Characteristics of the interaction mechanisms of procyanidin B1 and procyanidin B2 with protein tyrosine phosphatase-1B: Analysis by kinetics, spectroscopy methods and molecular docking

A Single Latent Plant Growth-Promoting Endophyte BH46 Enhances Houttuynia cordata Thunb. Yield and Quality

Plant growth-promoting endophytes (PGPE) can effectively regulate plant growth and metabolism. The regulation is modulated by metabolic signals, and the resulting metabolites can have considerable effects on the plant yield and quality. Here, tissue culture Houttuynia cordata Thunb., was inoculated with Rhizobium sp. (BH46) to determine the effect of BH46 on H. cordata growth and metabolism, and elucidate associated regulatory mechanisms. The results revealed that BH46 metabolized indole-3-acetic acid and induced 1-aminocyclopropane-1-carboxylate deaminase to decrease ethylene metabolism. Host peroxidase synthesis MPK3/MPK6 genes were significantly downregulated, whereas eight genes associated with auxins, cytokinins, abscisic acid, jasmonic acid, and antioxidant enzymes were significantly upregulated. Eight genes associated with flavonoid biosynthesis were significantly upregulated, with the CPY75B1 gene regulating the production of rutin and quercitrin and the HCT gene directly regulating the production of chlorogenic acid. Therefore, BH46 influences metabolic signals in H. cordata to modulate its growth and metabolism, in turn, enhancing yield and quality of H. cordata.

Mechanistic insights into pyridine exposure induced toxicity in model Eisenia fetida species: Evidence from whole-animal, cellular, and molecular-based perspectives

Pyridine and its derivatives are widely used in many applications and inevitably cause extreme scenarios of serious soil contamination, which pose a threat to soil organisms. Still, the eco-toxicological effects and underlying mechanisms of pyridine-caused toxicity toward soil fauna have not been well established. Thus, earthworms (Eisenia fetida), coelomocytes, and oxidative stress-related proteins were selected as targeted receptors to probe the ecotoxicity mechanism of extreme pyridine soil exposure targeted to earthworms by using a combination of in vivo animal experiments, cell-based in vitro tests, in vitro functional and conformational analyses, and in silico analyses. The results showed that pyridine caused severe toxicity to E. fetida at extreme environmental concentrations. Exposure of pyridine induced excessive ROS formation in earthworms, causing oxidative stress and various deleterious effects, including lipid damage, DNA injury, histopathological change, and decreased defense capacity. Also, pyridine destroyed the cell membrane of earthworm coelomic cells and triggered a significant cytotoxicity. Importantly, the intracellular ROS (e.g., O₂^-, H₂O₂, and OH·^-) was release-activated, which eventually inducing oxidative stress effects (lipid peroxidation, inhibited defense capacity, and genotoxicity) through the ROS-mediated mitochondrial pathway. Moreover, the antioxidant defence mechanisms in coelomocytes responded quickly to reduce ROS-mediated oxidative injury. It was conformed that the abnormal expression of targeted genes associated with oxidative stress in coelomic cells was activated after pyridine exposure. Particularly, we found that the normal conformation (particle sizes, intrinsic fluorescence, and polypeptide backbone structure) of CAT/SOD was destroyed by the direct binding of pyridine. Furthermore, pyridine bound easily to the active center of CAT, but preferentially to the junction cavity of two subunits of SOD, which is considered to be a reason for impaired protein function in cells and in vitro. Based on these evidences, the ecotoxicity mechanisms of pyridine toward soil fauna are elucidated based on multi-level evaluation.

Silicon Doped Carbon Dots as an New Ratiometric Fluorescence Probe for Proanthocyanidins Assay Based on the Redox Reaction Between Cr(VI) and Proanthocyanidins

In the study, silicon doped carbon quantum dots (Si-CQDs) was prepared by one-pot hydrothermal method with (3-aminopropyl) triethoxysilane (APTES) and o-phenylenediamine (OPD) as raw materials. Then a new ratiometric fluorescent probe (RF-probe) was successfully established for sensitively and selectively monitoring proanthocyanidins (PAs) with a linear range of 10-500 nM and limit of detection (LOD) of 5.6 nM. that is, the fluorescence (FL) intensity of Si-CQDs at 570 nm was used as the built-in reference, while dopamine (DA) reacting with 4-hexylresorcinol (4-HR) could produce a new fluorescent substance (named as azamonardine, AZMON), and its FL intensity at 480 nm was reduced because Cr(VI) could oxidize DA to generate quinone without fluorescence. In the presence of PAs, Cr(VI) was reduced to Cr(III), which caused that the amount of DA reacting with 4-HR was increased, thus the FL intensity of AZMON was recovered. Furthermore, the RF-probe was successfully used for the determination of PAs in black goji berry from two different areas and PAs capsule with satisfactory results compared to the standard HPLC method.

