Comprehensive Characterization of Secondary Metabolites in Fruits and Leaves of Cloudberry (Rubus chamaemorus L.)

Abstract

Cloudberry (Rubus chamaemorus L.) is a circumpolar boreal plant rich in bioactive compounds and is widely used in food and in folk medicine. In this study, a combination of two-dimensional NMR spectroscopy and liquid chromatography–high-resolution mass spectrometry was used for the comprehensive characterization of secondary metabolites in cloudberry lipophilic and hydrophilic extracts. Special attention was paid to the leaf extractives, which are highly enriched in polyphenolic compounds, the content of which reaches 19% in the extract (in gallic acid equivalent). The chemical composition of the polyphenolic fraction is represented mainly by the glycosylated derivatives of flavonoids, hydroxycinnamic (primarily caffeic), gallic (including the structure of galloyl ascorbate) and ellagic acids, catechin, and procyanidins. The contents of aglycones in the polyphenolic fraction were 64 and 100 mg g−1 for flavonoids and hydroxycinnamic acids, respectively, while the content of free caffeic acid was 1.2 mg g−1. This determines the exceptionally high antioxidant activity of this fraction (750 mg g−1 in gallic acid equivalent) and the ability to scavenge superoxide anion radicals, which is 60% higher than that of Trolox. The lower polar fractions consist mainly of glycolipids, which include polyunsaturated linolenic acid (18:3), pentacyclic triterpenic acids, carotenoid lutein, and chlorophyll derivatives, among which pheophytin a dominates. Along with the availability, the high antioxidant and biological activities of cloudberry leaf extracts make them a promising source of food additives, cosmetics, and pharmaceuticals.

Nutritionally Important Pro-Health Active Ingredients and Antioxidant Properties of Fruits and Fruit Juice of Selected Biennial Fruiting Rubus idaeus L. Cultivars

“…The average range of the total phenolic content in the R. idaeus fruits determined with the Folin-Ciocalteau method in the present study (1.0 mg/g in 'Glen Ample'-1.3 mg/g in 'Radziejowa') was in agreement with the range reported for the raspberry cultivars 'Aksu Kırmızısı' (1.0-1.8 mg/g), 'Rubin' (1.1-1.9 mg/g), 'Heritage' (1.3-1.9 mg/g), and 'Autumn Bliss' (1.1-2.5 mg/g), but lower than the values reported for R. idaeus 'Newburgh' (1.4-1.8 mg/g), Heritage (1.5-1.9 mg/g), 'Hollanda Boduru (1.8-2.1 mg/g) [62], 'Fallgold' (1.5-1.5 mg/g), 'Meeker' (2.1 mg/g) [63], and cloudberry R. chamaemorus L. (7.0 mg/g) [64]. These differences are mainly related to environmental factors.…”

“…Since the total phenolic content in the studied raspberry cultivars is comparable to the antioxidant activity determined by the DPPH and ABTS assays, it may be supposed that the antioxidant activity of fruits is mainly related to the presence of polyphenols. Faleva et al [64] have reported that the antioxidant activity of raspberry fruit extracts depends on the high content of ascorbic acid.…”

Warburgia Salutaris Metabolites of Medicinal Value – A Review

“…The authors performed a targeted metabolomic analysis using LC-MS/MS on syrup and powder matrices to optimise various factors to isolate and identify the largest number of metabolites per analysis. Also, recent attempts at comprehensive isolation and characterisation of secondary metabolites include the report by Faleva et al [18] in Rubus chamaemorus lipophilic and hydrophilic extracts using a combination of 2D nuclear magnetic resonance (NMR) spectroscopy and liquid chromatography-high-resolution mass spectrometry (LC-HRMS). They reported on a total of 68 compounds from their analyses.…”