Chemical composition and antioxidant and antibacterial properties of the essential oils extracted from Citrus sinensis peels by hydrodistillation and microwave methods

The present study is devoted to evaluate in vitro the chemical composition and the antioxidant and antibacterial properties of essential oils (Eo) extracted by hydrodistillation (HD) and microwave (MW) from the plant peels of Citrus sinensis. The extraction provided yields of 0.26% and 0.02%, respectively. The essential oils were analyzed by GC-MS whose major component is limonene that has a remarkable percentage (78.192% and 58.6%, respectively) for the essential oil extracted by HD and MW. The results of the antioxidant potential were noticeable in each of the essential oils with a higher priority to that extracted by hydrodistillation. The evaluation of the antioxidant power by the free radical scavenging method (DPPH) showed that the essential oils studied have good antioxidant activity, especially for the oil extracted by HD having presented an IC50 of (13.07 ± 0.169) mg/ml, while BHT and ascorbic acid showed very potent and effective anti-free radical activity with IC50 of the order of (19.54 ± 0.32) µg/ml and (1.17 ± 0.05) µg/ml respectively. According to the β-carotene/linoleic acid test, the oxidation of β-carotene was effectively inhibited by the two essential oils of Citrus sinensis peels with a percentage of inhibition of (56.46 ± 0.76) % and (31.39 ± 1.49) % respectively for HD and MW. Eo extracted by HD is more active than ascorbic acid (15.43%). In the antibacterial test, the activity was evaluated by the disc-diffusion method, the two types of sweet orange essential oils inhibited the growth of five bacterial strains out of six: The best activity was obtained against E. coli, Listeria monocytogenes, and Agrobacterium with a diameter of the zone of inhibition between 70 and 84 mm, with the exception of the strain of Bacillus subtilis, there is no zone of inhibition has been observed.

Chemical composition, antidiabetic, anti-inflammatory, antioxidant and toxicityactivities, of the essential oil of <em>Fortunella margarita</em> peels

The purpose of this study was to identify the principal components of the essential oil extracted from Fortunella margarita peels via hydrodistillation and to evaluate in vitro its anti-diabetic, anti-inflammatory, antioxidant, and toxicity properties. Among the detected compounds were limonene, D-germacrene, β-myrcene, and α-pinene. Method of inhibiting the denaturation of Bovine Serum Albumin (BSA) was utilized to assess the anti-inflammatory properties of Fortunella margarita. At a concentration of 400g/mL, a high anti-inflammatory effect was observed. The percentage of BSA protection against heat increased with increasing concentration. Also, the evaluation of antidiabetic activity by glucose uptake by yeast cells revealed that Fortunella margarita was more effective than the standard drug novoformine in the presence of 5 mM glucose. The antioxidant potential of the essential oil was evaluated using the DPPH free radical scavenging, reducing power and β-carotene/linoleic acid tests, where the essential oil had much lower antioxidant activity. A bioassay on the lethality of brine shrimp was conducted to determine the toxicity of the essential oil. The study reveals that the essential oil is a possible source of important bioactive compounds and that its constituents may exhibit synergistic effects. Our findings suggest that the essential oil from Fortunella margarita could be used in the future as a substitute for synthetic anti-diabetic, anti-inflammatory, and antioxidant agents with potential applications in the food and pharmaceutical industries.