Seasonal variations of phenolic compounds and biological properties in sage (Salvia officinalis L.).

The aim was to investigate the phenolic content, antioxidant capacity, and antibacterial activity of Dalmatian sage (Salvia officinalis L.) leaves collected during different vegetation periods. Separation and quantification of the individual phenols were performed by reversed-phase (RP)-HPLC coupled with a PDA (photodiode array) detector and using an internal standard, while the contents of total phenols, flavonoids, flavones, and flavonols were determined spectrophotometrically. The antioxidant properties of the sage leaf extracts were evaluated using five different antioxidant assays (FRAP, DPPH, ABTS, Briggs-Rauscher reaction, and ß-carotene bleaching). The antimicrobial activity of the extracts was tested against two Gram-positive (Bacillus cereus and Staphylococcus aureus) and two Gram-negative (Salmonella Infantis and Escherichia coli) bacterial reference strains. All extracts were extremely rich in phenolic compounds, and provided good antioxidant and antibacterial properties, but the phenophase in which the leaves were collected affected the phenolic composition of the sage extracts and consequently their biological activity. The May Extract, the richest in total flavonoids, showed the best antioxidant properties and the highest antimicrobial activity. Thus, collection of the plants during May seems the best choice for further use of them in the pharmaceutical and food industry.

[Antioxidative activity of propolis from Dalmatia (Croatia)]. / Antioksidacijski kapacitet dalmatinskog propolisa.

AIM: The aim of this study was to determine the antioxidative activity of propolis from ecologically clean parts of Dalmatia. METHODS: Phenol concentration in ethanolic propolis extracts was determined by Folin-Ciocalteu reagent using gallic acid as the standard. Flavonoid phenolic compounds were analyzed after precipitation with formaldehyde. The residual non-flavonoid phenolics were also determined by Folin-Ciocalteu method. By determining the change of peroxide number (PN), of tiobarbiture acid reactive species (TBARS), and of DPPH-radical activity, antioxidative efficiency of propolis was tested and compared with well known and widely used synthetic antioxidants. Values of PN and TBARS were determined at 60 degrees C in samples of trigyceride substrate (lard) without and with the addition of antioxidants. Compared was the efficiency of three antioxidants: propolis (alcoholic extract), vitamin E, and (+)-catechin in a concentration of 1%. PN was monitored during 50 days. By the method of Sedlacek, TBARS were measured during 30 days. Antioxidative activity of propolis extract was also measured in terms of hydrogen donating ability using stable radical alpha,alpha-diphenyl-beta-picril hidrazyl (DPPH*) and compared with commercial synthetic antioxidants of butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and (+)-cathecin. Inhibition degree of DPPH* was calculated by the formula of Yen and Duh. RESULTS: Total phenol content, expressed as gallic acid, in propolis extracts varied from 75.2 to 90.2 g/kg propolis. The proportion of flavonoids in total phenols ranged from 62% to 65%. Values of TBARS were not increased only in samples with added propolis. The inhibition of DPPH-radical by propolis extracts ranged from 93% to 96%, by catechin 95%, by BHT 49%, and by BHA 64%. Compared to BHT and BHA, propolis extracts showed greater reducing activity against DPPH-radical. DISCUSSION: The chemical composition of propolis, and thus its biological activity depend on the plant from which it has been collected, and on the macro- and microclimatic conditions. Many compounds in propolis exert antioxidative activity. A belief was expressed that the biological activity of propolis is very probably based mostly on its antioxidative efficiency. Dalmatian propolis showed high efficiency in the prevention of oxidative processes. This could be explained by the high proportion of polyphenol constituents, especially flavonoids. A very low and equal degree of increase of PN, as a measure of oxidative processes, was noticed in the samples of triglyceride substrate with the addition of propolis and (+)-catechin. The greatest rise of TBARS was measured in the samples of pure lard. There was no increase of TBARS only in the samples with added propolis. Propolis and (+)-catechin showed great efficiency in the inhibition of DPPH-radical, greater than BHT and BHA, which are widely used in food industry. CONCLUSION: The results indicate that Dalmatian propolis could be an efficient protective agent against oxidative processes in food. The high antioxidative activity of propolis, its natural origin, and present knowledge about its biological properties, make it a very promising nutritional additive for human diet.

Influence of the phenophase on the phenolic profile and antioxidant properties of Dalmatian sage.

This study aimed to research the influence of phenophase on the phenolic profile (phenolic acids, flavonoids and stilbenes) and related antioxidant properties of sage, one of the most characteristic plants of Dalmatian karst. The total phenol and flavonoid contents in sage leaves were determined spectrophotometrically, while the principal phenolics were determined using HPLC-RP-DAD. Antioxidant properties of this well known medicinal plant were determined as free radical scavenging activity (DPPH), ferric reducing/antioxidant power (FRAP) and by Briggs-Rauscher oscillating reaction (BR). The results strongly indicate that Dalmatian sage leaves are rich source of valuable phenolics, mainly phenolic acids, with extremely good antioxidant properties. The presence of resveratrol or its derivatives was confirmed in all extracts. The best results for total phenols and flavonoids, as well as the best antioxidant properties were obtained for May sage, while the highest amounts of catechin monomers and compounds from group of stilbenes were found in February extract.