Identification of Major Flavone C-Glycosides and Their Optimized Extraction from Cymbidium kanran Using Deep Eutectic Solvents.

Cymbidium kanran, an orchid exclusively distributed in Northeast Asia, has been highly valued as a decorative plant and traditional herbal medicine. Here, C. kanran extracts were prepared in 70% aqueous methanol using ultrasound-assisted extraction (UAE) and subjected to liquid chromatography-photodiode array detection and ultra-high performance liquid chromatography-quadrupole-time-of-flight-mass spectrometry analysis, which were used for quantitative and qualitative analysis, respectively. It was found that the extracts were rich in flavone C-glycosides including vicenin-2, vicenin-3, schaftoside, vitexin, and isovitexin. Ten deep eutectic solvents (DESs) were synthesized by combining choline chloride (hydrogen bond acceptor) with various polyols and diols (hydrogen bond donors) and were tested as a medium for the efficient production of extracts enriched with potentially bioactive flavone C-glycosides from C. kanran. A DES named ChCl:DPG, composed of choline chloride and dipropylene glycol at a 1:4 molar ratio, exhibited the best extraction yields. Then, the effects of extraction conditions on the extraction efficiency were investigated by response surface methodology. Lower water content in the extraction solvent and longer extraction time during UAE were desirable for higher extraction yields. Under the statistically optimized conditions, in which 100 mg of C. kanran powder were extracted in 0.53 mL of a mixture of ChCl:DPG and water (74:26, w/w) for 86 min, a total of 3.441 mg g-1 flavone C-glycosides including 1.933 mg g-1 vicenin-2 was obtained. This total yield was 196%, 131%, and 71% more than those obtained using 100% methanol, water, and 70% methanol, respectively.

Characterization of a Major Allergen from Mongolian Oak, Quercus mongolica, a Dominant Species of Oak in Korea.

BACKGROUND: Oaks are the most common trees in Korean forests, and Mongolian oak, Quercus mongolica, is the dominant species. However, no allergen has been characterized from Mongolian oak. In this study, we tried to characterize a major allergen from Mongolian oak. METHODS: A molecule homologous to pathogenesis-related 10 (PR-10)-like protein, Que m 1, was cloned by RT-PCR. Its recombinant protein, along with Que a 1, an allergen from white oak (Q. alba), was produced. The allergenicity and diagnostic value of recombinant Que m 1, Que a 1, and Bet v 1 proteins were compared by ELISA using sera from oak-sensitized subjects. A basophil activation test was also performed using CD63 expression as an activation marker. RESULTS: Que m 1 sequence shares 57.5-96.2% amino acid sequence identity with PR-10-like allergens from various plants. Specific IgE to recombinant Que m 1, Que a 1, and Bet v 1 were detected in 92.0, 74.0, and 38.0% of 50 serum samples from Korean tree pollinosis patients. Recombinant Que m 1 was able to inhibit IgE reactivity to Que a 1 and Bet v 1, indicating its strong cross-reactivity. The activation patterns of basophils from 5 patients were similar in terms of the CD63 expression and protein concentration of challenged Bet v 1 and Que m 1. CONCLUSIONS: A major allergen, Que m 1, was cloned, and its recombinant protein was produced from Mongolian oak, a dominant species in Korea. Recombinant Que m 1 is potentially useful for the diagnosis and treatment of tree pollinosis in Korea.