to control, manage and possibly cure cancers in its various specific stages. In the same understanding, these toxins can be instrumental in the pharmaceutical industry focusing on what they do as a means of their interaction with biological targets. Some can act better on fungi, others on bacteria, viruses and protozoa. Their interactions could span from cytotoxicity, metabolic modulation, imunal modulation, cell growth arrest or enhancement, transportation efficiency and excretion among other pharmacokinetic and physiological proccesses. All phytotoxins that have similar properties as described in the sections above can be categorised based on their pharmacological relevance and studied together.
2.3 Currently Available Classification Tools
Apart from some textbooks [14, 15], there is also software available to researchers to help them to make collections and classifications of phytotoxins that are uploaded in their respective libraries. These include the Aggregate Computational Toxicology Online Resource database [16], which is managed by the US Environmental Protection Agency; the Clinical Toxicology (CliniTox) database [17, 18]; the Toxic Plants–PhytoToxins (TPPT) database [19]; the SuperToxic database [20]; the compendium of the European Food Safety Authority [21]; the Super Natural II database [22]; and KNApSAcK‐3D [23–25]. Despite the existence of these databases, there are still gaps in systematically clustering phytotoxins because of the limitations of the tools. For example, the ACToR database fails to link toxins and toxin metabolites to some of their effects on, for example, environmental management [16] and the CliniTox database falls short in providing details of chemical characterization [19].
The TPPT database has made efforts to be better than most; however, it is primarily focused on European plant phytotoxins, in particular Swiss plants, apart from a few of the most commonly known toxins from elsewhere. The justification for this is that Swiss vegetation is a good representation of central Europe, with several altitude zones, giving it the advantage of having a wide range of plant species [26]. This being the case, there remains a need for a more improved version of a tool or a non‐computer‐based standard that can incorporate regional databases and standards into one that can give a wider picture in one resource. The databases that are available can be useful in modeling a standard that can be used in the classification of phytotoxins. In this way, phytotoxins can be optimized using the databases and/or the standards developed thereof to suit the needs of researchers, government agencies, and industries.
2.4 Role of Phytotoxin Classification
The classification of phytotoxins plays a role mainly in human survival and economic development [1]. This is evident in agricultural management, studies of natural medicines, the discovery of novel drugs and their pro‐drug metabolites, the preservation and protection of the quality of water in various water bodies, the security of societies, and the proper management of the environment to ensure people’s safety. The sections below briefly detail how important the classification of phytotoxins is to society.
2.4.1 Drug Discovery
The classification of phytotoxins by their biological activities is helpful in drug discovery as researchers can then easily target a metabolite and study it just because it has similar bioactivities to some already known standard drugs. Ascochytin, a phytotoxin from Ascochyta pisi that induces spotting disease on the leaves of peas, is structurally similar to citrinin, a mycotoxin with antifungal activities. As such, ascochytin was regarded as a potential hit for an antifungal [1, 27]. The same is true for griseofulvin, an antibiotic produced by Penicillium griseofulvum as one of its natural products, which is also a known phytotoxin [28].
2.4.2 Environmental Monitoring
Understanding the type and nature of phytotoxins in an environment is essential to the safety of the community. Among many other potentially harmful and toxic effects of phytotoxins, some can be fatal if ingested in very small amounts; others are irritants to the skin, eyes, and the respiratory tract and can cause more significant physiological harm with time; and yet other phytotoxins are carcinogenic. Understanding these phytotoxins can help in devising ways through which the community can avoid or effectively minimize the risks associated with each one of them or, at least, know which category they may fall in. It is imperative for environmental monitors to include phytotoxins in their various assessments, including environmental impact assessments for community projects. The incorporation of phytotoxins in environmental monitoring is said to be hampered by the high diversity of phytotoxin structures and the unavailability of reliable and well‐validated standard analytical methods [19]. This challenge can be overcome by devising standard protocols that are only feasible with the development of a sound systematic categorization of the toxins.
2.4.3 Phytotoxins, Aquatic Life, and Water Quality
Phytotoxins that are produced by algae in bodies of water, both fresh and oceans, are known as algal toxins [13]. They contaminate fish and other aquatic animals to different extents; they also contaminate drinking water and cannot be eliminated by freezing or cooking [13].
Phytotoxins can also potentially contaminate bodies of water, particularly in situations where leaching of chemicals from plants into the water is possible. This happens particularly for phytochemicals that are polar and are easily soluble in water owing to the molecular nature of their structures being similar to that of water. In this regard, it is imperative to always be alert and vigilant to find ways that are useful in both detecting the presence of phytochemicals in bodies of water and improving water quality following phytochemical contamination.
2.4.4 Air Contamination
In the same regard, air can also be susceptible to phytotoxin contamination. This is particularly the case for volatile phytochemicals or very lightweight microparticles that can be used as vehicles to ferry phytotoxins to various areas. Most of these phytotoxins are irritants to the eyes, respiratory tract, and skin. It is generally difficult to protect the environment from airborne phytotoxins because they are mostly distributed naturally by the wind. Non‐toxic materials with a higher density than that of the toxins or their carriers can be employed in limited areas to weigh down the contaminants to the ground. However, such interventions should only be done after thorough environmental and health impact assessments have been conducted and approved.
2.4.5 Food Contamination
Phytotoxins can potentially be found in foodstuffs, particularly those of marine origins. However, other terrestrial food sources can still contain phytotoxins from ground‐plant contamination through root uptake or through leaf and stem openings into the metabolic system of plants. Herbivorous meat sources can be easily contaminated by such phytotoxins or their metabolites from plants. Phytotoxin metabolites can be non‐toxic or as toxic as, or more toxic than, the original phytotoxin obtained from the ground or the air. In Malawian history, hunters and fishermen were known to use plant‐based phytotoxins, locally known as mwabvi, to make lethal material that could make their fish or animal targets drowsy.
2.4.6 Security and Safety Services
Phytotoxins should be considered a group of chemicals potentially endangering the security of communities. Their use in various historical conflicts should serve as a lesson from which security agents need to do all they can to prevent the recurrence of abuse and/or misuse of plant based materials as weapons during conflicts. Weaponisation of phytotoxins remain a worrisome thought that threaten water bodies and the general environment in which people live. Chatters and organizations that checks and controls the use of chemicals such as
