Essential oils from Ocimum basilicum L. varieties as source of natural antioxidants. Chemical analysis & antioxidant activity. G. Tsasi1*, E. Sakadani1, T. Mailis2, A. Daskalaki2, E. Skaltsa2, Y. Samaras1 1Department
of Food Technology, Technological Educational Institute of Ionian Islands, Vergoti Ave. 28100 Argostoli – Kefallinia, Greece, ⃰
[email protected] 2Department of Pharmacognosy & Chemistry of Natural Products, School of Pharmacy, University of Athens, Panepistimiopolis Zografou, Athens
Introduction
Ocimum basilicum L. (basil) is an aromatic plant belonging to Lamiaceae family, that has been traditionally used in the culinary arts and in the food processing industry.1 The leaves and flowering tops of the plant are perceived as carminative, galactogogue, stomachic and antispasmodic in folk medicine.2 Owing to the wide and varying chemical composition of O. basilicum essential oils (EOs) depending on the chemotype and the origin of the plants attention has been conducted towards the biological properties of the EOs, particularly as antimicrobial and antioxidant agents.
Materials and methods The aim of this study was to investigate the chemical composition of essential oils (EOs) from five different varieties of Ocimum basilicum L. and the evaluation of their antioxidant activity. Each essential oil was obtained with hydro-distillation using a Clevenger type apparatus. The GC-MS analyses of EOs were performed on a HewlettPackard 5973-6890 system operating in EI mode (70eV) equipped with a split/ splitless injector (220 °C), using a fused silica HP-5 MS capillary column (30m x 0.25mm (i.d.), film thickness: 0.25μm). The antioxidant activity of each EO was measured in terms of hydrogen-donating or radical-scavenging ability, using the stable DPPH as reagent and ascorbic acid as a positive control.
Results and Discussion
O. basilicum var. Lettuce
O. basilicum var. Cinnamon
O. basilicum var. Latifolia
O. basilicum var. Minimum
2.1
3.2
2.4
1.7
Oxygenated Monoterpenes Sesquiterpene Hydrocarbons Oxygenated Sesquiterpenes
35.8
32.8
11.5
41.8
43.5
38.5
7.4
7.3
18.4
13.3
8.8
2.0
2.6
4.8
5.1
Phenylpropanoid s Hydrocarbons
12.3
55.6
75.3
32.4
36.1
0.3
-
-
-
-
References: 1. Beatović et al., (2015) Rec. Nat. Prod. 9 (1), 62. 2. Sajjadi (2006). Daru, 14 (3), 128. 3. Hussain et al., (2008) Food Chem. 108 (3), 986.
0,180 0,160 0,140 0,120 0,100 0,080 0,060 0,040 0,020
Latifolia
O. basilicum var. Violetto 2.6
Monoterpenes
DPPH radical-scavenging activity of tested EOs
0,000
Varieties Grouped components
0,200
IC 50 values
The chemical analysis revealed that cultivars latifolia and minimum were dominated of oxygenated monoterpenes (41.8% and 43.5 %, respectively). Phenylpropanoids were the main components of cultivars lettuce, cinnamon (55.6 % and 75.3 %) while violetto cultivar was dominated of sesquiterpene hydrocarbons and oxygenated monoterpenes (38.5 % and 35.8% respectively). Among the EOs tested for their antioxidant activity the cultivars minimum, violetto, lettuce and latifolia showed high antioxidant activity with IC50 values of 0.009 ± 0.001, 0.02 ± 0.00, 0.163 ± 0.021 and 0.028 ± 0.003 mg/mL, respectively. Cultivar cinnamon revealed weak antioxidant activity with IC50 value of 6.267 ± 0.208 mg/mL. Noteworthy the IC50 value of ascorbic acid was 0.05 ± 0.002 mg/mL. The O. basilicum EOs, and particularly var. minimum, proved to be a promising source of natural antioxidants since they revealed to possess activity comparable to that of synthetic ascorbic acid. The chemical properties as well as the variation of compounds and biological activities of O. basilicum is still under progress from our research group.
Minimum Lettuce O. basilicum varieties
Violetto
Fig. 1: GC chromatogram of var. minimum