Chemical Compositions and Antioxidant Activities of Essential Oils, and Their Combinations, Obtained from Flavedo By-Product of Seven Cultivars of Sicilian Citrus aurantium L.

Natale Badalamenti,Mariarosaria Leporini,Rosa Tundis,Rosario Schicchi,Anna Geraci,Maurizio Bruno,Monica Rosa Loizzo,Luigia Gervasi

doi:10.3390/molecules27051580

Natale Badalamenti, Mariarosaria Leporini + Show 6 more

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https://doi.org/10.3390/molecules27051580

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Abstract

In this work, seven Citrus aurantium essential oils (EOs) derived from flavedo of cultivars ‘Canaliculata’, ‘Consolei’, ‘Crispifolia’, ‘Fasciata’, ‘Foetifera’, ‘Listata’, and ‘Bizzaria’ were investigated. EOs were also combined in 1:1 (v/v) ratio to identify possible synergism or antagonism of actions. GC-MS analysis was done to investigate Eos’ phytochemical profiles. The antioxidant activity was studied by using a multi-target approach based on FRAP, DPPH, ABTS, and β-carotene bleaching tests. A great difference was observed in EOs’ phytochemical profiles. d-limonene (33.35–89.17%) was the main monoterpene hydrocarbon, and α-Pinene, β-myrcene, and β-linalool were identified in almost all samples. Among EOs, only C3 showed high quantitative and qualitative variability in its chemical composition. The chemical diversity of EOs was also demonstrated by PCA and HCA statistical analysis. Samples C2, C4, C5, C6, and C7 were statistically similar to each other, while C1 and C3 were characterized as having a different amount of other compounds and oxygenated monoterpenes, respectively, with respect to the other EOs mentioned. The global antioxidant score (GAS) revealed that among the tested EOs, C. aurantium ‘Fasciata’ EO had the highest antioxidant potential, with a GAS value of −0.47, whereas among combinations, the EO obtained by mixing ‘Canaliculata’ + ‘Bizzaria’ was the most active. Comparison by theoretical and real data on inhibitory concentration (IC50) and FRAP values did not reveal any significant effect of synergism or antagonism of actions to be valid in all biological applied tests. These findings, considered together, represent an important starting point to understand which compounds are responsible for the activities and their future possible industrial application.

Highlights

Citrus aurantium L., known as bitter or sour orange, belongs to the Rutaceae family, and its genus is native to a wide area covering Asia and Oceania (Queensland, Australia) [1]
D-limonene was present in high quantities, but much lower when compared with all the other essential oils (EOs)
The majority class is that of oxygenated monoterpenes (44.79%), enriched by the presence of β-linalool (7.69%), α-terpineol (7.06%), bergamol (6.77%), and geranyl acetate (10.12%)

Summary

Introduction

Citrus aurantium L., known as bitter or sour orange, belongs to the Rutaceae family (order Sapindales), and its genus is native to a wide area covering Asia (from India to northern China) and Oceania (Queensland, Australia) [1]. Its origin can probably be placed between southern China, northern Burma, and north-east India [2]. It is marketed and planted in tropical and temperate areas such as France, Spain, Italy, and North Africa [3]. And Spain are responsible for 80% of European Citrus production [5]. In Sicily, an average of 34% of Citrus fruits, predominantly orange, are processed into juices, providing about half of its weight as waste, which reaches 24.3 million tons per year [6–8]

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