Effects of Latitude and Weather Conditions on Proanthocyanidins in Blackcurrant (Ribes nigrum) of Finnish Commercial Cultivars

Effects of geographical, soil and climatic factors on the two marker secondary metabolites contents in the roots of Rubia cordifolia L

The growth and quality of medicinal plants depend heavily on environmental variables. The quality of Rubia cordifolia, an important medicinal plant, is determined by the two main secondary metabolites of the root, purpurin and mollugin. However, their relationship with environmental factors has not been studied. In this study, the purpurin and mollugin contents of R. cordifolia roots from different sampling sites in China were measured using ultra-high-performance liquid chromatography, and the correlations between the two secondary metabolites and environmental variables were analyzed. The results showed that there were significant differences in the contents of purpurin and mollugin in the roots of R. cordifolia at different sampling points. The content of purpurin ranged from 0.00 to 3.03 mg g-1, while the content of mollugin ranged from 0.03 to 10.09 mg g-1. The quality of R. cordifolia in Shanxi, Shaanxi and Henan border areas and southeastern Liaoning was higher. Liaoning is expected to become a R. cordifolia planting area in Northeast China. Correlation and regression analysis revealed that the two secondary metabolites were affected by different environmental factors, the two secondary metabolites contents were positively correlated with longitude and latitude, and negatively correlated with soil nutrients. In addition, higher temperature and shorter sunshine duration facilitated the synthesis of purpurin. Annual precipitation might be the main factor limiting the quality of R. cordifolia because it had opposite effects on the synthesis of two major secondary metabolites. Therefore, this study is of great significance for the selection of R. cordifolia planting areas and the improvement of field planting quality.

Phenolic composition and bioactivity of Ribes magellanicum fruits from southern Patagonia

Eight Ribes magellanicum collections from three different places in southern Patagonia were compared for content of different groups of phenolics, antioxidant capacity and inhibition of enzymes related to metabolic syndrome (α-amylase, α-glucosidase and pancreatic lipase). The sample with the highest antioxidant capacity was assessed for glutathione (GSH) synthesis stimulation in human gastric adenocarcinoma (AGS) cells. The chemical profile was determined by high performance liquid chromatography with tandem mass spectrometry detection (HPLC-MS/MS) and the main phenolics were quantified. The samples from Navarino Island and Reserva Nacional Magallanes showed higher content of anthocyanins and caffeoylquinic acid, with better activity towards α-glucosidase and antioxidant capacity. A sample from Omora (Navarino Island), significantly increased intracellular GSH content in AGS cells. Some 70 compounds were identified in the fruit extracts by HPLC-MS/MS. The glucoside and rutinoside from delphinidin and cyanidin and 3-caffeoylquinic acid were the main compounds. Different chemical profiles were found according to the collection places.

Changes in marker secondary metabolites revealed the medicinal parts, harvest time, and possible synthetic sites of Rubia cordifolia L

Rubia cordifolia L. is a significant medicinal plant. To investigate the changes of marker metabolites of R. cordifolia, the purpurin, mollugin, carbon, nitrogen contents, and the expression of genes involved in anthraquinones synthesis were examined. The findings indicated that the two secondary metabolites were only detected in stems and roots. Root purpurin content was 5-26 times higher than in stems, and root mollugin content was 92 times higher than in stems in June. These findings suggest that the potential of the roots as a medicinal part. The roots were found to have highest purpurin content in October (2.406 mg g-1), whereas the mollugin content was highest in August (6.193 mg g-1). However, the purpurin content in August was only 0.029 mg g-1 lower than that in October, making August a suitable harvest period for R. cordifolia. The expression 1-deoxy-D-xylulose 5-phosphate synthase (dxs) and 1-deoxy-D-xylulose-5-phosphate reductorisomerase (dxr) genes in roots showed an upward trend. However, the expression level of dxr gene was significantly higher than dxs with the range of 60-518 times higher, indicating the important role of dxr gene. Through correlation and redundancy analyses, it was found that mollugin showed positive correlation with carbon contents and carbon-nitrogen ratio of aerial parts. Additionally, purpurin showed a positive correlation with the expression of both genes. As a result, mollugin is likely to be synthesized in the aerial parts and then stored in the roots, whereas purpurin might be synthesized in the stems and roots. These findings could provide cultivation guidelines for R. cordifolia.

Physicochemical characteristics, polyphenols and antioxidant activities of Dimocarpus longan grown in different geographical locations

Longan is widely consumed due to its high nutritional value. The growing area has substantial effect on nutrient component and secondary metabolism of fruits. The aim of this study was to analyze the differences in physicochemical characteristics, polyphenol profiles, and antioxidant activity of longan fruits grown in four regions of China. Two representative cultivars 'Shixia' and 'Chuliang' located in Chongqing, Guanxi, Zhanjiang and Hainan were collected and analyzed. The results showed that the fruit weights, edible rates, and total soluble solids were 5.63-12.57 g, 52.7-68.7% and 17.54-23.68%, respectively. The titratable acids, reducing sugars, vitamin C contents were 0.22-0.62%, 2.27-5.55% and 68.29-157.34 mg/100 g, respectively. Interestingly, contents of total polyphenols and antioxidant activities in longan pericarps from Chongqing were higher than those from low-latitude regions for two cultivars. In addition, 10 polyphenols were detected by UPLC-QqQ-MS/MS which showed that the content of polyphenols was much higher in longan pericarps than in pulps. The content of polyphenol profiles in longan was mainly influenced by its tissue distribution. Cultivar type may also affect the polyphenol profile of longan.

