Chemistry and Quality of Hibiscus (Hibiscus sabdariffa) for Developing the Natural-Product Industry in Senegal

ABSTRACT:  The objectives of this study were to assess and improve the quality of the hibiscus calyces from Senegal over 2 production seasons (2004 to 2005), to develop and adapt new procedures for the determination of hibiscus anthocyanins and analysis of the 2 major ones, delphinidin-3-sambubioside and cyanidin-3-sambubioside. The foreign matter, total ashes, and acid insoluble ashes showed that the calyces harvested in 2005 were produced following hygienic practices, while the color assessment of the calyces and analysis of hibiscus active principles also showed higher amounts of anthocyanins in 2005. A protocol to measure anthocyanins by pH-differential UV-Vis spectrophotometry was adapted to measure the hibiscus anthocyanins from a water extract. The spectrophotometric method for quantitation of total anthocyanins showed a close correlation ( r ²= 0.82) when compared with the HPLC method, suggesting the use of the colorimetric method in quality control programs as an affordable alternative method to assess anthocyanin content in hibiscus. New and raised standards for the cleanliness and active principle content in hibiscus are also proposed. This study demonstrated that the implementation of a quality control program and the application of agricultural good practices in the production and processing of hibiscus calyces can lead to higher quality natural plant products.     

Bioavailability study of a polyphenol‐enriched extract from Hibiscus sabdariffa in rats and associated antioxidant status

The aqueous extracts of Hibiscus sabdariffa have been commonly used in folk medicine. Nevertheless, the compounds or metabolites responsible for its healthy effects have not yet been identified. The major metabolites present in rat plasma after acute ingestion of a polyphenol‐enriched Hibiscus sabdariffa extract were characterized and quantified in order to study their bioavailability. The antioxidant status of the plasma samples was also measured through several complementary antioxidant techniques. High‐performance liquid chromatography coupled to time‐of‐flight mass spectrometry (HPLC‐ESI‐TOF‐MS) was used for the bioavailability study. The antioxidant status was measured by ferric reducing ability of plasma method, thiobarbituric acid reactive substances assay, and superoxide dismutase activity assay. Seventeen polyphenols and metabolites have been detected and quantified. Eleven of these compounds were metabolites. Although phenolic acids were found in plasma without any modification in their structures, most flavonols were found as quercetin or kaempferol glucuronide conjugates. Flavonol glucuronide conjugates, which show longer half‐life elimination values, are proposed to contribute to the observed lipid peroxidation inhibitory activity in the cellular membranes. By contrast, phenolic acids appear to exert their antioxidant activity through ferric ion reduction and superoxide scavenging at shorter times. We propose that flavonol‐conjugated forms (quercetin and kaempferol) may be the compounds responsible for the observed antioxidant effects and contribute to the healthy effects of H. sabdariffa polyphenolic extract.     

Hibiscus sabdariffa L. extracts inhibit the mutagenicity in microsuspension assay and the proliferation of HeLa cells

ABSTRACT:  Hibiscus sabdariffa L. is used as a refreshing beverage and as a traditional medicine. The objective of this study was to determine the in vitro effect of phenolic compounds present in aqueous, ethyl acetate, and chloroform extracts of H. sabdariffa against mutagenicity of 1-nitropyrene (1-NP), and also the antiproliferative effect of these extracts. Inhibition of cell proliferation and DNA fragmentation were tested on transformed human HeLa cells. The hot aqueous extract (HAE) contained 22.27 ± 2.52 mg of protocatechuic acid (PCA) per gram of lyophilized dried extract, and was not statistically different from the cold aqueous or chloroform extracts; the ethyl acetate extract produced the least amount of PCA. The H. sabdariffa extracts inhibited mutagenicity of 1-NP in a dose-response manner. The inhibition rate on HeLa cells of HAE was also dose-dependent. The HAE did not induce DNA fragmentation. The results suggest that H. sabdariffa L. extracts have antimutagenic activity against 1-NP and decrease the proliferation of HeLa cells, probably due to phenolic acid composition.     

