The Chemistry of Rose Pigments

In this article we present a survey of the pigments found in the flowers and fruits of old and modern varieties of roses. The yellow colors are produced by carotenoids, the reds by anthocyanins, and the modern oranges by a mixture of the two. The great structural diversity of the carotenoids contrasts with a surprisingly small number of anthocyanins. For the carotenoids found in roses, a clear correspondence exists between the structure and the breeding partners used; the old yellow roses, which arose from crosses with Chinese varieties, mainly contain carotenoids from early stages in the biosynthesis, while in the modern yellow roses, which are descended from Central Asian foetida types, hydroxylations, epoxidations, and epoxide transformations readily occur. A recently elucidated carotenoid degradation sequence follows the scheme C₄₀ → C₁₃ + C₂₇ → C₁₃ + C₁₄. The C₁₃ compounds are odoriferous substances that contribute to the scent of roses. In the physiological pH region, copigmentation with flavonol glycosides is crucial for stabilization of the anthocyanin chromophores. Many roses, including the “apothecary's rose”, which was once used medicinally, contain large amounts of strongly astringent ellagitannins, monosaccharide esters of gallic acid.     

Selective extraction, separation, and identification of anthocyanins from Hibiscus sabdariffa L. using solid phase extraction-capillary electrophoresis-mass spectrometry (time-of-flight /ion trap)

A method for selective extraction using SPE, electrophoretic separation at basic condition and the identification by using exact masses and fragmentation patterns has been developed in order to know the anthocyanins in dried calyces of Hibiscus sabdariffa L. A detailed and comparative study of several extraction procedures has been carried out to obtain the maximum number of anthocyanidins from the calyces and then a CE-TOF-MS method in positive mode using ESI has been developed for the separation and rapid identification of anthocyanins in H. sabdariffa L. Delphinidin-3-sambubioside, cyanidin-3-sambubioside have been detected as main components and cyanidin-3-O-rutinoside, delphinidin-3-O-glucoside and cyanidin-3,5-diglucoside, and chlorogenic acid as minor constituents. The confirmation of the anthocyanidins and chlorogenic acid was carried out using fragmentation ions with the IT-mass spectrometer (IT-MS).     

红外光谱法研究花色苷色素的酯化修饰

花色苷是一类广泛存在于植物中的水溶性色素。这类色素不仅色泽鲜艳,色调自然,而且安全性高,具有保健功能。然而,天然的花色苷色素存在稳定性差的缺陷,从而严重阻碍了其在食品工业中的广泛应用。为了改善花色苷色素的稳定性,采用分子修饰的方法,通过丁二酸酐酯化修饰花色苷色素,从而在保证色素色泽的前提下显著提高了花色苷色素的稳定性。由于花色苷的成分复杂,分析其酯化前后结构变化的步骤既繁琐又困难。利用红外光谱技术的宏观指纹特性对萝卜红色素的酯化修饰前后的结构进行分析。结果表明, 花色苷分子结构中糖环上的羟基与丁二酸酐发生酯化反应,形成了相应的酯类化合物,这可能是花色苷色素提高稳定性的根本原因。     

High resolution LC-MS characterization of phenolic compounds and the evaluation of antioxidant properties of a tropical purple radish genotype

This study reports qualitative profiling of the phenolic compounds in an indigenously developed purple radish genotype VRRAD-151 using ultra performance liquid chromatography with quadrupole time of flight mass spectrometry. The root and leaf samples were harvested at the horticultural maturity stage of the genotype. Roots were divided into the periderm, and xylem, and the leaf samples were divided into petiole, and lamina, and these were separately extracted with methanol before the LC-MS analysis. A total of 66 compounds, including 23 flavonols, 1 dihydroflavonols, 4 flavonones, 4 flavones, 28 anthocyanins, 2 isoflavonoids, 3 phenolic acids, and 1 hydroxybenzaldehyde were putatively identified based on high resolution accurate mass analysis with the data processing through UNIFI®, which is a comprehensive compound identification software solution. An in-house developed database comprising the secondary metabolites of polyphenols was used for the screening purpose, and each phenolic compound was identified based on the detection of the precursor ion, and at least one characteristic fragment ion, each with less than 5 ppm of mass error. Anthocyanins were the most abundant type of phenolics exhibiting 59% in leaf petiole, 80% in root periderm, and 90% in root xylem. The relative concentration of anthocyanins was lower (11%) in the leaf lamina. Cyanidins were the most predominant anthocyanins accounting for 54, 100, 90 and 65%, in leaf lamina, leaf petiole, root periderm and root xylem, respectively. Eight anthocyanins and 25 flavonols (except kaempferol-3-O-p-coumaryl-shophoroside-7-O-glucoside) are tentatively new identifications and reported for the first time in radish. Flavonols were found to be the predominant group of phenolic compounds in the leaf lamina, and interestingly, the gradient of antioxidant activity followed the (relative) concentration gradient of flavonols in the samples. The relative antioxidant activity of various fractions when compared with each other, followed the trend: leaf lamina > root periderm > leaf petiole ≈ root xylem. Based on the results it can be reflected that this genotype can be utilized as a functional food for management of various human and animal diseases. Since the detected anthocyanins were mostly present in acylated forms, this genotype can function as a potential source of stable natural colorants.     

