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Botrytis cinerea is a ubiquitous fungus that affects hundreds of plants, resulting in economic losses to the horticulture and fruit industry. The search for new antifungal agents is a matter of current interest. Thus, in this work a series of geranylated phenols in which the side alkyl chain has been hydrated have been synthesized, and their activity against B. cinerea has been evaluated. The coupling of phenol and geraniol has been accomplished under microwave irradiation obtaining the highest reaction yields in the shortest reaction times. Hydration of the side chain was carried out in dioxane with p-toluenesulfonic acid polymer-bound as the catalyst. All synthesized compounds were tested against B. cinerea using the growth inhibition assay and EC50 values were determined. The results show that activity depends on the number and nature of functional groups in the phenol ring and hydration degree of the geranyl chain. The most active compound is 1,4-dihydroquinone with one hydroxyl group attached at the end of the alkyl chain. Results from a molecular docking study suggest that hydroxyl groups in the phenol ring and alkyl chain are important in the binding of compounds to the active site, and that the experimental antifungal activity correlates with the number of H-bond that can be formed in the binding site.

Fruit rots caused by filamentous fungi such as Monilinia fructicola and Monilinia laxa have a strong impact on crop yield and fruit commercialization, especially as they affect a wide variety of stone fruits. The antifungal efficacy of benzylidene-cycloalkanones has been previously described in in vitro assays against M. fructicola; so, this study aims to evaluate the in vivo inhibitory potential of these hybrids on fruits that have been inoculated with M. fructicola, and use molecular docking to visualize the main interactions of these molecules in the active site of the enzyme succinate dehydrogenase (SDH). The results indicate that compound C achieves the highest inhibition of both Monilinia species (15.7–31.4 µg/mL), spore germination in vitro (C to SDH and contribute to the formation of hydrogen bonds with amino acid residues on the enzyme active site.

Currently, much effort is being placed into obtaining extracts and/or essential oils from Cannabis sativa L. for specific therapeutic purposes or pharmacological compositions. These potential applications depend mainly on the phytochemical composition of the oils, which in turn are determined by the type of C. sativa and the extraction method used to obtain the oils. In this work, we have evaluated the contents of secondary metabolites, delta-9-tetrahydrocannabinol (THC), and cannabidiol (CBD), in addition to the total phenolic, flavonoids, and anthraquinone content in oils obtained using solid–liquid extraction (SLE) and supercritical fluid extraction (SCF). Different varieties of C. sativa were chosen by using the ratio of THC to CBD concentrations. Additionally, antioxidant, antifungal and anticancer activities on different cancer cell lines were evaluated in vitro. The results indicate that oils extracted by SLE, with high contents of CBD, flavonoids, and phenolic compounds, exhibit a high antioxidant capacity and induce a high decrease in the cell viability of the tested breast cancer cell line (MCF-7). The observed biological activities are attributed to the entourage effect, in which CBD, phenols and flavonoids play a key role. Therefore, it is concluded that the right selection of C. sativa variety and the solvent for SLE extraction method could be used to obtain the optimal oil composition to develop a natural anticancer agent.

Pentacyclic triterpenes, including lupeol, α- amyrin, and β-amyrin, present a large range of biological activities including anti-inflammatory, anti-cancer, and gastroprotective properties. The phytochemistry of dandelion (Taraxacum officinale) tissues has been widely described. Plant biotechnology offers an alternative for secondary metabolite production and several active plant ingredients are already synthesized through in vitro cultures. This study aimed to establish a suitable protocol for cell growth and to determine the accumulation of α-amyrin and lupeol in cell suspension cultures of T. officinale under different culture conditions. To this end, inoculum density (0.2% to 8% (w/v)), inoculum age (2- to 10-week-old), and carbon source concentration (1%, 2.3%, 3.2%, and 5.5% (w/v)) were investigated. Hypocotyl explants of T. officinale were used for callus induction. Age, size, and sucrose concentrations were statistically significant in cell growth (fresh and dry weight), cell quality (aggregation, differentiation, viability), and triterpenes yield. The best conditions for establishing a suspension culture were achieved by using a 6-week-old callus at 4% (w/v) and 1% (w/v) of sucrose concentration. Results indicate that 0.04 (±0.02) α-amyrin and 0.03 (±0.01) mg/g lupeol can be obtained in suspension culture under these starting conditions at the 8th week of culture. The results of the present study provide a backdrop for future studies in which an elicitor could be incorporated to increase the large-scale production of α-amyrin and lupeol from T. officinale.