体重和性别对Ⅱ型糖尿病大鼠造模的影响

研究大鼠体重、性别对Ⅱ型糖尿病模型成功率的影响.分别对不同体重、性别的SD大鼠采用链脲霉素结合烟酰胺腹腔注射的方式,比较其建立Ⅱ型糖尿病模型时的差异.结果表明:220 g、雄性SD大鼠为最佳实验动物,雌性以及其他体重范围的大鼠成模率低且不稳定,原因可能是雄性对链脲霉素更为敏感;220 g体重时大鼠处于青年期,最适于造模.试验确定将空腹血糖、体重、肝糖原及糖化血红蛋白的含量作为Ⅱ型糖尿病大鼠评估模型的测定指标.     

Effects of Urtica dioica and Hibiscus sabdariffa on the quality and safety of sucuk (Turkish dry-fermented sausage)

In this study, the effect of Urtica dioica, Hibiscus sabdariffa butylatedhydroxytoluene (BHT) and nitrite/nitrate on the quality (pH, Hunter L-, a- and b-value and sensory attributes) and safety [2-thiobarbituric acid reactive substances (TBARS) value and biogenic amine] were investigated during the ripening periods of sucuk (Turkish dry-fermented sausage). During the first 2 days of ripening, pH values decreased (P<0.05) rapidly from 5.78 to about 4.49. pH values of batters were not significantly (P<0.05) affected by the addition of nitrite/nitrate, BHT, U. dioica, H. sabdariffa. TBARS values increased from 0.52 to about 0.95mg/kg significantly (P<0.05) during the first 4 days in control, and H. sabdariffa added batters. The highest (P<0.05) histamine concentration was determined in the control batter prepared without antioxidant. U. dioica was more effective (P<0.05) on decreasing histamine and putrescine concentration than the other antioxidants. Putrescine concentration in batters increased (P<0.05) from 1.13 to about 15.34mg/kg during the first 4 days. Tyramine concentration increased significantly (P<0.05) during the ripening period from 5.55 to 103.93mg/kg. The control batter had the highest (P<0.05) tyramine concentration about 50.21mg/kg. Hunter L-values were not affected (P>0.05) from ripening time and addition of antioxidants into batter. The Hunter a-value increased (P<0.05) during the ripening periods, however, b-values decreased (P<0.05) from 12.58 to about 10.53. Overall sensory quality evaluated from color, flavor and ease of cutting scores increased (P<0.05) from 3.25 to about 9.00.     

蒲公英提取物对2型糖尿病大鼠降血糖的作用

采用高脂高糖饲料和链脲佐菌素(STZ)建立2型糖尿病(T2DM)大鼠模型,设置正常组、模型组、蒲公英高剂量组(400mg/kg)、蒲公英低剂量组(200mg/kg)、阳性组(150mg/kg),测定T2DM大鼠空腹血糖值(FBG)、糖耐量水平(OGTT)、胰岛素抵抗(FINS)和胰岛素敏感性(HOMA-IR),以及TC、TG、ALT、AST、SOD、GSH、CAT、MDA相关指标。结果表明,与模型组相比,经蒲公英提取物治疗后的T2DM大鼠的FBG、FINS、HOMA-IR显著降低(P<0.05),TC、TG、ALT、AST水平极显著降低(P<0.01),SOD、GSH、CAT极显著增加(P<0.01),MDA极显著降低(P<0.01);表明蒲公英提取物可改善T2DM大鼠胰岛素抵抗,提高机体抗氧化水平,改善脂质代谢水平,从而发挥降血糖功效。     

复合营养粉对2型糖尿病大鼠的辅助降血糖试验

为评估以全脂乳粉、赤藓糖醇、杏仁粉、抗性糊精、聚葡萄糖、菊粉、罗汉果甜苷等为原料制成的复合营养粉对糖尿病大鼠的辅助降血糖功能,建立了胰岛素抵抗糖/脂代谢紊乱大鼠模型,并分别评估了复合营养粉对正常大鼠和胰岛素抵抗糖/脂代谢紊乱模型大鼠的影响。结果表明:复合营养粉对正常大鼠血糖无明显影响;对胰岛素抵抗糖/脂代谢紊乱模型大鼠的糖耐量指标为阳性、降血脂指标为阴性,胰岛素抵抗性未见明显变化。复合营养粉对糖尿病大鼠的辅助降血糖功能为阳性。     

