Determination of free and esterified carotenoid composition in rose hip fruit by HPLC-DAD-APCI⁺-MS

Highlights

• A simple and economical HPLC-DAD-APCI⁺-MS method is developed for systematic carotenoid analysis in rose hip fruit.

• Total carotenoid composition, including carotenoid esters, in rose hip fruit is reported for the first time.

• The rare natural compounds rubixanthin esters and violaxanthin esters are detected in rose hip fruit.

• Detailed interpretation of carotenoid identification.

Abstract

Rose hip fruit, which contains high concentration of carotenoids is commonly used for different food products in Europe and it is considered to have medical properties. In this study, a simple, rapid and efficient HPLC-DAD-APCI⁺-MS method was developed and applied to identify and quantify the carotenoids in rose hip fruit of four rose species, including both unsaponified and saponified extract. In the unsaponified extract 23 carotenoid esters were detected, in which either rubixanthin ester or violaxanthin ester was the dominant component of the ester composition. In the saponified extract 21 carotenoids, including 11 xanthophylls and 10 carotenes were detected. This is the first time the total carotenoid composition, including the carotenoid esters in rose hip fruit were identified and quantified. This work reveals the potential of rose hip fruit to be utilized as a healthy dietary material and give chemical information for the possible future development in the pharmacology field.

Introduction

The rose bush, is a woody perennial plant of the genus Rosa, within the family Rosaceae. It is widely spread in the world, mainly used as an ornamental plant for the showy and fragrant flower. The fruit of the rose plant, the rose hip, is typically orange to red in color, but dark purple to black color occurs in some special species. Depending on species, rose hip fruit ripens at the end of September or the beginning of October in Sweden (Uggla, 2004). The size and shape of rose hip fruits differ between species.

Rose hip fruit is commonly utilized as an edible material in the Eastern and Northern Europe. It can be used e.g. for herbal teas, jam, jelly, syrup, soup, and wine. For example, in Sweden the rose hip soup “nyponsoppa”, is a very common and popular drink product in the supermarket. Palinka, a traditional Hungarian alcoholic beverage, is also made of rose hip fruit, and is popular in Hungary, Romania, and other countries sharing Austro-Hungarian history. Rose hip fruit is known for its high vitamin C content, which can be up to 15 times higher than that of citrus fruits (Hornero-Méndez & Mínguez-Mosquera, 2000).

In recent decades, rose hip fruit has been more and more studied for its medical properties. It has been reported to be able to reduce osteoarthritis symptoms in clinical trials (Rein et al., 2004, Warholm et al., 2003). Rose hip fruit extract has also been shown to have the ability to inhibit cell proliferation in breast cancer (MCF-7), colon cancer (HT-29) and cervical cancer (HeLa) cell lines (Olsson et al., 2004, Tumbas et al., 2012). The medical properties of rose hip fruit derive from the rich phytochemical content, including compounds with health-promoting functions, such as vitamin C, flavonoids, phenolic acids, as well as carotenoids (Britton et al., 2004, Olsson et al., 2004, Su et al., 2007).

The group carotenoids, also named tetraterpenoids, constitutes a branch of the terpenoid group, consisting of eight isoprene units. The carotenoids are natural pigments, responsible for the coloration of different plant parts, and commonly abundant in fruit and vegetables. The long continuous conjugated double bond in the chemical structure contributes to the chromophore, so that carotenoid compounds have a special absorbance range in the visible light spectrum. Free and esterified carotenoid compounds can be found in the natural world, and the free carotenoids can be divided as xanthophylls and carotenes. In matured fruits and vegetables, certain amount of xanthophyll is esterified with fatty acids, generating xanthophyll esters. There are about 750 natural carotenoids and the number is still rising (Britton et al., 2004). Plants can synthesize carotenoids, while humans are not capable of synthesizing these compounds, and must obtain them through diet. Some carotenoids are pre-cursors of vitamin A, while others may have more specific functions. Presently research on the carotenoid composition in rose hip fruit is still limited. A number of methods, using mainly high performance liquid chromatography–mass spectrometry (HPLC–MS) for the detection of carotenoids have been reported (Rivera, Christou, & Canela-Garayoa, 2014). However, a detailed and systematic characterization of carotenoids (including esters) in rose hip fruit has not been reported so far.

Therefore, the main objective of this study was to develop an applicable method for systematic determination and quantification of carotenoids in rose hip fruit. Previous investigations, including from our research group (Andersson, Rumpunen, Johansson, & Olsson, 2011) and others (Hornero-Méndez & Mínguez-Mosquera, 2000), have not identified individual carotenoid esters present in rose hip fruit, though a large part of carotenoids are present as esters. In this work, MS was applied to identify xanthophyll esters in rose hip fruit. The key point of the new method should be the compatibility of a good HPLC separation with informative DAD-MS signals. Therefore, the aim of this investigation was to develop a methodology capable to separate and characterize individual carotenoids in both saponified and unsaponified extracts in rose hip fruit exactly, rapidly and economically.