Vöröshagyma (Allium cepa L.) 

A Kárpát-medencében majd minden ételünk alapvető összetevője, de a világban is a paradicsom után a legtöbbet termesztik belőle mintegy 135 országban. Országunkban Makó a legfontosabb termesztési területe a "BRONZ" alfajnak. Anti-oxidáns polifenolokban különösen a quercetinben és a luteolinban gazdag számos betegséget távol tart fogyasztóitól (Fuentes, Arias-Sante et al. 2020). Különösen a quercetin, a vöröshagyma fő flavonoljának feldúsulása figyelemre méltó (300 mg/kg), mivel 5 - 10-szerese is lehet benne, mint más zöldségekben és gyümölcsökben. Összevetve, a broccoli 100 mg/kg, az alma 50 mg/kg, és a kék áfonya mindössze 40 mg/kg mennyiségű quercetint tartalmaz.

Egy, az EFSA által is támogatott állítás, hogy a "BIOFLAVONOID-ok támogatják az egészséges immunrendszert" a vöröshagymában lévő bioflavonoidokra is igaz. Sőt, segíti az immunrendszert a vírusokkal folytatott ellenállásban. A quercetin továbbá elnyomja a vírusfertőzésekkel párhuzamban gyakori hisztamin oknélküli felszabadulását, és ezzel a kórokozók okozta allergikus szövődmények lehetőségét csökkenti ("citokin vagy bradikinin vihar"). A quercetinen kívül a vöröshagyma tartalmaz olyan bioflavonoidokat is, mint a luteolin. A kísérletek tanulságai szerint a quercetin, valamint az ábrán feltüntetett származékai, és a luteolin specifikusan a mutatott kötőhelyen megakadályozzák a koronatüske fehérjével rendelkező vírusok sejtjeinkbe jutását (Lopes, da Costa et al. 2020).

Fuentes, J., et al. (2020). "Low nanomolar concentrations of a quercetin oxidation product, which naturally occurs in onion peel, protect cells against oxidative damage." Food Chem 314: 126166.

• The occurrence of the quercetin oxidation metabolite 2-(3,4-dihydroxybenzoyl)-2,4,6-trihydroxy-3(2H)-benzofuranone (BZF), whose antioxidant potency is notably higher than the antioxidant potency of quercetin, was investigated in twenty quercetin-rich plant foods. BZF was identified (HPLC-DAD-ESI-MS/MS) only in the dry outer scales of onions and shallots. Aqueous extracts of onions (OAE) and shallots (SAE) were evaluated for their antioxidant and cytoprotective properties. OAE, whose potency did not differ from SAE, protected ROS-exposed Caco2 cells against oxidative (78%) and cellular (90%) damage at a 3 microg/L concentration (corresponding to 0.03 nM of BZF). After chromatographic resolution of OAE, the BZF peak accounted fully and exclusively for its antioxidant effect. The antioxidant effects of OAE and of a pure BZF were described by two perfectly overlapping curves whose concentration-dependence was within the 3 x 10(-4) to 10(2) nM BZF range. Such unprecedented low concentrations place BZF-containing plants on the frontier of the search for novel sources of antioxidants.

Lopes, B. R. P., et al. (2020). "Quercetin pentaacetate inhibits in vitro human respiratory syncytial virus adhesion." Virus Res 276: 197805.

• Human respiratory syncytial virus (hRSV) is one of the main etiological agents of diseases of the lower respiratory tract and is often responsible for the hospitalization of children and the elderly. To date, treatments are only palliative and there is no vaccine available. Natural products show exceptional structural diversity and they have played a vital role in drug research. Several investigations focused on applied structural modification of natural products to improved metabolic stability, solubility and biological actions them. Quercetin is a flavonoid that presents several biological activities, including anti-hRSV role. Some works criticize the pharmacological use of Quercetin because it has low solubility and low specificity. In this sense, we acetylated Quercetin structure and we used in vitro and in silico assays to compare anti-hRSV function between Quercetin (Q0) and its derivative molecule (Q1). Q1 shows lower cytotoxic effect than Q0 on HEp-2 cells. In addition, Q1 was more efficient than Q0 to protect HEp-2 cells infected with different multiplicity of infection (0.1-1 MOI). The virucidal effects of Q0 and Q1 suggest interaction between these molecules and viral particle. Dynamic molecular results suggest that Q0 and Q1 may interact with F-protein on hRSV surface in an important region to adhesion and viral infection. Q1 interaction with F-protein showed DeltaG= -14.22 kcal/mol and it was more stable than Q0. Additional, MTT and plate assays confirmed that virucidal Q1 effects occurs during adhesion step of cycle hRSV replication. In conclusion, acetylation improves anti-hRSV Quercetin effects because Quercetin pentaacetate could interact with F-protein with lower binding energy and better stability to block viral adhesion. These results show alternative anti-hRSV strategy and contribute to drug discovery and development.