Original article
Chemical composition and antioxidant activity of Borago officinalis L. leaf extract growing in Algeria
- Open Access funded by King Saud University
- Under a Creative Commons license
Abstract
The aqueous and hydroalcoholic extracts of borage (Borago officinalis) leaves from Annaba region (Algeria) were preliminary analyzed for their phenolic profile (total phenolics, total flavonoids, total flavonols, total tannins and total anthocyanins). These extracts were evaluated for their antioxidant properties by different methods such as DPPH radical scavenging, test NBT and total antioxidant activity. The two extracts have exhibited a high antiradical capacity. Indeed, the ethanolic extract showed the lower IC50 values and the highest amount of phenolics (94.09 ± 1.72 mg gallic acid/g dry extract). Using LC-MS/MS analysis, it was possible to identify phenolic acids, flavonoids, sterol and for the first time oleuropein was identified in the aqueous extract of the plant. The obtained results have demonstrated that phenolic compounds are the major contributor to the antioxidant activity of plants.
Abbreviations
- BHA, butylated hydroxy anisole;
- BHT, butylated hydroxy toluene;
- BO, Borago officinalis;
- C, catechin;
- C-3-G, cyanidin-3-glucoside;
- DE, dry extract;
- DPPH, 1,1-diphenyl-2-picrylhydrazyl;
- EDTA, ethylene diamine tetra acetic acid;
- ESI-MS/MS, electrospray Ionization Mass Spectrometry;
- GA, gallic acid;
- HPLC, high performance liquid chromatography;
- IC50, half maximal inhibitory concentration;
- IP,inhibition percentage;
- LC-MS/MS, liquid chromatography coupled to tandem mass spectrometry;
- Mo,molybdate;
- MS, mass spectrum;
- NBT, nitroblue tetrazolium;
- OD, optical density;
- Q, quercitin;
- R, rutin;
- ROS, reactive oxygen species;
- TBHQ, tert-butyl hydroquinone
Keywords
- Borago officinalis;
- Total phenol;
- Phenolic profile;
- DPPH;
- Antioxidant activity
1. Introduction
Recently, the biological and medical sciences are invaded by a new concept called “oxidative stress”, in which the cell cannot control the excessive presence of reactive oxygen species (ROS). ROS such as superoxide anions (O2
−), hydroxyl radical (OH) and nitric oxide (NO) are produced by biological combustion in the respiration process.
−), hydroxyl radical (OH) and nitric oxide (NO) are produced by biological combustion in the respiration process.
Currently, it is well known that although oxidative stress is not a disease in itself, it is potentially involved in many diseases as a trigger or associated with complications during their evolution as in cancer, cardiovascular diseases, inflammatory lung diseases, immune dysfunctions and neurodegenerative disorders. ROS can also cause a change in the organoleptic properties of foods by the oxidative degradation of their constituent lipids (Yamaguchi et al., 2004).
Hence, the balance between antioxidation and oxidation is believed to be a critical concept for maintaining a healthy biological system (Tiwari, 2001). So, to prevent or reduce the oxidative stress, sufficient amounts of antioxidants need to be consumed or added to foods.
The antioxidants can be of synthetic or natural origin. Fact, synthetic antioxidants, such as butylated hydroxy anisole (BHA), butylated hydroxy toluene (BHT) and tert-butyl hydroquinone (TBHQ), are widely used in the food industry. Although, they are effective and less expensive than natural antioxidants, some toxic effects have been reported (Choi et al., 2000). Thus, research for a safer and effective natural antioxidant is in progress. Among these natural antioxidants, phenolic antioxidants can be mentioned. Actually, various methods have been used to evaluate the antioxidant properties of phenolic compounds in vitro ( Antolovich et al., 2002). These compounds are proved to be more potent antioxidants than Vitamins E and C and carotenoids. Besides, they are reported to quench the oxygen-derived and substrate-derived free radicals by donating a hydrogen atom or an electron to the free radical ( Wettasinghe and Shahidi, 1999). Phenolic compounds are present in a wide range of vegetables and plants, playing an important role in defense mechanisms ( Arici et al., 2014).
Borage (Borago officinalis L.) is a herbaceous plant of the Boraginaceae family native to North Africa and widely spread in many Mediterranean countries. In Algeria, this plant is used not only for preparing beverages and salads but also for different medicinal purposes. Over the last years, in spite of being the subject of increasing agricultural interest thanks to its high content of γ- linolenic acid in seed ( Mhamdi et al., 2009), to the best of our knowledge, few research studies have been devoted to the investigation of its antioxidant activity. For example, Conforti et al. (2008) have demonstrated the strong antioxidant activity of borage leaves extract. Other research works have reported that the ethanolic extract of defatted seeds possess phenolic acids, antioxidant and free radical scavenging activities ( Mhamdi et al., 2010a). However, the information pertaining to the active components of borage leaves is very scarce. It is worthy to mention that the presence of fatty acids ( Ciriano et al., 2009), phenolic acids ( Mhamdi et al., 2010b), pyrrolizidines alkaloids ( El-Shazly and Wink, 2014), and sterols ( Conforti et al., 2008) was previously noticed.
In folk medication, the most of medicinal plants are used by making their aqueous extracts as raw materials but it is important to note that same biomass is more beneficiary if extracted in ethanol rather than water. Therefore, the Algerian borage was preliminarily characterised by comparing the aqueous extract and the ethanol extract through their chemical compositions by using colorimetric methods and mass spectrometry. Furthermore, the antioxidant activity of both extracts of borage was carried out using three methods: 2,2- diphenyl-picrylhydrazyl radical-scavenging assay (DPPH test), total antioxidant activity by phosphomolybdenum method, and scavenging of superoxide radical (NBT test).
