Peppermint (Mentha x piperita L.) is a medicinal plant with significant pharmacological and therapeutic activities but side effects and detrimental impacts on health have been described. Herein, we studied the literature concerning the reported inherent toxicity of peppermint. Accordingly, we classified peppermint and its main constituents in acute, subacute, chronic, developmental toxicity and cytotoxicity studies. The review outcome revealed that peppermint and its main constituents (pulegone, menthone, menthol and menthofuran) exhibit some evidence of moderate toxicity. Peppermint and its menthol isomers possess no major innate mutagenic, genotoxic or embryotoxic properties. However, there is evidence that peppermint essential oil interacts appreciably with cytochrome P450 isoenzymes to reduce or prevent their activities in rat and human liver microsomes and this has a substantial clinical implication for drug metabolism. Moreover, peppermint essential oil is contraindicated in patients with bile duct obstruction, gall bladder inflammation and liver disorders. In patients with gastrointestinal reflux or hiatus hernia, its use should be exercised with caution because it may exacerbate the symptoms of gastrointestinal reflux.

Background and Objective: Infectious diseases are amongst the leading causes of death in the world and central nervous system infections produced by viruses may either be fatal or generate a wide range of symptoms that affect global human health. Most antiviral plants contain active phytoconstituents such as alkaloids, flavonoids, and polyphenols, some of which play an important antiviral role. Herein, we present a background to viral central nervous system (CNS) infections, followed by a review of medicinal plants and bioactive compounds that are effective against viral pathogens in CNS infections. Method: A comprehensive literature search was conducted on scientific databases including: PubMed, Scopus, Google Scholar and Web of Science. The relevant key words used as search terms were: “myelitis”, “encephalitis”, “meningitis”, “meningoencephalitis”, “encephalomyelitis”, “central nervous system”, “brain”, “spinal cord”, “infection”, “virus”, “medicinal plants” and “biological compounds”. Results: The most significant viruses involved in central nervous system infections are: Herpes simplex virus (HSV), Varicella zoster virus (VZV), West Nile virus (WNV), Enterovirus 71 (EV71), Japanese encephalitis virus (JEV) and Dengue virus (DENV). The inhibitory activity of medicinal plants against CNS viruses are mostly active through prevention of viral binding to cell membranes, blocking viral genome replication, prevention of viral protein expression, scavenging reactive oxygen species (ROS) and reduction of plaque formation. Conclusion: Due to the increased resistance of microorganisms (bacteria, viruses and parasites) to antimicrobial therapies, alternative treatments, especially using plant sources and their bioactive constituents, appear to be more fruitful.

: Arboviruses are a diverse group of viruses that are among the major causes of emerging infectious diseases. Arboviruses from the genera flavivirus and alphavirus are the most important human arboviruses from a public health perspective. During recent decades, these viruses have been responsible for millions of infections and deaths around the world. Over the past few years, several investigations have been carried out to identify antiviral agents to treat these arbovirus infections. The use of synthetic antiviral compounds is often unsatisfactory since they may raise the risk of viral mutation, they are costly and possess either side effects or toxicity. One attractive strategy is the use of plants as promising sources of novel antiviral compounds that present significant inhibitory effects on these viruses. In this review, we describe advances in the exploitation of compounds and extracts from natural sources that target the vital proteins and enzymes involved in arbovirus replication.