Quercetin 3-O-malonylglucoside

Hydrothermal extraction, a promising method for concentrating phenolic antioxidants from red osier dogwood (Cornus stolonifer) leaves and stems.[Pubmed:33083615]

Heliyon. 2020 Oct 8;6(10):e05158.

Red osier dogwood (ROD) (Cornus stolonifer) is a popular ornamental shrub in most parts of North America. It has a record of ethnopharmacological uses by native North Americans. With increasing awareness about the health benefits of natural antioxidants, efforts are needed to develop methods for producing plant-based antioxidants as sources of nutraceuticals or functional food ingredients. This study aimed at establishing an optimum temperature for hydrothermal extraction of phenolic compounds from the leaves and stems of ROD. Spray-dried extracts obtained from hydrothermal extraction at four different temperatures, as well as their raw materials and spent residue were analyzed for moisture content and water activity. The samples were extracted with organic solvent and their total phenolic content, phenolic composition and antioxidant activity were also determined. Moisture content was below 10% and the water activity was below 0.6 inclusive, which are recommended for storing dry plant products. Glucogallic acid, ellagic acid, rutin, Quercetin 3-O-malonylglucoside and quercetin were the phenolic compounds identified in all the samples. Rutin was the predominant compound. As expected, all the spray-dried extracts had higher phenolic content and antioxidant activity than the raw materials and spent materials. Among the temperatures studied, 98 degrees C was the most effective in extracting the phenolic compounds. The spray-dried extracts may find application in high-value antioxidant-rich products such as functional food ingredients and nutraceuticals. The spent materials retained a considerable amount of phenolic antioxidants and can therefore be useful in preparing antioxidant-rich animal feed.

Quercetin 3-O-malonylglucoside in the leaves of mulberry (Morus alba) is a functional analog of ghrelin.[Pubmed:32700782]

J Food Biochem. 2020 Sep;44(9):e13379.

Mulberry (Morus alba) leaf is traditionally consumed as a functional tea with remedial effects, such as preventing aging-related diseases. Two similar compounds, Quercetin 3-O-malonylglucoside, and kaempferol 3-O-malonylglucoside, were detected in mulberry leaves and found to be structural recombinant composites of teaghrelin and emoghrelin, two classes of non-peptidyl compounds functionally identified as analogs of ghrelin. Molecular modeling showed that these two mulberry compounds were able to enter and interact with the ghrelin receptor and theoretical calculation revealed that they were similar to emoghrelin but slightly weaker than teaghrelin in terms of interaction with the receptor. The relatively abundant compound, Quercetin 3-O-malonylglucoside was subjected to a bioactivity assay, and the result confirmed that it was able to increase the growth hormone secretion of rat anterior pituitary cells. It seems that Quercetin 3-O-malonylglucoside is also a functional analog of ghrelin and presumably a key ingredient for the anti-aging activity of mulberry leaves. PRACTICAL APPLICATIONS: According to this study, Quercetin 3-O-malonylglucoside and kaempferol 3-O-malonylglucoside are suggested to serve as active ingredients in tea products prepared from mulberry leaves. Contents of these two compounds might be used as key factors for breeding or screening mulberry varieties for commercial cultivation. Moreover, water extract of mulberry leaves containing these compounds can be used as an adequate supplement for functional food.