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

Absolute configuration reassignment of two chromanes from Peperomia obtusifolia (Piperaceae) using VCD and DFT calculations

Previous analysis of the ECD spectra of two prenylated benzopyrans isolated from Peperomia obtusifolia, by means of the helicity rule for the chromane chromophore, resulted in the incorrect assignment of their absolute configuration, (5) instead of (R) for a deduced P-helicity of the chromane ring for the (+)-enantiomers. This was discovered by the application of DFT calculations and VCD spectroscopy. Experimental and calculated (B3LYP/6-31G(d)) VCD and IR spectra were compared, and a definitive absolute configuration of (+)-1 and (+)-2 is reassigned directly in solution as (R). The assumption of equatorial positioning of bulky groups, shown here to be invalid for the title molecules, is the underlying cause of the previous incorrect assignment of absolute configuration. Moreover, TDDFT (B3LYP/6-311++G(2d,2p)//B3LYP/6-31G(d)) calculations of ECD spectra have shown that both P- and M-helicity of the heterocyclic ring, for a given absolute configuration, lead to the same sign for the (1)L(b) ECD band, thus bringing into question the validity of the empirical ECD helicity rule for chromane molecules. (C) 2010 Elsevier Ltd. All rights reserved.

Composition and antifungal activity against Candida albicans, Candida parapsilosis, Candida krusei and Cryptococcus neoformans of essential oils from leaves of Piper and Peperomia species

This study was addressed to investigate the composition and antifungal activity of essential oils from leaves of Piperaceae species (Piper aduncum, Piper amalago, Piper cernuum, Piper diospyrifolium, Piper crassinervium, Piper gaudichaudianum, Piper solmsianum, Piper regnellii, Piper tuberculatum, Piper umbelata and Peperomia obtusifolia) against Candida albicans, C. parapsilosis, C. krusei and Cryptococcus neoformans. The essential oils from P. aduncum, P. gaudichaudianum and P. solmsianum showed the highest antifungal activity against Cryptococcus neoformans with the MIC of 62.5, 62.5 and 3.9 mg.mL-1, respectively. The oil from P. gaudichaudianum showed activity against C. krusei with MIC of 31.25 mg.mL-1.

Resolution and Absolute Configuration Assignment of a Natural Racemic Chromane from Peperomia obtusifolia (Piperaceae)

The resolution of the natural racemic chromane 3,4-dihydro-5-hydroxy-2,7-dimethyl-8-(3 ``-methyl-2 ``-butenyl)-2-(4`-methyl-1`,3`-pentadienyl)-2H-1-benzopyran-6-carboxylic acid (1) isolated from the leaves of Peperomia obtusifolia has been accomplished using stereoselective HPLC. The absolute coil figuration of the resolved enantiomers was determined by the analysis of optical rotations and CD spectra. The finding of a racemic mixture instead of an enantiomerically pure metabolite raises questions about the final steps in the biosynthesis of this class of natural products, suggesting that the intramolecular chromane ring formation step may not be enzymatically controlled at all in P. obtusifolia. Chirality 21:799-801, 2009. (C) 2008 Wiley-Liss, Inc.

In vitro Trypanocidal Activity of Phenolic Derivatives from Peperomia obtusifolia

The trypanocidal activity of crude extracts and fractions from the leaves and stems of Peperomia obtusifolia (Piperaceae) was evaluated in vitro against the epimastigote forms of Trypanosoma cruzi. Bioactivity-guided fractionation of the most active extracts afforded seven known compounds, including three chromanes, two furofuran lignans and two flavone C-diglycosides. The most active compounds were the chromanes peperobtusin A and 3,4-dihydro-5-hydroxy-2,7-dimethyl-8-(2 ``-methyl-2 ``-butenyl)-2-(4`-methyl-1`,3`-pentadienyl)-2H-1-benzopyran-6-carboxylic acid, with IC(50) values of 3.1 mu M (almost three times more active than the positive control benznidazole, IC(50) 10.4 mu M) and 27.0 mu M, respectively. Cytotoxicity assays using peritoneal murine macrophages indicated that the chromanes were not toxic at the level of the IC(50) for trypanocidal activity. This is the first report on the trypanocidal activity besides unspecific cytotoxicity of chromanes from Peperomia species. Additionally it represents the first time isolation of 3,4-dihydro5-hydroxy-2,7-dimethyl-8-(2 ``-methyl-2 ``-butenyl)-2-(4`-methyl-1`,3`-pentadienyl)-2H-1-benzopyran-6-carboxylic acid from P. obtusifolia.

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.

Trypanocidal tetrahydrofuran lignans from Peperomia blanda

Five tetrahydrofuran lignans and two known flavones were isolated from the aerial parts of Peperomia blanda. The structures of the isolated lignans were elucidated by interpretation of their spectroscopic data, including by gHMQC and gHMBC. The relative and absolute configurations of the isolates were determined from NOESY interactions and optical properties, respectively. Four of the lignans were diastercomeric whilst one was of mixed biosynthetic origin. All but one of the lignans exhibited high in vitro trypanocidal activity when assayed against epimastigotes of Trypanosoma cruzi strain Y. (C) 2007 Elsevier Ltd. 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.

Trypanocidal tetrahydrofuran lignans from Peperomia blanda

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

In vitro Trypanocidal Activity of Phenolic Derivatives from Peperomia obtusifolia

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

Further monoterpene chromane esters from Peperomia obtusifolia: VCD determination of the absolute configuration of a new diastereomeric mixture

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

Isoswertisin flavones and other constituents from Peperomia obtusifolia

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

Structure and absolute configuration of a secolignan from Peperomia blanda

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

Absolute configuration reassignment of two chromanes from Peperomia obtusifolia (Piperaceae) using VCD and DFT calculations

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