Caffeoylquinic Acid Derivatives of Purple Sweet Potato as Modulators of Mitochondrial Function in Mouse Primary Hepatocytes

Antidiabetic Potential of a Trimeric Anthranilic Acid Peptide Isolated from Malbranchea flocciformis

Compound 3, a trimeric anthranilic acid peptide, and another three metabolites were isolated from an organic extract from the culture medium of Malbranchea flocciformis ATCC 34530. The chemical structure proposed previously for 3 was unequivocally assigned via synthesis and X-ray diffraction analysis. Tripeptide 3 showed insulinotropic properties by decreasing the postprandial peak in healthy and hyperglycemic mice. It also increased glucose-induced insulin secretion in INS-1E at 5 μM, specifically at higher glucose concentrations. These results revealed that 3 might act as an insulin sensitizer and a non-classical insulin secretagogue. Altogether, these findings are in harmony with the in vivo oral glucose tolerance test and acute oral hypoglycemic assay. Finally, the chemical composition of the extract was established by the Global Natural Products Social Molecular Network platform. Phylogenetic analysis using the internal transcribed spacer region revealed that M. flocciformis ATCC 34530 is related to the Malbrancheaceae.

Vachellia farnesiana Pods or a Polyphenolic Extract Derived from Them Exert Immunomodulatory, Metabolic, Renoprotective, and Prebiotic Effects in Mice Fed a High-Fat Diet

Obesity causes systemic inflammation, hepatic and renal damage, as well as gut microbiota dysbiosis. Alternative vegetable sources rich in polyphenols are known to prevent or delay the progression of metabolic abnormalities during obesity. Vachellia farnesiana (VF) is a potent source of polyphenols with antioxidant and anti-inflammatory activities with potential anti-obesity effects. We performed an in vivo preventive or an interventional experimental study in mice and in vitro experiments with different cell types. In the preventive study, male C57BL/6 mice were fed with a Control diet, a high-fat diet, or a high-fat diet containing either 0.1% methyl gallate, 10% powdered VFP, or 0.5%, 1%, or 2% of a polyphenolic extract (PE) derived from VFP (Vachellia farnesiana pods) for 14 weeks. In the intervention study, two groups of mice were fed for 14 weeks with a high-fat diet and then one switched to a high-fat diet with 10% powdered VFP for ten additional weeks. In the in vitro studies, we evaluated the effect of a VFPE (Vachellia farnesiana polyphenolic extract) on glucose-stimulated insulin secretion in INS-1E cells or of naringenin or methyl gallate on mitochondrial activity in primary hepatocytes and C2C12 myotubes. VFP or a VFPE increased whole-body energy expenditure and mitochondrial activity in skeletal muscle; prevented insulin resistance, hepatic steatosis, and kidney damage; exerted immunomodulatory effects; and reshaped fecal gut microbiota composition in mice fed a high-fat diet. VFPE decreased insulin secretion in INS-1E cells, and its isolated compounds naringenin and methyl gallate increased mitochondrial activity in primary hepatocytes and C2C12 myotubes. In conclusion VFP or a VFPE prevented systemic inflammation, insulin resistance, and hepatic and renal damage in mice fed a high-fat diet associated with increased energy expenditure, improved mitochondrial function, and reduction in insulin secretion.

Chaya (Cnidoscolus aconitifolius (Mill.) I.M. Johnst) leaf extracts regulate mitochondrial bioenergetics and fatty acid oxidation in C2C12 myotubes and primary hepatocytes

ETHNOPHARMACOLOGICAL RELEVANCE

Chaya (Cnidoscolus aconitifolius (Mill.) I.M. Johnst) is an important component of the regular diet and traditional medicine of indigenous communities in Mexico. Customarily, Chaya is consumed as a beverage made of macerated leaf, cooked, or prepared in teas or infusions to empirically treat obesity, diabetes, gastrointestinal disorders, and kidney stones. The beneficial effects of Chaya can be attributed to the presence of protein, dietary fiber, vitamins, and especially polyphenols, which regulate mitochondrial function. Therefore, polyphenols present in Chaya extracts could be used to develop novel strategies to prevent and treat metabolic alterations related to mitochondrial dysfunction in the muscle and liver of subjects with obesity, type 2 diabetes, and cardiovascular diseases. However, limited information is available concerning the effect of Chaya extracts on mitochondrial activity in those tissues.

