Marta D. Mendes

Bioassays Against Pinewood Nematode: Assessment of a Suitable Dilution Agent and Screening for Bioactive Essential Oils

Acetone was investigated and found to be an appropriate alternative to Triton X-100 as a solvent of essential oils in bioassays aimed to investigate their effects on pinewood nematode (Bursaphelenchus xylophilus) mortality. Therefore it was used as dilution agent to screen the effectiveness of fifty two essential oils against this pest. Thirteen essential oils were highly effective, resulting in more than 90% pinewood nematode mortality at 2 mg/mL, with six of them resulting in 100% mortality. LC100 values ranged between 0.50 mg/mL and 0.83 mg/mL for the essential oils of Origanum vulgare and Satureja montana, respectively. Essential oils were submitted to gas chromatography and gas chromatography-mass spectrometry analysis and their chemical composition established. Data from essential oils with 100% mortality at 2 mg/mL and other essential oils previously found to have LC100 ≤ 2 mg/mL was combined, their chemical profiles investigated by correspondences analysis plus automatic classification.

Antimicrobial activity, cytotoxicity and intracellular growth inhibition of Portuguese Thymus essential oils

1CDCTPV, Faculdade de Ciências e Tecnologia, Universidade do Algarve, Portugal, 2Centro Biotecnologia Vegetal, Instituto de Biotecnologia e Bioengenharia, Faculdade Ciências Lisboa, Universidade de Lisboa, Portugal, 3Departamento de Química e Farmácia, Faculdade de Ciências e Tecnologia, Universidade do Algarve, Portugal, 4Centro de Biomedicina Molecular e Estrutural, Instituto de Biotecnologia e Bioengenharia, Faculdade de Ciências e Tecnologia, Universidade do Algarve, Portugal, 5Departamento de Biologia e Biotecnologia, Escola Superior Agrária, Instituto Politécnico de Bragança, Portugal.

Propolis volatiles characterisation from acaricide-treated and -untreated beehives maintained at Algarve (Portugal)

The variability of the volatile profile of 70 propolis samples from acaricide-treated and -untreated beehives maintained at Algarve (Portugal) was evaluated. Propolis samples were collected in three regions of Algarve at three different periods. Cluster analysis based on the propolis volatiles’ chemical composition defined two main clusters, not related to the time of year, collection site, altitude, temperature or humidity ranges, and was based mainly on the relative amounts of viridiflorol, n-tricosane and n-nonadecane for cluster I. Cluster II was mainly characterised by the high thymol content, followed by viridiflorol, n-tricosane and n-nonadecane. The presence of higher thymol levels in propolis samples from cluster II may reflect the long use of an acaricide with thymol as main active ingredient. All samples showed an intense rock-rose aroma supported by the presence of characteristic Cistus and labdanum oil volatile components. Given the nowadays frequent propolis household use, volatiles thorough characterisation may assist in its quality assessment.

Influence of culture media and fungal extracts on essential oils composition and on terpene synthase gene expression in Thymus caespititius

Thymus caespititius Brot. is an Iberian endemic species, whose essential oils possess high diversity and some of them could be used in pharmaceutical and food industries. The effect of culture media composition and fungal extracts on essential oils composition and on the expression of terpene synthase (TPS) genes was evaluated in T. caespititius shoots cultures. Nutrient composition influenced quantitatively the essential oils content. A decrease in the acetate compounds in the essential oils was observed in SH medium as compared with MS. The TPS transcripts accumulation was higher in all genotypes grown in SH, except in sabinene/carvacrol (SC) genotype. B. cinerea extracts highly induced TPS gene expression in the first hours after treatment in SC genotype, while in carvacrol/thymol (CT) only a slight increase was observed. TPS down-regulation observed during the next time points could result from reallocation of energy resources to plants’ vital functions. Fungal extracts did not affect qualitatively and quantitatively the CT essential oils, however in SC, the sabinene relative content decreased and this was inversely related to the increase of two antifungal compounds, carvacrol and thymol, in the oil. T. caespititius in vitro cultures revealed to be a good system for terpene metabolism study.