Nowadays, antimicrobial resistance is a serious concern associated with the reduced efficacy of traditional antibiotics and an increased health burden worldwide. In response to this challenge, the scientific community is developing a new generation of antibacterial molecules. Contributing to this effort, and inspired by the resveratrol structure, five new resveratrol-dimers (9a–9e) and one resveratrol-monomer (10a) were synthetized using 2,5-dibromo-1,4-diaminobenzene (8) as the core compound for Schiff base bridge conformation. These compounds were evaluated in vitro against pathogenic clinical isolates of Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus sp., and Listeria monocytogenes. Antibacterial activity measurements of resveratrol-Schiff base derivatives (9a–9e) and their precursors (4–8) showed high selectivity against Listeria monocytogenes, being 2.5 and 13.7 times more potent than chloramphenicol, while resveratrol showed an EC50 > 320 µg/mL on the same model. Moreover, a prospective mechanism of action for these compounds against L. monocytogenes strains was proposed using molecular docking analysis, finding a plausible inhibition of internalin C (InlC), a surface protein relevant in bacteria–host interaction. These results would allow for the future development of new molecules for listeriosis treatment based on compound 8.

Flavanones (–)-(2S)-5,4’-dihydroxy-7-methoxyflavanone (1) and (–)-(2S)-5,3’,4’-trihydroxy-7-methoxyflavanone (2) were isolated from the extracts of Calceolariathyrsiflora Graham, an endemic perennial small shrub growing in the central zone of Chile. The absolute configuration of these compounds was resolved by optical rotation experiments and in silico calculations. Three analogs (3, 4, and 5) were synthesized to do structure-activity relationships with the biological assays studied. Biological tests revealed that only flavanone 2 exhibited a moderate inhibitory activity against the methicillin-resistant strain S. aureus MRSA 97-77 (MIC value of 50 µg/ml). In addition, flavanone 2 showed a potent, selective, and competitive inhibition of 5-hLOX, which supports the traditional use of this plant as an anti-inflammatory in diseases of the respiratory tract. Also, 2 exhibited cytotoxic and selective effects against B16-F10 (8.07 ± 1.61 µM) but 4.6- and 17-fold lesser activity than etoposide and taxol.

Background: Taraxacum officinale G.H. Weber ex Wiggers is a wild plant used in folk medicine to treat several diseases owing to bioactive secondary metabolites present in its tissue. The accumulation of such molecules in plant cells can occur as a response against abiotic stress, but these metabolites are often deposited in low concentrations. For this reason, the use of a biotechnological approach to improve the yields of technologically interesting bioactive compounds such as anthocyanins is a compelling option. This work focuses on investigating the potential of in vitro T. officinale cultures as an anthocyanin source. Results: To demonstrate the suitability of anthocyanin induction and accumulation in calluses under specific conditions, anthocyanin was induced in the T. officinale callus. A specific medium of 5.5% sucrose supplemented with 6-benzylaminopurine /1-naphthaleneacetic acid in a 10:1 ratio was used to produce an anthocyanin yield of 1.23 mg g-1 fw. An in vitro dandelion callus line was established from this experiment. Five mathematical models were then used to objectively and predictably explain the growth of anthocyanin-induced calluses from T. officinale. Of these models, the Richards model offered the most suitable representation of anthocyanin callus growth in a solid medium and permitted the calculation of the corresponding kinetic parameters. Conclusions: The findings demonstrate the potential of an in vitro anthocyanin-induced callus line from T. officinale as an industrial anthocyanin source.How to cite: Martínez ME, Poirrier P, Prüfer D, et al. Kinetics and modelling of cell growth for potential anthocyanin induction in cultures of Taraxacum officinale G.H. Weber ex Wiggers (Dandelion) in vitro. Electron J Biotechnol 2018;36. https://doi.org/10.1016/j.ejbt.2018.08.006. Keywords: anthocyanins, bioactive chemicals, callus, Dandelion, folk medicine, hypocotyl explants, in vitro culture, in vitro modeling, modeling cell growth, phytochemicals, Taraxacum officinale