Wild strawberry (Arbutus unedo): Phytochemical screening and antioxidant properties of fruits collected in northern Morocco

The aim of this study was to determine the polyphenolic compounds and the antioxidant ability of Arbutus unedo fruits, collected from three regions of northern Morocco, using high-performance liquid chromatography coupled to diode array and electrospray ionization mass spectrometry detection. The proper extraction method has been selected to achieve this objective. After delipidation, the three harvests were extracted by sonication using two solvents with increased polarity ethyl acetate and MeOH:water, 80:20 (v/v). Total polyphenols, flavonoids, tannins and anthocyanins were respectively: 108.41 ± 9.29 mg GAE/g (w/w) dry weight (DW), 101.07 ± 5.6 mg QE/g (w/w) (DW), 0.45 ± 0.48 mg EC/g (w/w) (DW) and 0.35 ± 0.48 mg Pg-3-glu/g (w/w) (DW). EC50 values for reducing power and DPPH radical scavenging activities were between 1.37 ± 0.2 and 17.82 ± 0.12 µg/mL (w/v). A total of 75 compounds were tentatively identified and some of these had never been found until nowadays in Arbutus unedo. The average amount of antioxidant compounds obtained by semi-quantitative analyses was 120.35 ± 32.05 mg/100 g (w/w) (DW). The attained results clearly highlight the potential of A. unedo as a source of healthy compounds, which could be advantageously added to the daily diet, making it a potential candidate for the cure for many emerging diseases.     

Constituent analysis and quality control of anthocyanin constituents of dried Lycium ruthenicum Murray fruits by HPLC–MS and HPLC–DAD

In recent years, many investigations on the anthocyanins of the fresh Lycium ruthenicum Murray fruits have been reported; while few studies about dried fruits have been published. In this study, chemical profile of dried fruits was illustrated by a high-performance liquid chromatography–tandem mass spectrometry method, which provided evidence for the certain identification of the main anthocyanins. Among these compounds, nine of them were selected as marker compounds for the semiquantitative evaluation, using a simple and reliable method by high-performance liquid chromatography–photodiode array detection (HPLC–DAD), with the combination of chromatographic fingerprint analysis. Separation was achieved on a C18 ODS 80TS QA analytical column with linear gradient elution of acetonitrile and 10% formic acid and 0.1% trifluoroacetic acid (TFA) aqueous solution. Our results showed that the contents of anthocyanins of dried L. ruthenicum Murray from different origins were different. We also inferred the anthocyanin compositions of dried L. ruthenicum Murray through analyzing the UV spectrum, retention time, elution order, and MS data. Finally, eight kinds of anthocyanin compositions were identified and different from the anthocyanins in fresh L. ruthenicum Murray. In a word, this study may provide experimental data in further development and utilization of L. ruthenicum Murray.     

Fast determination of anthocyanins and free pelargonidin in fruits,fruit juices,and fruit wines by high‐performance liquid chromatography using a core–shell column

Anthocyanins are water‐soluble pigments that are liable for colors ranging from red to blue of most fruits, vegetables, and flowers. A novel and fast method was developed for the determination of five anthocyanins and free pelargonidin by high‐performance liquid chromatography coupled to photodiode array detection. A 10% formic acid and acetonitrile mixture was employed as mobile phase in the gradient elution mode. Mobile phase composition, column temperature, flow rate, injection volume, and column conditioning time were optimized by employing a stepwise strategy. Using a C₁₈ core–shell column (100 × 4.6 mm, 2.7 μm), the separation of six analytes was accomplished in less than 9.5 min with a run‐to‐run analysis time of 19 min. The developed method was validated with respect to linearity (r > 0.9999), limit of detection, limit of quantification, intra‐/interday precision (<2%), accuracy (98.6–104.4%), and specificity. Afterwards, the method was applied to the determination of anthocyanins present in 15 different samples including fruits, fruit juices, and fruit wines.     

