Flavonoids of Lotus (Nelumbo nucifera) Seed Embryos and Their Antioxidant Potential

Flavonoids from lotus (Nelumbo nucifera) seed embryos were fractionated over a macroporous resin chromatography into 2 main fractions (I and II), and subsequently identified by high‐performance liquid chromatography coupled with tandem mass spectrometry (HPLC‐MS²). Sixteen flavonoids were identified in lotus seed embryos, including 8 flavonoid C‐glycosides and 8 flavonoid O‐glycosides, in which the flavonoid C‐glycosides were the main flavonoids. Among them, 2 flavonoid O‐glycosides (luteolin 7‐O‐neohesperidoside and kaempferol 7‐O‐glucoside) were identified in lotus seed embryos for the 1st time. For further elucidating the effects of flavonoid C‐glycosides to the bioactivities of lotus seed embryos, we compared the differences of the flavonoids and their antioxidant activities between leaves and seed embryos of lotus using the same methods. The results showed the antioxidant activity of flavonoids in lotus seed embryos was comparable or higher than that in lotus leaves, whereas the total flavonoid content in seed embryos was lower than lotus leaves which only contained flavonoid O‐glycosides. The flavonoid C‐glycosides of lotus seed embryos had higher antioxidant properties than the flavonoid O‐glycosides presented in lotus leaves. This study suggested that the lotus seed embryos could be promising sources with antioxidant activity and used as dietary supplements for health promotion.     

Influence of autoclave treatment and enzymatic hydrolysis on the antioxidant activity of <Emphasis Type="Italic">Opuntia ficus</Emphasis>-<Emphasis Type="Italic">indica</Emphasis> fruit extract

The objectives of this study were to obtain Opuntia ficus-indica fruit (OFIF) extract by autoclave treatment, to convert the flavonoid glycosides in the autoclave extract (AE) to aglycones by enzymatic hydrolysis, and to compare the antioxidant activity of AE and OFIF extracts obtained by other conventional methods. It was revealed that the total polyphenol and flavonoid content and antioxidant activity of AE were higher than those of water extract but were a slightly lower than those of ethanol extract, which indicates that autoclave treatment might be an efficient extraction method for OFIF. Moreover, it was confirmed that the conversion of various flavonoid glycosides to aglycones in all the OFIF extracts does not significantly affect the antioxidant activities. Therefore, it is extrapolated that the antioxidant activity might be correlated to the intestinal absorption rates and metabolic pathway induction upon oral administration rather than the structure of compound itself.     

Antioxidant flavonoid glycosides from the leaves of Ficus pumila L.

The Okinawan folks in Japan use Ficus pumila L. as a beverage or herbal medicine to treat diabetes and high blood pressure. Four flavonoid glycosides were isolated and identified as rutin (1 and 3), apigenin 6-neohesperidose (2), kaempferol 3-robinobioside (4) and kaempferol 3-rutinoside (5). Among these compounds, rutin exhibited the strongest antioxidant activity in DPPH radical scavenging assay and superoxide radical inhibition assay. The preparation of Ooitabi leaves in water provide sufficient amount of flavonoid glycosides to the Okinawan although 50% of aqueous ethanol extracted these flavonoid glycosides more effectively. These results show the potential of Ooitabi leaves as a natural source of antioxidant for health management.     

Dietary flavonoid aglycones and their glycosides: Which show better biological significance?

