In this study, the effect of extraction conditions on the total phenolic content of clove buds was investigated. Clove buds were extracted using a deep eutectic solvents like mixtures choline chloride: lactic acid in the 1:2 molar ratio. Additionally, the HPLC-DAD method was used to determine the main components of the clove extracts, including eugenol, eugenol acetate, and β-caryophyllene. The conditions used in the extraction with choline chloride: lactic acid (molar ratio 1:2) included extraction temperature (t = 40 – 80°C), water addition (5.6 – 40%), and extraction time (30 – 90 min). Determination of the phenolic compounds was done by the Folin-Ciocalteu method. The optimum operating conditions for the total phenolic content were identified at 77°C, 30 min, and a water addition of 40%. Based on the results, the highest amount of eugenol (307.26 ± 8,44 mg/g dry raw material) was determined in clove extracts which were extracted under condition of 60°C, 22.8%, and 30 min.

Biodiesel is considered valuable to reduce dependency on petro-fuels. This work aimed to synthesize biodiesel from Silybum marianum using synthesized ZnO nanoparticles as a catalyst. The synthesized ZnO nanoparticles were examined by scanning electron microscopy and X-ray diffraction for confirmation. The synthesized biodiesel was confirmed by ASTM D-6751, H and C-NMR, GC-MS, and FT-IR spectroscopy. The optimal biodiesel yield of 91% was obtained in the oil-to-methanol ratio of 1:24, 15 mg of catalyst concentration, 60 0C temperature, and 45 minutes of reaction time. Fuel properties were determined according to the ASTM defined methods and found within the defined limits of ASTM D-6751. 1H-NMR and 13C-NMR showed characteristic peaks at 3.667 ppm, 2.000 to 2.060 ppm, 0.858-0.918 ppm, 5.288-5.407 ppm, 24.93-34.22 ppm, 172.71, 173.12, 130.16 ppm, and 128.14 ppm, respectively, which confirm biodiesel synthesis. The FAMEs composition of biodiesel was determined by GC-MS which recognized 19 peaks for different types of FAMEs. FT-IR spectroscopy showed two main peaks, first in the range of 1725-1750 cm-1 and second in the range of 1000-1300 cm-1, which confirmed that the transesterification process was completed successfully. The physicochemical characteristics of Silybum marianum confirm that it is a suitable source to produce biodiesel on industrial scale.

Enormous quantities of softwood and hardwood tree bark are generated yearly in the pulp and woodworking industry. Chemical compounds which can be found in bark extracts have important biological properties and therefore a high potential for using in the production of special formulations. In the present study, extraction of Picea abies bark with organosolv solvents was investigated to achieve a high yield of desirable compounds. For the extraction four different solvent ratios of ethanol and water were applied. The temperature range of extraction was set between 40 and 100 °C and stirring velocity of 400 rpm. Extractions were performed with a solid/liquid ratio of 1:20. Yields of phenolics, flavonoids and tannins were determined using gallic acid for total phenolic content (TPC), quercetin for total flavonoid content (TFC) and tannic acid for total tannins content (TTC) as calibration compounds. Qualitative analysis of phenolic constituents was performed after their derivatization, by gas chromatography coupled with mass spectrometry identification. The total yield of bark extract of 14.75 wt.% was achieved by using an ethanol/water ratio of 50% (v/v) and a temperature of 100 °C. Gas chromatography results show 9 aromatic carboxylic acids as phenolic acids and quercetin and (+)-catechin as flavonoid compounds. Highest concentrations of TPC = 3.21 mg gallic acid equivalent/g, TCF = 0.62 mg quercetin equivalent/g and TTC = 0.84 tannic acid equivalent/g were determined at the same process conditions by photometric method. This study determined the conditions for organosolv extraction of useful compounds and suggests that some of extractives, e.g., taxifolin and rhamnetin presented in the spruce bark extracts, have antiviral (SARS-CoV-2) effects. Therefore, this warrants further evaluation of the antiviral properties of spruce bark constituents.