VCD to determine absolute configuration of natural product molecules: secolignans from Peperomia blanda

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

VCD to determine absolute configuration of natural product molecules: secolignans from Peperomia blanda

The absolute configuration and solution-state conformers of three peperomin-type secolignans isolated from Peperomia blanda (Piperaceae) are unambiguously determined by using vibrational circular dichroism (VCD) spectroscopy associated with density functional theory (DFT) calculations. Advantages of VCD over the electronic form of CD for the analysis of diastereomers are also discussed. This work extends our growing knowledge about secondary metabolites within the Piperaceae family species while providing a definitive and straightforward method to assess the absolute stereochemistry of secolignans.

Bioactive lignans from Peperomia heyneana

Four new compounds, including three secolignans (1-3) and one tetrahydrofuran lignan (4), were isolated from the petroleum ether and EtOAc fractions of Peperomia heyneana. These compounds were accompanied by eight known secolignans, one known tetrahydrofu

C-glycosyl flavones from Peperomia blanda

The methanol extract from aerial parts of the Peperomia blanda (Piperaceae) yielded two C-glycosyl-flavones. Their structures were elucidated on the basis of extensive spectroscopic analysis, including 1D and 2D NMR, chemical transformation and comparison with the related known compounds. The structure of the new flavonoids were established as 4`-methoxy-vitexin 7-O-beta-D-xylopyranoside (1) (7-O-beta-D-xylopyranosyl-8-C-beta-D-glucopyranosyl-4`-methoxy-apigenin) and vicenin-2 (2). The antioxidant activity of both compounds was investigated using the DPPH assay. Both compounds showed only modest activity, with IC50 values of 357.2 mu M for 1, and 90.5 mu M for 2. (C) 2008 Elsevier B.V. All rights reserved.

Isoswertisin flavones and other constituents from Peperomia obtusifolia

A phytochemical investigation of the leaves and stems of Peperomia obtusifolia (Piperaceae) yielded a new flavone C-diglycoside isoswertisin-4`-methyl-ether-2 ``alpha-L-rhamnoside (1), along with four known compounds: isoswertisin-2 ``alpha-L-rhamnoside (2), (+)-diayangambin (3), 2-episesalatin (4) and corchoionoside C (5). The structures of the two flavone C-diglycosides (1, 2) were elucidated on the basis of 1D and 2D NMR spectroscopy and MS spectrometric data. These flavones were evaluated by bioautographic assay against Cladosporium cladosporioides and C. sphaerospermum and showed weak antifungal activity.

Estudo metabolômico e proteômico em Peperomia blanda (Piperaceae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo das lignanas de Peperomia blanda (Piperaceae): abordagem de aspectos estruturais, metabólitos e biossintéticos

Pós-graduação em Química - IQ