鹿茸草化学成分研究

目的:研究鹿茸草的化学成分。方法:鹿茸草用95%的乙醇提取,提取物依次经石油醚和乙酸乙酯萃取,再经硅胶柱色谱法、聚酰胺柱色谱法反复进行分离纯化,并通过波谱技术及理化性质鉴定化合物结构。结果:从鹿茸草中分离得到3个化合物,分别为胆甾醇(1)、芹菜素(2)、木犀草素(3)。结论:此3个化合物均为首次从该植物中分离得到。     

三种黄酮清除自由基活性的研究

为比较黄酮2、3位单双键不同及3'、4'邻位取代基不同对清除自由基活性的影响。采用UV-Vis光谱法测定了木犀草素、香叶木素及橙皮素对1,1-二苯基-2-三硝基苯肼自由基(DPPH·)、超氧阴离子自由基(O2-·)的清除作用。结果显示3种黄酮化合物对两种自由基都有一定的清除作用,清除效果随浓度的增大而增大。但对自由基清除能力表现为木犀草素远强于香叶木素、香叶木素与橙皮素无显著差别。说明具有B环3'、4'邻二羟基结构的黄酮清除自由基的能力明显强于具有B环3'羟基、4'甲氧基结构的黄酮;黄酮C环2、3位单双键不同对自由基清除能力影响不显著。     

花生壳中黄酮类成分的识别分离与结构确定

对花生壳中黄酮类活性成分进行分离纯化和结构确定。经过木犀草素分子印迹聚合物柱层析进行分离、纯化,并经核磁共振确定其结构。从花生壳的乙醇(70%)提取物中分离得到1个黄酮类化合物,其结构被确定为木犀草素。木犀草素是花生壳的主要黄酮活性成分。     

木犀草素-Zn(II)配位印迹聚合物的制备及在箬叶黄酮碳苷分离中的应用

以箬叶黄酮碳苷母核木犀草素为虚拟模板分子,结合Zn(II)的配位作用,以丙烯酰胺为功能单体,N,N?-亚甲基双丙烯酰酯胺为交联剂,以乙醇为溶剂制备木犀草素-Zn(II)配位印迹聚合物,将此聚合物与固相萃取相结合,分离醇水体系中的箬叶黄酮碳苷。结果表明 ,当n（模板分子）﹕n（功能单体）﹕n（交联剂）=1:5:30时,配位印迹聚合物具有最好的吸附性能,对醇相中木犀草素的吸附容量可达103.4mg?g-1,是未配位印迹聚合物吸附容量的1.71倍,空白印迹聚合物的13.75倍。采用木犀草素-Zn(II)配位印迹聚合物分离醇水相中箬叶黄酮碳苷,经1次分离后,荭草苷、异荭草、牡荆苷和异牡荆苷的回收率分别为91.95%、80.87%、60.43%和63.63%,含量相比粗提物分别提高55.46、48.78、36.45和38.38倍,4种黄酮碳苷总含量由提取前的0.70%提高32.68%。     

木犀草素-Zn(Ⅱ)配位分子印迹聚合物的制备及应用

以箬叶黄酮碳苷母核木犀草素为虚拟模板分子,结合Zn(Ⅱ)的配位作用,丙烯酰胺为功能单体,N,N?-亚甲基双丙烯酰胺(MBA)为交联剂,乙醇为溶剂制备了木犀草素-Zn(Ⅱ)配位印迹聚合物,并将此聚合物与固相萃取相结合,分离了醇水体系中的箬叶黄酮碳苷。结果表明:当n(模板分子)∶n(功能单体)∶n(交联剂)=1∶5∶30时,配位印迹聚合物具有最好的吸附性能,对醇相中木犀草素的吸附容量可达103.40 mg/g,是未配位印迹聚合物吸附容量(60.61 mg/g)的1.71倍,空白印迹聚合物(7.33 mg/g)的14.11倍。采用木犀草素-Zn(Ⅱ)配位印迹聚合物分离醇水相中箬叶黄酮碳苷,经一次分离后,荭草苷、异荭草苷、牡荆苷和异牡荆苷的回收率分别为91.95%、80.87%、60.43%和63.63%;质量分数分别是粗提物的55.36、48.89、36.64和38.35倍,4种黄酮碳苷总质量百分数由提取前的0.70%提高到32.68%。     

