Blueberry leaves as a promising sustainable source of polyphenols: Chemical composition, functional activities and future application perspectives

Blueberry leaves are a byproduct of blueberry cultivation, often overlooked despite their potential value. As global consumption of blueberries continues to rise, the area under cultivation expands, leading to an increased production of blueberry leaves. Blueberry leaves are a rich source of polyphenols, and in recent years, extensive research has been conducted on the composition and biological functions of these compounds. However, studies on blueberry leaves are often fragmented and lack a comprehensive overview of their potential applications. This review outlines the biosynthetic pathways of polyphenols in plants and compares the variations in polyphenol content and composition in blueberry leaves, influenced by factors such as cultivars, harvesting seasons, and extraction methods. Current research indicates that the primary constituents of blueberry leaf polyphenols (BLPs) are caffeoyl quinic acids, flavonols, and flavan-3-ols. These active compounds endow blueberry leaves with a range of functional properties, including antioxidant, anti-inflammatory, antibacterial, antiviral, antitumor, and metabolic syndrome-modulating effects. As a cost-effective and potentially beneficial by-product of agricultural production, blueberry leaves represent a promising area for further development. Therefore, this review discusses the opportunities and challenges associated with the applications of blueberry leaves, offering insights into their future processing, utilization, and potential for sustainable development.

Subchronic toxicity evaluation of leaves from rabbiteye blueberry (Vaccinium virgatum Aiton) in rats

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Blueberry leaf may contain multiple compounds with beneficial effects, but limited about the safety.

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Powdered blueberry leaf has no toxic event at oral dose of daily 500, 1000 and 2500 mg/kg for 90 days in SD rats.

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No significant changes in food consumption, body weight gain and organ weights.

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A daily dose up to 2,500 mg/kg body weight in both the sexes rats may indicate a NOAEL.

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An acceptable daily intake of blueberry leaf powder for humans is calculated to be 25 mg in dry weight per kg body weight.

Blueberry leaf may contain multiple compounds with beneficial effects. We conducted a 90-day toxicity study in rats to evaluate the safety of consuming the leaves of rabbiteye blueberry (Vaccinium virgatum Aiton; RB species). Powdered leaves were administered daily by oral gavage at doses of 500, 1000, and 2500 mg/kg body weight to male and female Sprague-Dawley rats for 90 days. Treatment did not result in death or changes in the behavior and external appearance of the animals. No alterations were observed in hematological and serum chemical parameters, urinalysis, food consumption, body weight gain, or absolute and relative organ weights at the end of the treatment period, with the exception of some leukocyte percentages in male rats treated with 500 and 1000 mg/kg blueberry leaf powder. The findings indicate that rabbiteye blueberry leaf is safe for consumption and should be investigated as a candidate functional food.

The salted radish takuan-zuke shows antihypertension effects in spontaneously hypertensive rats

Recently, we reported that the antihypertensive compound, γ-aminobutyrate (GABA), increases over time during the dehydration of salted radish, known as takuan-zuke, a popular pickle in Japan.