The dietary flavonoids, especially their glycosides, are the most vital phytochemicals in diets and are of great general interest due to their diverse bioactivity. The natural flavonoids almost all exist as their O-glycoside or C-glycoside forms in plants. In this review, we summarized the existing knowledge on the different biological benefits and pharmacokinetic behaviors between flavonoid aglycones and their glycosides. Due to various conclusions from different flavonoid types and health/disease conditions, it is very difficult to draw general or universally applicable comments regarding the impact of glycosylation on the biological benefits of flavonoids. It seems as though O-glycosylation generally reduces the bioactivity of these compounds - this has been observed for diverse properties including antioxidant activity, antidiabetes activity, anti-inflammation activity, antibacterial, antifungal activity, antitumor activity, anticoagulant activity, antiplatelet activity, antidegranulating activity, antitrypanosomal activity, influenza virus neuraminidase inhibition, aldehyde oxidase inhibition, immunomodulatory, and antitubercular activity. However, O-glycosylation can enhance certain types of biological benefits including anti-HIV activity, tyrosinase inhibition, antirotavirus activity, antistress activity, antiobesity activity, anticholinesterase potential, antiadipogenic activity, and antiallergic activity. However, there is a lack of data for most flavonoids, and their structures vary widely. There is also a profound lack of data on the impact of C-glycosylation on flavonoid biological benefits, although it has been demonstrated that in at least some cases C-glycosylation has positive effects on properties that may be useful in human healthcare such as antioxidant and antidiabetes activity. Furthermore, there is a lack of in vivo data that would make it possible to make broad generalizations concerning the influence of glycosylation on the benefits of flavonoids for human health. It is possible that the effects of glycosylation on flavonoid bioactivity in vitro may differ from that seen in vivo. With in vivo (oral) treatment, flavonoid glycosides showed similar or even higher antidiabetes, anti-inflammatory, antidegranulating, antistress, and antiallergic activity than their flavonoid aglycones. Flavonoid glycosides keep higher plasma levels and have a longer mean residence time than those of aglycones. We should pay more attention to in vivo benefits of flavonoid glycosides, especially C-glycosides.     

油菜蜂花粉黄酮醇苷的体内外抗氧化研究

以油菜蜂花粉黄酮醇苷组分为原料,以还原力和DPPH 自由基清除率为指标研究黄酮醇苷在化学模拟体系中的抗氧化活性。结果表明,油菜蜂花粉黄酮醇苷的抗氧化活性不及其苷元成分。以CCl4 制备小鼠脂质过氧化损伤模型,通过体内自由基发生体系进一步研究花粉黄酮醇苷的抗氧化作用,并对可能的作用机制进行探讨。结果显示：油菜蜂花粉黄酮醇苷组分能够显著地降低脂质过氧化小鼠肝匀浆和血清中MDA 含量,提高小鼠SOD 活性和总抗氧化能力(T-AOC),对脂质过氧化损伤有很好的保护作用,原因可能是体内有关酶系可将黄酮醇苷水解使其游离出酚羟基而发挥作用。本研究进一步肯定了油菜蜂花粉黄酮醇苷对机体氧化损伤的保护作用。     

Determination of flavonoids by LC/MS and anti-inflammatory activity in Moringa oleifera

Moringa oleifera is an important multipurpose tropical tree under-recognized for its nutritional and medicinal properties. Leaves of moringa collected from sub-Sahara Africa were analyzed for phenolic components by HPLC–UV–MS. Twelve flavonoids were identified, including quercetin and kaempferol glucosides and glucoside malonates as major constituents. To facilitate quantitative analysis, acid hydrolysis during extraction of moringa samples was employed to convert the conjugates into their respective flavonoid aglycones, allowing accurate quantitation of total flavonoids as aglycones. Validation of the method demonstrated recoveries ranging from 92.6% to 107.5% for the two analytes. Using this method, total flavonoids from moringa collected from Ghana, Senegal and Zambia were determined and their content ranged from 0.18% to 1.64% (g/dry weight) across the respective environment or country of production and by variety. Moringa was found to exhibit anti-inflammatory activity of constituents-rich varieties. As flavonoid malonates are among the major constituents in the original plant material, a study examining thermal stability of flavonoid malonyl derivatives showed that these compounds were not thermally stable and easily cleaved to yield their respective flavonoid glycosides.     