木犀草素分子印迹聚合物的分子识别特性及固相萃取研究

采用分子印迹技术,以木犀草素为模板分子,丙烯酰胺为功能单体,乙二醇二甲基丙烯酸酯为交联剂,通过热引发聚合,制备了木犀草素分子印迹聚合物,并通过装入固相萃取柱研究了聚合物对木犀草素的选择性能.结果表明,该分子印迹聚合物对模板分子具有高度选择性和识别能力,而空白聚合物却不具备这样的特性.将木犀草素分子印迹聚合物用于固相萃取花生壳提取物,分离富集其中的木犀草素活性成分,在萃取柱上载样品之后,先用V(乙醇):V(水)=1:1溶液进行清洗,再用V(乙醇):V(水)=7:5溶液进行目标分子的洗脱,木犀草素的纯度可由1.6%提高到94.1%,回收率90.0%.木犀草索分子印迹固相萃取柱具有较好的稳定性和耐用性能,使用4次后其选择识别性能仍未降低,显示该聚合物具有直接作为复杂天然产物中木犀草素分离提取材料的潜能.     

木犀草素-铕(Ⅲ)配合物的制备及生物活性研究

采用紫外光谱法,以木犀草素与铕离子溶液为原料合成了木犀草素-铕配合物,配合物制备的最佳条件为:在1.0×10~(-4)mol/L、pH3.5的NaAc-HAc缓冲溶液中,木犀草素与铕离子按照摩尔比2∶1加入,30℃下反应40 min。同时对木犀草素、木犀草素-铕配合物的清除羟基自由基活性、抗氧化活性等进行了研究,研究结果表明配合物的活性明显优于木犀草素。     

木犀草素Zn(II)和Cu(II)配合物的合成及电化学性质研究

在无水乙醇溶液中,用木犀草素和醋酸铜、醋酸锌合成两种鲜见报道的木犀草素金属配合物,并通过元素分析、红外光谱、电子光谱和摩尔电导等表征手段,确定了配合物的结构。并研究了木犀草素Zn(II)和木犀草素Cu(II)配合物化学修饰碳糊电极在pH 5 B-R缓冲溶液中的电化学行为。     

木犀草素Zn(Ⅱ)和Cu(Ⅱ)配合物的合成及电化学性质研究

在无水乙醇溶液中,用木犀草素和醋酸铜、醋酸辞合成两种鲜见报道的木犀草素金属配合物,并通过元素分析、红外光谱、电子光谱和摩尔电导等表征手段,确定了配合物的结构。并研究了木犀草素Zn（Ⅱ）和木犀草素Cu（Ⅱ）配合物化学修饰碳糊电极在pH5 B-R缓冲溶液中的电化学行为。     

花生壳中总黄酮和木犀草素提取工艺研究

研究花生壳中总黄酮和木犀草素的提取工艺.经正交试验,以提取物中总黄酮和木犀草素含量为评价指标.优选提取工艺.确立以75%乙醇为溶剂,料液比1:10,每次提取2h,提取3次为优选工艺,花生壳中总黄酮和木犀草素均可有效提取.该工艺简捷、经济、可行,适合工业化生产.     

金花葵粗黄酮的提取工艺研究

通过对金花葵黄酮超声辅助提取工艺单因素和正交实验的研究,获得了金花葵黄酮粗提物的提取工艺参数:80℃下超声30min后,用60％乙醇、料液比1:40、提取时间75min,提取1次.经分析提取液中黄酮类物质的含量,计算每克原料的黄酮提取量为56.37mg.提取液经旋转蒸发浓缩后用冷冻干燥制得黄酮粗提物的冻干粉,每g金花葵...     