AIM OF THE STUDY

The aim of this study was to evaluate the antioxidant capacity of an aqueous extract (AE) or mixed (methanol/acetone/water) extract (ME) of Chaya leaf and their effect on C2C12 myotubes and primary hepatocyte mitochondrial bioenergetics and fatty acid oxidation (FAO).

MATERIALS AND METHODS

Total polyphenol content and antioxidant activity were determined using the Folin-Ciocalteu method and the oxygen radical absorbance capacity assay, respectively. The effect of AE and ME from Chaya leaf on mitochondrial activity and FAO of C2C12 myotubes and primary hepatocytes was evaluated using an extracellular flux analyzer.

RESULTS

The AE and ME from Chaya leaf exhibited antioxidant activity and a polyphenol content similar to nopal, another plant used in Mexican traditional medicine. AE significantly (p < 0.05) decreased the maximal respiration and spare respiratory capacity (SRC) of C2C12 cells, whereas ME had little effect on C2C12 mitochondrial function. Conversely, ME significantly (p < 0.05) decreased SRC in primary hepatocytes, whereas AE increased maximal respiration and SRC at low doses (5 and 10 μM). Moreover, low doses of Chaya AE significantly (p < 0.05) increased AMPK phosphorylation, acyl-coenzyme A oxidase protein abundance, and palmitate oxidation in primary hepatocytes.

CONCLUSION

The AE of Chaya leaf increases mitochondrial function and FAO of primary hepatocytes, indicating its potential to treat hepatic mitochondrial dysfunction underlying metabolic diseases.

Analysis of phytochemical composition and biological activities of Helichrysum pallasii (Sprengel) ledeb leaves

This study aimed at the investigation of in vitro biological activities (antioxidant and enzyme inhibition) and phytochemical composition of various extracts (ethanol maceration, aqueous infusion, and aqueous decoction) obtained from leaf organs of Helichrysum pallasii, which has been traditionally used as herbal tea and medicine in Eastern Anatolia. Experimental analysis showed that ethanol-based extract had higher total phenolic content (TPC: 103 mg GAE/gE) and showed superior antioxidant potentials (FRAP: 2205 μmol Fe2+/gE; ORAC: 2540 μmol Trolox Eq./gE; DPPH: IC50=0.58 mg/ml; CUPRAC: IC50=0.37 mg/ml; Phosphomolybdenum: IC50=1.34 mg/ml ve metal chelation: IC50=1.42 mg/ml) and enzyme inhibition (Acetylcholinesterase: IC50=1.49 mg/ml; Butyrylcholinesterase: IC50=1.98 mg/ml; Tyrosinase: IC50=0.68 mg/ml; Alpha-amylase: IC50=2.09 mg/ml; Alpha-glucosidase: IC50=0.51 mg/ml; and Pancreatic lipase: IC50=42.5 μg/ml) and contained higher amounts of phenolic (chlorogenic acid isomers and rutin) and fatty acid (palmitic, linoleic, and linolenic acids) compounds than traditional preparations (infusion and decoction). The current study's findings indicate that the leaves of the Helichrysum pallasii are a source of phytochemicals with strong antioxidant and enzyme inhibitory properties, implying that it could be a candidate for biotherapeutic agent research and development.

