Hibiscus sabdariffa extract inhibits the development of atherosclerosis in cholesterol-fed rabbits

Hibiscus sabdariffa L., a local soft drink material and medicinal herb, is usually used effectively in native medicines against hypertension, pyrexia, and liver disorders. Here, we report an extract, HSE (H. sabdariffa extract), which is designed to exhibit hypolipidemia and antiatherosclerotic effects in rabbits with experimental atherosclerosis. New Zealand White rabbits were fed with a normal diet, high cholesterol (1.3%), lard oil (3%) diet (HCD) with or without 0.5 or 1% HSE for 10 weeks. The levels of triglyceride, cholesterol, and low-density lipoprotein cholesterol (LDL-C) were lower in the serum of rabbits fed HCD plus HSE than in the serum of rabbits fed HCD. Feeding HSE (0.5 and 1% in the diet) to rabbits significantly reduced severe atherosclerosis in the aorta. Histopathological examination showed that HSE reduced foam cell formation and inhibited smooth muscle cell migration and calcification in the blood vessel of rabbits. These results suggest that HSE inhibits serum lipids and shows an antiatherosclerotic activity.     

Adsorption and desorption properties of macroporous resins for anthocyanins from the calyx extract of roselle (Hibiscus sabdariffa L.)

Adsorption of roselle anthocynins, a natural pigment, onto various macroporous resins was optimized to develop a simple and efficient process for industrial separation and purification of roselle anthocyanins. Nine different macroporous resins (AB-8, X-5, HPD-100, SP-207, XAD-4, LS-305A, DM-21, LS-610B, and LS-305) were evaluated for the adsorption properties of the anthocyanins extracted from the calyx extract of Hibiscus sabdariffa L. The influences of phase contact time, solution pH, initial anthocyanin concentration, and ethanol concentration with different citric acid amounts were studied by the static adsorption/desorption method. The adsorption isotherm data were fitted well to the Langmuir isotherm, and according to this model, LS-610B and LS-305 exhibited the highest monolayer sorption capacities of 31.95 and 38.16 mg/g, respectively. The kinetic data were modeled using pseudo-first-order, pseudo-second-order, and intraparticle diffusion equations. The experimental data were well described by the pseudo-second-order kinetic model. Continuous column adsorption-regeneration cycles indicated negligible capacity loss of LS-305 during operation. The overall yield of pigment product was 49.6 mg/g dried calyces. The content of roselle anthocynins in the pigment product was 4.85%.     

Antioxidant and antimutagenic properties of Hibiscus tiliaceus L. methanolic extract

The genus Hibiscus thrives in a variety of climates and produces a diversity of natural compounds with bioactive properties. We have studied the chemical composition and the in vivo antioxidant properties of Hibiscus tiliaceus L. methanolic flower extract, as well as its mutagenic/antimutagenic effects. Vitamin E and some stigmasterol derivatives that might confer an antioxidant effect to the extract were present. Treatment with this extract protected several Saccharomyces cerevisiae strains defective in antioxidant defenses against H2O2 and t-BOOH cytotoxicities, showing a clear antioxidant activity. The effect is the same for all strains used, independent of the antioxidant defense disrupted, suggesting that protection may be due to molecules that act as versatile and wide spectrum nonenzymatic antioxidants, such as vitamins or phytosterols. The extract was not mutagenic in either Salmonella typhimurium or S. cerevisiae and showed a significant antimutagenic action against oxidative mutagens in S. cerevisiae.     

