Giffonins A–I, Antioxidant Cyclized Diarylheptanoids from the Leaves of the Hazelnut Tree (Corylus avellana), Source of the Italian PGI Product “Nocciola di Giffoni”

Abstract

Eight new diaryl ether heptanoids, giffonins A-H (1-8), and one diaryl heptanoid, giffonin I (9), were isolated from the methanol extract of the leaves of Corylus avellana. Its hazelnut is the PGI product of the Campania region (Italy) known as "Nocciola di Giffoni". The MeOH extract of C. avellana leaves and giffonins A-I (1-9) were evaluated for their inhibitory effects on human plasma lipid peroxidation induced by H2O2 and H2O2/Fe(2+), by measuring the concentration of TBARS (thiobarbituric acid reactive substances). Compounds 4 and 8 at 10 μM reduced both H2O2- and H2O2/Fe(2+)-induced lipid peroxidation by more than 60% and 50%, respectively, indicating higher activity than curcumin used as reference compound.

Quali-quantitative analysis of the phenolic fraction of the flowers of Corylus avellana, source of the Italian PGI product “Nocciola di Giffoni”: Isolation of antioxidant diarylheptanoids

“…Moreover, compounds 1e9 were identified by analysis of spectroscopic data in comparison to those reported in literature as (Matlawska et al, 1994) (Kirmizibekmez et al, 2014), quercetin 3-O-a-L-rhamnopyranoside (4) (Materska et al, 2003), giffonin I (5) (Masullo et al, 2015b), kaempferol 3-O-a-Lrhamnopyranoside (6) (Ahmed et al, 1989), kaempferol 3-O-(4 00 -cis-p-coumaroyl)-a-L-rhamnopyranoside (7) (Yang et al, 2013), kaempferol 3-O-(4 00 -trans-p-coumaroyl)-a-L-rhamnopyranoside (8) (Yang et al, 2013), and alnusone (9) (Masullo et al, 2015b).…”

“…Moreover, the 1 H NMR spectrum displayed signals due to a disubstituted trans-olefinic group at d 6.59 (m, H-9) and 5.82 (d, J ¼ 16.1 Hz, H-10), and four methylene groups at d 3.05 (2H, br t, J ¼ 6.5 Hz), 2.73 (2H, br t, J ¼ 6.5 Hz), 2.69 (2H, m), 2.37 and 2.35 (each 1H, m). The 13 C NMR spectrum of 10 showed 19 carbon signals, typical of diaryl ether heptanoid derivatives (Masullo et al, 2015b), comprising a signal at d 203.9, ascribable to a carbonyl group (Table 1). The signal at d 5.76 was attributed to H-6, which generally resonates at an abnormally high field, due to the anisotropic effect of the A ring in diaryl ether heptanoids (Masullo et al, 2015a(Masullo et al, , 2015b.…”

“…The 13 C NMR spectrum of 10 showed 19 carbon signals, typical of diaryl ether heptanoid derivatives (Masullo et al, 2015b), comprising a signal at d 203.9, ascribable to a carbonyl group (Table 1). The signal at d 5.76 was attributed to H-6, which generally resonates at an abnormally high field, due to the anisotropic effect of the A ring in diaryl ether heptanoids (Masullo et al, 2015a(Masullo et al, , 2015b. This observation together with the ROESY correla- 134.4 (C-5), 115.8 (C-6) and 32.0 (C-7) suggested the 1,2, dihydroxylation of the A-ring.…”

“…On the basis of the antioxidant activity reported for the MeOH extract of C. avellana leaves and for giffonins A-I (Masullo et al, 2015b;Shahidi et al, 2007) and with the aim to explore the antioxidant capacity of C. avellana flowers, the MeOH extract and the isolated compounds were evaluated for their inhibitory effects on human plasma lipid peroxidation induced by H 2 O 2 and H 2 O 2 /Fe 2þ , by measuring the concentration of TBARS (thiobarbituric acid reactive substances). Exposure of human plasma to strong chemical oxidants such as H 2 O 2 and H 2 O 2 /Fe 2þ resulted in enhanced level of plasma lipid peroxidation.…”

“…In our previous investigations we reported from the methanol extract of the leaves of C. avellana cultivar 'Tonda di Giffoni', sixteen diarylheptanoids, giffonins A-P, some of which able to prevent oxidative damages of human plasma lipids, induced by H 2 O 2 and H 2 O 2 /Fe 2þ (Masullo et al, 2015a(Masullo et al, , 2015b. To date, no investigation has been reported on the flowers of C. avellana.…”