Biodegradable polymers as carriers for tuning the release and improve the herbicidal effectiveness of Dittrichia viscosa plant organic extracts

Modern Approaches for the Development of New Herbicides Based on Natural Compounds

Weeds are a permanent component of anthropogenic ecosystems. They require strict control to avoid the accumulation of their long-lasting seeds in the soil. With high crop infestation, many elements of crop production technologies (fertilization, productive varieties, growth stimulators, etc.) turn out to be practically meaningless due to high yield losses. Intensive use of chemical herbicides (CHs) has led to undesirable consequences: contamination of soil and wastewater, accumulation of their residues in the crop, and the emergence of CH-resistant populations of weeds. In this regard, the development of environmentally friendly CHs with new mechanisms of action is relevant. The natural phytotoxins of plant or microbial origin may be explored directly in herbicidal formulations (biorational CHs) or indirectly as scaffolds for nature-derived CHs. This review considers (1) the main current trends in the development of CHs that may be important for the enhancement of biorational herbicides; (2) the advances in the development and practical application of natural compounds for weed control; (3) the use of phytotoxins as prototypes of synthetic herbicides. Some modern approaches, such as computational methods of virtual screening and design of herbicidal molecules, development of modern formulations, and determination of molecular targets, are stressed as crucial to make the exploration of natural compounds more effective.

Biochemical Analyses of Bioactive Extracts from Plants Native to Lampedusa, Sicily Minor Island

Major threats to the human lifespan include cancer, infectious diseases, diabetes, mental degenerative conditions and also reduced agricultural productivity due to climate changes, together with new and more devastating plant diseases. From all of this, the need arises to find new biopesticides and new medicines. Plants and microorganisms are the most important sources for isolating new metabolites. Lampedusa Island host a rich contingent of endemic species and subspecies. Seven plant species spontaneously growing in Lampedusa, i.e., Atriplex halimus L. (Ap), Daucus lopadusanus Tineo (Dl), Echinops spinosus Fiori (Es) Glaucium flavum Crantz (Gf) Hypericum aegypticum L: (Ha), Periploca angustifolia Labill (Pa), and Prasium majus L. (Pm) were collected, assessed for their metabolite content, and evaluated for potential applications in agriculture and medicine. The HPLC-MS analysis of n-hexane (HE) and CH2Cl2 (MC) extracts and the residual aqueous phases (WR) showed the presence of several metabolites in both organic extracts. Crude HE and MC extracts from Dl and He significantly inhibited butyrylcholinesterase, as did WR from the extraction of Dl and Pa. HE and MC extracts showed a significant toxicity towards hepatocarcinoma Huh7, while Dl, Ha and Er HE extracts were the most potently cytotoxic to ileocecal colorectal adenocarcinoma HCT-8 cell lines. Most extracts showed antiviral activity. At the lowest concentration tested (1.56 μg/mL), Dl, Gf and Ap MC extracts inhibited betacoronavirus HCoV-OC43 infection by> 2 fold, while the n-hexane extract of Pm was the most potent. In addition, at 1.56 μg/mL, potent inhibition (>10 fold) of dengue virus was detected for Dl, Er, and Pm HE extracts, while Pa and Ap MC extracts dampened infections to undetectable levels. Regarding to phytotoxicity, MC extracts from Er, Ap and Pm were more effective in inhibiting tomato rootlet elongation; the same first two extracts also inhibited seed cress germination while its radicle elongation, due to high sensitivity, was affected by all the extracts. Es and Gf MC extracts also inhibited seed germination of Phelipanche ramosa. Thus, we have uncovered that many of these Lampedusa plants displayed promising biopesticide, antiviral, and biological properties.