Hibiscus sabdariffa polyphenolic extract inhibits hyperglycemia, hyperlipidemia, and glycation-oxidative stress while improving insulin resistance

H. sabdariffa polyphenolic extract (HPE) was demonstrated to inhibit high glucose-stimulated cellular changes. In this study, we analyzed the composition of HPE and used a type 2 diabetic rat model to test its protective effect. At least 18 phenolic compounds were found in HPE. Treatment with HPE reduced hyperglycemia and hyperinsulinemia, especially at the dose of 200 mg/kg. HPE decreased serum triacylglycerol, cholesterol, and the ratio of low density lipoprotein/high density lipoprotein (LDL/HDL). Diabetes promoted plasma advanced glycation end product (AGE) formation and lipid peroxidation, while HPE significantly reduced these elevations. Immunohistological observation revealed that HPE inhibited the expression of connective tissue growth factor (CTGF) and receptor of AGE (RAGE), which was increased in type 2 diabetic aortic regions. Furthermore, HPE recovered the weight loss found in type 2 diabetic rats. In conclusion, we demonstrated the anti-insulin resistance properties of HPE and its effect on hypoglycemia, hypolipidemia, and antioxidation. HPE has the potential to be an adjuvant for diabetic therapy.     

Dietary fiber content and associated antioxidant compounds in Roselle flower (Hibiscus sabdariffa L.) beverage

The beverage of Hibiscus sabdariffa flowers is widely consumed in Mexico. Polyphenols contained in plant foods are frequently associated with dietary fiber. The aim of this work is to quantify the dietary fiber, associated polyphenols, and antioxidant capacity of the Roselle flower and the beverage traditionally prepared from it and its contribution to the Mexican diet. Roselle flower contained dietary fiber as the largest component (33.9%) and was rich in phenolic compounds (6.13%). Soluble dietary fiber was 0.66 g/L in beverage, and 66% of total extractable polyphenols contained in Roselle flower passed to the beverage and showed an antioxidant capacity of 335 micromoL trolox equivalents/100 mL beverage measured by ABTS. These data suggest that Roselle flower beverage intake in the Mexican diet may contribute around 166 and 165 mg/per serving to the intake of dietary fiber and polyphenols, respectively. The health benefits from consumption of Hibiscus beverage could be of considerable benefit to the whole population.     

Encapsulation of olive leaf extract in beta-cyclodextrin

Olive leaf extract, rich in oleuropein, formed an inclusion complex with beta-cyclodextrin (beta-CD) upon mixing of the components in aqueous media and subsequent freeze-drying. Inclusion complex formation was confirmed by differential scanning calorimetry (DSC). DSC thermograms indicated that the endothermic peaks of both the olive leaf extract and the physical mixture of olive leaf extract with beta-CD, attributed to the melting of crystals of the extract, were absent in DSC thermogram of inclusion complex. Moreover, DSC studies under oxidative conditions indicated that the complex of olive leaf extract with beta-CD was protected against oxidation, since it remained intact at temperatures where the free olive leaf extract was oxidized. Phase solubility studies afforded A L type diagrams, 1:1 complex stoichiometry, a moderate binding constant ( approximately 300 M (-1)), and an increase of the aqueous solubility by approximately 50%. The formation of the inclusion complex was also confirmed by nuclear magnetic resonance (NMR) studies of beta-CD solutions in the presence of both pure oleuropein and olive leaf extract. The NMR data have established the formation of a 1:1 complex with beta-CD that involves deep insertion of the dihydroxyphenethyl moiety inside the cavity from its secondary side.     

The genome biogeography of Hibiscus L. section Furcaria DC

Summary Hibiscus L. section Furcaria DC. (Malvaceae) is a natural group of more than 100 known species, many of which are handsome ornamentals with large, showy, delicate flowers. This group includes the fiber, food, and medicinal plants kenaf, H. cannabinus L., and roselle, H. sabdariffa L. The basic chromosome number is x = 18. In nature are found diploid, tetraploid, hexaploid, octoploid, and decaploid taxa. This group displays a remarkable amount of genome diversity, as shown by cytological analysis of 140 hybrid combinations from over 60,000 crosses. At least 13 genomes are present: A, B, C, D, E, G, H, J, P, R, V, X, and Y. Subsaharan Africa is the center of genome diversity; nine of the 13 genomes are represented in African taxa, and nine of the 10 confirmed diploid species occur in Africa. Five (possibly six) genomes reside in extant diploids. The G genome (or a modified G genome) is widely distributed. Found in only one diploid species in Africa, it is found also in African tetraploid and African and Indian octoploid species, in New World tetraploid and decaploid species, and in Australian hexaploid species. The G-genome apparently was widely dispersed and differentiated, followed by hybridization, subsequent chromosome doubling, and radiation. The A, B, X, and Y genomes, on the other hand, are confined mainly to Africa, with a few taxa in Asia, and apparently are the products of a later round of hybridization and allopolyploidy.     

