Abstract
In our investigation, the chemical composition and bioactive potential of leaf buds of raspberry, blackberry, and a raspberry-blackberry hybrid were determined. Antioxidant and antimicrobial properties were tested in water (W), ethanol-water (EW), and glycerol-water (GW) extracts from the buds. These plant organs contain relatively large amounts of minerals, especially Fe. The total antioxidant capacity (TAC) measured by the ABTS and DPPH methods ranged from 2.86 to 12.19 and 6.75 to 24.26 mmol per 100 g fresh weight (FW) of buds, respectively. TAC values were generally higher in the raspberry than in the case of blackberry and raspberry-blackberry hybrid extracts. The antioxidant properties of the extracts were strongly positively correlated with their content of total phenolic (TP). No such relationship was noted for ascorbic acid (AA), whose concentration in all extracts was at a similarly low level. Antioxidant properties determined in vitro were confirmed for the GW extract from raspberry leaf buds in biological test based on the growth parameters of Δsod1 Saccharomyces cerevisiae mutant cells in hypertonic medium. The extracts also exhibited strong antibacterial properties against Staphylococcus aureus and Enterococcus faecalis and weaker against Enterobacter aerogenes. The studied leaf buds could be therefore an unconventional source of minerals, natural antioxidants and antibacterial compounds with potential applications in the food, pharmaceutical, and cosmetics industries.
Highlights
Leaf and flower buds of many plant species, due to their high content of biologically active substances, are used in pharmacology, cosmetics, and food production
Raspberry-blackberry hybrid buds had the highest levels of Mg and Mn, raspberry buds of the ‘Octavia’ cultivar had the highest content of Zn, and the highest content of Cu was found in the buds of wild blackberry (Table 1)
Blackberry, and raspberry-blackberry contain relatively high levels of minerals (K, Ca, Mg, Fe, Cu, Mn, and Zn) that are essential in the human diet as well as high concentrations of bioactive substances with antioxidant and antimicrobial properties
Summary
Leaf and flower buds of many plant species, due to their high content of biologically active substances, are used in pharmacology, cosmetics, and food production. They are a valuable component of the diet, rich in bioactive substances and minerals Rubus fruits, such as raspberries, blackberries, and hybrid berries, have high content of vitamins (C, A, E, B1, B2, B3, B6, and K), organic acids (citric, malic), phenolic acids (derivatives of cinnamic and benzoic acids), polyphenols, cyanidin, aromatic compounds, pectins, minerals, sugars, and dietary fibre [2,3]. They exhibit the health-promoting properties through anti-cancer, anti-atherosclerotic, anti-inflammatory, anti-diabetic, and anti-allergic effects, and reduce body weight [4]. These bioactive substances could be obtained from other organs of these plants, such as young shoots, leaf buds or leaves, which are available throughout the growing season
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