Ultrasonic-assisted modifications of macroporous resin to improve anthocyanin purification from a Pyrus communis var. Starkrimson extract

The present study presents an attempt to modify the surface properties of macroporous resins (MRs) in order to improve anthocyanin adsorption and desorption from Pyrus communis var Starkrimson fruit peel extract. A number of MRs were tested to optimise the ultrasonic-assisted adsorption (UAA) conditions; including ultrasonic power (100–400 W), resin-to-extract ratio (1–3 g/50 mL) and temperature (20–40 °C). Similarly, varying ultrasonic-assisted desorption (UAD) conditions were optimised; including ultrasonic power (200–600 W), resin-to-solvent ratio (1–4 g/50 mL), ethanol concentration (60–90% v/v) and temperature (20–40 °C). The Amberlyst 15 (H) cationic resin was found to be superior to the other tested resins. The maximum adsorption capacity (659 µg/g) of cyanidin 3-galactoside (Cy 3-gal) was achieved under the optimised UAA conditions (400 W, 20 °C and 1 g/50 mL), while 616 µg/g of Cy 3-gal was recovered under the optimised UAD conditions (582 W, 1 g/50 mL, 60% and 20 °C). Moreover, titratable-acid and total-sugar contents were found to be significantly lower under UAA than under conventional-assisted adsorption (CAA). ANOVA revealed that process factors had significant effects on the Cy 3-gal purification, as depicted by their linear, quadratic and interactive effects. While anthocyanin adsorption was found to be significantly improved at lower ultrasonic power, higher power promoted the desorption process. Adsorption under optimized UAA conditions followed pseudo second-order kinetics and multilayer adsorption (Freundlich isotherm) onto the Amberlyst 15 (H) resin surface was observed. The particle-size distribution curve and scanning electron microscopic images also revealed higher resin-surface roughness, peeling and the appearance of pores on the surface under ultrasonication. This is the first study to use ultrasonication to modify a cationic exchange resin for the improvement of Cy 3-gal purification from a fruit extract. This study can recommend the use of ultrasonication as a low-cost green technique that can improve macroporous resin characteristics for better purification of compounds from an extract.     

亲水相互作用色谱-串联质谱法快速测定葡萄酒中四种花青素

采用亲水相互作用色谱-串联质谱法(HILIC-MS/MS)建立同时测定葡萄酒中矢车菊素-3-O-葡萄糖苷、氯化葡萄糖苷芍药素、飞燕草素葡萄糖苷和氯化锦葵色素-3-O-葡糖苷4种花青素的分析方法。葡萄酒样品用甲醇直接稀释后,采用Merck ZIC HILIC色谱柱(150×2.1mm,3.5μm)分离;以乙腈-20mmol/L乙酸铵溶液作为流动相,梯度洗脱,目标化合物在多反应监测(MRM)模式下进行检测,外标法定量。在优化的条件下,4种花青素在1.0~50.0ng/mL范围内呈良好的线性关系,相关系数均不低于0.9992,方法定量限为0.05~1.0ng/mL。方法平均回收率为93.1%~96.7%,相对标准偏差不大于5.2%。该方法前处理简单、选择性好、灵敏度高,非常适用于葡萄酒中花青素的测定。     

Anthocyanins profile as fingerprint of wines using atmospheric pressure photoionisation coupled to quadrupole time-of-flight mass spectrometry

Present work shows for the first time the suitability of the atmospheric pressure photoionisation (APPI) coupled to quadrupole time-of-flight mass spectrometry (QqTOF) to characterise anthocyanins in wines. Results obtained are satisfactorily compared with the electrospray ionisation (ESI-MS) that has also been used. Parameters concerning the direct infusion-APPI-MS have been studied and optimised to generate information-rich mass spectra for wine fingerprinting.The proposed analytical methodology has been used to obtain a classification rule for unknown samples according to their anthocyanins profiles. In addition, the procedure shows high sample throughput since the time consuming sample treatment required for the extraction of anthocyanins from wines has been drastically reduced in this fingerprint-targeted approach.