Inhibitory mechanism and molecular analysis of furoic acid and oxalic acid on lipase

Identification of marker compounds in fermented Benincasa hispida and validation of the method for its analysis

Fermentation is a process that improves health functionality by inducing the production and increase of bioactive compounds. In this study, to standardize the fermentation process for Benincasa hispida, marker compounds that are increased or produced during fermentation were identified based on UPLC-QTOF-MS/MS. Analysis method verification and content analysis were conducted using HPLC-PDA. The marker compounds produced or increased in content were identified as 2-furoic acid, 2,3-dihydroxybenzoic acid, and rubinaphthin A by comparing their retention times, UV and MS spectra, and molecular formulas with those reported in previous studies. In addition, the increase in the content of the marker compounds by fermentation was confirmed, and the analytical method was validated by measuring its specificity, linearity, limit of detection and quantitation, precision, and accuracy. These results suggest that the developed fermentation process, marker compound identification, and verified analysis method can be applied to develop potential functional food ingredients from fermented B. hispida.

Effects of dietary wild bitter melon (Momordica charantia var. abbreviate Ser.) extract on glucose and lipid metabolism in HFD/STZ-induced type 2 diabetic rats

ETHNOPHARMACOLOGICAL RELEVANCE

Plant-based extracts to interfere with the onset of diabetes may be a promising approach towards type 2 diabetes mellitus (T2DM). Bitter gourd (Momordica charantia L.) is popularly consumed as an edible and medicinal resource with hypoglycemic effect in China. Wild bitter gourd (Momordica Charantia var. abbreviata Ser.) is a variant of bitter gourd, but there are relatively few studies on it.

AIM OF THE STUDY

The purpose of the experiment is to first screen out the most effective extraction part of Momordica charantia L. and Momordica Charantia var. abbreviata Ser. through the hypoglycemic activity experiment in vitro, and by using a high-fat and high-sugar diet with STZ-induced diabetic rat model in vivo to explore the possible mechanism of action against diabetes.

MATERIALS AND METHODS

This study first performed α-glucosidase, PTP1B and lipase activities inhibition experiments on the alcohol and water extracts of Momordica charantia L. and Momordica Charantia var. abbreviata Ser. Sprague Dawley rats were either given normal feed or a high sugar and fat diet for four weeks, followed STZ (25 mg/kg, via i. p.) was given. Rats with fasting blood glucose ≥11.1 mmol/l after one week were deemed to be diabetic, treatments were administered for four weeks, and then blood samples were used to evaluate hematological and biochemical indicators, and liver was removed for post-analysis. The expression levels of p-AMPK, AMPK, p-PI3K, PI3K, p-AKT, AKT, p-GSK3β, GSK3β, p-IRS-1, IRS-1, GLUT2 were determined by Western blot. At the same time, the chemical components was identified by liquid-mass spectrometry.

RESULTS

Data showed that the ethanol extract of wild bitter gourd (WBGE) had the best ability to regulate glucose and lipid metabolism in vitro. Therefore, we further investigated the antidiabetic effects of oral consumption of WBGE on high-fat diet (HFD) and streptozotocin (STZ)-induced T2DM in SD rats. WBGE effectively reduced blood glucose and lipid levels, alleviated glucose intolerance and insulin resistant. Moreover, WBGE consumption could also inhibited oxidant responses and inflammatory damage. Mechanism studies have shown that WBGE may act by regulating AMPK/PI3K signaling pathway. On the other hand, the content of total phenol, total flavonoids, total saponins and total polysaccharide were measured by UV, 27 compounds were identified by LC-MS.

CONCLUSIONS

These studies explored the role and mechanism of WBGE in regulating glucose and lipid metabolism, and may support the utilization and further investigation of wild bitter gourd as a dietary intervention strategy to prevent diabetes and related metabolic abnormalities.