Proanthocyanidins and Where to Find Them: A Meta-Analytic Approach to Investigate Their Chemistry, Biosynthesis, Distribution, and Effect on Human Health

Proanthocyanidins (PACs) are a class of polyphenolic compounds that are attracting considerable interest in the nutraceutical field due to their potential health benefits. However, knowledge about the chemistry, biosynthesis, and distribution of PACs is limited. This review summarizes the main chemical characteristics and biosynthetic pathways and the main analytical methods aimed at their identification and quantification in raw plant matrices. Furthermore, meta-analytic approaches were used to identify the main plant sources in which PACs were contained and to investigate their potential effect on human health. In particular, a cluster analysis identified PACs in 35 different plant families and 60 different plant parts normally consumed in the human diet. On the other hand, a literature search, coupled with forest plot analyses, highlighted how PACs can be actively involved in both local and systemic effects. Finally, the potential mechanisms of action through which PACs may impact human health were investigated, focusing on their systemic hypoglycemic and lipid-lowering effects and their local anti-inflammatory actions on the intestinal epithelium. Overall, this review may be considered a complete report in which chemical, biosynthetic, ecological, and pharmacological aspects of PACs are discussed.

Reactivity of flavanols: Their fate in physical food processing and recent advances in their analysis by depolymerization

Flavanols, a subgroup of polyphenols, are secondary metabolites with antioxidant properties naturally produced in various plants (e.g., green tea, cocoa, grapes, and apples); they are a major polyphenol class in human foods and beverages, and have recognized effect on maintaining human health. Therefore, it is necessary to evaluate their changes (i.e., oxidation, polymerization, degradation, and epimerization) during various physical processing (i.e., heating, drying, mechanical shearing, high-pressure, ultrasound, and radiation) to improve the nutritional value of food products. However, the roles of flavanols, in particular for their polymerized forms, are often underestimated, for a large part because of analytical challenges: they are difficult to extract quantitatively, and their quantification demands chemical reactions. This review examines the existing data on the effects of different physical processing techniques on the content of flavanols and highlights the changes in epimerization and degree of polymerization, as well as some of the latest acidolysis methods for proanthocyanidin characterization and quantification. More and more evidence show that physical processing can affect content but also modify the structure of flavanols by promoting a series of internal reactions. The most important reactivity of flavanols in processing includes oxidative coupling and rearrangements, chain cleavage, structural rearrangements (e.g., polymerization, degradation, and epimerization), and addition to other macromolecules, that is, proteins and polysaccharides. Some acidolysis methods for the analysis of polymeric proanthocyanidins have been updated, which has contributed to complete analysis of proanthocyanidin structures in particular regarding their proportion of A-type proanthocyanidins and their degree of polymerization in various plants. However, future research is also needed to better extract and characterize high-polymer proanthocyanidins, whether in their native or modified forms.

Phenolic compounds in Nordic berry species and their application as potential natural food preservatives

An increasing demand for natural food preservatives is raised by consumers. For Nordic berry species, abundance of phenolic compounds and potent activities of anti-oxidation and anti-bacteria enables a great potential as food preservatives. This review provides a systematic examination of current literature on phenolic profiles, anti-oxidative and anti-bacterial activities of various extracts of Nordic berry species, as well as the impact of various structure features of phenolics on the bioactivities. Special attention is placed on exploitation of leaves of berry species and pomaces after juice-pressing as side-streams of berry production and processing. The current progress and challenges in application of Nordic berry species as food preservatives are discussed. To fully explore the potential application of Nordic berry species in food industry and especially to valorize the side-streams of berry cultivation (leaves) and juice-pressing industry (pomaces), it is crucial to obtain extracts and fractions with targeted phenolic composition, which have high food preserving efficacy and minimal impact on sensory qualities of food products.

Hydrophilic Interaction Liquid Chromatography to Characterize Nutraceuticals and Food Supplements Based on Flavanols and Related Compounds

Purified extracts from different types of berries and medicinal plants are increasingly used as raw materials for the production of nutraceuticals and dietary supplements, mainly due to their high content in bioactive substances. This is, for instance, the case of phenolic compounds such as flavonoids, which exhibit a wide range of beneficial properties, including antioxidant, anti-inflammatory, antineoplastic and antimicrobial activities. This paper tackles the characterization of several kinds of nutraceuticals based on hydrophilic interaction liquid chromatography (HILIC) with fluorescence detection (FLD). The study focused on the determination of flavanols and related compounds such as condensed tannins. Analytes were recovered by solvent extraction using methanol:water:hydrochloric acid (70:29:1 v:v:v) as the extraction solvent under sonication for 30 min at 55 °C. Experimental design with response surface methodology was used to optimize the HILIC separation to achieve good resolution of the main components, using acetonitrile:acetic acid (99:1 v/v) (solvent A) and methanol:water:acetic acid, (95:3:2 v/v/v) (solvent B) as the components of the mobile phase. For the assessment of the elution gradient, factors under study were solvent B percentage and gradient time. The best conditions were achieved with 10% solvent B as the initial percentage and 30 min of linear gradient to reach 25% solvent B. Principal component analysis and partial least square-discriminant analysis were used to characterize and compare the compositional features of dietary supplements based on both targeted and non-targeted approaches. Results revealed that the sample distribution relied on the oligomeric nature of descriptors.