Limonene and eucalyptol rich essential oils with their antimicrobial activity from the leaves and rhizomes of Conamomum vietnamense N.S. Lý & T.S. Hoang (Zingiberaceae) Danh Duc Nguyen 1 , Hieu Nguyen-Ngoc 2 , Hieu Tran-Trung 3 , Dang-Khoa Nguyen 1 , Lien-uong i Nguyen 1 1 Institute of Applied Technology, u Dau Mot University, 06 Tran Van On, Phu Hoa Ward, u Dau Mot City 75100, Binh Duong, Vietnam 2 Faculty of Pharmacy, PHENIKAA University, Hanoi 12116, Vietnam 3 Department of Chemistry, College of Education, Vinh University, 182 Le Duan, Vinh City, Nghean 43000, Vietnam. Corresponding author: Lien-uong i Nguyen (thuongntl@tdmu.edu.vn) Received 31 October 2022  ♦  Accepted 30 November 2022  ♦  Published 26 January 2023 Citation: Nguyen DD, Nguyen-Ngoc H, Tran-Trung H, Nguyen D-K, i Nguyen L-T (2023) Limonene and eucalyptol rich essen- tial oils with their antimicrobial activity from the leaves and rhizomes of Conamomum vietnamense N.S. Lý & T.S. Hoang (Zingiber- aceae). Pharmacia 70(1): 91–96. https://doi.org/10.3897/pharmacia.70.e96946 Abstract Conamomum vietnamense, a new species of Zingiberaceae family, has been discovered and described from Tay Nguyen (Central Highlands, Vietnam) in 2022. e present study described the preparation of essential oil from leaves and rhizomes of the plant by hydrodistillation process. en, the chemical composition of these essential oils was analyzed by Gas Chromatography-Mass Spec- trometry (GC-MS), which indicated that limonene (18.74 and 26.20%) and eucalyptol (40.47 and 49.49%) were the main components, respectively. e essential oils also showed moderate antimicrobial activities against Gram-positive bacterial strains (Enterococcus faecalis ATCC 299212, Staphylococcus aureus ATCC 25923, Bacillus cereus ATCC 14579), Gram-negative bacterial strains (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Salmonella enterica ATCC 13076), and a pathogenic yeast (Candida albicans ATCC 10231) in the MIC range of 32–256 μg/mL, which was comparable to those of positive controls, streptomycin and cyclohexim- ide. For the first time, the chemical composition and antimicrobial activity of the essential oil of C. vietnamense were studied. Keywords Conamomum vietnamense, GC-MS, essential oil, limonene, eucalyptol, antimicrobial activity Introduction e genus Conamomum Ridl. is a small genus in the Zingiberaceae family with only 12 accepted species worldwide, mainly occurring in evergreen lowland and montane forests in Southeast Asian countries, such as Vietnam, Cambodia, ailand, Malaysia, Singapore, Sumatra and Borneo (Boer et al. 2018; Luu et al. 2019; Ngoc-Sam et al. 2022). Before 2018, the genus Conamomum had been a synonym of the genus Amomum Roxb., however, based on the combination of molecular (nrITS and matK) and morphological evidence, the botanist De Boer proposed Conamomum as a separate genus (Boer et al. 2018). To date, there have been a limited number of studies on the essential oils of Conamomum species and their bioactivities. Conamomum rubidium (Lamxay Copyright Nguyen DD et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Pharmacia 70(1): 91–96 DOI 10.3897/pharmacia.70.e96946 Research Article