Novel Lead Compound Discovery from Aspergillus fumigatus 1T-2 against Meloidogyne incognita Based on a Chemical Ecology Study

To replace biohazardous nematicides, there is an ever-increasing need to identify natural product-based agents to contain root-knot nematodes (RKNs) in agriculture. In this chemical ecology study, an antagonistic fungus Aspergillus fumigatus 1T-2, which could cause the formation of withering of the gut and vacuole-like structures in the nematode body, was isolated based on the gradually increased antagonistic interactions between the soil fungi and RKNs. Based on these typical morphological characteristics, a potent nematode-antagonistic compound 2-furoic acid, which had a simple structure, was successfully identified from 1T-2 fermentation broth by liquid chromatography-mass spectrometry (LC-MS). 2-Furoic acid showed effective mortality activity in vitro, of which the LC₅₀ value to Megalaima incognita at 24 h was 37.75 μg/mL. 2-Furoic acid had similar mortality activity to the positive control fosthiazate at 30 μg/mL. Continuous 2-furoic acid exposure had obvious negative influences on both nematode vitality and egg hatchability. Notably, significant variations were observed in nematodes and eggs with 2-furoic acid treatment, which might be induced by novel nematocidal mechanisms. Furthermore, the 1T-2 fermentation broth and 2-furoic acid had significant control efficacy on M. incognita under the greenhouse test-tube assay. Overall, these findings provide valuable insights into the use of 2-furoic acid with biocontrol potential as a preferable lead structure for the development of innovative nematicides.

Theophylline Extracted from Fu Brick Tea Affects the Metabolism of Preadipocytes and Body Fat in Mice as a Pancreatic Lipase Inhibitor

The dramatic increase in obesity is putting people under increasing pressure. Lipase inhibitors, as a kind of effective anti-obesity drug, have attracted more and more researchers’ attention in recent years because of their advantages of acting on the intestinal tract and having no side effects on the central nervous system. In this study, lipase inhibitor Fu Brick Theophylline (FBT) was screened based on enzyme molecular dynamics, and the inhibition mechanism of lipase inhibitors on obesity was analyzed and discussed at the cellular level and animal model level. We found that FBT had high inhibition effects of lipase with an IC₅₀ of 1.02~0.03 μg/mL. Firstly, the laboratory used 3T3-L1 proadipocytes as models, flow cytometry was used to detect the effects of FBT on the cycle, apoptosis and intracellular ROS activity of proadipocytes. To study the contents of triglyceride, total cholesterol, related metabolites and related gene and protein expression in adipocytes. The results showed that FBT could reduce ROS production and inflammatory factor mRNA expression during cell differentiation. Secondly, by establishing the animal model of high-fat feed ob nutritional obese mice, the morphological observation and gene expression analysis of body weight, fat rate, adipocyte and hepatocyte metabolism of FBT obese mice were further discussed. It was proven that FBT can effectively reduce the degree of fatty liver, prevent liver fibrosis and fat accumulation, and improve the damage of mitochondrial membrane structure. This study provides a theoretical basis for the screening and clinical treatment of lipase inhibitors.

Stability comparison of four lipases and catalytic mechanism during the synthesis of 1,3-di-oleic-2-medium chain triacylglycerols in a trace water-in-oil system: Experimental analyses and computational simulations

