Polyphenols from Ginkgo biloba

By Sephadex LH-20 gel chromatography of an extract from Gingko biloba leaves, polymeric proanthocyanidins were eluted after the fractions of flavonol glycosides and biflavone glycosides. A purified proanthocyanidin polymer accounted for 86.6% of the total proanthocyanidins, and for 37.7% of the total antioxidant activity of this leaf extract. For structure elucidation, the polymer was submitted to acidic depolymerization in the presence of phloroglucinol. The structures of the resulting flavan-3-ols and phloroglucinol adducts were determined on the basis of 1D-and reverse 2D-NMR (HSQC, HMBC) spectra of their peracetylated derivatives, MALDI-TOF-MS and CD-spectroscopy. The observations resulting from the degradation with phloroglucinol were confirmed by 13C-NMR spectroscopy of the polymer. The mean molecular weight of the polymeric fraction was estimated to be 9–10 flavan-3-ol-units

Hydroxycinnamic Acid Derivatives Obtained from a Commercial Crataegus Extract and from Authentic Crataegus spp.

Eleven hydroxycinnamic acid derivatives were isolated from a 70% methanolic Crataegus extract (Crataegi folium cum flore) and partly verified and quantified for individual Crataegus species (C. laevigata, C. monogyna, C. nigra, C. pentagyna) by HPLC: 3-O-(E)-p-coumaroylquinic acid (1), 5-O-(E)-p-coumaroyl-quinic acid (2), 4-O-(E)-p-coumaroylquinic acid (3), 3-O-(E)-caffeoylquinic acid (4), 4-O-(E)-caffeoylquinic acid (5), 5-O-(E)-caffeoylquinic acid (6), 3,5-di-O-(E)-caffeoylquinic acid (7), 4,5-di-O-(E)-caffeoylquinic acid (8), (−)-2-O-(E)-caffeoyl-L-threonic acid (9), (−)-4-O-(E)-caffeoyl-L-threonic acid (10), and (−)-4-O-(E)-p-coumaroyl-L-threonic acid (11). Further, (−)-2-O-(E)-caffeoyl-D-malic acid (12) was isolated from C. submollis and also identified for C. pentagyna and C. nigra by co-chromatography. The isolates 10 and 11 were not found in the authentic fresh specimen, indicating that they may be formed during extraction by acyl migration from the 2-O-acylderivatives. Also, 9 and 11 are described here for the first time. All structures were assigned on the basis of their spectroscopic data (1H-, 13C-NMR, MS, optical rotation)

Polymeric Proanthocyanidins from Psidium guajava

From the aqueous acetone extract of the leaves of Psidium guajava L. the flavanols catechin and gallocatechin, the procyanidins B1, B2, B3 and two prodelphinidins (gallocatechin - (4α→8) - catechin; gallocatechin - (4α→8) - gallo-catechin) were isolated. A more abundant proanthocyanidin polymer was also isolated, purified and its chemical constitution studied by 13C-NMR and phloroglucinol degradation. The mean molecular weight of the polymer was estimated to be about 9 to 10 flavan-3-ol-units with a ratio of procyanidin: prodelphinidin units at 2 : 1 some of which are derivatized by gallic acid

Antimicrobial activity of selected extracts and some compounds from Ruscus aculeatus L., R. hypoglossum L. and R. alexandrinus Garsault (Ruscaceae)

nul

Bioactivity of the extracts and compounds of Ruscus aculeatus L. and Ruscus hypoglossum L.

Here we report on the antimicrobial and antioxidant activity of several extracts of Ruscus aculeatus L. and Ruscus hypoglossum L., as well as of some compounds previously isolated from them (p-coumaric and caffeic acids, rutin). For antimicrobial activity, the microdilution technique was used against eight bacterial and five fungal strains, along with standard drugs (streptomycin, ampicillin, bifonazole, ketoconazole). Investigated extracts and isolated compounds showed antibacterial and especially antifungal activity. In some cases this activity was better than standard drugs (streptomycin, ampicillin, bifonazole, ketoconazole) and was more evident for some of isolated compounds. Antioxidant activity was investigated by DPPH and 2-deoxyribose assays, along with spectrophotometrical determination of total phenolics content (TPC) using Folin-Ciocalteu reagent. In DPPH test obtained SC50 values were in a range of 173-541 mu g/mL, while inhibition of 2-deoxyribose for some extracts reached up to maximal 50%. Results of antioxidant assays were strongly correlated with total phenolics content. The most active was the EtOAc fraction of the MeOH extract of R. aculeatus herb regarding all investigated parameters