Isolation, content determination, and in vitro activity study of new suona extract I from roses
Rosa rugosa Thunb. is a perennial deciduous shrub belonging to the Rosaceae family and the Rosaceae genus. Wild roses are distributed in temperate regions of East Asia, originating from northern China, Korea, Japan, the Kamchatka Peninsula, and the subarctic region of the Okhotsk Sea. Roses are the dried buds of roses, with a sweet and slightly bitter taste, a warm nature, and the function of soothing the liver and regulating qi, as well as regulating blood flow and meridians. They can be used to treat liver and stomach qi pain, nausea and vomiting caused by insufficient food intake, menstrual disorders, diarrhea, and pain caused by falls, rheumatism and rheumatism. Rose, as a medicinal and edible plant, is cultivated and planted in various parts of China. Its main production areas include Pingyin County in Shandong Province, Kushui Town in Gansu Province, Hotan Prefecture in Xinjiang, Weinan City in Shaanxi Province, Tongshan County in Jiangsu Province, and Miaofeng Mountain in Beijing.
The main chemical components of roses are phenolic compounds, volatile oils, polysaccharides, flavonoids, and tannins. Among them, research mainly focuses on the phenolic compounds and their antioxidant activity in rose petals, while there is little research on the pharmacological effects and biological activities of other components.
Hydrolyzable tannin compounds are a class of compounds formed by phenolic acids and their derivatives with glucose or polyols through glycosidic or ester bonds. Its pharmacological effects include various biological activities such as antioxidant, anti-tumor, antiviral, antibacterial, hypoglycemic, anti allergic, and anti lipid peroxidation. In the preliminary research, several hydrolysable tannic compounds with glycosidase inhibitory effects, including new suona extract I, were found in Xinjiang Hetian roses, with a total content of about 3% to 5% in dried rose petals. Okuda et al. isolated a new suona extract I from wild roses in Japan for the first time. According to reports, the new suona grass extract I has anti acne and anti-inflammatory activities, liver protection and antioxidant effects, and antibacterial effects.
This study isolated new suona extract I from roses produced in the Altai Mountains of Inner Mongolia, identified its structure, determined the content of new suona extract I in roses from different origins, investigated its inhibitory effect on α – glucosidase activity and antioxidant activity, and provided a theoretical basis for the development and application of rose health products that reduce postprandial blood sugar.

 

In this paper, a hydrolyzable tannin compound, neosuonagenin I, which is composed of gallic acid groups at positions 2 and 3 of glucose and HHDP (hexahydroxydiphenyl) groups at positions 4 and 5, was isolated and prepared from the extract of Arxan rose by Sephadex LH-20 column chromatography and semi preparative high-performance liquid chromatography. The terminal group of glucose in this compound is a free hydroxyl group, and two peaks were detected at a wavelength of 280nm in liquid chromatography analysis. The evaluation experiment of enzyme inhibitors using pNPG as a substrate found that the new suona extract I has a strong inhibitory effect relative to acarbose (IC50 of 38.00 μ g/mL), with an IC50 of 10.0 μ g/mL. The DPPH radical scavenging ability evaluation experiment showed that the new suona extract has strong antioxidant activity, with a half maximal scavenging rate IC50 of 8.1 μ g/mL for DPPH radicals.

Roses are rich in a large amount of hydrolyzable tannins, mainly containing compounds such as Neosuona I, Neosuona II, Rosarin A, Rosarin B, Rosarin D, Ephedra Tanning Pavilion, Ephedra Epiphyllum, Isoephedrine, etc. Among them, Neosuona Epiphyllum I has the highest content. These hydrolysable tannins are hydrolyzed into small molecule phenolic acid compounds and sugars or polyols under the action of acids, bases, and enzymes. In this study, the content of new suona extract I was determined in 11 roses from different origins. The results showed that all roses contained new suona extract I, with a content of 0.8% to 7.4%. Therefore, it can be seen that new suona extract I is one of the main components with relatively high content in hydrolysable compounds in roses. In vitro activity experiments showed that rose extracts from different regions exhibited inhibitory activity against α – glucosidase and scavenging activity against DPPH free radicals. Except for the Hetian rose from Xinjiang, roses from the other 10 regions showed higher inhibitory activity against α – glucosidase than the positive drug acarbose, indicating the presence of chemical components with α – glucosidase inhibitory function in rose medicinal materials, which can serve as effective ingredients for the development of new functions in roses. This study proves that the new suona extract I is one of the components in roses that inhibits alpha glucosidase activity and antioxidant activity. The higher the content of new suona herb I in rose extracts from different regions, the higher the corresponding α – glucosidase inhibitory activity and DPPH radical scavenging activity of the extracts, but there was no significant difference, indicating no dose-response relationship. This may be due to the differences in tannins or phenolic compounds with similar structures and activities of other new suona herb I in roses. Therefore, further research on other phenolic components in roses is necessary.