In the present study, a kind of structured lipids, namely 1,3-di-oleic-2-medium chain (OMO) triacylglycerols, were synthesized through lipase-catalyzed reactions using coconut oil and rapeseed acid as materials in a trace water-in-oil system. Experimental analysis and computational simulations were undertaken to compare the stability of four lipases including Lipozyme RMIM, Lipozyme TLIM, Novozym 435, and Aspergillus oryzae immobilized lipase (AOIM), and illustrate catalytic mechanism of Novozym 435 during the synthesis of OMO. Fourier transform infrared and molecular dynamics simulation results demonstrated that a decrease in ordered structure (α-helix and β-sheet) led to a reduction in enzyme activity. Compared with Lipozyme RMIM and Novozym 435, Lipozyme TLIM and AOIM exhibited better stability due to a short-chain lid in TLIM, which covers activity sites, and hydrogen bonds formed between activity center of AOIM and water. Among four lipases, AOIM exhibited best catalytic performance: a OMO yield of 30.7% at 3 hr and a good stability of long term (48 hr). Density functional theory results demonstrated that specifically, during the synthesis of OMO triacylglycerol, the addition of Novozym 435 (derived from Candida antarctica lipase B, CALB) substantially lowered reaction barriers (64.4 KJ/mol with CALB vs. 332.7 KJ/mol with no lipase), aiding in the generation of OMO because of the formations of transitional tetrahedral intermediates. A trace water-in-oil system was a green and efficient alternative for lipase-catalyzed production of OMO, and this study provided crucial insights into the stability/instability and catalytic mechanisms of lipase in the synthesis of structured lipids. PRACTICAL APPLICATIONS: We compared the stability of Lipozyme RMIM, Lipozyme 435, Lipozyme TLIM, and AOIM during the synthesis of the OMO triacylglycerols in a trace water-in-oil system, where exhibited a high catalytic activity of lipase in water-oil interface. AOIM had the highest stability and showed the best catalytic performance due to the formation of hydrogen bonds. Besides, for the first time, the transition tetrahedral structure was revealed in the enzymatic synthesis of medium- and long-chain triacylglycerols. This study provides a rational approach to compare lipase stability and a possible hint to choose appropriate enzyme in a specific catalytic condition.

Targeting of CAT and VCAM1 as Novel Therapeutic Targets for DMD Cardiomyopathy

Duchenne muscular dystrophy (DMD) related cardiomyopathy is the leading cause of early mortality in DMD patients. There is an urgent need to gain a better understanding of the disease molecular pathogenesis and develop effective therapies to prevent the onset of heart failure. In the present study, we used DMD human induced pluripotent stem cells (DMD-hiPSCs) derived cardiomyocytes (CMs) as a platform to explore the active compounds in commonly used Chinese herbal medicine (CHM) herbs. Single CHM herb (DaH, ZK, and CQZ) reduced cell beating rate, decreased cellular ROS accumulation, and improved structure of DMD hiPSC-CMs. Cross-comparison of transcriptomic profiling data and active compound library identified nine active chemicals targeting ROS neutralizing Catalase (CAT) and structural protein vascular cell adhesion molecule 1 (VCAM1). Treatment with Quecetin, Kaempferol, and Vitamin C, targeting CAT, conferred ROS protection and improved contraction; treatment with Hesperidin and Allicin, targeting VCAM1, induced structure enhancement via induction of focal adhesion. Lastly, overexpression of CAT or VCAM1 in DMD hiPSC-CMs reconstituted efficacious effects and conferred increase in cardiomyocyte function. Together, our results provide a new insight in treating DMD cardiomyopathy via targeting of CAT and VCAM1, and serves as an example of translating Bed to Bench back to Bed using a muti-omics approach.

Strong inhibitory activities and action modes of lipopeptides on lipase

Lipopeptides have been reported to exhibit anti-obesity effects. In this study, we obtained a Bacillus velezensis strain FJAT-52631 that could coproduce iturins, fengycins, and surfactins. Results showed that the FJAT-52631 crude lipopeptide, purified fengycin, iturin, and surfactin standards exhibited strong inhibition activities against lipase with dose-dependence manners (half maximal inhibitory concentration (IC₅₀) = 0.011, 0.005, 0.056, and 0.005 mg/mL, respectively). Moreover, fengycin and surfactin had the comparable activities with orlistat, but iturin not. It was revealed that the inhibition mechanism and type of the lipopeptides were reversible and competitive. The quenching mechanism of lipase was static and only one binding site between lipase and lipopoeptide was inferred from the fluorescence analysis. The docking analysis displayed that fengycin and surfactin could directly interact with the active amino acid residues (Ser or Asp) of lipase, but not with iturin. Our work suggests that the B. velezensis lipopeptides would have great potential to act as lipase inhibitors.

