Abstract The purpose of this study was to identify the principal compo- nents 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 concentra- tion of 400 g/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 scaveng- ing, 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 toxi- city 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-inflam- matory, and antioxidant agents with potential applications in the food and pharmaceutical industries. Introduction Kumquats (Fortunella margarita) are a small, sweet and sour fruit belonging to the Rutaceae family. They are typically con- sumed raw as a whole fruit with the peel and without the seeds. 1,2 The nutrient and phytochemical content of kumquats includes carotenoids, ascorbic acid, flavonoids, and essential oils. Due to the presence of terpenoids and flavonoids, the peel has a palatable, sweet aroma. 3 Kumquat is a small citrus fruit and is native to Asia, specifically China and India. In Algeria, it is still an uncommonly known and consumed fruit. In some states of Algeria, kumquats are commercialized and sold as exotic fruits with high added value in large supermarkets and open markets in small towns. It is com- mon knowledge that kumquat peels are abundant in essential oils, which play a key role in the flavour of the fruit and are widely used in the food and pharmaceutical industries. 2 Not only are plant-derived essential oils prized for their nutri- tional value, but also for their functional and technical properties. Moreover, due to the presence of bioactive compounds with antioxidant properties, the quality of these fruit essential oils is enhanced. 4,5 As oxidative bursts in various cells are one of the inflammatory reactions, essential oils can also act as anti-inflam- matory agents. Inflammation is a complex biological response of vascular tissues to stimuli that may be harmful. Inflammation is also associated with pain and involves, among other things, an Correspondence: Zineb Lakache, Laboratory of Ethnobotany and Natural Substances, ENS-Kouba, Algiers, Algeria. E-mail: lakache.zineb@gmail.com Key words: Fortunella margarita; essential oil; GC-MS; biological activities. Contributions: All authors contributed significantly to this work, including drafting and revising the manuscript. Conflict of interests: The Authors declare no conflict of interest Availability of data and materials: All data generated or analyzed dur- ing this study are included in this published article. Ethics approval and consent to participate: Not applicable. Informed consent: Not applicable. Received for publication: 26 May 2022. Revision received: 17 September 2022. Accepted for publication: 22 September 2022. Publisher’s note: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher. © Copyright: the Author(s), 2022 Licensee PAGEPress, Italy Journal of Biological Research 2022; 95:10641 doi:10.4081/jbr.2022.10641 This article is distributed under the terms of the Creative Commons Attribution-NonCommercial International License (CC BY-NC 4.0) which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. [page 170] [Journal of Biological Research 2022; 95:10641] Journal of Biological Research 2022; volume 95:10641 Chemical composition, antidiabetic, anti-inflammatory, antioxidant and toxicity activities, of the essential oil of Fortunella margarita peels Zineb Lakache, 1 Hinda Hacib, 1 Hamza Aliboudhar, 2 Mohamed Toumi, 1 Mohamed Mahdid, 1 Nassima Lamrani, 1 Hassina Tounsi, 1 Abdelkrim Kameli 1 1 Laboratory of Ethnobotany and Natural Substances, ENS-Kouba, Algiers; 2 USTHB, Laboratory of Functional Organic Analysis, Faculty of Chemistry, University of Sciences and Technology Houari Boumediene, El Bab-Ezzouar, Algiers, Algeria Non-commercial use only