Abstract

The Rubiaceae family is rich in medicinal plants that have been used since ancient times in the traditional medicine of many countries, including the Republic of Moldova. Species of the genus Galium (G. verum and G. aparine) have been used for their anti-inflammatory, antioxidant, spasmolytic, diuretic, sedative, and healing properties. The aim of the study was to determine the total content of polyphenols and flavonoids in aerial parts of G. verum and G. aparine depending on the method of dry extract obtaining. Liquid extracts of the aerial parts of G. verum and G. aparine, harvested from the spontaneous flora of the Republic of Moldova, were obtained by heat-assisted extraction, using a digital water bath model 601, at 80°C, respecting the ratio of 1:10 (5 g of vegetal product in 50 ml of 60% ethyl alcohol) for 30 min extraction. The ethanol extracts were dried through evaporation of solvent at a rotary evaporator (Laborota 4011) and lyophilizer (Alpha 1-2 LDplus). The total polyphenol content was determined spectrophotometrically (Metertech UV/VIS SP 8001) according to Folin-Ciocalteu method at a wavelength of 765 nm, the result being expressed in gallic acid (mg GA/g) and total flavonoids – with the reagent AlCl₃, in rutozide (mg RU/g). Following the conducted study, the extracts concentrated using a rotary evaporator showed a higher polyphenol content compared to those obtained through lyophilization in the extracts of G. verum (10.49 and 9.35). In contrast, extracts from G. aparine had a lower polyphenol content (6.10 and 5.23, respectively). A similar tendency was observed for flavonoids, so as the total flavonoid content was higher in extracts obtained using a rotary evaporator from G. verum (11.0 and 8.5), followed by G. aparine (3.90 and 2.3, respectively). The comparative phytochemical study of polyphenols and flavonoids in the extracts of G. verum and G. aparine varied according to the drying method, the total polyphenol content being insignificantly higher in G. verum extracts followed by G. aparine, and the same being observed for flavonoid content. The decrease of polyphenol content in the lyophilized extract could be attributed to changes in the structure of phenolic compounds in the process of subjecting the liquid extract to low temperatures. The reduction of polyphenol content in lyophilized extracts compared to liquid extracts from plant products was demonstrated by the study of Dina Cheaib et al. in 2018. The research was carried out within the project: Impact of different habitats and abiotic stress factors on plant metabolites of genus Galium and Helichrysum, project no. PN-IV-P8-8.3-ROMD-2023-0022.