紫背天葵黄酮的体内外抗氧化作用

采用体积分数80%的乙醇提取紫背天葵中的总黄酮并测定其含量,将粗提液萃取,经AB-8型大孔吸附树脂纯化,以Vc为对照,测定紫背天葵总黄酮粗提液、纯化液对二苯代苦味酰基自由基(DPPH.)、羟基自由基(.OH)和超氧阴离子自由基(O2-.)的清除能力,并考察紫背天葵黄酮纯化物的体内抗氧化效果。结果表明,紫背天葵中粗黄酮含量为13.928 mg/g,纯化比率为32.79%;紫背天葵总黄酮粗提液、纯化液对3种自由基均有不同程度的清除作用,且清除作用随黄酮质量浓度的升高而增强,纯化液的清除作用强于粗提液;低剂量紫背天葵黄酮纯化物实验组小鼠肝脏和脑组织中超氧化物歧化酶(SOD)活力和肝脏过氧化氢酶(CAT)活力显著高于对照组(p<0.05),而脑中的丙二醛(MDA)含量显著低于正常对照组(p<0.05)。     

Cottonseed flavonoids as lipid antioxidants

Methanolic extracts of cottonseeds were found to possess antioxidant activity. Separation of antioxidant components was achieved by paper, thin layer (TLC) and gas liquid chromatography (GLC) and spectral analysis. Chromatographic technique indicated that the flavonoids quercetin and rutin were the major flavonoids present. GLC analysis of the cottonseed extract eluted from TLC plates, developed in n-butanol/acetic acid/water (4:1:5, v/v/v) and ethyl acetate/methyl ethyl ketone/formic acid/water (5:3:1:1, v/v/v) solvents, corresponded in retention times to the rutin standard (10⁻⁴ M). TMS derivatives of the aglycone fraction, prepared by acid hydrolysis, correlated to the retention time of quercetin. Spectral analysis of the aglycone fraction also indicated quercetin derivatives to be present in cottonseed. The glycosyl substitution of the flavonoids were identified by the 3 chromatographic procedures to be glucose and rhamnose. Chromogenic spray reagents were used to further characterize the cottonseed flavonoids and flavonoid components on TLC and paper chromatography. The investigation, therefore, demonstrated that quercetin derivatives appear to be the main flavonoid species in cottonseed. Rutin was found to be one of the major quercetin glycosides. Quercetin and rutin are shown to possess potent antioxidant activity.     

Sequestration and Metabolism of Host-Plant Flavonoids by the Lycaenid Butterfly Polyommatus bellargus

Larvae of the lycaenid butterfly Polyommatus bellargus were reared on leaves of Coronilla varia that are rich in flavone C-glycosides. Six flavonoids including isovitexin and isoorientin, as well as several of their congeners were isolated and identified by spectroscopic means. Comparative HPLC analysis of the host plant and of larvae, pupae, and imagines of P. bellargus indicated selective uptake of isovitexin versus isoorientin derivatives. Isovitexin-2″-O-xyloside was the major flavonoid detected in pupae and in imagines of P. bellargus. Several minor components were tentatively identified as quercetin- and kaempferol-O-glycosides based on their on line-UV spectra and by comparison with known standards. Since leaves of the host plant accumulate exclusively flavones, the flavonol glycosides are considered to be biotransformation products that are formed by the insects and/ or by symbiotic bacteria. Imagines of P. bellargus caught in the wild exhibited similar flavonoid patterns compared to imagines reared in the laboratory. Within the imagines, approximately 80% of all flavonoids are stored in the wings (especially in the orange submarginal lunules), whereas the remaining 20% resides in the bodies. Female butterflies show a significantly higher flavonoid concentration than males. It is suggested that the sequestered flavonoids are involved in visual mate recognition.     