LC–DAD–ESIMS/MS characterization of antioxidant and anticholinesterase constituents present in the active fraction from Persicaria hydropiper

Persicaria hydropiper or ‘kesum’ is a herb used extensively as flavoring agent in food. The antioxidant activity was evaluated by measuring the hydroperoxide production resulting from linoleic acid oxidation using ferric thiocyanate (FTC) as well as the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging ability. Moreover, inhibition activity against cholinesterase, an enzyme that responsible in several physio-pathological processes, was also determined. Identification of phytochemical constituents in the bioactive fraction of P. hydropiper was carried out by LC–DAD–ESIMS/MS technique. Fifteen compounds were identified including flavonoids, flavonoid glycosides and phenylpropanoid glycosides. Six of the compounds were isolated and their structures were elucidated in order to confirm their identities. The antioxidant and antiacetylcholinesterase activities of the isolated compounds were also evaluated.     

超高效液相色谱-质谱联用技术解析沙棘果超临界CO2萃取物中黄酮类天然产物结构

采用超临界CO2萃取技术获得沙棘果油,通过超高效液相色谱-质谱联用技术和Peakview色谱工作站拟合、二级质谱解析和紫外光谱及质谱数据比对,确定有关化合物的组成和分子结构。共鉴定出沙棘果超临界CO2萃取物中含有18?种黄酮类化合物,其中包括8?种黄酮醇苷元及黄酮醇苷,3?种二氢黄酮醇苷元及二氢黄酮醇苷,5?种黄酮苷元及黄酮苷,1?种二氢黄酮苷元和1?种黄烷醇苷,其中芹菜素-6-C-葡萄糖苷-8-C-木糖苷、儿茶素-7-吡喃葡萄糖苷、苜蓿素、紫罗兰素、刺槐黄素这5?种黄酮首次被发现存在于沙棘中。     

Comparison of methods for the hydrolysis of flavonoids and phenolic acids from onion and spinach for HPLC analysis

For the quantitative determination of individual flavonoid glycosides in plant materials, the glycosides are normally hydrolysed and the resulting aglycones are identified and quantified. However, the hydrolysis conditions which result in optimal breakdown of glycosides are too harsh for some of the other phenolic compounds present in the same plant material. Therefore, the effects of different hydrolysis conditions and different antioxidants on pure flavonoid glycones and aglycones were studied. On the basis of the results obtained with standards, suitable hydrolysis methods for red spring onion and spinach were developed. The best results from these vegetables were obtained by refluxing at 80 °C for 2 h with 1.2 M HCl in 50% aqueous methanol with addition of 2 mg ascorbic acid as an antioxidant. The method developed in this study is suited to the screening of flavonoids in vegetables and leafy vegetables.     

Polyphenolic compounds and anthocyanin content of Prosopis nigra and Prosopis alba pods flour and their antioxidant and anti-inflammatory capacities

The aim of this study was to determine the content of total free and bound phenolics, free and bound flavonoids, anthocyanins, and alkaloids and the profile of polyphenols of edible ripe pods of Prosopis alba and Prosopis nigra.P. alba flour showed significantly higher total (sum of Free- and Bound) phenolic content and total flavonoid compounds than P. nigra (p < 0.05) while P. nigra had higher concentrations of anthocyanins than P. alba (p < 0.05). The P. nigra flour shows a pattern characterized by the occurrence of anthocyanins as well as 14 flavonoid glycosides, with higher chemical diversity than P. alba, which shows 8 flavonoid glycosides as relevant constituents. The main compounds were quercetin O-glycosides and apigenin-based C-glycosides. The phenolic composition of two South American algarrobo pod flour is presented for the first time. P. nigra pods having higher content of anthocyanins are darker (purple) than those of P. alba (light brown). Furthermore, the sugar-free polyphenolic extracts of P. nigra and P. alba as well as anthocyanins enriched extracts from P. nigra showed antioxidant activity. P. nigra and P. alba polyphenolic extracts showed activity against a pro-inflammatory enzyme. In conclusion, algarrobo pods meal contained biologically active polyphenols, with a positive impact on human health.     