Comparison of Caffeoylquinic Acids and Functional Properties of Domestic Sweet Potato (Ipomoea batatas (L.) Lam.) Storage Roots with Established Overseas Varieties

Root samples of sweet potato varieties originating from South Africa (‘Ndou’, ‘Bophelo’, ‘Monate’, and ‘Blesbok’), the USA (‘Beauregard’), and Peru (‘199062.1′) were analyzed using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC/QTOF/MS) and chemometrics to characterize and compare the locally developed varieties with well-known established overseas varieties. The highest total phenol content was detected in ‘Bophelo’, followed by ‘Beauregard’ and Peruvian variety ‘199062.1’. The Orthogonal Projections to Latent Structures Discriminant Analysis (OPLS-DA) model classified the storage roots of six sweet potato varieties into two clusters. In the OPLS-DA scatter plot, one cluster, which included Peruvian variety ‘199062.1’, was separated from the others. L-tryptophan and 3-caffeoylquinic acid (CQA) showed variable importance in projection (VIP) scores greater than 1.5. Based on the OPLS-DA-S-plot, L-tryptophan separated the other varieties from Peruvian variety ‘199062.1’. Peruvian variety ‘199062.1’ contained higher concentrations of CQA (1,3-diCQA, 1,4-diCQA, 3,5-diCQA, 4,5-diCQA, 3-CQA, and 5-CQA) and 5-hydroxy-6-methoxycoumarin 7-glucoside than other varieties. Among all sweet potato varieties analyzed, Peruvian variety ‘199062.1′ showed the highest ferric reducing antioxidant power (2,2-diphenyl-1-picryl-hydrazyl-hydrate) free radical scavenging activity, and [2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonate)] scavenging activity. Among the local sweet potato varieties, ‘Bophelo’ has the greatest potential for commercialization as it is the richest source of CQA.

3,4,5-O-tricaffeoylquinic acid alleviates ionizing radiation-induced injury in vitro and in vivo through regulating ROS/JNK/p38 signaling

Ionizing radiation (IR) brings many health problems to humans, causing damage to the digestive system, hematopoietic system, and immune system. Natural compounds derived from plants have attracted widespread attention due to their low toxicity. Here, we found that 3,4,5-O-tricaffeoylquinic acid (tCQA) extracted from natural plant Azolla imbricata could significantly alleviate the systemic damage in mice caused by IR. In order to further explore the molecular mechanism of the radioprotective effect of tCQA, in vitro experiments confirmed that tCQA could attenuate the cytotoxic effect of IR on the colonic epithelial cell line NCM460 and alleviate the IR-induced mitochondrial dysfunction characterized by the decrease of mitochondrial transmembrane potential, ROS production, and caspase-dependent apoptosis. In addition, the generation of ROS induced by H₂ O₂ could also be reversed by tCQA. Then, Western blot demonstrated that tCQA could reverse the MAPK signaling pathway activated by IR. However, the inhibitory effect of tCQA on JNK and P38 levels activated by the JNK agonist anisomycin is not obvious; meanwhile, tCQA could inhibit the activation of JNK/P38 induced by H₂ O₂ , which suggests that tCQA might inhibit the JNK/P38 signaling pathway by reducing ROS. In short, tCQA inhibits the generation of ROS caused by IR, and then regulates the activity of caspase in the mitochondrial pathway by inhibiting the JNK/P38 signaling pathway, thereby alleviating the apoptosis of NCM460. This research provides an experimental basis for the development of new types of radioprotective agents for medical diagnosis and radiotherapy.

Antioxidant and Mitochondria-Targeted Activity of Caffeoylquinic-Acid-Rich Fractions of Wormwood (Artemisia absinthium L.) and Silver Wormwood (Artemisia ludoviciana Nutt.)

