Clécio S. Ramos

Metabolism by grasshoppers of volatile chemical constituents from Mangifera indica and Solanum paniculatum leaves

The chemical volatiles from plant leaves and their biological activities have been extensively studied. However, no studies have addressed plant-chemical volatiles after undergoing the digestive process in host insects. Here we describe for the first time chemical profiles of volatile constituents from Solanum paniculatum and Mangifera indica leaves metabolized by grasshoppers. Both profiles were qualitatively and quantitatively different from the profiles of non-metabolized leaves. The amount of nerolidol, the major constituent of S. paniculatum leaves, decreased and other sesquiterpenes, such as spathulenol, were formed during the digestive process of the grasshopper Chromacris speciosa. In M. indica, the presence of phenylpropanoids was observed (dillapiole, Z-asarone, E-asarone and γ-asarone) in the leaves metabolized by the grasshopper Tropidacris collaris, but these compounds were not found in the non-metabolized leaves.

VOLATILES FROM Solanum paniculatum LEAVES IN RESPONSE TO MECHANICAL DAMAGE

The yield of the essential oil obtained by hydrodistillation of intact S. paniculatum leaves was 0.04%, and that of mechanically damaged leaves was 0.05%. The chemical profile obtained by GC of essential oil from intact leaves indicated a major peak at 31.1 min (54.3%), identified as E-nerolidol based on the GC-MS data. Besides nerolidol, three other compounds were identified: verbenene (1.1%), ionone (4.3%), and tricosane (38.3%), making up 98.0% of the total composition (Table 1). Along with E-nerolidol (27.3%), also found in the intact leaves, seven more compounds were identified in the essential oil from mechanically damage leaves: spathulenol (0.3%), dillapiole (13.1%), epi--muuralol (1.1%), -eudesmol (1.1%), -cadinol (3.1%), oleic acid (2.7%), and hexacosane (14.9%), making up 63.6% of the total composition. An unexpected finding was the presence of dillapiole in high amounts, since production of phenylpropanoids has been identified in plants as an induced resistance mechanism in response to abiotic and biotic stresses [11]. The results of our experiment demonstrate that S. paniculatum leaves respond very clearly to mechanical damage by biosynthesizing several stress-related volatile compounds,

Chemical constituents of essential oils from Solanum torvum leaves, stems, fruits, and roots

Published in Khimiya Prirodnykh Soedinenii, No. 4, July–August, 2012, pp. 622–623. Original article submitted May 12, 2011.

Configuration and stability of naturally occurring all-cis-tetrahydrofuran lignans from Piper solmsianum

The study of variability of the tetrahydrofuran lignan (−)-grandisin in leaves of Piper solmsianum (Piperaceae) revealed two unknown compounds, that were isolated and determined to be the all-cis tetrahydrofuran lignans 1a [rel-(7R,8S,7′S,8′R)-3,4,5,3′,4′,5′-hexamethoxy-7,7′-epoxylignan] and 1b [rel-(7R,8S,7′S,8R′)-3′,4′-methylenedioxy-3,4,5,5′-tetramethoxy-7,7′-epoxylignan]. Their structures were determined by spectroscopic analysis including 1D and 2D-NMR while their configurations were determined by ECD associated to the density functional theory (DFT) at the B3LYP/6-31G(d,p) level. The hydrogen bonds between methoxy groups in trimethoxyphenyl rings stabilizes the all-trans tetrahydrofuran lignan grandisin by 6.5 kcal mol−1 as compared to the corresponding all-cis isomer of grandisin. The occurrence of all-cis tetrahydrofuran lignans as natural products is a very rare event.

The occurrence of phenylpropanoids in the saps of six Piper species (Piperaceae) from Brazil

Las especies de la familia Piperaceae son ampliamente investigadas debido a su importancia biológica, económica y ecológica. Sin embargo, los estudios químicos con las savias de la familia de las Piperaceae no han recibido tanta atención como la mayoría de otras especies de plantas. El presente estudio demostró la presencia de fenilpropanoides en la savia de seis especies de Piperaceae. Este estudio contribuye significativamente al conocimiento químico de la savia vegetal, hasta el momento poco explorado.

CHEMICAL STUDY AND ANTIMICROBIAL ACTIVITIES OF Piper arboreum (PIPERACEAE)

ABSTRACT This study evaluated the antifungal and antibacterial activities of the extracts and their fractions, essential oils, and major constituents of Piper arboreum tissues. The chemical compositions of P. arborem tissues and major constituent were identified using GC/MS, 1 H and 13 C NMR. All the botanic material tested proved to be specific bactericidal agents against Staphylococcus aureus , with MBC/MIC = 2, including the amide piperetine, the major compound isolated of P. arboreum for the first time. The essential oil of leaves showed antifungal activity against Microsporum gypseum and Epidermophyton floccosum, with MFC values of 312.5 and 125 µg/mL, respectively. Keywords : Piperaceae; Piper arboreum; Antimicrobial; Piperetine. e-mail: clecio@dcm.ufrpe.br INTRODUCTION The genus Piper (Piperaceae) includes about 1,400 species, distributed pantropically and taking the form of shrubs, herbs, and lianas, common in the understory of lowland wet forests. It is one of the most diverse lineages among basal angiosperms.

Development and validation of a method for the analysis of paroxetine HCl by circular dichroism.

A simple, rapid, and sensitive method for the analysis of paroxetine, in tablets as well as the pure drug, by circular dichroism is described. The method was validated for repeatability, linearity, limit of detection, limit of quantification, and recovery according to the International Conference on Harmonization guidelines. Excellent results were obtained, within the globally accepted validation reference values, particularly taking into account the low concentration levels investigated. This is the first report of the quantitation of paroxetine, a chiral drug, without previous separation of the analyte. Additionally, the solid state CD spectrum of PXT was obtained.

Metabolism of neolignans from P. regnellii (Piperaceae) in the beetle Naupactus bipes (Coleoptera: Curculionidae)

Piper regnellii (Piperaceae) contains high levels neolignans with diverse biological activities, including insecticidal. Despite the insecticidal activity of these neolignans, Naupactus bipes (Coleoptera: Curculionidae) larvae and adults were found feeding on the leaves (adults) and roots (larvae) of P. regnellii. The present study investigated the metabolic pathway of neolignans from P. regnellii leaves in the beetle N. bipes, focusing on possible biotransformation or sequestration of these compounds by the beetle. Two of the four plant neolignans could be recovered in the feces of adults feeding on P. regnellii leaves. In addition, four degradation products were detected, including the neolignan 3-[(2R,3R)-2,3-dihydro-3-(methyl)-2-(4-hydroxyphenyl)-5-benzofuranyl]-(2E)-propenal (7), an oxidation product of conocarpan, the major plant neolignan. The adult beetle sequesters the neolignan conocarpan selectively from leaves as well as accumulates neolignan 7. Neolignan 7 was also detected in the larvae of lab-reared beetles.