302: Phytochemical, In Vitro Antioxidant, and Antihypertensive Properties of Wild Blueberry (Vaccinium Angustifolium)

Introduction

It is a physiological fact that all living cells generate free radicals as part of their normal functioning. However, the production of an excessive amount of free radicals, either from external or internal sources, has been identified as a key contributor to various pathological conditions. An imbalance between oxidants (reactive oxygen/nitrogen species, ROS) and antioxidants leads to oxidative stress. Blueberries have antioxidant and antihypertensive properties that reduce oxidative stress and lower blood pressure and lipids in people at risk of chronic diseases associated with metabolic syndrome.

Methods

Ultra-High-performance liquid chromatography (UHPLC) analysis of polyphenolic extracts from freeze-dried wild blueberry powder was conducted on a Vanquish UHPLC system coupled with a quadrupole orbitrap mass spectrometer with electrospray ionization (H-ESI). The polyphenolic compounds were identified by comparing their retention times and exact mass with those of the standard compounds. Total phenolic content, total flavonoids content, and radical scavenging activity of the samples were conducted using the Folin-Ciocalteu, aluminum chloride colorimetric assay and 2,2-diphenyl-1-picrylhydrazyl radical scavenging assays respectively to determine the in vitro antioxidant properties. The inhibitory activity of angiotensin converting enzyme by blueberry polyphenolic extracts were estimated spectrophotometrically using N-[3-(2-Furyl) acryloyl]-Phe-Gly-Gly,98% (FAPGG) respectively.

Results

The results showed that the identified polyphenolic compounds were quercetin, gallic acid, cyanidin chloride, Vitamin C, trans caffeic acid, procyanidin B1, and procyanidin B2. The investigation of their in vitro antihypertensive and antioxidant activities demonstrated that blueberries exhibited significantly higher ACE-inhibitory activity (p < 0.05) of 32.7±0.6%, 34.5±4.7% and 56.2±2.0% at different concentrations of 0.1mg/ml, 0.5mg/ml and 2.0mg/ml and an increasing radical scavenging activities of 66.4±2.9%, 72.3±2.0% and 83.4±0.5% with increased concentrations at 1.0mg/ml, 2.0mg/ml and 4.0mg/ml respectively. It had a high total phenolic and flavonoid content of 741.11± 5.0 mg gallic acid equivalents [GAE]/g) and 679.2 ± 5.0 mg catechin equivalents/g) respectively at concentration of 15mg/ml.

Significance

Our results show that wild blueberries are high in bioactive polyphenolic compounds and display significant antioxidant and antihypertensive properties that could benefit health. This suggests that wild blueberries may represent an important source of functional food that could be used as nutraceutical ingredients with the potential to positively impact human health.

Authors: Deborah O Omachi, Thaniyath Shahnaz, Gines Brandon, John O Onuh, Norma Dawkins