Frontiers in Phytochemicals

Dear Colleagues,

Phytochemicals are a large group of secondary metabolites produced by plant organisms and involved in the complex network of ecological interactions within the ecosystem. For instance, they attract pollinators, giving color and scent to the flowers. These low molecular weight metabolites arise from different biosynthetic pathways and are grouped into chemical classes such as phenylpropanoids, isoprenoids and alkaloids derived from precursors (e.g., amino acids) that are final products of primary metabolic pathways. Phytochemicals also contribute to increase the adaptability of plants to environmental changes.

Indeed, plants need to defend themselves from the surrounding biota, including pathogens, nematodes, noxious insects, phytophages, parasitic plants and weeds. In addition, they have to cope with a plethora of adverse abiotic conditions due to extreme meteorological events, temperature fluctuations, drought, flooding, UV and high solar radiation, and anthropogenic pollutants. As sessile organisms, plants are not able to escape from a harsh environment, and, therefore, they have evolved an array of strategies to defend themselves from biotic and abiotic stress factors affecting the plant health and distribution. Phytochemicals are an essential part of these strategies, as UV and light protectants, antimicrobials, repellents, antifeedants and reactive oxygen species scavengers to name just a few. In other words, the evolutionary success of plants has depended on their metabolic plasticity and chemical diversity.

Since the appearance of humanity on earth, phytochemicals entered the human diet and life through consumption of plant foods and use of herbal remedies, in a process of coevolution between plants and humans. Nowadays, this coevolutionary relationship has led to the human’s dependence on food and medicinal plants as source of macronutrients, micronutrients, and bioactive phytochemicals. Indeed, compelling evidence has demonstrated that dietary patterns rich in plant foods may contribute to lower the risk of chronic-degenerative disorders such as cardiovascular and neurodegenerative diseases, some cancers and diabetes. Phytochemicals can also be consumed as dietary supplements to ameliorate the physiological functions of the organism in healthy subjects.

In addition, due to their multitarget mechanism of action, phytochemicals can be developed as adjuvant agents and sensitizers in conventional antibiotic and anticancer therapies, to reduce the risk of selecting resistant microbial strains and cancer cells. However, some preclinical (i.e., in vitro and in vivo) pharmacological activities of phytochemicals need to be further substantiated by clinical studies in healthy and unhealthy subjects, as well as their effective dose, administration route, possible adverse effects and interaction with drugs. Likewise, in observational epidemiological studies, a causal relationship between diet and risk of disease has not been fully demonstrated yet.

Prof. Dr. Marcello Iriti
Dr. Sara Vitalini
Topic Editors