PRELIMINARY RESEARCH REGARDING THE THERAPEUTIC USES OF URTICA DIOICA L. NOTE I. THE POLYPHENOLS EVALUATION
The use of stinging nettle leaves for the treatment of diabetes mellitus without a scientific evaluation, persuaded us to study them, in order to obtain pharmacological active extracts. According to scientific data, polyphenols are known as HMG-CoA reductase inhibitors and have potent anti-glycation activity. These compounds are the main active principles in the Urticae folium. The aim of this study was to evaluate the polyphenols’content (polyphenolcarboxilic acids = PPCA, and flavonoids) of stinging nettle leaves, harvested from culture and wild flora, originated from Racari, Dambovita district, Romania. Spectrophotometric and chromatographic methods were used. A new HPLC method for the identification and quantification of caffeic and chlorogenic acids from Urticae folium was also developed. The highest contents of polyphenolcarboxilic acids (expressed as % of chlorogenic acid) and flavonoids (expressed as % of rutin) were found in the leaves of wild nettles harvested in the month of March (4.2295% chlorogenic acid and 0.6237% rutin). The polyphenols’ content is slightly lower than the ones mentioned in the scientific literature. The content of PPCA decreases from March till September, both in wild and cultivated samples. The variation of the flavonoids’content differs with the origin of raw material (culture or spontaneus flora). The new HPLC method for polyphenols’analysis is reproductible. Rezumat Utilizarea tradiţională a produsului Urticae folium in diabet, fără o justificare stiintifica a acţiunii precum si menţionarea flavonelor si acizilor fenolcarboxilici (compusii majoritari) ca inhibitori ai HMG-CoA reductazei si ai proceselor de glicozilare si lipoxidare avansată, ne‐au determinat să abordăm cercetarea acestora, in vederea valorificării terapeutice sub formă de extracte selective. In acest scop am derulat o cercetare spectrofotometrică si cromatografică (HPLC) pentru a pune in evidenţă polifenolii prezenţi in frunzele de urzică recoltate din flora spontană si de cultură, din localitatea Răcari, judeţul Dâmboviţa. De asemenea, ne-am propus să separăm acizii cafeic si clorogenic si să-i determinăm cantitativ printr-o nouă metodă HPLC/UV.
Phenolic Content and Antioxidant Activity of a Raspberry Leaf Dry Extract
Polyphenols are known for their beneficial effects towards chronic disease caused by oxidative stress (diabetes mellitus, cancer, atherosclerosis). In the present study, a raspberry (Rubus idaeus L.) leaf dry extract was evaluated for its phenolic content and antioxidant activity. Spectrophotometric and HPLCUV/HPLC-MS methods were used for polyphenols determination and 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2’-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+), ferric reducing ability (FRAP), oxygen radical absorbance capacity (ORAC) methods for antioxidant activity. 2’,7’dichloro-dihydrofluorescein diacetate (DCFH-DA) assay was used to investigate the cytoprotective effect against oxidative stress in human HepG2 cell line. It was found that the extract is a rich source of flavonoids and phenolcarboxylic acids (43.08 mg% quercitrin, 14.33% isoquercitrin, 43.40 mg% p-coumaric acid, 17.51 mg% caffeic acid, 11.41 mg% ferulic acid, 220.26 mg% quercetin) and has a modest antioxidant activity (EC50 = 0.0991 mg/mL DPPH assay, EC50 = 0.2274 mg/mL ABTS•+, EC50 = 0.0682 mg/mL FRAP and 7243.7 μM trolox/g ORAC) compared with standards (ascorbic acid, gallic acid). The dry extract showed a dose-response antioxidant activity against alloxan, induced oxidative stress inHepG2 cells, with a maximum effect at 0.01 mg/mL. Due to its phenolic content, the extract might be used for hepatic disorders treatment, associated with oxidative stress.
Determination of genistein in the Turkish Genista L. species by LC-MS.
In this study, Genista species growing in Turkey were analysed for their total and free genistein content by using LC-MS method. The highest amount of total and free genistein was found in Genista tinctoria as 1.05% and 0.27% respectively and trace amount in G. libanotica. Total and free genistein content of the aerial parts of other Genista species varied from 0.01 to 0.18% and from 0.01 to 0.13% respectively.