A new flavonol glycoside and other flavonoids from the aerial parts of Taverniera aegyptiaca

Isolation of flavonoids from the aerial parts of Taverniera aegyptiaca Bioss. (Fabaceae) led to identification of one new flavonol glycoside, isorhamnetin-3-O-α-l-rhamnopyranosyl-(1→2)-α-l-arabinopyranoside (1), along with eleven compounds, which previously have not been isolated from this plant quercetin-3-O-α-l-rhamnopyranosyl-(1→2)-[α-l-rhamnopyranosyl-(1→6)-β-d-galactopyranoside] (2), isorhamnetin-3-O-α-l-arabinopyranoside (3), quercetin-3-O-α-l-rhamnopyranosyl-(1→6)-β-d-glucopyranoside (4), isorhamnetin-3-O-α-l-rhamnopyranosyl-(1→6)-β-d-glucopyranoside (7), isorhamnetin 3-O-α-l-rhamnopyranosyl-(1→2)-[α-l-rhamnopyranosyl-(1→6)-β-d-galactopyranoside] (8), isorhamnetin 3-O-α-l-rhamnopyranosyl-(1→2)-[α-l-rhamnopyranosyl-(1→6)-β-d-glucopyranoside] (9), kaempferol 3-O-α-l-rhamnopyranosyl-(1→2)-[α-l-rhamnopyranosyl-(1→6)-β-d-galactopyranoside] (10), isorhamnetin (11), 4,4′-dihydroxy-2′-methoxychalcone (12), formononetin (13) and calycosin (15)] and some compounds already known from this plant [quercetin-3-O-robinobioside (5), isorhamnetin-3-O-robinobioside (6), afrormosin (14) and odoratin (16)].     

The Isorhamnetin-Containing Fraction of Philippine Honey Produced by the Stingless Bee Tetragonula biroi Is an Antibiotic against Multidrug-Resistant Staphylococcus aureus

Honey exhibits antibacterial and antioxidant activities that are ascribed to its diverse secondary metabolites. In the Philippines, the antibacterial and antioxidant activities, as well as the bioactive metabolite contents of the honey, have not been thoroughly described. In this report, we investigated the in vitro antibacterial and antioxidant activities of honey from Apis mellifera and Tetragonula biroi, identified the compound responsible for the antibacterial activity, and compared the observed bioactivities and metabolite profiles to that of Manuka honey, which is recognized for its antibacterial and antioxidant properties. The secondary metabolite contents of honey were extracted using a nonionic polymeric resin followed by antibacterial and antioxidant assays, and then spectroscopic analyses of the phenolic and flavonoid contents. Results showed that honey extracts produced by T. biroi exhibits antibiotic activity against Staphylococcal pathogens as well as high antioxidant activity, which are correlated to its high flavonoid and phenolic content as compared to honey produced by A. mellifera. The bioassay-guided fractionation paired with Liquid Chromatography Mass Spectrometry (LCMS) and tandem MS analyses found the presence of the flavonoid isorhamnetin (3-methylquercetin) in T. biroi honey extract, which was demonstrated as one of the compounds with inhibitory activity against multidrug-resistant Staphylococcus aureus ATCC BAA-44. Our findings suggest that Philippine honey produced by T. biroi is a potential nutraceutical that possesses antibiotic and antioxidant activities.     

Flavonoid glycosides from Astragalus galegiformis leaves

New flavonoid oligosides, the structures of which were established by chemical transformations and UV, IR, PMR, and ¹³C NMR spectra, were isolated from Astragalus galegiformis leaves. __________ Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 555–558, November–December, 2006.     

沙棘果粉中异鼠李素和芦丁标准物质的制备与鉴定

异鼠李素（IS）和芦丁（RU）是沙棘中存在的两种黄酮类化合物,具有很强的抗氧化活性,能有效清除体内的自由基。由于其在沙棘原料中含量低,还原性强,其标准品的制备和提纯难度较大。该研究采用乙醇溶解和高压液相制备相结合的方法制备了高纯度的IS和RU,并通过红外光谱、紫外光谱、质谱和核磁共振C/H谱进一步鉴定其化学结构。采用典型高效液相色谱法对获得的IS和RU产品的均一性（瓶内和瓶内）和稳定性（长期：6个月,－20 ℃;短期：1周,4 ℃和－20 ℃）进行验证。统计分析数据表明,IS和RU产品具有良好的均匀性和稳定性。采用多家实验室（n = 8）联合定值方式确定所制备的IS和RU标准物质的纯度分别为99.16%和99.22%,扩展不确定度分别为0.14%和0.13%。该研究获得的IS和RU标准物质可作参考物质用于药物分析或沙棘类产品的质量评价,具有良好的应用前景。该研究为沙棘中IS和RU标准物质的制备和质量验证提供了有效的方法,可推广应用于其他标准物质的制备过程。     

碳量子点荧光猝灭法检测药物中的异鼠李素

以L-天冬氨酸为碳源,尿素为氮源,采用微波加热法制备荧光碳量子点(CDs),得到的CDs具有球形结构和单一分散性,平均粒径约为5 nm。红外光谱、X射线光电子能谱、紫外和荧光光谱的表征结果表明,合成的CDs具有较高的荧光稳定性,良好的水溶性和对异鼠李素(ISOR)高的选择性。在优化条件下,ISOR浓度在0.22～180 nmol/L范围内时与CDs荧光猝灭程度(I_(F_0)/I_F)呈良好的线性关系,检出限(LOD)为1.32 nmol/L,回收率为90.8%～107%。结果表明,该CDs可用于ISOR的快速、高效、灵敏检测。