hrvatski

Sadržaj polifenola, nitrata i antioksidacijska aktivnost metanolnih ekstrakata koprive

The goal of our study was to determine polyphenol content (total phenols ; TP, total flavonoids ; TF, total hydroxycinnamic acids ; THA, total flavanols ; TFL and total proanthocyanidins ; TPAN), nitrate content and antioxidant activity (ABTS, DPPH i FRAP) of methanolic extracts (80 v/v) of nettle leaf collected on two locations in Istria (Valtura ; V and Poreč ; P) in two growth stages (vegetative ; v and inflorescence ; if). In order to determine the correlation between the antioxidant activity variables (DPPH, ABTS and FRAP) and the concentration of polyphenolic metabolites (TP, TF, THA, TFL, TPAN) and nitrate, the Pearson correlation coefficient was calculated. The highest content of TP was measured in the sample "Pif". The highest content of TF, THA, TFL and TPAN was measured in the samples "Pif" and "Pv". The nettle samples from Poreč showed 2.26±0.43, 2.89±0.73, 3.67±0.39, 3.32±0.16 and 1.18±0.01 times higher values compared to samples from Valtura for the TP, TF, THA, TFL and TPAN methods, respectively. The highest nitrate content was measured in the sample "Vv" (246.89±16.24 mg NO3-/g dw) and the lowest in the samples "Pif" (36.77±2.16 mg NO3-/g dw) and "Pv" (57.93±9.84 mg NO3-/g dw). In most nettle extracts, a strong antioxidant activity was measured in all three methods with the exception of the samples "Vv" and "Vc" in ABTS method. The percentage of inhibition in the nettle samples ranged from 66.26-69.24 for DPPH and 46.59-96.76 for ABTS radical in relation to the Trolox as standard (DPPH ; 94.32 and ABTS ; 98.93). In the FRAP method, the percentage of reduction of Fe3+ in the nettle samples ranged from 95.45-97.52 compared to the FeSO4 as standard (98.85). The highest values in ABTS and FRAP methods were measured in the samples "Pif" and "Pv". Statistically significant difference in the percentage of DPPH radical inhibition was not recorded in all nettle samples. A very strong positive correlation was recorded between polyphenols (TP, TF, THA, TFL) and antioxidant activity (ABTS and FRAP), while a very strong negative correlation was recorded between nitrates, polyphenols (TP, TF, THA, TFL) and antioxidant activity (ABTS and FRAP). The obtained results indicate that the content of polyphenols and nitrates is significantly influenced by the location of plant collection.

Urtica dioica L., polifenoli, nitrati, antioksidacijska aktivnost

nije evidentirano

engleski

Polyphenols, nitrate and antioxidant activity of methanolic extracts of nettle

The goal of our study was to determine polyphenol content (total phenols ; TP, total flavonoids ; TF, total hydroxycinnamic acids ; THA, total flavanols ; TFL and total proanthocyanidins ; TPAN), nitrate content and antioxidant activity (ABTS, DPPH i FRAP) of methanolic extracts (80 v/v) of nettle leaf collected on two locations in Istria (Valtura ; V and Poreč ; P) in two growth stages (vegetative ; v and inflorescence ; if). In order to determine the correlation between the antioxidant activity variables (DPPH, ABTS and FRAP) and the concentration of polyphenolic metabolites (TP, TF, THA, TFL, TPAN) and nitrate, the Pearson correlation coefficient was calculated. The highest content of TP was measured in the sample "Pif". The highest content of TF, THA, TFL and TPAN was measured in the samples "Pif" and "Pv". The nettle samples from Poreč showed 2.26±0.43, 2.89±0.73, 3.67±0.39, 3.32±0.16 and 1.18±0.01 times higher values compared to samples from Valtura for the TP, TF, THA, TFL and TPAN methods, respectively. The highest nitrate content was measured in the sample "Vv" (246.89±16.24 mg NO3-/g dw) and the lowest in the samples "Pif" (36.77±2.16 mg NO3-/g dw) and "Pv" (57.93±9.84 mg NO3-/g dw). In most nettle extracts, a strong antioxidant activity was measured in all three methods with the exception of the samples "Vv" and "Vc" in ABTS method. The percentage of inhibition in the nettle samples ranged from 66.26-69.24 for DPPH and 46.59-96.76 for ABTS radical in relation to the Trolox as standard (DPPH ; 94.32 and ABTS ; 98.93). In the FRAP method, the percentage of reduction of Fe3+ in the nettle samples ranged from 95.45-97.52 compared to the FeSO4 as standard (98.85). The highest values in ABTS and FRAP methods were measured in the samples "Pif" and "Pv". Statistically significant difference in the percentage of DPPH radical inhibition was not recorded in all nettle samples. A very strong positive correlation was recorded between polyphenols (TP, TF, THA, TFL) and antioxidant activity (ABTS and FRAP), while a very strong negative correlation was recorded between nitrates, polyphenols (TP, TF, THA, TFL) and antioxidant activity (ABTS and FRAP). The obtained results indicate that the content of polyphenols and nitrates is significantly influenced by the location of plant collection.

Urtica dioica L., polyphenols, nitrate, antioxidant activity

nije evidentirano