菊花多糖对2型糖尿病大鼠的降血糖作用

目的:研究菊花多糖对2型糖尿病(T2DM)大鼠的降血糖作用。方法:利用水提醇沉法对菊花多糖进行提取,高脂高糖饲料饲养大鼠6周后,一次性腹腔注射STZ(30 mg/kg·BW),建立T2DM大鼠模型,试验过程中记录大鼠体重、摄食量、饮水量,每2周测定大鼠空腹血糖值(FBG),试验最后1周进行糖耐量(OGTT)试验,采用Elisa法测定大鼠胰岛素(INS)水平,并计算胰岛素抵抗指数(HOMA-IR)。测定大鼠血清中总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白(HDL-C)、低密度脂蛋白(LDL-C)水平,以及超氧化物歧化酶(SOD)、谷胱甘肽(GSH)、过氧化氢酶(CAT)、丙二醛(MDA)等水平,采用蛋白质免疫印迹法(Western Blot)检测Nrf2、Keap1、HO-1的表达水平。结果:经菊花多糖治疗后,能够缓解T2DM大鼠体重的下降,减少其摄食量和饮水量,提高T2DM大鼠糖耐量,降低大鼠INS及HOMA-IR。能够显著降低T2DM大鼠TC、TG、LDL-C水平(P<0.05),并显著提高HDL-C水平(P<0.05)。T2DM大鼠SOD、GSH、CAT水平有显著提高(P<0.05),MDA水平显著下降(P<0.05)。经菊花多糖治疗后的T2DM大鼠的Nrf2、Keap1、HO-1蛋白水平均趋于正常组的蛋白水平。结论:菊花多糖能够有效改善T2DM大鼠“三多一少”的症状,降低FBG水平,提高OGTT,改善INS水平及HOMA-IR,改善T2DM大鼠异常脂代谢和氧化应激水平,并通过调控Nrf2/Keap1/HO-1通路相关蛋白起到治疗T2DM的作用。     

桑叶总黄酮对2型糖尿病模型大鼠肝脏的保护作用

目的:探讨桑叶总黄酮对2型糖尿病（T2DM）大鼠肝脏的保护作用。方法:选用雄性wistar大鼠,高脂饲料喂养且用链脲佐菌素诱导,复制T2DM模型,模型成功后随即分成模型组、二甲双胍组、桑叶总黄酮高、中、低(200、100、50 mg·kg^-1·bw^-1)剂量组,各药干预4周后,比较各组大鼠的体重和空腹血糖值;称重肝脏,计算肝脏指数;测定血清中甘油三酯（TG）、总胆固醇（TC）和丙氨酸氨基转移酶（ALT）水平;测定肝脏中肝糖原水平,葡萄糖激酶（GK）活性;对肝脏进行HE染色,做病理组织学检查。结果:与模型组相比,桑叶总黄酮高剂量组能降低T2DM大鼠的体重,为（390.79±77.27）g;降低TC、TG和ALT水平,分别为（2.25±0.58）mmol·L^-1、（0.92±0.36）mmol·L^-1和（69.36±5.58）U·L^-1;增加肝糖原含量,为（12.22±1.50）mg·g^-1;提高GK活性,为（10.33±1.30）m IU·min^-1·mg protein^-1;减轻肝脏脂肪变性,改善肝脏病理。结论:桑叶总黄酮在预防和改善T2DM肝损伤方面具有一定的应用开发潜力。      

蝙蝠蛾拟青霉Cs-4提取物对糖尿病SD大鼠肾脏的保护作用

本文通过链脲佐菌素建立早期糖尿病肾病大鼠模型,考察蝙蝠蛾拟青霉Cs-4提取物高剂量组(2 g/kg·d、中剂量组（0.5 g/kg·d）和低剂量组（0.05 g/kg·d）灌胃给药3周后,对糖尿病大鼠肾脏的保护作用。实验结果表明,与模型组相比,Cs-4高剂量组能够缓解糖尿病大鼠体重的下降（p<0.05）,降低血糖、尿糖和尿微量白蛋白排泄率（p<0.01）;对肾功能检测指标结果表明,Cs-4能显著降低血清尿素氮（BUN）、尿酸（UA）、肌酐含量（p<0.01）,同时提高血清超氧化物转化酶（SOD）活力（p<0.01）,丙二醛（MDA）含量明显减少（p<0.01）。肾脏组织切片HE染色结果也表明,Cs-4给药后,肾脏炎症细胞浸润现象明显减少,说明Cs-4提取物能够很好的抗糖尿病和保护肾脏损伤。      

