Biodiversity of Salix spp. Honeydew and Nectar Honeys Determined by RP‐HPLC and Evaluation of Their Antioxidant Capacity

Abstract

Rare unifloral willow (Salix spp.) honeys obtained from nectar or honeydew were investigated by direct RP-HPLC-DAD method in order to identify and quantify compounds that can be used as possible markers of their origin. Antioxidant and antiradical activities of willow honeys were evaluated using FRAP (=ferric reducing antioxidant assay) and DPPH (=1,1-diphenyl-2-picrylhydrazyl radical) tests, respectively. Also HMF (=5-(hydroxymethyl)furfural), diastase activity, and CIE L*a*b*C*h* chromatic coordinates were evaluated. Abscisic acids (ABA) are typical of willow nectar honey, with a predominance of (Z,E)-ABA on (E,E)-ABA (98.2 and 31.7 mg/kg, resp.). Kinurenic acid and salicylic acid are useful to mark willow honeydew honey. The proposed HPLC-DAD method proved to be easy and reliable to identify the two different Salix spp. honeys, being not affected from any sample preparation artifact. Total antioxidant activity measured with the FRAP assay ranged from 3.2 to 12.6 mmol Fe(2+) /kg, and the antiradical activity measured with the DPPH assay ranged from 0.6 to 3.0 mmol TEAC (=Trolox equivalent antioxidant capacity)/kg in nectar and honeydew honeys, respectively. Salix spp. nectar and honeydew honeys proved to be two completely different honeys, because, besides color attributes, they show different antioxidant properties and specific compounds.

HPTLC Phenolic Profiles as Useful Tools for the Authentication of Honey

“…Abscisic acid was found in high quantities. In relation to the literature data, abscisic acid was found in Polish (Jerkovic et al 2014) and Croatian willow honey (Tuberoso et al 2011) in concentrations of 25.8-35.6 and 31.7-98.2 mg/kg, respectively. A similar dependence between the composition of the willow honey samples and the harvest year was observed by both HPTLC and HPLC.…”

Monofloral honeys by Sicilian black honeybee ( Apis mellifera ssp. sicula ) have high reducing power and antioxidant capacity

“…This was not unexpected. Honeydew honeys have been reported to possess higher total phenol and flavonoid content, and higher antioxidant power than many nectar honeys (Escriche et al, 2014; Escuredo et al, 2013; Rodríguez Flores et al, 2015; Tuberoso et al, 2011). The TPC and TF reducing components of the two honeydews, however, were substantially comparable with those in the ferula and dill monofloral honeys (Table 1).…”

Riboflavin and lumichrome in Dalmatian sage honey and other unifloral honeys determined by LC–DAD technique

“…Water content, electrical conductivity, diastase (a-amilase), total polyphenols and antioxidant activity assays Determination of water content was performed with an ATAGO portable refractometer (Atago Co. Ltd., Tokyo, Japan) which allows to measure the percentage of water from 12% to 26%. Electrical conductivity was measured in a solution of 20 g of honey in 100 mL of low-conductivity water at 20°C using a Hanna HI 8733 conductometer (Hanna, Baranzate, Milan, Italy) according to Tuberoso, Jerković , Bifulco, and Marijanovic (2011). Diastase activity was evaluated with a spectrophotometric method that uses the Phadebas Ò amylase test according to the International Honey Commission.…”

“…The determination was performed with a spectrophotometer UV-Visible Varian Cary 50 scan (Varian, Leinì, Torino) at a wavelength of 620 nm. The total phenol (TP) content, antiradical (1,1-diphenyl-2-picryl-hydrazyl assay, DPPH) and total antioxidant (ferric reducing antioxidant assay, FRAP) activities were measured through spectrophotometric determinations as described by Tuberoso, Jerković , et al (2011). Briefly, the TP content was determined according to a modified Folin-Ciocalteu method.…”

“…Detection and quantitative analyses of riboflavin, lumichrome and specific compounds used as markers (homogentisic acid, kynurenic acid, abscisic acid diastereomers, phenyllactic acid, caffeine, methyl syringate, benzoic acid, caffeic acid and p-coumaric acid) were carried out using an LC-DAD method as described by Tuberoso, Jerković , et al (2011). Briefly, a Varian system ProStar HPLC fitted with a ThermoSeparation diode array detector SpectroSystem UV 6000lp (ThermoSeparation, San Jose, CA, USA) set at 210, 280 and 360 nm was used.…”