Direct characterisation of phenolic antioxidants in infusions from four Mapuche medicinal plants by liquid chromatography with diode array detection (HPLC-DAD) and electrospray ionisation tandem mass spectrometry (HPLC-ESI-MS)

A simple, fast and direct method was developed for the qualitative analysis of phenolic constituents from infusions of Mapuche medicinal plants. Teas made of Linum chamissonis Schiede, Quinchamalium chilensis Mol., Adesmia emarginata Clos. and Escallonia illinita K. Presl. were analysed by high-performance liquid chromatography with diode array detector (HPLC-DAD) and electrospray mass spectrometry (ESI-MS). This technique allowed for the first time the tentative identification of 16 phenolic compounds in E. illinita, 27 in Q. chilensis, 10 in L. chamissonis and 19 in A. emarginata. The compounds were mainly phenolic acids, flavonoid glycosides, anthocyanins and tannins. The total phenolic and flavonoid content of the infusions was assessed as well as the free radical scavenging capacity measured by the bleaching of a solution of the 2,2-diphenyl-1-picrylhydrazyl (DPPH⁻) radical. From the four species, Q. chilensis exhibited the strongest antioxidant activity with highest total phenolic and flavonoid content.     

瑞香属植物化学成分及生物活性研究进展

瑞香属植物自古是药用性植物。近年来研究发现,瑞香属植物主要含二萜类、香豆素类、木脂素类、黄酮及双黄酮类等多种活性成分。研究证明其具有抗炎、免疫调节、镇痛、抑菌、抗肿瘤、降血压、抗HIV、抗白血病、抗血栓形成和抑制蛋白激酶等生物活性。全文简要综述了国内外对瑞香属植物化学成分及生物活性的新近研究进展。     

The influence of isoflavone glycosides on the taste of subterranean clover leaves

Four variants of subterranean clover cultivar Geraldton were fed to sheep. One variant, whose flavonoid glycosides were stable due to absence of glucosidase activity in the leaves, was more distasteful to the sheep than were the other clovers. These results suggest that flavonoid glycosides may be unpalatable to the sheep whilst the products of hydrolysis (glucose and aglycone) are not. Taste testing by human subjects of seven purified isoflavone glycosides indicated a slight but distinctive astringent–bitter taste in contrast to the lack of taste of the aglycones.     

Flavonoid recovery and stability from Ginkgo biloba subjected to a simulated digestion process

Absorption from the diet is normally a prerequisite for the potential in vivo beneficial role of flavonoids. Antioxidant activity of flavonoids in vitro has been the subject of several studies, and important structure–activity relationships of the antioxidant activity have been established. However, there is still debate about the stability and absorption of polyphenols under gastrointestinal conditions. Ginkgo biloba, a product well known for its flavonoid content, was chosen for this study. Ginkgo biloba leaves, standardised leaf extract EGb 761 and commercial tablets (containing EGb761) were incubated in simulated gastrointestinal fluids to determine the stability of their flavonoid profiles. The experiment was designed to mimic the human gut condition. HPLC analysis was then conducted to determine the resulting breakdown compounds and intact flavonoids after the incubation, thus indicating those compounds likely to be available for absorption. The different samples seem to react differently to the simulated digestion process. The results indicate a trend of conversion from the glycosides to the aglycones for some samples and subsequent degradation of the aglycones. This may indicate a need to further investigate the reported benefits of Ginkgo flavonoids as in vivo antioxidants and/or to consider the antioxidant activity of the resulting digestion-derived compounds.     