Influence of weather on the fibre yield of mesta (Hibiscus sabdariffa) in the north coastal zone of Andhra Pradesh,India

Mesta (Hibiscus sabdariffa) is an important fibre crop in the north coastal zone of Andhra Pradesh which accounts for 59% of India's total production of mesta. The area under this crop has reduced dramatically in recent years and in order to understand the contribution of weather to this decline, long-term experimental data (14 years) on mesta cv. AMV-4 and regional crop yields were analysed. Crop yields decreased in seasons when rainfall exceeded 900 mm and maximum temperature remained below 32.0°C during 10–16 weeks after sowing (WAS), which coincided with the active vegetative stage. The average yields of the region were high when seasonal rainfall ranged between 600 and 725 mm. Increased fibre yields were observed when increasing seasonal rainfall coincided with maximum temperatures exceeding 33.5°C. Fibre yields from a long-term experiment showed strong positive correlations with maximum temperature during 6–16 WAS (r = 0.79) and with mean diurnal temperature range (8.6–10.7°C) during 11–19 WAS (r = 0.66). Step-wise regression showed that maximum variability in fibre yield was explained by maximum temperature which could be used to develop models to predict yield at least one month in advance with acceptable accuracy. This prediction could then be used as an input for crop planning and market intelligence.     

Study on furundu, a traditional Sudanese fermented roselle (Hibiscus sabdariffa L.) seed: effect on in vitro protein digestibility, chemical composition, and functional properties of the total proteins

Furundu, a meat substitute, is traditionally prepared by cooking the karkade (Hibiscus sabdariffa L.) seed and then fermenting it for 9 days. Physicochemical and functional properties of raw and cooked seed and of furundu ferments were analyzed. Furundu preparation resulted in significant changes in karkade seed major nutrients. Total polyphenols and phytic acid were also reduced. The increase in total acidity and fat acidity coupled with a decrease in pH indicates microbial hydrolysis of the major nutrients; proteins, carbohydrates, and fats. In vitro digestibility of the seed proteins reached the maximum value (82.7%) at the sixth day of fermentation, but thereafter it significantly decreased. The effect of furundu preparation on N solubility profiles and functional properties, such as emulsification and foaming properties and other related parameters, is investigated in water and in 1 M NaCl extracts from defatted flour samples. The results show that cooking followed by fermentation affects proteins solubility in water and 1 M NaCl. The foaming capacity (FC) from the flour of raw seed decreased as a result of cooking. Fermentation for 9 days significantly increased the FC of the cooked seed, restoring the inherent value. Foam from fermented samples collapsed more rapidly during a period of 120 min as compared to the foam from raw and cooked karkade seeds; stability in 1 M NaCl was lower as compared to those in water. In water, the emulsion stability (ES) from the fermented samples was significantly higher than that of the raw seed flour. Addition of 1 M NaCl significantly decreased the ES of the fermented samples.     

