Investigating a Potential Auxin-Related Mode of Hormetic/Inhibitory Action of the Phytotoxin Parthenin

Parthenin-A Sesquiterpene Lactone with Multifaceted Biological Activities: Insights and Prospects

Parthenin, a sesquiterpene lactone of pseudoguaianolide type, is the representative secondary metabolite of the tropical weed Parthenium hysterophorus (Asteraceae). It accounts for a multitude of biological activities, including toxicity, allergenicity, allelopathy, and pharmacological aspects of the plant. Thus far, parthenin and its derivatives have been tested for chemotherapeutic abilities, medicinal properties, and herbicidal/pesticidal activities. However, due to the lack of toxicity–bioactivity relationship studies, the versatile properties of parthenin are relatively less utilised. The possibility of exploiting parthenin in different scientific fields (e.g., chemistry, medicine, and agriculture) makes it a subject of analytical discussion. The present review highlights the multifaceted uses of parthenin, on-going research, constraints in the practical applicability, and the possible workarounds for its successful utilisation. The main aim of this comprehensive discussion is to bring parthenin to the attention of researchers, pharmacologists, natural product chemists, and chemical biologists and to open the door for its multidimensional applications.

Evolving Multiple Resistance to EPSPS, GS, ALS, PSI, PPO, and Synthetic Auxin Herbicides in Dominican Republic Parthenium hysterophorus Populations. A Physiological and Biochemical Study

Two Parthenium hysterophorus populations resistant (R) and susceptible (S) harvested in banana crop from the Dominican Republic were studied. All S plants died when the herbicides were applied at field dose, except with paraquat. For the R population, the order of plant survival was as follows: glyphosate and paraquat > flazasulfuron > glufosinate > fomesafen > 2,4-D. The resistance factors obtained in the dose–response assays showed a high resistance to glyphosate, flazasulfuron, and fomesafen, medium resistance to glufosinate and 2,4-D, and a natural tolerance to paraquat (resistance factor (RF) = 1.0). The I50 values obtained in the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), acetolactate synthase (ALS), and glutamine synthetase (GS) activity studies with glyphosate, flazasulfuron, and glufosinate, respectively, were greater in R than in S. The effect of fomesafen was measured by the Proto IX levels, obtaining five times more Proto IX in the S than in the R population. The resistance to 2,4-D in the R was determined by the lower accumulation of ethylene compared to the S population. The studies with 14C-paraquat conclude that the lower absorption and translocation in both the R and S populations would explain the natural tolerance of P. hysterophorus. This is the first case of multiple resistance to herbicides with different mechanisms of action confirmed in P. hysterophorus.

Recent advances in allelopathy for weed control: from knowledge to applications

Allelopathy is the biological phenomenon of chemical interactions between living organisms in the ecosystem, and must be taken into account in addressing pest and weed problems in future sustainable agriculture. Allelopathy is a multidisciplinary science, but in some cases, aspects of its chemistry are overlooked, despite the need for a deep knowledge of the chemical structural characteristics of allelochemicals to facilitate the design of new herbicides. This review is focused on the most important advances in allelopathy, paying particular attention to the design and development of phenolic compounds, terpenoids and alkaloids as herbicides. The isolation of allelochemicals is mainly addressed, but other aspects such as the analysis and activities of derivatives or analogs are also covered. Furthermore, the use of allelopathy in the fight against parasitic plants is included. The past 12 years have been a prolific period for publications on allelopathy. This critical review discusses future research areas in this field and the state of the art is analyzed from the chemist's perspective. © 2019 Society of Chemical Industry.

Multiple-species hormetic phenomena induced by indole: A case study on the toxicity of indole to bacteria, algae and human cells

Hormesis is a dose-response relationship phenomenon characterized by low-dose stimulation and high-dose inhibition. Although hormetic phenomena have been reported in broadly ranging biological areas, there is still no unified mechanism of hormesis. Investigating multiple-species hormesis of one compound and then exploring the possible mechanism may be an effective approach to clarify the reason for the occurrence of hormetic phenomena in a broad range of organisms. In this study, indole was selected as the test chemical due to the broad biological and hormetic effects of indole compounds. The results show that indole induces multiple-species hormetic phenomena in bacteria (Aliivibrio fischeri (A. fischeri), Escherichia coli and Bacillus subtilis), algae (Microcystis aeruginosa and Selenastrum capricornutum), and human cells (human skin fibroblasts and human cervical cancer cells). Through in-depth investigation of the time-dependent hormetic effects of indole, indole derivatives and indole's structural analogs on the bioluminescence of A. fischeri, indole ring has been identified as the potential key structure that causes indole to act on quorum sensing of A. fischeri to induce hormetic effects on the bioluminescence at lag, logarithmic, and stationary phases. Therefore, the occurrence of multiple-species hormetic phenomena is speculated to be derived from the action of indole on the cell-to-cell communication of organism cells. This paper can not only further confirm the generalizability of hormesis but also provide a reasonable explanation for hormesis, which will benefit the development of hormesis and the risk assessment of environmental pollutants.