Biological activity and tentative identification of flavonoid components in velvetleaf (Abutilon theophrasti Medik.) seed coats

The biological activity of aqueous extracts of velvetleaf (Abutilon theophrasti Medik.) seed coats and their flavonoid components against three plant species and five soil fungi was investigated. Aqueous extracts slightly inhibited germination and significantly inhibited radicle growth of all plant species tested. Fungal growth was inhibited or not affected, depending on species, by aqueous extracts. The aqueous extracts were extracted into methanol and separated using paper chromatography for identification of compounds responsible for inhibition of seedling and fungal growth. Six flavonoid compounds were isolated and tentatively identified as delphinidin, cyanidin, quercetin, myricetin, (+)-catechin, and (–)-epicatechin. Bioassays revealed that the flavonoid compounds significantly inhibited germination and radicle growth of all test species at a concentration of 1.0 mM. Individual flavonoids had variable effects on fungi but appeared to inhibit growth and sporulation of potential seed-decomposing fungi rather than beneficial fungi. These results indicate that the flavonoid complement of velvetleaf seed coats may function in a dual defensive role against competing seedlings and seed-attacking fungi.Journal article No. 9878 of the Missouri Agricultural Experiment Station.     

Highly simplified preparation of tea flavonoids from surplus tea leaves by the novel three-phase extraction and purification

A novel three-phase extraction and purification procedure was developed to prepare high-quality flavonoids from surplus tea leaves. Flavonoids were selectively extracted in ethyl acetate (EtOAc) by the EtOAc-water-leaf three-phase extraction, with 91.2% extraction efficiency, more than 50% higher than the traditional water extraction. The EtOAc extracts were purified by the EtOAc-water- montmorillonite/charcoal three-phase adsorptive purification at 98% recovery. Highly purified flavonoids were obtained with less than 1.0% caffeine. The overall flavonoid recovery reached 90.3%, more than 40% higher than traditional methods. This procedure highly simplified the processes and significantly increased the recovery of flavonoid production from tea leaves.     

Synthesis of Phenolics and Flavonoids in Ginger (Zingiber officinale Roscoe) and Their Effects on Photosynthesis Rate

The relationship between phenolics and flavonoids synthesis/accumulation and photosynthesis rate was investigated for two Malaysian ginger (Zingiber officinale) varieties grown under four levels of glasshouse light intensity, namely 310, 460, 630 and 790 μmol m(-2)s(-1). High performance liquid chromatography (HPLC) was employed to identify and quantify the polyphenolic components. The results of HPLC analysis indicated that synthesis and partitioning of quercetin, rutin, catechin, epicatechin and naringenin were high in plants grown under 310 μmol m(-2)s(-1). The average value of flavonoids synthesis in leaves for both varieties increased (Halia Bentong 26.1%; Halia Bara 19.5%) when light intensity decreased. Photosynthetic rate and plant biomass increased in both varieties with increasing light intensity. More specifically, a high photosynthesis rate (12.25 μmol CO(2) m(-2)s(-1) in Halia Bara) and plant biomass (79.47 g in Halia Bentong) were observed at 790 μmol m(-2)s(-1). Furthermore, plants with the lowest rate of photosynthesis had highest flavonoids content. Previous studies have shown that quercetin inhibits and salicylic acid induces the electron transport rate in photosynthesis photosystems. In the current study, quercetin was an abundant flavonoid in both ginger varieties. Moreover, higher concentration of quercetin (1.12 mg/g dry weight) was found in Halia Bara leaves grown under 310 μmol m(-2)s(-1) with a low photosynthesis rate. Furthermore, a high content of salicylic acid (0.673 mg/g dry weight) was detected in Halia Bara leaves exposed under 790 μmol m(-2)s(-1) with a high photosynthesis rate. No salicylic acid was detected in gingers grown under 310 μmol m(-2)s(-1). Ginger is a semi-shade loving plant that does not require high light intensity for photosynthesis. Different photosynthesis rates at different light intensities may be related to the absence or presence of some flavonoid and phenolic compounds.     

