A Simple Method for the Determination of Polyphenolic Compounds from Grapevine Leaves

Abstract

Grapevine leaves are photosynthetically the most active green organs providing carbohydrates that are of utmost importance for the regular vine’s metabolism and growth. Moreover, leaves are the pioneers of fungal infections caused by B. cinerea, E. necator, and P. viticola. Plant response to these microorganisms mostly depends on the content and composition of phenolic compounds abundantly found in the leaf’s outer tissues (epidermis, cuticle, trichomes). In order to obtain a satisfactory quantity of phenolic compounds, an experiment was conducted towards optimizing a solid–liquid extraction method. Variables were as follows: the type of organic solvent, the sample weight, the extraction temperature, and the extraction time. The optimal conditions were obtained by applying the response surface methodology. Therefore, by using acetonitrile as the organic solvent, conducting a single-step extraction at the temperature of 48 °C during the time period of 2 h and 25 min with a solid-to-solvent ratio of 1:56 g mL−1 (178 mg of leaves powder and 10 mL of extraction solvent) the optimal content of phenolic compounds was obtained. This protocol is reliable, fast, and relatively easy to perform for the determination of the abovementioned compounds.

Leaf Polyphenolic Profile as a Determinant of Croatian Native Grapevine Varieties’ Susceptibility to Plasmopara viticola

“…Before analysis, the leaves were lyophilized (freeze-dried) and then ground using MiniG Mill (SPEX SamplePrep, United States) (1 min, 1,500 rpm) to obtain a powder. The extraction was conducted according to the method described by Sikuten et al (2021) and Štambuk et al (2022) with slight modifications. In brief, the solid–liquid extraction technique was performed on the magnetic stirrer (RTC basic, IKA, Staufen, Germany) in the following conditions: extraction temperature of 60°C at 400 rpm for 2 h. The mass of 40 mg of ground grapevine leaves and the volume of 3 ml of extraction solvent was used.…”

Valorization of grape (Vitis vinifera) leaves for bioactive compounds: novel green extraction technologies and food-pharma applications

“…Although it does not have phenolic chemicals, the tissue is primarily chlorophyll rich. The cuticle, a very thin but significant layer rich in phenolics (particularly hydroxycinnamic acids and flavonoids), protects the top and lower epidermis, which in turn protects the mesophyll ( Štambuk et al, 2022 ).…”

“…The extent to which a material can endanger people or animals is known as its toxicity. Acute and sub-acute toxicity are the two different forms of toxicity ( Štambuk et al, 2022 ). Acute toxicology experiments identify the LD50, or median lethal dose, as dosage level at which half of the animals’ death take place.…”

An update of Åhlberg (2021a): A profound explanation of why eating green (wild) edible plants promote health and longevity

“…According to Štambuk et al. (2022), plant cell walls are mainly composed of the following structural components: polyphenols, polysaccharides, and cell wall proteins.…”