Multi-Targeted Molecular Effects of Hibiscus sabdariffa Polyphenols: An Opportunity for a Global Approach to Obesity

Improper diet can alter gene expression by breaking the energy balance equation and changing metabolic and oxidative stress biomarkers, which can result in the development of obesity-related metabolic disorders. The pleiotropic effects of dietary plant polyphenols are capable of counteracting by modulating different key molecular targets at the cell, as well as through epigenetic modifications. Hibiscus sabdariffa (HS)-derived polyphenols are known to ameliorate various obesity-related conditions. Recent evidence leads to propose the complex nature of the underlying mechanism of action. This multi-targeted mechanism includes the regulation of energy metabolism, oxidative stress and inflammatory pathways, transcription factors, hormones and peptides, digestive enzymes, as well as epigenetic modifications. This article reviews the accumulated evidence on the multiple anti-obesity effects of HS polyphenols in cell and animal models, as well as in humans, and its putative molecular targets. In silico studies reveal the capacity of several HS polyphenols to act as putative ligands for different digestive and metabolic enzymes, which may also deserve further attention. Therefore, a global approach including integrated and networked omics techniques, virtual screening and epigenetic analysis is necessary to fully understand the molecular mechanisms of HS polyphenols and metabolites involved, as well as their possible implications in the design of safe and effective polyphenolic formulations for obesity.Some of the investigations described in this review have been partially or fully supported by competitive public grants from the following institutions: AGL2011-29857-C03-03 and IDI-20120751 grants (Spanish Ministry of Science and Innovation); projects AGL2015-67995-C3-1-R, AGL2015-67995-C3-2-R and AGL2015-67995-C3-3-R from the Spanish Ministry of Economy and Competitiveness (MINECO); and PROMETEO/2012/007, PROMETEO/2016/006, ACOMP/2013/093, ACIF/2010/162, ACIF/2015/158 and ACIF/2016/230 grants from Generalitat Valenciana and CIBER (CB12/03/30038, Fisiopatologia de la Obesidad y la Nutricion, CIBERobn, Instituto de Salud Carlos III, Spain)

The Potential Synergistic Modulation of AMPK by Lippia citriodora Compounds as a Target in Metabolic Disorders

Lippia citriodora (LC) represents a complex plant-derived source of polyphenols and iridoids that has shown beneficial properties against obesity-related metabolic disorders. The complete extract and its major compound, verbascoside, have shown AMPK-activating capacity in cell and animal models. In this work, we aimed to elucidate the contribution of the different compounds present in the LC extract on the AMPK activation capacity of the whole extract. Semipreparative reversed-phase high-performance liquid chromatography coupled to electrospray ionization time-of-flight mass spectrometry (RP-HPLC-ESI-TOF-MS) was used to identify the major compounds with bioassay-guided fractionation in an adipocyte cell model for the measurement of AMPK activity. Twenty-two compounds were identified and purified almost to homogeneity in 16 fractions, and three compounds, namely verbascoside, luteolin-7-diglucuronide and loganic acid, showed the highest AMPK-activating capacity. The synergy study using the checkerboard and fractional inhibitory concentration index (FICI) methods exhibited synergistic behavior between loganic acid and luteolin-7-diglucuronide. Molecular docking experiments revealed that these three compounds might act as direct agonists of AMPK, binding to the AMP binding sites of the gamma subunit and/or the different sites of the interaction zones between the gamma and beta subunits. Although our findings conclude that the bioactivity of the extract is mainly due to verbascoside, the synergy found between loganic acid and luteolin-7-diglucuronide deserves further research aimed to develop optimized combinations of polyphenols as a new nutritional strategy against obesity-related metabolic disorders

Bioactive Antioxidant Compounds from Chestnut Peels through Semi-Industrial Subcritical Water Extraction

Chestnut peels are a poorly characterized, underexploited by-product of the agri-food industry. This raw material is rich in bioactive compounds, primarily polyphenols and tannins, that can be extracted using different green technologies. Scaling up the process for industrial production is a fundamental step for the valorization of the extract. In this study, subcritical water extraction was investigated to maximize the extraction yield and polyphenol content. Lab-scale procedures have been scaled up to the semi-industrial level as well as the downstream processes, namely, concentration and spray drying. The extract antioxidant capacity was tested using in vitro and cellular assays as well as a preliminary evaluation of its antiadipogenic activity. The temperature, extraction time, and water/solid ratio were optimized, and the extract obtained under these conditions displayed a strong antioxidant capacity both in in vitro and cellular tests. Encouraging data on the adipocyte model showed the influence of chestnut extracts on adipocyte maturation and the consequent potential antiadipogenic activity. Chestnut peel extracts characterized by strong antioxidant power and potential antiadipogenic activity were efficiently obtained by removing organic solvents. These results prompted further studies on fraction enrichment by ultra- and nanofiltration. The semi-industrial eco-friendly extraction process and downstream benefits reported here may open the door to production and commercialization

AMPK modulatory activity of olive-tree leaves phenolic compounds: Bioassay-guided isolation on adipocyte model and in silico approach.