The Flavonoid Molecule Procyanidin Reduces Phase Separation in Model Membranes

Procyanidin extracted from fruits, such as apples, has been shown to improve lipid metabolization. Recently, studies have revealed that procyanidin interacts with lipid molecules in membranes to enhance lipid metabolism; however, direct evidence of the interaction between procyanidin and lipid membranes has not been demonstrated. In this study, the phase behaviors and changes in the membrane fluidity of cell-sized liposomes containing apple procyanidin, procyanidin B2 (PB2), were demonstrated for the first time. Phase separation in 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC)/1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)/cholesterol ternary membranes significantly decreased after the addition of PB2. The prospect of applying procyanidin content measurements, using the results of this study, to commercial apple juice was also assessed. Specifically, the PB2 concentrations were 50%, 33%, and 0% for pure apple juice, 2-fold diluted apple juice, and pure water, respectively. The results of the actual juice were correlated with PB2 concentrations and phase-separated liposomes ratios, as well as with the results of experiments involving pure chemicals. In conclusion, the mechanism through which procyanidin improves lipid metabolism through the regulation of membrane fluidity was established.

Hypoglycemic bioactivity of anthocyanins: A review on proposed targets and potential signaling pathways

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disease with complicated interrelationships responsible for initiating its pathogenesis. Novel strategies for the treatment of this devastating disease have attracted increasing attention worldwide. Anthocyanins are bioactive compounds that are widely distributed in the plant kingdom, and multiple studies have elucidated their beneficial role in preventing and managing T2DM. This review summarizes and comments on the hypoglycemic actions of anthocyanins from the perspective of molecular mechanisms and different target-related signaling pathways in vitro, in vivo, and clinical trials. Anthocyanins can ameliorate T2DM by functioning as carbohydrate digestive enzyme inhibitors, facilitating glucose transporter 4 (GLUT4) translocation, suppressing the effectiveness of dipeptidyl peptidase IV (DPP-IV), promoting glucagon-like peptide-1 (GLP-1) secretion, inhibiting protein tyrosine phosphatase 1B (PTP1B) overexpression, and interacting with sodium-glucose co-transporter (SGLT) to delay glucose absorption in various organs and tissues. In summary, anthocyanin is a promising and practical small molecule that can hyperglycemic symptoms and accompanying complications suffered by patients with diabetes. However, rational and potent doses for daily intake and clinical studies are required in the future.

Antioxidant activity, stability, in vitro digestion and cytotoxicity of two dietary polyphenols co-loaded by β-lactoglobulin

The combination of multiple dietary polyphenols may have synergistic beneficial effects. And the beneficial effects can be further improved by the encapsulation of proteins. The interactions of procyanidin B2 (PB2) and/or dihydromyricetin (DMY) with β-lactoglobulin (β-LG) were investigated using multi-spectroscopic techniques and molecular docking. The structural change of β-LG in the presence of PB2 and/or DMY was demonstrated by dynamic light scattering, Fourier transform infrared spectroscopy and circular dichroism spectroscopy. Response surface analysis was used to optimize the synergistic antioxidant activity between PB2 and DMY. Besides, the antioxidant activity, stability, in vitro digestion and cytotoxicity of PB2 and DMY in the binary and ternary systems were investigated. These studies will elucidate the interaction mechanism of PB2 and/or DMY with β-LG. The research results can provide theoretical support for the development of functional foods and beverages with synergistic activity, improved stability and bioaccessibility, thereby promoting human health and preventing diseases.

