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The use of herbal supplements and medicines is increasing rapidly as most people consider them to be of natural origin and therefore safe. Many herbal medications are used to treat diseases but while they are often efficacious, their safety has not sufficiently considered by physicians or users. One particular safety concern is the risk of interactions with drugs, which often lead to toxicity or loss of therapeutic efficacy. A significant number of patients combine herbal remedies with prescription medications and there is growing evidence for interactions of drugs with herbal remedies or single compound originating from plants. Current antiretroviral treatment has allowed human immunodeficiency virus (HIV) infection to become a chronic manageable condition with many HIV patients living longer. Among this HIV + community, the use of natural health products and other forms of complementary and alternative medicines is increasing. As million of patients with HIV are put on treatment with the highly active antiretroviral therapy (HAART), drug interactions have become a major concern for healthcare providers. The use of HAART as a combination of three or four drugs creates the potential for antiretroviral drug interactions, and this is complicated by the addition of other drugs for treatment of other ailments such as comorbid chronic conditions and/or opportunistic infections. In this review, we have aimed to provide an overview of the effects of herbal medicines on antiretroviral drug-metabolizing and transporting enzymes, focusing on potential herb–antiretroviral drug interactions, as well as interactions at the pharmacodynamic level.

Natural products represent a goldmine of innovative therapeutic molecules to prevent and/or treat human diseases. For over 1,000 years, malaria has been one of the major causes of suffering and death for mankind. Artemisinin is an unusual sesquiterpene lactone (SL) endoperoxide that has been isolated as the active principle of the Chinese antimalarial herb Artemisia annua L. Since artemisinin was discovered to be the active component of A. annua in the early 1970s, hundred of papers have focused on the antiparasitic effects of artemisinin and its semi-synthetic analogues. Nowadays, artemisinin and its derivatives have become essential components of antimalarial treatment and are recommended by the World Health Organization (WHO) to treat especially multidrug-resistant forms of malaria. These features have prompted various scientists around the world to evaluate the potential of artemisinin and derivatives to control other human diseases. This review will centre on the significant achievements in recent years (2000 to date) with regard the chemistry and biological properties of SL from A. annua, with particular attention on artemisinin and related compounds. The discussion will also focus on the understanding of its mechanism of action and structure/activity relationships.

The genus Artemisia L. is a member of the family Compositae, widely distributed in the warmer temperate zones of the northern hemisphere. The Artemisia species have been known since ancient times for their curative properties and used for the treatment of various ailments such as malaria, inflammation, cancer and infections by fungi, bacteria and viruses. There is a renewed interest in Artemisia species, and several scientific investigations have aimed to isolate and identify their active constituents, scientifically verify their pharmacological actions and constituents, and determine the basis for the use of Artemisia species in a range of diseases and conditions. According to the literature, over 260 Artemisia species have been investigated, and results reveal that they contain many classes of secondary metabolites with pharmacological activity, including sesquiterpene lactones. The present review will summarize some of the important reports on the chemistry and biological activities of Artemisia sesquiterpene lactones from the literature data of recent years (2000 to date). The discussion will also focus on the understanding of their mechanism of action and structure/activity relationships. The information summarized here is intended to serve as a reference tool for practitioners in the fields of ethnopharmacology and the chemistry of natural products.

Infectious diseases account for one third of all deaths worldwide. The spread of multidrug-resistant strains of microbes makes it necessary to discover new classes of antimicrobials and compounds that inhibit these resistance mechanisms. In the past few decades, the search for new anti-infective agents has occupied many research groups in the field of ethnopharmacology. Many focus on determining the antimicrobial activity of plant extracts found in folk medicine, essential oils or isolated compounds. The Anthemideae tribe of the Asteraceae comprises a large number of species that have been and are still used as medicinal plants, particularly in folk medicine. In the present review, we analyze the past, present and future of medicinal plants of the Anthemideae tribe, both as potential antimicrobial crude drugs as well as a source for natural compounds that act as new anti-infectious agents.

The oceans are unique resources that provide a diverse array of natural products, primarily from invertebrates such as sponges, tunicates, bryozoans and molluscs and from marine bacteria and cyanobacteria. Pharmacologic research with marine chemicals continue to contribute potentially novel chemical leads in the ongoing global search for therapeutic agents in the treatment of multiple diverse categories. As infectious diseases evolve and develop resistance to existing pharmaceuticals, the marine environment provides novel leads against fungal, parasitic, bacterial and viral diseases. Limitations in our current antiviral treatment options and the continuing emergence of new pathogenic viruses have contributed to a growing need for new and effective chemotherapeutic agents to treat viral diseases. The search for potent antiviral agents is urgent in view of the dramatic situation of the global human immunodeficiency virus (HIV) epidemic, a possible spread of avian influenza and of other viral diseases. Effective antiviral therapeutics are not available, and the presently approved therapy for HIV has been recognized to be toxic, unable to eradicate the causative virus, and to induce severe drug resistance. The marine environment provides a rich source of chemical diversity for the screening and identification of new compounds with desirable antiviral properties. Antiviral testing has revealed numerous compounds from structural classes including polysaccharides, terpenoids, steroids, alkaloids and peptides that potentially inhibit both RNA and DNA viruses. This review presents an account of some research directed toward the discovery of new antiviral agents from marine sources.

The ever increasing resistance of human pathogens to current anti-infective agents is a serious medical problem, leading to the need to develop novel antibiotic prototype molecules. In the case of viruses, the search for antiviral agents involves additional difficulties, particularly due to the nature of the infectious viral agents. Thus, many compounds that may cause the death of viruses are also very likely to injure the host cell that harbours them. Natural products are increasingly appreciated as leads for drug discovery and development. Screening studies have been carried out in order to find antiviral agents from natural sources, and the occurrence of antiviral activity in extracts of plants, marine organisms and fungi is frequent. The evidence indicates that there may be numerous potentially useful antiviral phytochemicals in nature, waiting to be evaluated and exploited. In addition, other plants, not previously utilized medicinally, may also reveal antivirals. Among natural antiviral agents, recent investigations have reconsidered the interest of phyto-polysaccharides, which act as potent inhibitors of different viruses. This chapter will illustrate a variety of antiviral polysaccharides from natural sources since 1990, with the aim of making this matter more accessible to drug development