Abstract:
Introduction.The genus Galium L. (fam. Rubiaceae) includes more than 600 species in the world flora,
of which 45 species in the European flora and 28 species in the Romanian one. Among them, there are
20 species identified in the Republic of Moldova flora - G. verum is considered the most valuable in
chemical compounds due to its content of iridoids, polyphenols, flavonoids, essential oils and tannins.
Aim of study. Investigation of extraction methods of polyphenol compounds from aerial parts of G.
verum for optimization of polyphenol extraction techniques in research products.
Methods and materials. The herbal products G. veri herba were harvested from the spontaneous flora
of the Republic of Moldova in the Bugeac steppe (2021), throughout the blooming period. The plant was
identified by botanists from the Botanical Garden of the ASM and have been processed in agreement to
recommendations for the purposes of chemical studies. Polyphenol compounds from G. veri herba were
extracted with 60% ethanol solution for 30 min at 80°C, respecting the ratio of 1:10 (5 g of product in
50 ml of 60% ethanol solution) for all technical methods: water bath extraction, ultrasound assisted
extraction and magnetic stirring extraction. Total phenolic contents (TPC) was determined by the FolinCiocalteu method with gallic acid as reference substance.
Results. Extraction of polyphenolic compounds from G. veri herba was carried out taking into account
parameters influencing ultrasound-assisted extraction: sonication time, amplitude, solvent and particle
size that depends on the destructive effects of ultrasonic waves. The extraction mechanism involves
diffusion through cell walls and washing out the cell contents, in this order the cavitation effects of these
waves facilitate the extractable compounds release. The high temperature increases solubility, diffusivity
and pressure, which helps the waves penetrate the tissue and transport the contents in a variety of
solvents. Extraction of polyphenolic compounds performed at different ultrasonic amplitudes from 50
to 100% shows a maximum TPC content (29.21 mg/g) at 80% amplitude, followed by the magnetic
stirring method (28.17 mg/g) and water bath extraction (27.56 mg/g).
Conclusion. The diversity of phenolic compounds found in vegetal products makes it difficult to develop
a universal extraction method. In the case of G. veri herba the optimal method of polyphenol extraction
is ultrasound-assisted extraction.