黄秋葵实时荧光定量PCR内参基因的克隆与筛选评价

为筛选黄秋葵实时荧光定量PCR的稳定内参基因,本研究以绿白1号为试验材料,根据黄秋葵RNA-seq数据库,筛选并验证获得18SrRNA、ACT、EF-1α、TUA、TUB、GAPDH等6个内参基因ORF序列;以黄秋葵不同组织、不同发育时期果实、不同发育时期叶片和低温、高温、干旱胁迫处理的叶片为材料,利用实时荧光定量PCR技术分析测定基因表达量,并结合GeNorm、NormFinder和BestKeeper软件评价6个内参基因的稳定性。结果表明,6个基因在不同组织、各发育阶段及不同胁迫下均有表达,但表达稳定性不尽相同,其中,EF-1α在黄秋葵果荚发育、高温胁迫下表达稳定性最好;18SrRNA在黄秋葵各组织、叶发育和干旱胁迫下表达稳定性最优;ACT在低温胁迫下表现最稳定。此外,在29个处理中,18SrRNA、EF-1α、ACT表达均较稳定,可以用于荧光定量表达分析。本研究结果为黄秋葵基因功能分析和调控机理研究提供了基础。     

Stabilization of caffeic acid derivatives in Echinacea purpurea L. glycerin extract

Recent work has shown that enzymatic degradation and oxidation of cichoric acid and other caffeic derivatives occurs in Echinacea preparations. However, very little is known as to the means of stabilizing these phytopreparations. To stabilize the glycerin extract of Echinacea purpurea, we have evaluated the effects of 3 natural antioxidants (citric acid, malic acid, and hibiscus extract) on the stability of the major caffeic acid derivatives (caftaric acid, caffeic acid, cichoric acid, and 2-O-feruloyl-tartaric acid). Chlorogenic acid, which normally occurs in an ethanol extract of E. purpurea, was not present in the glycerin extract. The caffeic acid derivatives, with the exception of 2-O-feruloyl-tartaric acid, were subject to degradation in the control sample. 2-O-Feruloyl-tartaric acid was stable during the whole testing period. All antioxidant treatments greatly improved the stability of caffeic acid derivatives. Stability was dependent upon the concentration of antioxidant added.     

Structure, dynamics, and stability of beta-cyclodextrin inclusion complexes of aspartame and neotame

Studies of the high-intensity sweetener aspartame show that its stability is significantly enhanced in the presence of beta-cyclodextrin (beta-CyD). At a 5:1 beta-CyD/aspartame molar ratio, the stability of aspartame is 42% greater in 4 mM phosphate buffer (pH 3.1) compared to solutions prepared without beta-CyD. Solution-state (1)H NMR experiments demonstrate the formation of 1:1 beta-CyD/aspartame complexes, stabilized by the interaction of the phenyl-ring protons of aspartame with the H3 and H5 protons of beta-CyD. Inclusion complex formation clearly accounts for the observed stability enhancement of aspartame in solution. The formation of inclusion complexes in solution is also demonstrated for beta-CyD and neotame, a structural derivative of aspartame containing an N-substituted 3,3-dimethylbutyl group. These complexes are stabilized by the interaction of beta-CyD with both phenyl-ring and dimethylbutyl protons. Solid-state NMR experiments provide additional characterization, clearly demonstrating the formation of inclusion complexes in lyophilized solids prepared from solutions of beta-CyD and either aspartame or neotame.     

