Orange peel extract from Xinhui and Sichuan boast 'best' anti-inflammatory properties, study finds
Chenpi has a history of traditional use to treat and relieve symptoms of digestive disorders associated with acute or chronic inflammation.
Previous studies have found the orange peel extract, a byproduct from fruit and juice production, contains numerous flavonoids - including polymethoxylated flavones (PMF) - flavonols and many phenolic acids, providing antioxidant, anti-inflammatory, anti-carcinogenic, and anti-atherosclerosis activities.
Research has also shown that the flavonoid constituents and antioxidant activity of orange peel extract varies according to the orange species, cultivars and the growing conditions.
However, information on the influence of growing location on important bioactive properties, such as anti-inflammatory activity, is limited, state researchers from the University of British Columbia in collaboration with Vancouver's Tait Laboratories Inc., writing in Food Chemistry.
“Hence, more information is required to characterize the flavonoid profile and its related antioxidant and anti-inflammatory bioactivities in order to ensure that orange peel extract sources retain value for [chenpi] production and processing industries as valuable ingredients for nutraceutical, functional food or beverage industries.”
Therefore, researchers compared three sources of conventional chenpi from California, Guangxi, Zhejiang, and two sources of so-called superior ‘nchenpi’, which contain greater levels of the flavonoid nobiletin, from Sichuan and Xinhui.
The researchers explain “We applied an effective combination of heat treatment with hot alkaline water extraction to recover flavonoids from mandarin peels grown in five distinctly different geographical regions. The flavonoid profile, antioxidant and anti-inflammatory activities of the resulting orange peel extract were compared.”
Although the yields of the Sichuan and Xinhui sources of orange peel were significantly lower than the other three sources, they had higher levels of PMF, which positively correlated with anti-inflammatory activity.
“The Xinhui and Sichuan peel samples tested herein can be classified as ‘nchenpi’, based on relatively higher PMF content than conventional chenpi derived from Guangxi, Zhejiang, and California sources,” the study states, adding the results reveal nobiletin levels are a good chemical marker for assessing the anti-inflammatory potential of extracts from different sources.
The Xinhui orange peel extract had the highest PMF content of all samples tested, along with the greatest antioxidant and anti-inflammatory activities, explaining why “Xinhui-sourced peel is considered a high quality source of chenpi (i.e. nchenpi).”
The study concludes: “Other regions, such as Sichuan, may also represent an alternative location from which dried citrus peels can be used as a potential novel ingredient in anti-inflammatory health products.”
Source: Food Chemistry
Food Chemistry 218 (2017) 15–21. http://dx.doi.org/10.1016/j.foodchem.2016.09.016
“Flavonoid composition of orange peel and its association with antioxidant and anti-inflammatory activities”
Authors: Xiu-Min Chen, et al.