Influence of light quality on in vitro growth and essential-oil composition of Chenopodium ambrosioides L.

Chenopodium ambrosioides L. (CA) is a medicinal plant extensively used for its anthelmintic, anti-inflammatory, antileishmanial and antidiarrheal properties. One of the most important factors that regulates the growth and development of plants in vitro is light. Therefore, the aim of this study was to determine how spectral composition of light influences in vitro growth and chemical composition of CA essential oil (EO). To do that, nodal segments of CA were inoculated in a growth medium and cultured for 40 days in a growth room with different diodes emitting lights: blue (B), red (R), white (W), combinations of blue and red (B:R=1:1; 2:1; 1:2, respectively) and cool white fluorescent lamp (F). The chemical profiles of CAplant specimens grown under lights of different quality were mutually compared using principal component analysis (PCA). The results of PCA showed significant light-quality-related variations in EO profiles (Fig. 1): monochromatic B light inhibited the biosynthesis of ascaridole, while W, B:R=1:2 and 2:1 lights promoted ascaridole production. The herein obtained results suggest that explants kept in a growth room with W or B:R=2:1 lights had optimal chemical profile

Effect of macro- and micro-element-deficiency on growth and essential-oil composition of Mentha arvensis L. cultivated in solution

Because of its olfactory properties, the essential oil (EO) of Mentha arvensis L. is readily used in perfumery and cosmetics and has a great commercial value. However, the agronomic aspects of M. arvensis cultivation were not sufficiently studied. Herein, we assessed the effect of the absence of selected macro- and micronutrients on the growth and essential-oil composition of M. arvensis cultivated in solution. The experiment was completely randomized, with three replications and 12 treatments. Acclimated scions of M. arvensis were transferred into pots containing either the complete Hoagland & Arnon (HA) nutrient solution or modified HA solution, deficient in one of the following macro- or microelements: N, P, K, Ca, Mg, S, B, Cu, Fe, Mn and Zn. The experimental plot consisted of one plant per pot. Plants were cultured in the greenhouse under natural light for 45 days, during which air was supplied to the nutrient system and the nutrient solution was changed each week [1]. Plants were harvested at the end of the culture period and growth parameters (development and appearance of leaves, shoots, roots and the total dry weight) and leaf EO composition were evaluated. The results showed that the composition of the nutrient solution exerted a significant effect on all of the growth parameters and essential-oil chemical profile. With regard to the total dry matter, the order of limiting nutrients was N=Ca>P=B>K=S>Fe=Mg>Zn=Mn>Cu=HA. The most pronounced changes in the M. arvensis development were observed in the absence of N, P, Ca and B. The omission of Mn and Cu in the culture solution did not adversely affect the growth of M. arvensis. Omission of B, P, Ca, Mg and S from the nutritive solution resulted in a higher production of menthol, relative to the control

Biological screening of herbal extracts and essential oil from Plectranthus species: α-amylase and 5-lipoxygenase inhibition and antioxidant and anti-Candida potentials

The phenolic compound content, the antioxidant and α-amylase inhibition potentials of different extracts of the Plectranthus amboinicus, P. barbatus and P. ornatus were evaluated. We also evaluated the influence of plant growth and harvest time on the chemical composition of the essential oil (EO) of P. amboinicus, its antioxidant and anti-Candida activities and the α-amylase and lipoxygenase inhibitions. The turbo-extract of P. barbatus showed the greatest phenolic compound content and antioxidant activity. No α-amylase inhibition activity was observed in the analyzed extracts, but the turbo-extraction and refluxing extracts possessed high antioxidant activities. Protected cultivation and morning harvest conditions gave the best antioxidant activities, which was associated to the highest carvacrol content. P. amboinicus EO antioxidant activity could contribute to the reduction of oxidative stress in diabetes. Causal Candida strains of diabetic foot ulcers showed sensitivity to P. amboinicus EO. C. albicans and C. dubliniensis were the most sensitive of the selected Candida strains. Turbo-extracts or refluxing of the three species extracts and the EO of P. amboinicus should be considered as a potential candidate for the management the complications of type 2 diabetes

Crescimento, teor de óleo essencial e conteúdo de cumarina de plantas jovens de gauco (Mikania glomerata Sprengel) cultivadas sob malhas coloridas

Mikania glomerata Sprengel é uma planta medicinal, largamente empregada na medicina popular, utilizada principalmente no tratamento de afecções respiratórias, que age dilatando os brônquios, sendo a cumarina uma das substâncias associadas a esse efeito. Por isso, entendimento do comportamento fisiológico dessa espécie e as suas respostas às condições do ambiente tornam-se necessários ao aperfeiçoamento dos métodos de cultivo. Nesse contexto, o objetivo deste trabalho foi avaliar o efeito do controle do espectro da luz, utilizando malhas coloridas, sobre o crescimento, teor de óleo essencial e cumarina em Mikania glomerata Sprengel. As plantas foram cultivadas por quatro meses sob malhas de 50% de sombreamento nas cores cinza, vermelha, azul, e a pleno sol (0%). O óleo essencial foi extraído das folhas secas por hidrodestilação em aparelho de Clevenger modificado.A identificação e a quantificação da cumarina foram realizadas por cromatografia líquida de alta eficiência (CLAE).Os resultados permitiram concluir que a malha azul proporcionou aumento no acúmulo de massa seca total e particionada da área foliar, enquanto que as plantas sob malha vermelha apresentaram maior alocação de matéria seca para as raízes. A menor quantidade de matéria seca foliar foi verificada nas plantas crescidas a pleno sol. Não foram observadas, entretanto, alterações na razão de peso foliar e na relação raiz/parte aérea. O teor de óleo essencial das plantas crescidas sob malha azul foi de 0,14%, o que correspondeu a um acréscimo de 142% em relação ao teor verificado nas plantas crescidas a pleno sol, enquanto que o conteúdo de cumarina não foi influenciado pela cor da malha. Tais resultados evidenciam que a luz pode ser modulada durante o cultivo a fim de se obter características morfológicas desejáveis e maximizar a produção de princípios ativos nessa espécie

Use of light-emitting diode (LED) in the physiology of cultivated plants – review

The objective of this study was to demonstrate the effects of the use of LED bulbs in the physiology of cultivated plants. Light-emitting diodes (LEDs) have been proposed as a light source for controlled environments or in plant growth chambers, since they have desirable characteristics for plant development. The development and physiology of plants are strongly influenced by the environment light spectrum provided by the LEDs, among which we can mention the blue, red, green, and their combinations. The blue light, for example, is responsible for a number of important photomorphogenetic features in plants, including stomatal control. Studies indicate that the red wavelength is efficiently absorbed by the pigments present in the plants, since its wavelength is very close to the absorption peak of chlorophyll. The relevance of green light responses is based on the assumption that there are situations in nature that the plant may find conditions of increased green radiation in its growing environment. LED bulbs offer many advantages as radiation sources for plants, but there are difficulties that delay their implementation for applications in the plant cultivation. With the advancement of technologies, the characteristics and performance of LED bulbs, as a source of radiation for plants, tend to be improved. However, this efficiency varies among the light spectra and the species. Thus, the advancement in the use of LEDs in the protected cultivation of cultivated plants is linked to specific physiological responses of each species