苦荞麸皮黄酮提取物及有效成分的抑菌活性

研究苦荞麸皮总黄酮粗品及精品对病原菌的抑制作用,并初步分析其黄酮类成分,评价不同黄酮单体的抑菌活性。通过平板打孔法及二倍稀释法检测苦荞麸皮总黄酮粗品及精品及其4种黄酮单体的抗菌活性,使用高效液相色谱法定性定量检测苦荞麸皮总黄酮粗品及精品的黄酮成分。结果表明,苦荞麸皮黄酮精品对金黄色葡萄球菌、藤黄微球菌、肠球菌、大肠杆菌、志贺氏杆菌、沙门氏菌的抑制效果优于粗品。苦荞麸皮黄酮主要黄酮成分为芦丁、山奈酚-3-O-芸香糖苷、槲皮素和山奈酚,精品的总黄酮含量是粗品总黄酮含量的2.84倍。4种黄酮单体的抑菌能力具有一定的构效关系,其中槲皮素对所有供试菌均表现出较好的抑菌活性。     

Total flavan glycoside from Abacopteris penangiana rhizomes and its acid hydrolysate: Characterisation and anti-benign prostatic hyperplasia potential

This study was conducted to characterise the flavonoid components of total flavan glycoside from Abacopteris penangiana rhizomes (TFA) and its acid hydrolysate (AHT) through HPLC–DAD–ESI–MS/MS analysis, and to investigate the hypothesis that TFA and AHT exhibit anti-benign prostatic hyperplasia (BPH) potential in castrated rats with testosterone-induced BPH. HPLC–MS/MS analysis indicated that TFA is rich in flavan-4-ol glycosides and AHT mainly contains 3-deoxygenated anthocyanidin. After 4 weeks of administration, TFA and AHT successfully decreased the prostate index and prostate specific antigen plasma concentrations in the rats. Histoarchitectural improvement in the prostate gland was also observed. Reduced dihydrotestosterone, VEGF, bFGF, EGF, and KGF levels were observed both in TFA- and AHT-treated rats. Furthermore, the prostatic expression of Blc-2 was inhibited, whereas that of Bax and p53 was activated by TFA and AHT. In conclusion, TFA and AHT have anti-BPH properties. Hence, plants with flavan glycosides have potential use in the treatment of BPH.     

Recovery of flavanones from wastes of industrially processed lemons

 The flavonoids present in the wastes and residues obtained during the industrial processing of lemons were characterized and quantified. Selected products of the juice-extraction line and essential-oil-recovery line were studied. Industrial lemon juice is characterized by containing hesperidin and eriocitrin as the main flavonoid glycosides (130 μg/ml), other minor flavanones and C-glycosylflavones. After the concentration process, the concentrated juice contained a 5-fold increase in the concentration of flavonoids, but some of the hesperidin present in the initial juice was lost. The flavanone glycosides were mainly concentrated in the peel and solid residues, where hesperidin was present as the prevailing flavonoid with concentrations of up to three times higher than those of eriocitrin. In liquid residues eriocitrin was the main flavonoid. The solid residues (peel and frit precipitates) were the most interesting sources for the industrial recovery of flavonoids (13 kg/t processed lemons). Received: 8 October 1997     

柑桔属水果皮渣的综合利用

本文介绍了从柑桔属水果加工副产物果皮和渣中制取天然香料、食用色素、果胶及保健食品添加剂如黄酮甙类的方法,这些产品在食品、饮料等行业有许多功能性的用途。     

Quercetin content in some food and herbal samples

Quercetin is a typical flavonoid ubiquitously present in vegetables and fruits, and its antioxidant effect is implied to be helpful for human health. The efficiency of extraction process and acidic hydrolysis parameters for HPLC analysis of quercetin present in glycosides and aglycone forms was investigated. Hydrolysis for 5 min in the presence of 2.8 M HCl as well as for 10 min with 1.1 M HCl efficiently released quercetin from rutin. The method developed in this study was applied for quantitative determination of quercetin in some food (onion, apple) and herbal (Hypericum perforatum and Sambucus nigra) products.