Edible Polymers and Secondary Bioactive Compounds for Food Packaging Applications: Antimicrobial, Mechanical, and Gas Barrier Properties

Edible polymers such as polysaccharides, proteins, and lipids are biodegradable and biocompatible materials applied as a thin layer to the surface of food or inside the package. They enhance food quality by prolonging its shelf-life and avoiding the deterioration phenomena caused by oxidation, humidity, and microbial activity. In order to improve the biopolymer performance, antimicrobial agents and plasticizers are also included in the formulation of the main compounds utilized for edible coating packages. Secondary natural compounds (SC) are molecules not essential for growth produced by some plants, fungi, and microorganisms. SC derived from plants and fungi have attracted much attention in the food packaging industry because of their natural antimicrobial and antioxidant activities and their effect on the biofilm’s mechanical properties. The antimicrobial and antioxidant activities inhibit pathogenic microorganism growth and protect food from oxidation. Furthermore, based on the biopolymer and SC used in the formulation, their specific mass ratio, the peculiar physical interaction occurring between their functional groups, and the experimental procedure adopted for edible coating preparation, the final properties as mechanical resistance and gas barrier properties can be opportunely modulated. This review summarizes the investigations on the antimicrobial, mechanical, and barrier properties of the secondary natural compounds employed in edible biopolymer-based systems used for food packaging materials.

Complex Synergistic Interactions among Volatile and Phenolic Compounds Underlie the Effectiveness of Allelopathic Residues Added to the Soil for Weed Control

The introduction of allelopathic cover crops for green manuring or mulching is a regular practice in Integrated Weed Management. In this context, the alternative use of the abundant phytotoxic residues of allelopathic plants from the agroecosystem, e.g., the foliage of Eucalyptus, Acacia, or Cytisus species, is promising. Previous studies identified the phytotoxic compounds potentially involved in the effectiveness of some plant residues when added to the soil for weed control. The low quantities of allelochemicals present in the tissues and the weak phytotoxicity of each of them in their natural concentrations did not explain the significant levels of weed control observed at field scale. Here, to study hypothetical synergistic interactions among the volatile (VOCs) and water-soluble compounds released to the soil matrix, complex mixtures of VOCs, phenolics, or both, mimicking the chemical profiles of Cytisus scoparius were prepared and then tested in vitro on the germination and early growth of two weeds. The effects were calibrated against the VOCs naturally emitted by the fresh plant material and aqueous extract, acting together or not, and with or without soil. The presence of the aqueous extract significantly increased the phytotoxicity of VOCs on Amaranthus retroflexus root growth compared to the volatiles emitted alone. In addition, the soil factor enhanced synergistic interactions among VOCs and water-soluble compounds, resulting in a 54% decrease in total germination and an 80% inhibition of root and shoot growth. Multi-level synergistic chemical interactions should explain the bioherbicidal effectiveness of allelopathic residues applied as a soil amendment.

Allelopathic Effect of Quercetin, a Flavonoid from Fagopyrum esculentum Roots in the Radicle Growth of Phelipanche ramosa: Quercetin Natural and Semisynthetic Analogues Were Used for a Structure-Activity Relationship Investigation

Allelopathic potential of buckwheat roots on the radicle growth of the broomrape weed species Orobanche cumana and Phelipanche ramosa was studied. Buckwheat root exudates induced a significant growth inhibition in P. ramosa radicles but radicles of O. cumana were not affected. Among the metabolites present in the root organic extract we identified the flavonol quercetin and the stilbene p-coumaric acid methyl ester with only quercetin showing inhibitory effect on P. ramosa. The activity of quercetin was compared with other two similar flavanoids, the flavone apigenin and the dihydroflavanol 3-O-acetylpadmatin extracted respectively from Lavandula stoechas and Dittrichia viscosa plants. In this comparative assay only 3-O-acetylpadmatin besides quercetin, showed inhibition activity of radicle growth while apigenin was inactive. These results indicated that the presence of two ortho-free hydroxy groups of C ring, like catechol, could be an important feature to impart activity while the carbon skeleton of B ring and substituents of both A and B rings are not essential. Besides reduction of radicle growth, haustorium induction was observed at the tip of P. ramosa radicles treated with quercetin which swelled and a layer of papillae was formed. Activity of quercetin on haustorium induction in P. ramosa was assayed in comparison with the known haustorium-inducing factor 2,6-dimethoxy-p-benzoquinone (DMBQ) and a three partial methyl ether derivatives semisynthetized from quercetin. Results indicated that P. ramosa haustorium was induced by DMBQ at concentrations of 1–0.5 mM and quercetin and its derivatives at concentration range 0.1–0.05 mM.