Validated methods for the quantification of biologically active constituents of poplar‐type propolis

Abstract

The validation of rapid, low-cost spectrophotometric procedures for the quantification of the three main groups of bioactive substances (flavones and flavonols, flavanones and dihydroflavonols, and total phenolics) in poplar-type propolis has been performed. A spectrophotometric assay based on the formation of an aluminium chloride complex was applied for the quantification of total flavones and flavonols using galangin as standard. Because of the high amount of flavanones and dihydroflavonols in "poplar type" propolis, the introduction of a distinct procedure for their quantification was considered of special significance and the DAB9 colorimetric method was applied for the purpose. Total phenolic content was measured by the Folin-Ciocalteu procedure using a mixture of pinocembrin and galangin as a reference. The procedures were validated using a model mixture of compounds representing the poplar-type propolis composition as found in previous studies. The accuracy (recovery) varied in the range 84-109%, and the relative standard deviation was 0.5-6.2%. The developed spectrophotometric procedures were applied to six poplar type propolis samples. The results were verified independently by a HPLC procedure. The two sets of results agreed satisfactory, as proven by Student's t-test.

Color, phenolic and flavonoid content, and antioxidant activity of honey from Roraima, Brazil

“…The first method uses aluminum chloride and is based on the formation of a complex between the aluminum ion, Al (III), and the carbonyl and hydroxyl groups of flavones and flavonols that produce a yellow color (Popova et al, 2004). In this study, the total flavone and flavonol content ranged from 9.0 to 48.6 mg of quercetin kg -1 of honey ( Table 2).…”

“…1474242/2008-0) and to Coordenação de Aperfeiçoamento de Pessoal de Nível Superior for granting a scholarship (Jonierison Alves Pontis). and others (Popova et al, 2004) stated the importance of using both methods (aluminum chloride and DNP) to determine flavonoid content in samples of poplar propolis because there are large quantities of flavonones in poplar propolis standards. Although it is a major honey constituent, flavonones were not used as a reference compound for determining the total flavonoid content in poplar propolis.…”

“…The total flavonoid content is generally determined using a spectrophotometric assay based on the formation of an aluminum chloride complex, which has been applied for quantification of flavones and flavonols in honey (Meda et al, 2005;Liberato et al, 2011). Although the flavonone and dihydroflavonol content has not yet been determined in honey, these compounds have largely been determined in propolis and pollen using the 2,4-dinitrophenylhydrazine method (Chang et al, 2002;Popova et al, 2004Popova et al, , 2007Lebranc et al, 2009;Tylkowski et al, 2010). An important parameter of honey is its color, which reflects the floral source (Bertoncelj et al, 2007) and can be determined by spectrophotometric measurement of the absorbance of a 50% honey solution at 635 nm and classified according to the Pfund scale (Ferreira et al, 2009;Lacerda et al, 2010).…”

“…Data on the antioxidant activity of honey from Malaysia suggest that the phenolics are responsible for free-radical scavenging and antioxidant activity. Another important class of compounds in products derived from bees are flavonoids (Chang et al, 2002;Popova et al, 2004Popova et al, , 2007Lebranc et al, 2009;Tylkowski et al, 2010). The total flavonoid content is generally determined using a spectrophotometric assay based on the formation of an aluminum chloride complex, which has been applied for quantification of flavones and flavonols in honey (Meda et al, 2005;Liberato et al, 2011).…”

“…The absorbance of the supernatant solution was measured at 486 nm against a methanol blank. A standard curve of pinocembrin was drawn within a concentration range of 5.0 x 10 -4 to 4.0 x 10 -3 mg/mL (Chang et al, 2002;Popova et al, 2004Popova et al, , 2007Tylkowski et al, 2010;Gómez-Caravaca et al, 2006).…”