蝙蝠蛾拟青霉Cs-4提取物对糖尿病SD大鼠肾脏的保护作用

本文通过链脲佐菌素建立早期糖尿病肾病大鼠模型,考察蝙蝠蛾拟青霉Cs-4提取物高剂量组(2 g/kg·d、中剂量组(0.5 g/kg·d)和低剂量组(0.05 g/kg·d)灌胃给药3周后,对糖尿病大鼠肾脏的保护作用。实验结果表明,与模型组相比,Cs-4高剂量组能够缓解糖尿病大鼠体重的下降(p0.05),降低血糖、尿糖和尿微量白蛋白排泄率(p0.01);对肾功能检测指标结果表明,Cs-4能显著降低血清尿素氮(BUN)、尿酸(UA)、肌酐含量(p0.01),同时提高血清超氧化物转化酶(SOD)活力(p0.01),丙二醛(MDA)含量明显减少(p0.01)。肾脏组织切片HE染色结果也表明,Cs-4给药后,肾脏炎症细胞浸润现象明显减少,说明Cs-4提取物能够很好的抗糖尿病和保护肾脏损伤。     

桔梗多糖抗氧化特性及对2型糖尿病大鼠降血糖作用

目的：研究桔梗多糖抗氧化性及其对2型糖尿病(T2DM)大鼠降血糖作用。方法：提取并测定桔梗多糖含量及桔梗多糖对不同自由基的清除能力。采用高脂高糖饲料喂养大鼠6周后,大鼠腹腔注射STZ(30 mg/kg·BW)建立T2DM模型,将其分为正常组、模型组、桔梗多糖高剂量组(400 mg/kg)、桔梗多糖低剂量组(200 mg/kg)、阳性组(二甲双胍200 mg/kg),定期测定大鼠体重及空腹血糖值(FBG);并进行口服糖耐量(OGTT)测试,测定大鼠总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白(HDL-C)、低密度脂蛋白(LDL-C)、丙二醛(MDA)、超氧化物歧化酶(SOD)、谷胱甘肽(GSH)和过氧化氢酶(CAT)的变化。结果：桔梗多糖含量为89.65%,在1 000 μg/mL质量浓度下其对DPPH·、ABTS+·、·OH、PTIO的清除能力分别为91.3%,89.7%,83.8%,90.4%。与模型组相比,桔梗多糖能够有效缓解T2DM大鼠体重的下降,显著降低其FBG(P＜0.05),以及显著提高OGTT水平(P＜0.05),经桔梗多糖高剂量治疗后,TC、TG、LDL-C、MDA 水平显著下降,HDL-C、SOD、GSH、CAT水平显著上升(P＜0.05),且所有指标均呈剂量依赖性。结论：桔梗多糖具有较好的抗氧化性,可以通过改善T2DM大鼠脂代谢水平和氧化应激水平从而起到降血糖作用。     

益生菌复配富铬酵母缓解2型糖尿病的作用机制涉及调节肠道菌群失调

本研究通过高脂饲料和腹腔注射链脲佐菌素STZ诱导2型糖尿病小鼠模型,实验小鼠随机分为5组:空白组、模型组、药物组、乳酸菌组、复合组。实验结果发现肠道菌群失调与2型糖尿病的发生发展存在着密不可分的关联。模型组小鼠短链脂肪酸含量和物种丰富度显著下降,部分有益菌丰度降低,而致病菌丰度显著提升。此外,药物组、乳酸菌组和复合组均在一定程度上改善了糖尿病小鼠的肠道菌群结构和功能。其中与乳酸菌组相比,复合组的保护效果更显著,更显著增加Lactobacillus的丰度,降低Coprococcus和Rikenellaceae-g_的丰度,同时短链脂肪酸含量被显著增加。综上,复合组对2型糖尿病小鼠肠道菌群失调具有最显著的改善作用。本研究将为益生菌复配剂应用于2型糖尿病的干预治疗提供重要参考依据。     

Effect of agitated bed drying on the retention of phenolic compounds,anthocyanins and antioxidant activity of roselle (Hibiscus sabdariffa L.)