There are several studies on the medicinal properties of dandelions (Taraxacum officinale), but few studies are aimed at understanding the in vitro germination process of this plant to improve its propagation. This research was focused on studying in vitro seed germination and development of seedlings under different carbon sources, glucose (GLU) or sucrose (SUC) and its concentrations (1.0–5.5%). Additionally, the effect of supplementation with plant growth regulators (PGRs) was studied, measuring the germination capacity, uncertainty and synchrony. Germination was promoted under low carbon source concentrations (≤2.3%), whereas higher concentrations (≥3.2%) had a detrimental effect on this process. GLU allowed the final germination percentages to be slightly better than SUC. Uniformity and synchrony values improved with the presence of PGRs. Results suggested that the best condition to assess T. officinale seed germination is in a medium containing GLU 2.3%, 0.5 mg/L 1-Naphthaleneacetic acid (NAA) and 0.5 mg/L 6-Benzylaminopurine acid (BAP). After germination, the best condition for optimal growth of T. officinale seedlings was 1.0% SUC supplemented with 0.225 mg/L of NAA and 3.0 mg/L of BAP for initial shoot development. The survival rate was 97% after greenhouse acclimatization. This new method of germination was implemented for the massive propagation of T. officinale for further medicinal studies.

Gray mold disease, which is caused by Botrytis cinerea Pers ex. Fr., results in serious economic losses to Lycopersicum esculentum (tomato) crop productivity. In this study, we explored the possibility that mixtures of essential oils (EOs) and their respective hydrolates (HYSs) could be used to control this disease. Thus, EOs and HYSs were obtained from Origanum vulgare, Thymus vulgaris, Citrus limon, and Citrus sinensis by hydrodistillation. In vitro antifungal activities were evaluated, and EC50 values of 15.9 and 19.8 µg/mL were obtained for EOs of thyme and oregano, respectively. These activities are due mainly to volatile compounds, thymol and carvacrol. Results from in vivo assays show that although most tomatoes were infested five days after inoculation, the damage was considerably reduced by the application of an EO/HYS mixture of thyme. The disease incidence indexes of B. cinerea tomato rot, percentage and severity, measured four days after inoculation, were reduced by 70% and 76%, respectively, as compared with the inoculum control. These results suggest that a combination of HYSs and EOs enhances antifungal activity, and that optimization of relative concentrations, volumes, and the nature of the compounds, could design a formulation able to control B. cinerea inoculum on tomato fruits.

The aim of this study was to synthesize a series of novel and known dihydrocarvone-hybrid derivatives (2–9) and to evaluate mycelial growth activity of hybrid molecules against two strains of Monilinia fructicola, as well as their toxicity. Dihydrocarvone-hybrid derivatives have been synthesized under sonication conditions and characterized by FTIR, NMR, and HRMS. Antifungal efficacy against both strains of M. fructicola was determined by half maximal effective concentration (EC50) and toxicity using the brine shrimp lethality test (BSLT). Among the synthesized compounds, 7 and 8 showed the best activity against both strains of M. fructicola with EC50 values of 148.1 and 145.9 µg/mL for strain 1 and 18.1 and 15.7 µg/mL for strain 2, respectively, compared to BC 1000® (commercial organic fungicide) but lower than Mystic® 520 SC. However, these compounds showed low toxicity values, 910 and 890 µg/mL, respectively, compared to Mystic® 520 SC, which was highly toxic. Based on the results, these hybrid compounds could be considered for the development of more active, less toxic, and environmentally friendly antifungal agents against phytopathogenic fungi.

Taraxacum officinale (L.) Weber ex F.H. Wigg, commonly known as dandelion, is a cosmopolitan and perennial weed, which has medicinal properties. In vitro propagation methods are widely used on plants that have difficulties in cultivation and, consequently, low extraction yields of active metabolites. Thus, callus culture has been considered to be useful for the accumulation of several metabolites. In this study, we aimed to establish an efficient protocol for callus induction and maintenance of T. officinale, for which explant type, carbon source, light conditions, and nine different combinations of plant growth regulators (PGRs), such as 1-naphthaleneacetic acid (NAA) (from 0.05 to 0.5 mg/L) and 6-benzylaminopurine acid (BAP) (from 0.5 to 3.0 mg/L), were evaluated. The results showed that hypocotyls and roots from sterile seedlings are the best sources for callus induction, with 100% of callogenesis at every condition tested, and more than 95% of viability and friability. Complete darkness and a medium supplemented with sucrose at 2.3% (w/v) and 0.5 mg/L of NAA and 0.5 mg/L of BAP were the best conditions for callus induction, showing callus with low organogenesis and high friability. This study provides a basis for future studies on improving large-scale callus propagation and further establishment of suspension culture systems for commercial purposes.

