Physicochemical and thermodynamic characterization of the encapsulation of methyl jasmonate by natural and modified cyclodextrins using reversed-phase high-pressure liquid chromatography

Microbial Metabolites of 3-n-butylphthalide as Monoamine Oxidase A Inhibitors

Novel compounds with antidepressant activity via monoamine oxidase inhibition are being sought. Among these, derivatives of 3-n-butylphthalide, a neuroprotective lactone from Apiaceae plants, may be prominent candidates. This study aimed to obtain the oxidation products of 3-n-butylphthalide and screen them regarding their activity against the monoamine oxidase A (MAO-A) isoform. Such activity of these compounds has not been previously tested. To obtain the metabolites, we used fungi as biocatalysts because of their high oxidative capacity. Overall, 37 strains were used, among which Penicillium and Botrytis spp. were the most efficient, leading to the obtaining of three main products: 3-n-butyl-10-hydroxyphthalide, 3-n-butylphthalide-11-oic acid, and 3-n-butyl-11-hydroxyphthalide, with a total yield of 0.38-0.82 g per g of the substrate, depending on the biocatalyst used. The precursor-3-n-butylphthalide and abovementioned metabolites inhibited the MAO-A enzyme; the most active was the carboxylic acid derivative of the lactone with inhibitory constant (K_i) < 0.001 µmol/L. The in silico prediction of the drug-likeness of the metabolites matches the assumptions of Lipinski, Ghose, Veber, Egan, and Muegge. All the compounds are within the optimal range for the lipophilicity value, which is connected to adequate permeability and solubility.

Enhanced production of 2-phenylethanol by salicylic acid and cyclodextrins in cell suspension cultures of the unexplored filamentous fungus Monochaetinula geoffroeana

BACKGROUND

2-Phenylethanol (PEA) is a higher aromatic alcohol with a rose-like odor, which is used in several industries. Although PEA can be synthesized, consumers are increasingly concerned about the toxicity of chemically synthesized products, and prefer natural aroma compound. PEA occurs naturally in the environment but concentrations are too low to justify extraction.

RESULTS

The present study offers a novel biological source of PEA: the filamentous fungi Monochaetinula geoffroeana. We report the highest recorded yield of PEA of fungal origin to date: 6.52 g L^-1 . The volatility and low water solubility of PEA can affect its use in many industries, for which reason complexation studies of PEA and cyclodextrins were carried out using the phase solubility technique. PEA formed 1:1 stoichiometric inclusion complexes with natural and modified CDs, the highest encapsulation constant being obtained with MβCD (K_1:1  = 299.88 L mol^-1 ). The complexation process significantly increased the water solubility of PEA. A computational study showed a high degree of correlation between computed scores and experimental values. Furthermore, this study reports the role of salicylic acid as an effective elicitor for improved PEA production by the studied fungi. Supplementation with 10 μmol L^-1 salicylic acid increased PEA production from 6.52 to 10.54 g L^-1 .

CONCLUSION

The best treatment to enhance PEA production by M. geoffroeana under laboratory conditions was to use salicylic acid 10 μmol L^-1 . Due to the commercial importance of PEA, further investigation is needed to improve PEA production by M. geoffroeana and to optimize culture conditions in order to standardize yields. © 2021 Society of Chemical Industry.

Effects of Metal Nanoparticles and Other Preparative Materials in the Environment on Plants: From the Perspective of Improving Secondary Metabolites

The influence of preparation material residues in wastewater and soil on plants has been paid more and more attention by researchers. Secondary metabolites play an important role in the application of plants. It was found that nanomaterials can increase the content of plant secondary metabolites in addition to their role in pharmaceutical preparations. For example, 800 mg/kg copper oxide nanoparticles (NPs) increased the content of p-coumaric acid in cucumber by 225 times. Nanoparticles can cause oxidative stress in plants, increase signal molecule, and upregulate the synthase gene expression, increasing the content of secondary metabolites. The increase of components such as polyphenols and total flavonoids may be related to oxidative stress. This paper reviews the application and mechanism of metal nanomaterials (Ag-NP, ZnO-NP, CeO₂-NP, Cds-NP, Mn-NP, CuO-NP) in promoting the synthesis of secondary metabolites from plants. In addition, the effects of some other preparative materials (cyclodextrins and immobilized molds) on plant secondary metabolites are also involved. Finally, possible future research is discussed.