An agitated fluidised bed dryer was employed to dry lixiviated roselle (Hibiscus sabdariffa L.) calyxes. The effects of operational drying variables on the chemical attributes such as the retention of monomeric anthocyanins (MA), phenolic compounds, polymeric colour, antioxidant activity and drying rate were analysed. Drying curves showed only decreasing falling rate period. To determine the kinetic parameters, the drying data were fitted to a Page's model, based on the moisture content ratio vs. the drying time; the k values ranged from 1.58 × 10^?5 to 6.28 × 10^?2 s^?1. The different drying conditions showed significant differences in the chemical parameters. When processing wet feeds, as lixiviated roselle calyxes, the mechanical assisted fluidisation can be considered as an innovative concept.     

Inhibitory effects of Hibiscus sabdariffa L extract on low‐density lipoprotein oxidation and anti‐hyperlipidemia in fructose‐fed and cholesterol‐fed rats

Hibiscus sabdariffa L extract (HSE) is an aqueous extract of Hibiscus sabdariffa L flowers that is used as a local soft drink and medical herb in Taiwan. Oxidation of low‐density lipoprotein (LDL) has been shown to increase the incidence of atherosclerosis. In this study, we determined the antioxidative activity of HSE on LDL oxidation by examining relative electrophoretic mobilities (REM) and thiobarbituric acid‐reactive substances (TBARS). The data revealed an inhibitory effect of HSE on Cu²⁺‐mediated REM and TBARS. HSE exhibited a remarkable ability to reduce cholesterol degradation and ApoB fragmentation. Overall, HSE showed a high potency to inhibit the production of oxidized LDL induced by copper and, specifically, to reduce serum triglycerides in high‐fructose diet (HFD) fed rats and serum cholesterol in high‐cholesterol diet (HCD) fed animals. The levels of LDL and the ratio of LDL‐cholesterol (LDL‐C) to HDL‐cholesterol (HDL‐C) were reduced by HSE in both hyperlipidaemia models. Based on these findings, we suggest that HSE may be used to inhibit LDL oxidation and to prevent various types of hyperlipidaemia in HFD‐ or HCD‐fed rats. Copyright © 2004 Society of Chemical Industry     

美味牛肝菌多糖对2型糖尿病大鼠肝损伤的改善作用

目的:研究美味牛肝菌多糖对2型糖尿病(T2DM)大鼠肝损伤的改善作用。方法:采用高脂高糖饲料喂养联合链脲佐菌素(STZ)腹腔注射法构建T2DM大鼠模型。将T2DM大鼠随机分成模型组、牛肝菌多糖低、高剂量组(200,400 mg/kg·bw)、二甲双胍组(200 mg/kg·bw),以正常组作对照,正常组与模型组给予生理盐水。各组灌胃给药1次/d,4周后,测定各组大鼠空腹血糖(GLU)值并计算肝脏指数;测定血清中甘油三酯(TG)含量,谷丙转氨酶(ALT)、谷草转氨酶(AST)的活力;检测肝脏中过氧化氢酶(CAT)、超氧化物歧化酶(SOD)和谷胱甘肽过氧化物酶(GSH-Px)活力,还原型谷胱甘肽(GSH)和丙二醛(MDA)含量。结果:与模型组相比,三组药物组大鼠的GLU水平显著降低(p<0.05)。TG和MDA含量减少,肝脏指数下降,ALT、AST的活力显著降低(p<0.01);CAT、SOD、GSH-Px活力和GSH的含量极显著升高(p<0.01)。结论:美味牛肝菌多糖对减轻T2DM大鼠的肝损伤有显著的疗效。