Effect of Enzymatically Modified Isoquercitrin, a Flavonoid, on Symptoms of Japanese Cedar Pollinosis: A Randomized Double-Blind Placebo-Controlled Trial

Abstract

Background: Flavonoids exert antiallergic and antioxidant effects. We investigated the efficacy of enzymatically modified isoquercitrin (EMIQ), a flavonoid, to relieve symptoms of pollinosis. Methods: In a parallel-group, double-blind placebo-controlled study design, 20 subjects with Japanese cedar pollinosis took two capsules daily of 100 mg EMIQ or a placebo for 8 weeks during the pollen season. Subjective symptoms and activities of daily living (ADL) scores were recorded every day, and the quality of life (QOL) score was obtained every 4 weeks. Blood sampling was performed before and after the study to measure serum cytokines, chemokines, IgE, quercetin and oxidized biomarkers. Results: During the entire study period, total ocular score and ocular itching score for the EMIQ group were significantly lower (p < 0.05) than for the placebo group. When limited to the individual periods, total symptom score for the EMIQ group was significantly lower (p < 0.05, week 4–5) than that for the placebo group while other scores for the EMIQ group, such as total nasal score (p = 0.06, week 4–5), nasal obstruction score (p = 0.08, week 4–5), lacrimation score (p = 0.06, week 5–6), ocular congestion score (p = 0.08, week 4–7) and ADL score (p = 0.08, week 4–7), all tended to be lower. The levels of serum cytokines such as interleukin (IL)-4, IL-5, IL-12, IL-13, interferon-γ, and eotaxin and IgE were not significantly downregulated by the intake of EMIQ but the serum concentrations of oxidized low-density lipoprotein and thymus and activation-regulated chemokine were reduced. Conclusion: Intake of the quercetin glycoside EMIQ was safe and influenced ocular symptoms caused by pollinosis.

Therapeutic effect of topical administration of red onion extract in a murine model of allergic rhinitis

“…Remberg et al . 20 have reported that significant nasal and ocular symptom relief was observed in allergic rhinitis patients with topical nasal application of Artemisia abrotanum L. extract, which contains flavonols such as centauredin, casticin and quercetin. Thus, we also thought that topical application of onion extracts might have effects for control of allergic rhinitis symptoms.…”

Flavonoids and Asthma

“…Indeed, the results of recent clinical trials using flavonoid extracts or flavonoids indicate that flavonoids have beneficial effects on allergic rhinitis [104,105,106,107,108,109,110,111,112]. …”

Flavones and Flavonols may have Clinical Potential as CK2 Inhibitors in Cancer Therapy

“…141 With respect to quercetin, the approved food additive enzymatically-modified isoquercitrin (EMIQ), unlike quercetin, is highly soluble, but is metabolized to yield free quercetin at the intestinal brush border; a human pharmacokinetic study found that when equimolar amounts of quercetin and EMIQ were administered orally, the plasma levels of quercetin achieved were twenty-fold higher with EMIQ. [147][148][149][150][151] This agent apparently has not yet been tested in rodent tumor models.…”