黄秋葵MYB转录因子的鉴定及与果实老化关系分析

黄秋葵(Hibiscus esculentus L.)纤维素和木质素的大量积累极易引起果实老化,而植物MYB转录因子参与纤维素和木质素等生物合成与沉积,在次生细胞壁形成中起着重要的调控作用。为研究MYB转录因子在黄秋葵老化中的作用,从黄秋葵果实转录组测序数据库中筛选得到10条功能注释为MYB基因的片段序列,克隆获得了HeMYB4、HeMYB6、HeMYB26、HeMYB28、HeMYB44、HeMYB46、HeMYB59、HeMYB86、HeMY108和HeMYB113的基因全长,分析其核苷酸及编码氨基酸序列特征,同时进行了亚细胞定位、磷酸化位点、功能域、进化等生物信息学分析。结果显示,10个MYB基因均定位于细胞质膜上,具有丰富的磷酸化位点和功能域,与拟南芥等物种中参与纤维素和木质素合成的MYB蛋白亲缘关系较近。通过实时荧光定量PCR分析黄秋葵MYB基因家族的10个基因在果实发育过程、采后常温贮藏期间的表达,结果发现,HeMYB46、HeMYB86、HeMY108的表达量与纤维素含量呈极显著正相关,推测上述基因在黄秋葵果实衰老过程纤维素合成中起重要作用;HeMYB46、HeMYB59的表达量与木质素含量呈极显著正相关,推测其在木质素合成中起到重要调控作用。本研究结果初步明确了黄秋葵MYB转录因子在黄秋葵老化过程中的作用, 为黄秋葵的生产、分子育种等提供了理论基础。     

Antioxidant activity of a flavonoid-rich extract of Hypericum perforatum L. in vitro

A flavonoid-rich extract of Hypericum perforatum L. (FEHP) was prepared by adsorption on macroporous resin and desorption by ethanol. Total flavonoid content of FEHP was determined by a colorimetric method. The major constituents of FEHP, including rutin, hyperoside, isoquercitrin, avicularin, quercitrin, and quercetin, were determined by HPLC analysis and confirmed by LC-MS. Different antioxidant assays were utilized to evaluate free radical scavenging activity and antioxidant activity of FEHP. FEHP was an effective scavenger in quenching DPPH and superoxide radical with IC50 of 10.63 microg/mL and 54.3 microg/mL, respectively. A linear correlation between concentration of FEHP and reducing power was observed with a coefficient of r2 = 0.9991. Addition of 150 microg of FEHP obviously decreased the peroxidation of linoleic acid during 84 h incubation, but the amount of FEHP over 150 microg did not show statistically significant inhibitory effect of peroxidation of linoliec acid (p > 0.05). FEHP exhibited inhibitory effect of peroxidation of liposome induced both by hydroxyl radical generated with iron-ascorbic acid system and peroxyl radical and showed prominent inhibitory effect of deoxyribose degradation in a concentration-dependent manner in site-specific assay but poor effect in non-site-specific assay, which suggested that chelation of metal ion was the main antioxidant action. According to the results obtained in the present study, the antioxidant mechanism of FEHP might be attributed to its free radical scavenging activity, metal-chelation activity, and reactive oxygen quenching activity.     

Stabilization of the avicide 3-chloro-p-toluidine as the beta-cyclodextrin adduct.

Stabilization of the avicide 3-chloro-p-toluidine (CPTH) on rice baits by pseudo latex polymeric coating and beta-cyclodextin inclusion was investigated. When CPTH-treated rice baits were exposed to sunlight, the CPTH formed colored compounds, which exacerbated problems with bait acceptance and efficacy. Fluidized bed coating with controlled-release polymeric psuedo latexes (RS, RL, NE) reduced CPTH loss but did not eliminate color formation. Enteric pseudo latex coatings (CAP and 4110) gave mixed results. Coating 4110 reduced CPTH loss but still allowed color formation, whereas CAP allowed more CPTH loss than any other coating as well as increased color formation. Inclusion in beta-cyclodextrin (molar ratio 1:1) led to enhanced retention of CPTH and minimal color formation. The CPT/beta-cyclodextrin adduct increased retention of CPTH from 43 to 70% upon simulated weathering. The retention was independent of the adhesives used for attachment.     