Synergistic Effects of Combined Anthocyanin and Metformin Treatment for Hyperglycemia In Vitro and In Vivo

The mechanism underlying the hypoglycemic effect of the simultaneous use of metformin and anthocyanin-rich foods is not yet clear. Hence, the effects and possible mechanisms of action of these substances, alone and in combination, were evaluated in insulin-resistant HepG2 cells and a diabetic mouse model. The results indicated that anthocyanin and metformin had a significant synergistic effect on glucose consumption (CI < 0.9) compared with metformin alone in HepG2 cells. In the mouse model, combined treatment (50 and 100 mg/kg metformin + anthocyanin groups) demonstrated synergistic restorative effects on the blood glucose level, insulin resistance, and organ damage in the liver, pancreas, and ileum. Additionally, combined metformin and anthocyanin treatment suppressed protein tyrosine phosphatase 1B expression and regulated the PI3K/AKT/GSK3β pathway. Combined treatment also altered the gut microbial composition and structure by increasing the relative abundance of beneficial bacteria and the short-chain fatty acid content. These results suggest that the use of anthocyanins can enhance the efficacy of metformin treatment for hyperglycemia and provide a reference for further clinical research regarding nutrition and supplementary treatment.

Flavonoid constituents of Amomum tsao-ko Crevost et Lemarie and their antioxidant and antidiabetic effects in diabetic rats - in vitro and in vivo studies

Amomum tsao-ko Crevost et Lemarie (A. tsao-ko) is a well-known dietary spice and traditional Chinese medicine. This study aimed to identify the flavonoids in A. tsao-ko and evaluate their antioxidant and antidiabetic activities in in vitro and in vivo studies. A. tsao-ko methanol extracts possessed a high flavonoid content (1.21 mg QE per g DW) and a total of 29 flavonoids were identified by employing UPLC-MS/MS. In vitro, A. tsao-ko demonstrated antioxidant activity (ORAC value of 34276.57 μM TE/100 g DW, IC₅₀ of ABTS of 3.49 mg mL^-1 and FRAP value of 207.42 μM Fe²⁺ per g DW) and α-amylase and α-glucosidase inhibitory ability with IC₅₀ values of 14.23 and 1.76 mg mL^-1, respectively. In vivo, type 2 diabetes mellitus (T2DM) models were induced by a combined high-fat diet (HFD) and streptozotocin (STZ) injection in rats. Treatment with the A. tsao-ko extract (100 mg freeze-dried powder per kg bw) for 6 weeks could significantly improve impaired glucose tolerance, decrease the levels of fasting blood glucose (FBG), insulin, and malondialdehyde (MDA), and increase the superoxide dismutase (SOD) level. Histopathology revealed that the A. tsao-ko extract preserved the architecture and function of the pancreas. In conclusion, the flavonoid composition of A. tsao-ko exhibits excellent antioxidant and antidiabetic activity in vitro and in vivo. A. tsao-ko could be a novel natural material and developed as a related functional food and medicine in T2DM management.

Structure basis of the caffeic acid O-methyltransferase from Ligusiticum chuanxiong to understand its selective mechanism

Caffeic acid O-methyltransferase from Ligusticum chuanxiong (LcCOMT) showed strict regiospecificity despite a relative degree of preference. Compared with caffeic acid, methyl caffeate was the preferential substrate by its low Km and high Kcat. In this study, we obtained the SAM binary (1.80 Å) and SAH binary (1.95 Å) complex LcCOMT crystal structures, and established the ternary complex structure with methyl caffeate by molecular docking. The active site of LcCOMT included phenolic substrate pocket, SAM/SAH ligand pocket and conserved catalytic residues as well. The regiospecificity of LcCOMT that permitted only 3-hydroxyl group to be methylated arise from the interactions between the active site and the phenyl ring. However, the propanoid tail governed the relative preference of LcCOMT. The ester group in methyl caffeate stabilized the anionic intermediate caused by His268-Asp269 pair, whereas caffeic acid was unable to stabilize the anionic intermediate due to the adjacent carboxylate anion in the propanoid tail. Ser183 residue formed an additional hydrogen bond with SAH and its role was identified by S183A mutation. Ile318 residue might be a potential site for determination of substrate preference, and its mutation led to the change of tertiary conformation. The results supported the selective mechanism of LcCOMT.

