laevigata farmed in summer under 80% shading. Both Mikania species produced higher amounts of kaurane diterpenes when cultivated in plenty of sunlight. Hence, maximum contents of 1 are reached in M. laevigata cultivated under high shading, but with reduced concentrations of 3-5. Conversely, M. glomerata should be cultivated under full sunlight and harvested in winter for highest concentrations of kaurane-type diterpenes.