The North American highbush blueberry (Vaccinium corymbosum L.) is the most common edible blueberry, well known for its antioxidant properties. However, there are more than 600 other species of edible blueberries, known as neotropical blueberries, which have not yet been investigated. In this study, five species of neotropical blueberries: Cavendishia grandifolia, Anthopterus wardii, Sphyrospermum buxifolium, Macleania coccoloboides, and Sphyrospermum cordifolium were examined for their antioxidant and iron chelating properties and the results were compared with the highbush blueberry (V. corymbosum).
Reactive oxygen species (ROS) are free radicals that are formed naturally as byproducts of normal metabolic processes in our bodies. They play a major role in cell signaling processes. Unfortunately, they also damage cells by causing oxidative stress. This stress is a significant factor in the development of diabetes, cardiovascular disorders and central nervous system disorders. Fruits and vegetables contain antioxidants, which are helpful in scavenging these free radicals. Highbush blueberries are known to contain antioxidants in abundance and are considered to be “super fruits” because of their ROS-scavenging ability. The current study investigated the antioxidant properties of lesser-known species of blueberries.
* Extracts of freeze-dried fruits of the selected blueberry species were concentrated and stored at 4 C.
* The total phenol content in the extracts was measured
* The iron-chelating properties of the extracts and the amounts of the two antioxidants primarily responsible for free radical scavenging in blueberries (1,1 – Diphenyl-2-picrylhydrazul (DPPH) and 2,2’-Azinobis (3-ethylbenzothiazoline-6-sulfonate, ABTS), were estimated.
* Phenols in the extracts were separated and analyzed to determine their nature and amounts.
* The total phenolic content of C.grandifolia and A.wardii was greater than that of V. corymbosum.
* C.grandifolia, A.wardii and S.buxifolium showed significantly higher levels of DPPH free radical scavenging activity than V.corymbosum.
* ABTS free radical scavenging activities of all blueberries increased with time up to 40 minutes, after which there was no significant increase in activity. C.grandifolia and A.wardii showed significantly higher scavenging ability than V.corymbosum.
* Iron-chelating ability was seen to be significantly higher in extracts obtained from C.grandifolia, A.wardii and M.coccoloboides than in V.corymbosum.
* There was a correlation between the total phenolic content, DPPH and ABTS scavenging and the iron chelating effect.
* Chlorogenic acid was found in significant quantities in all five neotropical blueberries as well as V.corymbosum.
V.corymbosum used as the control for comparison of antioxidant activity was obtained from a local grocery store and the other neotropical blueberries were obtained fresh from botanical garden greenhouses and conservatories. The effects of environmental factors and storage conditions of the control sample on the antioxidant activity were not considered.
Phenolic compounds in blueberries are responsible for their inherent antioxidant properties. Based on the results of this study, chlorogenic acid found in all the blueberries seems to be responsible for their free radical scavenging activities. Prior to this study, the commercially available edible highbush blueberry (V. corymbosum) was the only species known for its antioxidant property. However, this study showed that that other neotropical blueberries with better antioxidant profiles are available. Among the five species studied, C.grandifolia and A.wardii were found to have a better free radical scavenging and iron chelating activity than the currently popular highbush blueberry, V. corymbosum.
For More Information:
Edible Neotropical Blueberries: Antioxidant and Compositional Finger Print Analysis
Publication Journal: Journal of Agricultural and Food Chemistry, March 2011
By Keyvan Dastmalchi; Gema Flores, et al., The Department of Biological Sciences, Lehman College, Bronx, New York and Graduate Centre, City University of New York, Bronx, New York.