Approaches to Decrease Hyperglycemia by Targeting Impaired Hepatic Glucose Homeostasis Using Medicinal Plants

Liver plays a pivotal role in maintaining blood glucose levels through complex processes which involve the disposal, storage, and endogenous production of this carbohydrate. Insulin is the hormone responsible for regulating hepatic glucose production and glucose storage as glycogen, thus abnormalities in its function lead to hyperglycemia in obese or diabetic patients because of higher production rates and lower capacity to store glucose. In this context, two different but complementary therapeutic approaches can be highlighted to avoid the hyperglycemia generated by the hepatic insulin resistance: 1) enhancing insulin function by inhibiting the protein tyrosine phosphatase 1B, one of the main enzymes that disrupt the insulin signal, and 2) direct regulation of key enzymes involved in hepatic glucose production and glycogen synthesis/breakdown. It is recognized that medicinal plants are a valuable source of molecules with special properties and a wide range of scaffolds that can improve hepatic glucose metabolism. Some molecules, especially phenolic compounds and terpenoids, exhibit a powerful inhibitory capacity on protein tyrosine phosphatase 1B and decrease the expression or activity of the key enzymes involved in the gluconeogenic pathway, such as phosphoenolpyruvate carboxykinase or glucose 6-phosphatase. This review shed light on the progress made in the past 7 years in medicinal plants capable of improving hepatic glucose homeostasis through the two proposed approaches. We suggest that Coreopsis tinctoria, Lithocarpus polystachyus, and Panax ginseng can be good candidates for developing herbal medicines or phytomedicines that target inhibition of hepatic glucose output as they can modulate the activity of PTP-1B, the expression of gluconeogenic enzymes, and the glycogen content.

Maturation Process, Nutritional Profile, Bioactivities and Utilisation in Food Products of Red Pitaya Fruits: A Review

Red pitaya (Hylocereus polyrhizus, red pulp with pink peel), also known as dragon fruit, is a well-known species of pitaya fruit. Pitaya seeds and peels have been reported to exhibit higher concentrations of total polyphenols, beta-cyanins and amino acid than pulp, while anthocyanins (i.e., cyanidin 3-glucoside, delphinidin 3-glucoside and pelargonidin 3-glucoside) were only detected in the pulp extracts. Beta-cyanins, phenolics and flavonoids were found to increase gradually during fruit maturation and pigmentation appeared earlier in the pulp than peel. The phytochemicals were extracted and purified by various techniques and broadly used as natural, low-cost, and beneficial healthy compounds in foods, including bakery, wine, dairy, meat and confectionery products. These bioactive components also exhibit regulative influences on the human gut microbiota, glycaemic response, lipid accumulation, inflammation, growth of microbials and mutagenicity, but the mechanisms are yet to be understood. The objective of this study was to systematically summarise the effect of red pitaya’s maturation process on the nutritional profile and techno-functionality in a variety of food products. The findings of this review provide valuable suggestions for the red pitaya fruit processing industry, leading to novel formulations supported by molecular research.

Ethnopharmacological, Phytochemical, Pharmacological, and Toxicological Review on Senna auriculata (L.) Roxb.: A Special Insight to Antidiabetic Property

Avartaki (Senna auriculata (L.) Roxb. syn. Cassia auriculata L.; Family- Fabaceae ) is a traditional medicinal plant, widely used for the treatment of various ailments in Ayurveda and Siddha system of medicine in India. Almost all the parts of the plant, such as flowers, leaves, seeds, barks, and roots have been reported for their medicinal uses. Traditionally, it has been used in the treatment of diabetes, asthma, rheumatism, dysentery, skin disease, and metabolic disorders. The principle phytochemicals in Senna auriculata (L.) Roxb. are alkaloids, anthraquinone, flavone glycosides, sugar, saponins, phenols, terpenoids, flavonoids, tannins, steroids, palmitic acid, linoleic acid, benzoic acid 2-hydroxyl methyl ester, 1-methyl butyl ester, resorcinol, α-tocopherol-β-D-mannosidase, epicatechin, ferulic acid, quercetin-3-O-rutinoside, quercetin, proanthocyanidin B1. The extracts from its different parts and their isolated compounds possess a wide range of pharmacological activities such as antidiabetic, antioxidant, anti-inflammatory, antihyperlipidemic, hepatoprotective, nephroprotective, cardioprotective, anti-atherosclerotic, anticancer, antimutagenic, antimicrobial, antiulcer, antipyretic, anthelmintic, immunomodulatory, antifertility, anti-venom, and anti-melanogenesis. The toxicological findings from preclinical studies ensured the safety of the plant, but comprehensive clinical studies are required for the safety and efficacy of the plant in humans. The current review article aimed to provide up-to-date information about Senna auriculata (L.) Roxb. covering its ethnomedicinal, phytochemical, pharmacological, and toxicological aspects with special emphasis on its clinical implications in diabetes.