Chemical Composition of the Essential Oils of Three Popular Sideritis Species Cultivated in Greece Using GC-MS Analysis.

(1) Background: The essential oils (EOs) of Sideritis L. have attracted great interest due to their pharmacological activities and potential applications in the cosmetic and perfume industries. The aim of this work was to study the EO chemical composition of three of the most popular, in Greece, mountain tea species: namely, these include Sideritis scardica, Sideritis raeseri, and Sideritis syriaca. (2) Methods: The EOs were obtained from the aerial parts of three Sideritis species that were cultivated in various regions of Greece by hydrodistillation, and the chemical composition was studied by gas chromatography-mass spectrometry (GC-MS) analysis. (3) Results: The EOs of the Sideritis species-S. scardica (SSC1, SSC2, SSC3), S. raeseri (SR1, SR2, SR3), and S. syriaca (SS1, SS2, SS3)-were analyzed by GC-MS, and they showed both qualitatively and quantitatively high variation in their chemical composition. (4) Conclusions: The EOs of S. scardica and S. raeseri from three different regions of Greece, and the S. syriaca from three different localities of Crete Island in Southern Greece, showed high chemical variability. Although 165 different components were found to be present in the nine samples through GC-MS analysis, only 7 (1-octen-3-ol, linalool, trans-pinocarveol, p-mentha-1,5-dien-8-ol, α-terpineol, myrtenol, and verbenone) were common components in the nine EOs, which were identified to be highly variable in different percentages among the samples. Even the EOs of SS1 and SS2, which were cultivated nearby, showed different GC profiles. The composition variation observed might be attributed to differentiations in the soil and climatic conditions.

Determining the Nutrient Content of Hydroponically-Cultivated Microgreens with Immersible Silicon Photonic Sensors: A Preliminary Feasibility Study.

Microgreens have gained attention for their exceptional culinary characteristics and high nutritional value. The present study focused on a novel approach for investigating the easy extraction of plant samples and the utilization of immersible silicon photonic sensors to determine, on the spot, the nutrient content of microgreens and their optimum time of harvest. For the first time, it was examined how these novel sensors can capture time-shifting spectra caused by the molecules' dynamic adhesion onto the sensor surface. The experiment involved four types of microgreens (three types of basil and broccoli) grown in a do-it-yourself hydroponic installation. The sensors successfully distinguished between different plant types, showcasing their discriminative capabilities. To determine the optimum harvest time, this study compared the sensor data with results obtained through standard analytical methods. Specifically, the total phenolic content and antioxidant activity of two basil varieties were juxtaposed with the sensor data, and this study concluded that the ideal harvest time for basil microgreens was 14 days after planting. This finding highlights the potential of the immersible silicon photonic sensors for potentially replacing time-consuming analytical techniques. By concentrating on obtaining plant extracts, capturing time-shifting spectra, and assessing sensor reusability, this research paves the way for future advancements in urban farming.

Quantitative determination of aloin, antioxidant activity, and toxicity of Aloe vera leaf gel products from Greece.

BACKGROUND: Aloe vera is a popular medicinal plant used widely by the cosmetic, pharmaceutical, and food industries. The A. vera leaf gel, which is used mostly for its positive effects on human health, contains over 75 different bioactive compounds, including aloin. Aloin is a toxic compound, and its content in A. vera leaf gel products depends on the different cultivation conditions and especially on leaf processing. RESULTS: In this study, A. vera leaf gel products, varied in terms of leaf processing, were analyzed using liquid chromatography for their aloin content, their antioxidant activity by 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) radical cation (ABTS·+ ) and the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH· ) antioxidant activity assays and their toxicity against Aliivibrio fisheri and SH-SY5Y cells. In the samples processed with industrial methods and in those filtered in the lab, the content of aloin was found below the limit (0.1 mg L-1 ) of the EU legislation however, the unprocessed and unfiltered samples were found to contain more than 10 mg L-1 . Antioxidant activity was estimated to vary from 1.64 to 9.21 µmol Trolox mL-1 for DPPH· and from 0.73 to 5.14 µmol Trolox mL-1 for ABTS·+ . Toxicity values on A. fisheri, expressed as the concentration at 50% loss of initial luminescence, ranged from 0.03 to 0.09 mg mL-1 . The cytotoxic study indicated that aloin A at low concentrations (1 and 10 µg mL-1 ) protects SH-SY5Y cells from toxicity induced by hydrogen peroxide. CONCLUSIONS: Consequently, the filtration process of A. vera leaf gels, either laboratory or industrial, resulted in aloin A content below the EU legislation detection limits. © 2020 Society of Chemical Industry.