Evaluation of the inhibition of monoamine oxidase A by bioactive coffee compounds protecting serotonin degradation

Monoamine oxidase A (MAO-A) is a major enzyme responsible for the deamination of neurotransmitters such as serotonin (5-HT) in the central nervous system. The decrease in 5-HT levels is accompanied by disorders at the affective and somatic levels, leading to depression and disorders of the satiety center. The aim of this study was to evaluate the degree of MAO-A inhibition by chlorogenic acids, as well as green, light-, and dark-roasted coffee extracts and bioactive compounds from beans of the species Coffea canephora and Coffea arabica. Data for analysis was obtained using isothermal titration calorimetry and molecular docking. The results showed that caffeine and ferulic acid, as well as green Robusta coffee, demonstrated the greatest inhibition of MAO-A activity, which may increase the bioavailability of serotonin. We believe that green coffee shows potential antidepressant activity by inhibiting MAO-A, and may be used for treating depression and potentially, type 2 diabetes.

Interactions between β-cyclodextrin and tea catechins, and potential anti-osteoclastogenesis activity of the (-)-epigallocatechin-3-gallate-β-cyclodextrin complex

Galloylated catechins, the most important secondary metabolites in green tea including (-)-epigallocatechin-3-gallate (EGCG) and (-)-epicatechin-3-gallate, constitute nearly 75% of all tea catechins and have stronger health effects than non-galloylated catechins such as (-)-epigallocatechin and (-)-epicatechin. EGCG is the most abundant, active, and thoroughly investigated compound in green tea, and its bioactivity might be improved by complexing with β-cyclodextrin (β-CD). We investigated interactions between four catechins and β-CD in a PBS buffer solution of pH 6.5 at 25 °C using biolayer interferometry and isothermal titration calorimetry, and to determine whether β-CD could enhance the anti-osteoclastogenesis effect of EGCG. β-CD could directly bind galloylated catechins at a stoichiometric ratio close to 1 : 1, with high specificities and affinities, and these inclusion interactions were primarily enthalpy-driven processes. We synthesized the EGCG-β-CD complex and identified it using infrared radiation and nuclear magnetic resonance spectra. Interestingly, we revealed that the EGCG-β-CD complex could inhibit osteoclastogenesis significantly more than EGCG.

An integral study of cyclodextrins as solubility enhancers of α-methylstilbene, a resveratrol analogue

trans-α-Methylstilbene (tMS), a resveratrol analogue, has recently been studied in a search for new bioactivities. However, such studies do not take into account that the poor solubility of tMS in aqueous solutions could affect its bioactivity. For this reason, we propose, for the first time, using cyclodextrins (CDs) as solubilizers to increase tMS solubility, in aqueous solutions. The HPLC-RP results obtained, point to a 1 : 1 stoichiometry for all the natural (α-, β- and γ-CD) and modified (HPβCD and MβCD) CDs tested. The K_Fapp (apparent formation constant) for the tMS-CD complexes was seen to be closely dependent on several factors, including the temperature and type of CD. Indeed, the highest K_Fapp value was obtained for MβCD, while the K_Fapp decreased with increasing temperature. In addition, the results showed negative entropy (-8.86 × 10^-3 ± 0.40 kJ mol^-1 K^-1) and enthalpy (-16.70 ± 0.98 kJ mol^-1) changes and a negative Gibbs free energy value at 25 °C (-14.00 ± 0.55 kJ mol^-1) for the encapsulation process. A computational study carried out using molecular docking calculations showed a high degree of correlation between the computed scores and experimental values. Finally, the complexation of trans-stilbene and pinosylvin with HPβCD was compared with tMS.

Physico-chemical studies of resveratrol, methyl-jasmonate and cyclodextrin interactions: an approach to resveratrol bioproduction optimization

trans-Resveratrol (RSV) is a natural phenolic molecule of the stilbene family known for its anti-oxidant properties in the field of nutraceuticals and cosmetics. Its production by grapevine cell suspensions is induced by the addition to the culture medium of elicitor compounds, methyl jasmonate (MeJA) and cyclodextrins (CDs). Physico-chemical studies were performed to understand the mechanism of action of CDs on this bioproduction of RSV. Inclusion complexes of RSV in CDs were first observed and then interactions with MeJA were identified using various analytical techniques such as UV and nuclear magnetic resonance (NMR) spectroscopies, mass spectrometry (MS) and isothermal titration calorimetry (ITC).

Selective binding of methotrexate to monomeric, dimeric and polymeric cyclodextrins

Selective binding of methotrexate to monomeric, dimeric and polymeric cyclodextrins characterized by formation of more stable complexes with dimeric β-cyclodextrin.

