Chrysolina herbacea Modulates Terpenoid Biosynthesis of Mentha aquatica L.

Interactions between herbivorous insects and plants storing terpenoids are poorly understood. This study describes the ability of Chrysolina herbacea to use volatiles emitted by undamaged Mentha aquatica plants as attractants and the plant's response to herbivory, which involves the production of deterrent molecules. Emitted plant volatiles were analyzed by GC-MS. The insect's response to plant volatiles was tested by Y-tube olfactometer bioassays. Total RNA was extracted from control plants, mechanically damaged leaves, and leaves damaged by herbivores. The terpenoid quantitative gene expressions (qPCR) were then assayed. Upon herbivory, M. aquatica synthesizes and emits (+)-menthofuran, which acts as a deterrent to C. herbacea. Herbivory was found to up-regulate the expression of genes involved in terpenoid biosynthesis. The increased emission of (+)-menthofuran was correlated with the upregulation of (+)-menthofuran synthase

An improved HPLC-DAD method for clavulanic acid quantification in fermentation broths of Streptomyces clavuligerus

Clavulanic acid (CA) is an important secondary metabolite commercially produced by cultivation of Streptomyces clavuligerus (Sc). It is a potent inhibitor of bacterial beta-lactamases. In this work, a specific and improved high performance liquid chromatography (HPLC) method, using a C-18 reversed phase column, diode array detector and gradient elution for CA quantification in fermentation broths of Sc, was developed and successfully validated. Samples were imidazole-derivatized for the purpose of creating a stable chromophore (clavulanate-imidazole). The calibration curve was linear over a typical range of CA concentration between 0.2 and 400 mg/L. The detection and quantification limits were 0.01 and 0.02 mg/L, respectively. The precision of the method was evaluated for CA spiked into production media and a recovery of 103.8%, on average, was obtained. The clavulanate-imidazole complex was not stable when the samples were not cooled during the analysis. The recovery rate was 39.3% on average. This assay was successfully tested for CA quantification in samples from Sc fermentation, using both, a chemically defined and a complex medium. (C) 2015 Elsevier B.V. All rights reserved

Alternativas de propagação na produção de óleo essencial de Mentha canadensis L. no Litoral Norte Catarinense Propagation alternatives for the production of Mentha canadensis L. essential oil at the Santa Catarina State northern coast

O gênero Mentha é cultivado mundialmente para a produção de óleo essencial, com ênfase no constituinte mentol, amplamente utilizado nas indústrias farmacêutica, cosmética, alimentícia e de higiene pessoal. Este trabalho teve como objetivo avaliar o efeito da utilização de diferentes estruturas de propagação e épocas de colheita de Mentha canadensis L. no Litoral Norte Catarinense. O delineamento experimental foi em blocos ao acaso em esquema fatorial 4x2, comparando quatro estruturas de propagação (estolões com 10, 15 e 20 cm de comprimento e estacas com 5 cm de comprimento) e duas épocas de colheita (95 dias após o plantio e 60 dias após a rebrota). Em cada colheita foi avaliado o crescimento vegetativo e produtividade de óleo essencial e de mentol. Na primeira colheita, houve maior acúmulo de massa seca de folhas, caules e total; produtividade de óleo essencial e de mentol quando o plantio foi realizado com mudas obtidas por estaquia. Na segunda colheita, no entanto, não houve diferença significativa entre os tratamentos para todas as variáveis analisadas. A primeira colheita resultou em médias superiores em relação à segunda colheita à exceção do plantio por estolão com 10 cm em todas as variáveis e estolão com 20 cm para a massa seca de caules. Os constituintes majoritários do óleo essencial foram mentol, mentona e neomentol. Os teores de mentol foram significativamente superiores na segunda colheita e de mentona na primeira colheita, sendo que o neomentol não apresentou diferença significativa em ambas as colheitas. Os resultados obtidos sugerem que a colheita antecipada da rebrota proporciona maior concentração de mentol no óleo essencial. O uso de estolões como estrutura de propagação pode ser considerada uma alternativa viável para menta, pois além de apresentar níveis similares de produção de óleo essencial e de mentol a partir da segunda colheita ao de áreas implantadas com mudas, diminui o custo de produção.<br>The genus Mentha is cultivated worldwide for essential oil production, with emphasis on its major constituent, menthol, which is used in the pharmaceutical, cosmetics, and food industries and for personal care. This work investigates the use of different propagation structures and harvesting times of Mentha canadensis L., in the Santa Catarina State north coast. The experimental design was in randomized blocks in a 4X2 factorial, comparing four propagation structures (stolon with 10, 15 and 20 cm and stem cuttings with 5 cm) and two harvesting times (95 days after planting and 60 days after the regrowth). In each harvesting time, the vegetative growth, essential oil and menthol productivities were evaluated. The first harvest showed greater leaf, branch and total dry mass accumulation, and essential oil and menthol productivities when stem cuttings were used. In the second harvest, no differences were observed for all evaluated variables. The first harvest resulted in higher averages than the second harvest, with exception in all variables for the use of stolon with 10 cm and in stem dry mass for stolon with 20 cm. The major constituents of the essential oil were menthol, menthone, neomenthol. The levels of menthol were significantly higher in the second harvest and of menthone in the first harvest, while neomenthol showed no significant difference. The results suggest that early harvest of the regrowth results in great menthol concentrations in the essential oil. The use of stolons as a propagation structure can be considered a viable alternative for mint, as it provides similar levels of essential oil and menthol productions after the second harvest, when compared to stem cuttings and also reduces the production cost