Caffeoylquinic acids are some of the chemophenetically significant specialized metabolites found in plants of the family Asteraceae Dumort., possessing a broad spectrum of biological activities. As they might be potential mitochondria-targeted antioxidants, effective preparation methods—including extraction, isolation, and purification of caffeoylquinic acids from plant sources—are in great demand. The aim of this study was to fractionate the caffeoylquinic acids from cultivated wormwood (Artemisia absinthium L.) and silver wormwood (Artemisia ludoviciana Nutt.) herb acetone extracts and evaluate their phytochemical profiles, antioxidant activity (radical scavenging and reducing activities), effects on kidney mitochondrial functions, and cytochrome-c-reducing properties. The main findings of our study are as follows: (1) Aqueous fractions purified from wormwood and silver wormwood herb acetone extracts are rich in monocaffeoylquinic acids (chlorogenic acid, neochlorogenic acid, 4-O-caffeoylquinic acid), while methanolic fractions purified from wormwood and silver wormwood herb acetone extracts are rich in dicaffeoylquinic acids (4,5-dicaffeoylquinic acid, 3,4-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid). Aqueous fractions purified from wormwood and silver wormwood herb acetone extracts were solely composed of monocaffeoylquinic acids. Methanolic fractions purified from wormwood and silver wormwood herb acetone extracts contained only dicaffeoylquinic acids. (2) Fractions purified from silver wormwood herb acetone extracts stood out as having the greatest content of caffeoylquinic acids. (3) The greatest radical scavenging activity was determined in the dicaffeoylquinic-acid-rich fraction purified from silver wormwood herb acetone extract; the greatest reducing activity was determined in the dicaffeoylquinic-acid-rich fraction purified from wormwood herb acetone extract. (4) The effect of both fractions on mitochondrial functions was dose-dependent; lower concentrations of caffeoylquinic-acid-rich fractions had no effect on mitochondrial functions, whereas higher concentrations of caffeoylquinic-acid-rich fractions reduced the state 3 respiration rate (with the complex-I-dependent substrate glutamate/malate). (5) Both monocaffeoylquinic- and dicaffeoylquinic-acid-rich fractions possessed cytochrome-c-reducing properties; the greatest cytochrome c reduction properties were determined in the dicaffeoylquinic-acid-rich fraction purified from wormwood herb acetone extract. In summary, these findings show that caffeoylquinic acids might be beneficial as promising antioxidant and cytochrome-c-reducing agents for the modulation of mitochondria and treatment of various mitochondrial-pathway-associated pathologies.

A Novel Ultrasound-Assisted Extraction Method for the Analysis of Anthocyanins in Potatoes (Solanum tuberosum L.)

Purple potato is one of the least known and consumed potato varieties. It is as rich in nutrients, amino acids and starches as the rest of the potato varieties, but it also exhibits a high content of anthocyanins, which confer it with some attractive health-related properties, such as antioxidant, pain-relieving, anti-inflammatory and other promising properties regarding the treatment of certain diseases. A novel methodology based on ultrasound-assisted extraction has been optimized to achieve greater yields of anthocyanins. Optimal extraction values have been established at 70 °C using 20 mL of a 60% MeOH:H₂O solution, with a pH of 2.90 and a 0.5 s⁻¹ cycle length at 70% of the maximum amplitude for 15 min. The repeatability and intermediate precision of the extraction method have been proven by its relative standard deviation (RSD) below 5%. The method has been tested on Vitelotte, Double Fun, Highland and Violet Queen potatoes and has demonstrated its suitability for the extraction and quantification of the anthocyanins found in these potato varieties, which exhibit notable content differences. Finally, the antioxidant capacity of these potato varieties has been determined by means of 2,2-diphenyl-1-picrylhydrazyl (DDPH) radical scavenging and the values obtained were similar to those previously reported in the literature.

Dietary bioactive compounds as modulators of mitochondrial function

The increase in incidence and prevalence of metabolic diseases, such as diabetes, obesity, and metabolic syndrome, is a health problem worldwide. Nutritional strategies that can impact on mitochondrial activity represent a novel and effective option to modulate energy expenditure and energetic metabolism in cells and tissues and could be used as adjuvant treatments for metabolic-associated disorders. Dietary bioactive compounds also known as "food bioactives" have proven to exert multiple health benefits and counteract metabolic alterations. In the last years, it has been consistently reported that the modulation of mitochondrial function represents one of the mechanisms behind the bioactive compounds-dependent health improvements. In this review, we focus on gathering, summarizing, and discussing the evidence that supports the effect of dietary bioactive compounds on mitochondrial activity and the relation of these effects in the pathological context. Despite the evidence presented here on in vivo and in vitro effects, more studies are needed to determine their effectiveness in humans.