Role of Ecological Variables in the Seasonal Variation of Flavonoid Content of Cistus ladanifer Exudate

The leaves and photosynthetic stems of Cistus ladanifer, a plant that colonizes arid lands, secrete an exudate that shows a large seasonal variation in its flavonoid content. The maximum secretion of flavonoids in the exudate is produced during summer, increasing approximately three-to fourfold with respect to the secretion measured in spring. Summer is the season in which the plant suffers the greatest stress from environmental physical variables such as UV irradiation, high temperatures, and hydric stress. Studies were conducted in plants from several locations, which were selected considering daily UV irradiation (open or shaded areas), annual precipitation, and annual average maximum and minimum temperatures. Additional studies to control UV irradiation, drought, and temperature separately were performed with C. ladanifer plants growing in a glasshouse and in a culture room. The UV irradiation was found to be the major inducer of the enhanced flavonoid secretion during summer, because no significant increase of flavonoid secretion during summer was observed when the C. ladanifer plants in the field were covered with a Plexiglas box (total UV absorption below 380 nm). These results support an ecophysiological role of the flavonoids in the exudate to protect the plant against the damaging effects of UV irradiation. The culture room experiments confirmed this point and also showed that the induction of flavonoid secretion by UV irradiation is synergistically augmented by drought. The glasshouse and culture room experiments showed drought and high temperatures (between 30° and 45°C) to correlate with the summer increase of the more methylated flavonoids (kaempferols and 7-methylated apigenins) in the exudate. Because these more methylated flavonoids have higher hydropathy than the less methylated, these results suggest that the secretion of more methylated flavonoids is part of the defense mechanism of the plant against the hydric stress of summer.     

溪黄草黄酮配合物的合成及抑制亚硝化反应研究

超声波最优化法提取溪黄草总黄酮,提取物经乙酸乙酯萃取后进行柱层析分离纯化,得一纯物质,鉴定为黄酮化合物,并以该化合物为配体合成了锌(Ⅱ)、铜(Ⅱ)和铁(Ⅲ)配合物,研究它们对亚硝化反应的抑制作用。结果表明该黄酮化合物及其配合物在一定浓度范围能阻断亚硝胺的合成及清除亚硝酸盐,其中配合物作用较黄酮配体强。     

Comparison of different extraction methods for the extraction of major bioactive flavonoid compounds from spearmint (Mentha spicata L.) leaves

Different bioactive flavonoid compounds including catechin, epicatechin, rutin, myricetin, luteolin, apigenin and naringenin were obtained from spearmint (Mentha spicata L.) leaves by using conventional soxhlet extraction (CSE) and supercritical carbon dioxide (SC-CO₂) extraction at different extraction schemes and parameters. The effect of different parameters such as temperature (40, 50 and 60 °C), pressure (100, 200 and 300 bar) and dynamic extraction time (30, 60 and 90 min) on the supercritical carbon dioxide (SC-CO₂) extraction of spearmint flavonoids was investigated using full factorial arrangement in a completely randomized design (CRD). The extracts of spearmint leaves obtained by CSE and optimal SC-CO₂ extraction conditions were further analyzed by high performance liquid chromatography (HPLC) to identify and quantify major bioactive flavonoid compounds profile. Comparable results were obtained by optimum SC-CO₂ extraction condition (60 °C, 200 bar, 60 min) and 70% ethanol soxhlet extraction. As revealed by the results, soxhlet extraction had a higher crude extract yield (257.67 mg/g) comparing to the SC-CO₂ extraction (60.57 mg/g). Supercritical carbon dioxide extract (optimum condition) was found to have more main flavonoid compounds (seven bioactive flavonoids) with high concentration comparing to the 70% ethanol soxhlet extraction (five bioactive flavonoids). Therefore, SC-CO₂ extraction is considered as an alternative process compared to the CSE for obtaining the bioactive flavonoid compounds with high concentration from spearmint leaves.