SCOPE:Olive-tree polyphenols have demonstrated potential for the management of obesity-related pathologies. We aimed to explore the capacity of Olive-tree leaves extract to modulate triglyceride accumulation and AMP-activated protein kinase activity (AMPK) on a hypertrophic adipocyte model. METHODS:Intracellular triglycerides and AMPK activity were measured on the hypertrophic 3T3-L1 adipocyte model by AdipoRed and immunofluorescence microscopy, respectively. Reverse phase high performance liquid chromatography coupled to time-of-flight mass detection with electrospray ionization (RP-HPLC-ESI-TOF/MS) was used for the fractionation of the extract and the identification of the compounds. In-silico molecular docking of the AMPK alpha-2, beta and gamma subunits with the identified compounds was performed. RESULTS:Olive-tree leaves extract decreased the intracellular lipid accumulation through AMPK-dependent mechanisms in hypertrophic adipocytes. Secoiridoids, cinnamic acids, phenylethanoids and phenylpropanoids, flavonoids and lignans were the candidates predicted to account for this effect. Molecular docking revealed that some compounds may be AMPK-gamma modulators. The modulatory effects of compounds over the alpha and beta AMPK subunits appear to be less probable. CONCLUSIONS:Olive-tree leaves polyphenols modulate AMPK activity, which may become a therapeutic aid in the management of obesity-associated disturbances. The natural occurrence of these compounds may have important nutritional implications for the design of functional ingredients

The Potential Synergistic Modulation of AMPK by Lippia citriodora Compounds as a Target in Metabolic Disorders

Lippia citriodora (LC) represents a complex plant-derived source of polyphenols and iridoids that has shown beneficial properties against obesity-related metabolic disorders. The complete extract and its major compound, verbascoside, have shown AMPK-activating capacity in cell and animal models. In this work, we aimed to elucidate the contribution of the different compounds present in the LC extract on the AMPK activation capacity of the whole extract. Semipreparative reversed-phase high-performance liquid chromatography coupled to electrospray ionization time-of-flight mass spectrometry (RP-HPLC-ESI-TOF-MS) was used to identify the major compounds with bioassay-guided fractionation in an adipocyte cell model for the measurement of AMPK activity. Twenty-two compounds were identified and purified almost to homogeneity in 16 fractions, and three compounds, namely verbascoside, luteolin-7-diglucuronide and loganic acid, showed the highest AMPK-activating capacity. The synergy study using the checkerboard and fractional inhibitory concentration index (FICI) methods exhibited synergistic behavior between loganic acid and luteolin-7-diglucuronide. Molecular docking experiments revealed that these three compounds might act as direct agonists of AMPK, binding to the AMP binding sites of the gamma subunit and/or the different sites of the interaction zones between the gamma and beta subunits. Although our findings conclude that the bioactivity of the extract is mainly due to verbascoside, the synergy found between loganic acid and luteolin-7-diglucuronide deserves further research aimed to develop optimized combinations of polyphenols as a new nutritional strategy against obesity-related metabolic disorders.This work was supported by projects AGL2015-67995-C3-1-R and RTI2018-096724-B-C21 (Spanish Ministry of Economy and Competitiveness), PROMETEO/2016/006 from Generalitat Valenciana and CIBER (CB12/03/30038, Fisiopatologia de la Obesidad y la Nutricion, CIBERobn, Instituto de Salud Carlos III). Scholarships ACIF/2016/230 and APOSTD/2017/023 from Generalitat Valenciana cofinanced with the European Social Fund, and by a grant from the Federative Research Structure TERSYS from Avignon University, France

HPLC-MS characterization of Olive-tree leaves extract.

<p>Base peak chromatogram (BPC) of the Olive-tree leaves extract in the negative ion mode obtained by RP-HPLC-ESI-TOF/MS, in which the peaks are identified by numbers 1–78 according to the elution order.</p

Relevant mass data of the proposed compounds detected in the Olive-tree leaves extract analyzed by RP-HPLC-ESI-TOF/MS.

<p>From left to right: peak number, retention time, calculated <i>m/z</i>, calculated <i>m/z</i>, molecular formula, error (ppm), millisigma value, proposed compound; and reference and matrix in which the proposed compound has been previously described.</p

Intracellular triglyceride accumulation inhibitory effect of the complete Olive-tree leaves extract in 3T3-L1 hypertrophic adipocytes.

<p>(A) Quantitative assessment of lipid vesicles in hypertrophic adipocytes incubated with 400, 600, or 800 μg/mL of Olive-tree leaves extract and compared to the control in a high glucose medium. Values have been normalized with respect to the control incubated in a high glucose medium. ** p<0.01 indicates significant differences compared to the control. Representative microphotographs for the qualitative assessment of 3T3-L1 lipid droplets: hypertrophic adipocytes differentiated for 22 days, phase contrast (panel B), same cells stained for triglycerides in lipid droplets (green, panel D) and nuclei stained with DAPI to show the localization of nuclear DNA (blue, panel C). Superimposed lipid droplets and cellular nucleus (panel E).</p