Separating and Identifying the Four Stereoisomers of Methyl Jasmonate by RP-HPLC and using Cyclodextrins in a Novel Way

INTRODUCTION

Several authors have reported on the different bioactivities of methyl jasmonate (MeJA) stereoisomers. However, no simple, precise and cheap method for separating and identifying them using reversed-phase high performance liquid chromatography (RP-HPLC) has been developed.

OBJECTIVE

(1) To create a simple, precise and cheap method for separating and identifying the four stereoisomers present in commercial racemic mixtures of MeJA and (2) to identify the four stereoisomers using molecular docking techniques and coinjection. Materials and Methods - RP-HPLC using a 250 mm C18 column and different proportions of cyclodextrins (CDs) and organic solvents was applied to a commercial sample of racemic MeJA.

RESULTS

The results show that the best conditions for separating the MeJA stereoisomers are: 20% methanol in the mobile phase, a temperature of 45 °C and a 16 mM concentration of methyl-β-cyclodextrin (M-β-CD). A simple C18 250 mm column and a flow rate of 1.25 mL/min were used. The reduction in the retention time of MeJA observed when M-β-CD is added to the mobile phases was used to determine the complexation constants of the guest/CD complex and compared with the obtained when other CDs were used. The K_F for M-β-CD (117.49 ± 5.9 1/M) was obtained with a 1:1 stoichiometry. The four stereoisomers were identified by molecular docking techniques and coinjection of a commercially available rosemary essential oil.

CONCLUSION

The new method identified and classified the four stereoisomers of MeJA in the following ordination: (-)epiMeJA, (-)MeJA; (+)MeJA and (+)epiMeJA. These results could be used to improve the elicitation of cell cultures with only the best isomer. Copyright © 2016 John Wiley & Sons, Ltd.

The inclusion complex of oxyresveratrol in modified cyclodextrins: A thermodynamic, structural, physicochemical, fluorescent and computational study

The interaction between oxyresveratrol (a type of stilbene with high biological activity) and modified cyclodextrins (CDs) was studied. Using HPLC-RP, was seen to form a 1:1 complex with all the CDs tested. The best CD in this respect was MβCD (K_F=606.65±30.18M^-1), the complexation showing a strong dependence on pH and temperature: The complexation constant (K_F) decreased as the pH and temperature increased. The thermodynamic parameters studied (ΔH°, ΔS° and ΔG°) showed negative entropy, enthalpy and Gibbs free energy change at 25°C. In addition, fluorescence signal of oxyresveratrol increased when MβCD was added. The oxyresveratrol emission and excitation spectra were obtained for first time. A ¹H NMR was carried out to study the structure of the complex and, DSC studied demonstrated the complexation. A computational study by molecular docking was made to complement the structural study.

Enhanced Zn2+ion-sensing behavior of a benzothiazole derivative on encapsulation by β-cyclodextrin

We report, in this paper, a benzothiazole derivative which shows selective binding of zinc ions among a pool of metal ions and the enhanced selectivity of the same metal ion by the derivative in its β-cyclodextrin bound form.

Enhanced Production of Resveratrol, Piceatannol, Arachidin-1, and Arachidin-3 in Hairy Root Cultures of Peanut Co-treated with Methyl Jasmonate and Cyclodextrin

Peanut (Arachis hypogaea) produces stilbenoids upon exposure to abiotic and biotic stresses. Among these compounds, the prenylated stilbenoids arachidin-1 and arachidin-3 have shown diverse biological activities with potential applications in human health. These compounds exhibit higher or novel biological activities in vitro when compared to their nonprenylated analogues piceatannol and resveratrol, respectively. However, assessment of these bioactivities in vivo has been challenging because of their limited availability. In this study, hairy root cultures of peanut were induced to produce stilbenoids upon treatment with elicitors. Co-treatment with 100 μM methyl jasmonate (MeJA) and 9 g/L methyl-β-cyclodextrin (CD) led to sustained high levels of resveratrol, piceatannol, arachidin-1, and arachidin-3 in the culture medium when compared to other elicitor treatments. The average yields of arachidin-1 and arachidin-3 were 56 and 148 mg/L, respectively, after co-treatment with MeJA and CD. Furthermore, MeJA and CD had a synergistic effect on resveratrol synthase gene expression, which could explain the higher yield of resveratrol when compared to treatment with either MeJA or CD alone. Peanut hairy root cultures were shown to be a controlled and sustainable axenic system for the production of the diverse types of biologically active stilbenoids.