OICC Press Trends in Phytochemical Research 2588-3631 7 4 2023 11 10 A review on biosynthesis, regulation, and applications of terpenes and terpenoids 228 245 10.30495/tpr.2023.1989410.1358 EN Anjali Singh Faculty of Biosciences, Shri Ramswaroop Memorial University, Lucknow-Deva Road, Barabanki, Uttar Pradesh-225003, India Dhananjay Singh Department of Biosciences, Integral University, Kursi Road, Lucknow, Uttar Pradesh-226026, India Sapna Sharma Faculty of Biosciences, Shri Ramswaroop Memorial University, Lucknow-Deva Road, Barabanki, Uttar Pradesh-225003, India Nishu Mittal Faculty of Biosciences, Shri Ramswaroop Memorial University, Lucknow-Deva Road, Barabanki, Uttar Pradesh-225003, India Journal Article 2023 11 10 Essential oils (EOs) are concentrated liquids extracted from various parts of plants and can be classified based on their phytochemical compounds. Terpenes and terpenoids have a wide range of biological activities, including anticancer, anti-inflammatory, antimicrobial, antioxidant, and antiallergic properties. Terpenes are plant-based compounds commonly used in the pharmaceutical, food, biofuel, and chemical industries by humans. In synthetic biology, genomic resources and emerging tools facilitate the production of high-quality terpenoids in plants and microbes. Terpenoids, however, are difficult to produce in large quantities due to their complex chemical structures and the limited amounts found in plants. The regulation of terpenoid biosynthesis has gradually emerged as a research priority. This review presents an overview of the biological activities, synthesis pathways, and key enzymes involved in the biosynthetic pathways and regulation of terpenes or terpenoids. This review will also include references for further research on molecular regulation, biological advancements, and increasing the content of terpenes or terpenoids in plants.