Effect of phosphate on stability of pyridoxal in the presence of lysine

The stability of the biologically active compound vitamin B(6) in aqueous solution was investigated. Schiff base formation is the major reaction between the epsilon-amino group of lysine and the aldehyde group of both pyridoxal and pyridoxal phosphate. Model systems composed of equal molar concentrations of lysine with either pyridoxal or pyridoxal phosphate were used to study the effect of proton transfer on Schiff base formation. Pyridoxylidenelysine was found to be the major product in both lysine/pyridoxal and lysine/pyridoxal phosphate systems. Quantitation of residual pyridoxal and pyridoxal phosphate was conducted using an HPLC to evaluate the degradation of pyridoxal and pyridoxal phosphate. The results indicate both the free phosphate ion in the buffer system and the bound phosphate on pyridoxal phosphate can enhance the formation of the Schiff base. The phosphate group serves as both proton donor and acceptor, which catalyzes the Schiff base formation. The aldehyde group on pyridoxal phosphate was found to be much more reactive than that on pyridoxal. The bound phosphate group on pyridoxal phosphate, with proton donating and accepting groups in close proximity, can simultaneously donate and accept protons, thus enhancing Schiff base formation between the aldehyde group and the epsilon-amino group. The deterioration rate of pyridoxal phosphate was faster than that of pyridoxal in an aqueous system.     

Competitive binding of aroma compounds by beta-cyclodextrin.

Retention of six aroma compounds has been studied after dehydration of ternary mixtures of aroma water and beta-cyclodextrin. A maximal retention of a mole of aroma per mole of beta-cyclodextrin has been observed for five of the aroma compounds, whereas retention of benzyl alcohol can be twice as high. Retention of a mixture of aroma compounds has also been studied. It has been noted that when volatile compounds compete for the same binding sites on beta-cyclodextrin, ethyl hexanoate, 2-methylbutyric acid, and benzyl alcohol are, respectively, better retained than ethyl propionate, hexanoic acid, and hexanol. Preferential retention observed with esters can be simply explained by their difference of physicochemical properties, but for the acids and alcohols a study at the molecular scale has been necessary. The better retention of 2-methylbutyric acid can be explained by differences in the nature of interaction between the acids and their carrier. At least selectivity of retention noted for the alcohol could be due to a difference in the location of the guest and also a difference in the number of aroma molecules that can be bound per polysaccharide molecule.     

Olea europaea L. leaf extract and derivatives: antioxidant properties

This paper reports a very simple and fast method to collect eluates with high amounts of hydroxytyrosol, biotransforming Olea europaea L. leaf extract by a thermophilic beta-glycosidase immobilized on chitosan. Some phenolic compounds in the leaf tissue and in the eluates obtained by biotransformation are identified. To propose the eluates as natural substances from a vegetal source, their antioxidant properties have been compared with those of the leaf extract from which they are originated. The eluates possess a higher concentration of simple phenols, characterized by a stronger antioxidant capacity, than those available in extra virgin olive oils and in many tablets of olive leaf extracts, commercially found as dietetic products and food integrators.     

Regulation of anthocyanin accumulation in rice (Oryza sativa L. subsp. indica) using MgSO4 spraying and low temperature

Pericarp pigmented grains of rice have been reported as anthocyanin enriched source of antioxidants. The aim of this investigation was to regulate anthocyanin accumulation in pericarp pigmented rice cv. ‘Hom Nil’ using 0, 10, 50, and 100 mM MgSO₄ foliar spray. The level of magnesium content in the leaf tissues treated with 100 mM MgSO₄ for 2 d increased 2.6 times over control (0 mM MgSO₄). After growing the treated plants under 16°C for 28 d, photosynthetic abilities were reduced by 17?93%, leading to retarded plant height (39?42% less than control). In addition, grain yield per panicle of the plants grown under 16°C for 28 d was reduced by 26?75% compared to the plants grown under 32°C.Total anthocyanin concentration, cyanidin-3-glucoside and peonidin-3-glucoside in the pericarp of the grains derived from the rice treated with 100 mM MgSO₄ was increased 3.8 times over the control. Peonidin-3-glucoside, a dominant compound was reported for the first time. The study concludes that Mg?enrichment may play a key role as a metalloid in stabilizing anthocyanin, a secondary metabolite in the leaf sheath tissues and pericarp of grains in ‘Hom Nil’ rice cultivar.