Review Genotoxicity and Carcinogenicity of Medicinal Herbs and Their Nanoparticles Sameer H. Qari 1, * , Abdulmajeed F. Alrefaei 1 , Ahmed B. Ashour 1 and Mona H. Soliman 2   Citation: Qari, S.H.; Alrefaei, A.F.; Ashour, A.B.; Soliman, M.H. Genotoxicity and Carcinogenicity of Medicinal Herbs and Their Nanoparticles. Nutraceuticals 2021, 1, 31–41. https://doi.org/10.3390/ nutraceuticals1010005 Academic Editor: Herbert Ryan Marini Received: 4 October 2021 Accepted: 11 November 2021 Published: 18 November 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Biology Department, Aljumum University College, Umm Al-Qura University, Makkah 2203, Saudi Arabia; afrefaei@uqu.edu.sa (A.F.A.); s44181957@st.uqu.edu.sa (A.B.A.) 2 Biology Department, Faculty of Science, Taibah University, Al-Sharm, Yanbu El-Bahr, Yanbu 46429, Saudi Arabia; monahsh1@gmail.com * Correspondence: shqari@uqu.edu.sa Abstract: Medicinal plants (MPs) account for 70–80% of use in primary care around the world, and this percentage indicates that the number of MP users is high; thus, it is necessary to focus studies on medicinal herbs to ensure their proper use. In addition, MPs have strong genotoxic effects, as some types of MPs can cause DNA damage. Any substance that raises the risk of cancer or a tumor in an organism is called a carcinogen. There are many genotoxic and carcinogenic substances in the environment that can directly or indirectly affect genetic material. There are also nanoparticles (NPs) derived from MPs. Carbon-based NPs contain many nanoscale materials, such as fullerenes and carbon nanotubes, as well as metals such as gold (Au), silver (Ag), and aluminum (Al). Unfortunately, few studies are concerned with the carcinogenicity of NPs from MPs, whereas many researchers are interested in genotoxic assessment. For this reason, there is an urgent need for more studies into the safety of MPs and NPs. Therefore, this study reviewed the genotoxicity and carcinogenicity of MPs and their derived NPs. We also emphasized the need for strict regulation and monitoring of MP usage. Keywords: genotoxicity; carcinogenicity; nanoparticles; medicinal herbs; DNA damage 1. Introduction The first remedies that humans used were medicinal herbs [1]. Medicinal plants (MPs) are used all over the world, and interest in them began in developed countries in recent years [2]. Because of the economic and health benefits to countries, the percentage of those who use MPs in primary care is indicated to be between 70% and 80% [3]. This percentage indicates that users of MPs are highly significant. Therefore, the field needs more studies to ensure the safety of these medicinal plants. There are also many tests to evaluate genotoxicity, some of which are used at the molecular level and some at the chromosome level; these tests are used to detect the genetic toxicity that occurs from many causes, such as chemicals and some types of compounds derived from MPs. Nanotechnology is an interdisciplinary science that can be defined as the design, synthesis, and application of materials and devices at the nanoscale level in different fields, including medicine, biology, physics, chemistry, and medicine [4,5]. Different types of nanomaterials of a wide range of sizes and shapes have been exploited in various fields of science. The global nanotechnology industry is expected to reach its climax by 2020 [6]. The emerging field of interest in nanoscience is due to the unique physical, chemical, and natural properties of nanomaterials compared to those of bulk materials [5]. There are two methods of obtaining micronutrient powders (MNPs): the top-down ap- proach, and the bottom-up approach. In the top-down approach, MNPs are synthesized by cutting bulk materials via various mechanical procedures to produce nanostructures. In the bottom-up approach, the MNPs are synthesized at the molecular level via different chemi- cal or biological procedures [6,7]. Among the biological, chemical, and physical methods of Nutraceuticals 2021, 1, 31–41. https://doi.org/10.3390/nutraceuticals1010005 https://www.mdpi.com/journal/nutraceuticals