The metabolism of brassinosteroid leads to structural modifications in the ring skeleton or the side alkyl chain. The esterification and glycosylation at C-3 are the most common metabolic pathways, and it has been suggested that conjugate brassinosteroids are less active or inactive. In this way, plants regulate the content of active brassinosteroids. In this work, the synthesis of brassinosteroid 24-norcholane type analogs conjugated at C-3 with benzoate groups, carrying electron donor and electron attractant substituents on the aromatic ring, is described. Additionally, their growth-promoting activities were evaluated using the Rice Lamina Inclination Test (RLIT) and compared with that exhibited by brassinolide (used as positive control) and non-conjugated analogs. The results indicate that at the lowest tested concentrations (10−8–10−7 M), all analogs conjugated at C-3 exhibit similar or higher activities than brassinolide, and the diasteroisomers with S configuration at C-22 are the more active ones. Increasing concentration (10−6 M) reduces the biological activities of analogs as compared to brassinolide.

Brassinosteroids (BRs) play an important role in the growth and development of plants. Herein, we describe the synthesis of epimeric mixtures of BR analogs with 24-norcholane type side chains, S/R configuration at C22 and A/B ring cis-type fusion. All epimeric mixtures were synthetized from hyodeoxycholic acid. The biological activity of mixtures was evaluated by using rice lamina inclination test and germination of tomato (Lycopersicum esculentum) seeds. The results show that these epimeric mixtures exhibit similar bioactivity to brassinolide in both bioassays. Thus, our results corroborate that the A/B junction has almost no effect on bioactivity and open the possibility of using epimeric mixtures instead of pure compounds. In this approach, the synthesized BR analogs maintain a good level of bioactivity, whereas the synthesis is shorter, cheaper and with higher yields. All these factors make this alternative very interesting for potential application.

Fungal diseases, both pre- and post-harvest, are currently difficult to control—increased antifungal resistances have further stimulated the search for natural alternatives. The objective of the present research work was to evaluate the antifungal activities of Mentha pulegium essential oil (EO) and its major constituents. The EO was obtained from hydro distillation of fresh leaves, and composition was determined using gas chromatography/mass spectrometry (GC/MS). The main components were identified as pulegone (29.33%), menthol (28.79%), menthone (20.48%), and isopulegol (9.75%). EO and isopulegol exhibited the highest antifungal activity, with half maximal effective concentrations (EC50) inhibiting mycelial activity of Monilinia fructicola at 24.6 µg/mL and 20.8 µg/mL, respectively, and against Botrytis cinerea, at 301.45 µg/mL and 333.84 µg/mL, respectively. These findings could lay the foundation for developing antifungal agents of agricultural value.

Color and other quality parameters of “Redglobe” grape (Vitis vinifera L.) berries were evaluated after treatment with brassinosteroid (BR) analogs. Three BRs analogs (24-epibrassinolide, Triol, or Lactone) were applied at three concentrations (0.0, 0.4, or 0.8 mg⋅L-1), at the onset of veraison. A commercial formulation (B-2000®) was also applied, at a recommended rate of 0.06 mg⋅L-1. The tested BR analogs were effective improving berry color (evaluated as color index for red grapes, CIRG), increasing the levels of soluble solids and anthocyanins, and changing the types of anthocyanins present without altering other quality and yield parameters. The effects of BR analogs on color enhancement could be explained by an increase in soluble solids content and/or anthocyanin content. Treatment with 24-epibrassinolide (at 0.4 mg⋅L-1) or the commercial formulation tended to favor the production of dihydroxylated anthocyanins, which are responsible for the red and pink colors of grape berries. Results indicate that the use of BRs constitutes a potential tool in the production of table grapes. This is the first report of this enhancement effect in a productive context.

Phytophthora cinnamomi is a phytopathogen that causes extensive damage in different crops, and therefore, produces important economic losses all around the world. Chemical fungicides are a key factor for the control of this disease. However, ecological and environmental considerations, as well as the appearance of strains that are resistant to commercial fungicides, have prompted the quest for new antifungal agents which are of low ecological impact. In this work, a series of new 2-allylphenol derivatives was synthesized, and their structures were confirmed by FT-IR, NMR, and MS. Some of the synthesized compounds, more specifically nitro derivatives, exhibit strong growth inhibition of P. cinnamomi with EC50 as low as 10.0 µg/mL. This level of activity is similar to that exhibited by METALAXYL MZ 58 WP, a commonly-used commercial fungicide; therefore, these compounds might be of agricultural interest due to their potential use as fungicides against P. cinnamomi. The results indicate that this activity depends on the chemical structures of the 2-allylphenol derivatives, and that it is strongly enhanced in molecules where nitro and hydroxyl groups adopt a -para configuration. These effects are discussed in terms of the electronic distribution of the aromatic ring induced by substituent groups.