Inhibitory kinetics and bioactivities of Nuciferine and Methyl Ganoderate on Mucor miehei lipase and 3T3-L1 preadipocytes

In this study, inhibitory kinetics of Nuciferine and Methyl Ganoderate extrated from Lotus Leaves and Ganoderma lucidum on Mucor miehei Lipase were studied first. The molecular structure of Nuciferine and Methyl Ganoderate were determined. The inhibitory effects of two extracts on lipase were reversible, with the IC₅₀ values of 0.194 and 0.332 mg/mL, respectively. The inhibition kinetic analysis by Lineweaver-Burk plots showed that they were a mixed-type inhibitor of lipase, with inhibition constants K_I of 0.16 and 0.29 mg/mL, and K_IS of 0.36 and 0.49 mg/mL, respectively. Results of spectral analysis showed that the UV absorption and the molecule fluorescence spectrum of the lipase hydrolyzate were significantly decreased after the inhibitor was added. The molecular docking further suggested that the interaction site between the active substance and inhibitor was located in an α-helix and a β-sheet of the lipase, and the lipase active site was interfered by the inhibitor near the cap structure. In addition, the proliferation and differentiation of 3 T3-L1 preadipocytes were inhibited by two extracts. Total triglycerides and cholesterol were significantly reduced in the cells. The results confirmed that Nuciferine and Methyl Ganoderate can be used as potential obesity treatment drugs.

Phytopharmacological Strategies in the Management of Type 2 Diabetes Mellitus

Type 2 Diabetes Mellitus (T2DM) is a chronic disease which corresponds to 90% of the worldwide cases of diabetes, mainly due to epigenetic factors such as unhealthy lifestyles. First line therapeutic approaches are based on lifestyle changes, most of the time complemented with medication mostly associated with several side effects and high costs. As a result, the scientific community is constantly working for the discovery and development of natural therapeutic strategies that provide lower financial impact and minimize side effects. This review focus on these nature-based therapeutic strategies for prevention and control of T2DM, with a special emphasis on natural compounds that present pharmacological activity as dipeptidyl peptidase-4 (DPP4), alpha-amylase, alpha-glucosidase, lipase, and protein tyrosine phosphatase 1B (PTP1B) inhibitors.

The inhibitory kinetics and mechanism of glycolic acid on lipase

Obesity is prone to cause a variety of chronic metabolic diseases, and it has aroused people's attention that the rapid increase in the global population of obese people in the past years. As a kind of weight-loss drug acting in the intestine, lipase inhibitor does not enter the bloodstream without producing central nervous side effects. Because they do not affect the metabolism system, lipase inhibitors and obesity have become one of the hot spots in recent years. Glycolic acid is a new substrate analog inhibitor with the value of the semi-inhibitory concentration of lipase is estimated to be 17.29 ± 0.14 mM. Using the plots of Lineweaver-Burk, the inhibition mechanism of lipase by glycolic acid was reversible and the inhibition type belongs to competitive inhibition with a K_I value of 19.61 ± 0.26 mM. The inhibitory kinetics assay showed that the microscopic velocity constant k₊₀ of inhibition kinetics is 1.79 × 10^-3mM^-1s^-1, and k_-0 is 0.73 × 10^-3 s^-1. The results of UV full-wavelength scanning on product cumulative, fluorescence quenching and molecular simulation also indicated that glycolic acid and substrate competitive with lipase by binding to Lys137. Thereby glycolic acid inhibiting the oxidation-catalyzed reaction and reducing the product of the enzyme and substrate. This adds a new direction for the search for lipase inhibitors and provides new ideas about the development of anti-obesity drugs.Communicated by Ramaswamy H. Sarma.

Inhibition of UGT1A1 by natural and synthetic flavonoids

Flavonoids are widely distributed phytochemicals in vegetables, fruits and medicinal plants. Recent studies demonstrate that some natural flavonoids are potent inhibitors of the human UDP-glucuronosyltransferase 1A1 (UGT1A1), a key enzyme in detoxification of endogenous harmful compounds such as bilirubin. In this study, the inhibitory effects of 56 natural and synthetic flavonoids on UGT1A1 were assayed, while the structure-inhibition relationships of flavonoids as UGT1A1 inhibitors were investigated. The results demonstrated that the C-3 and C-7 hydroxyl groups on the flavone skeleton would enhance UGT1A1 inhibition, while flavonoid glycosides displayed weaker inhibitory effects than their corresponding aglycones. Further investigation on inhibition kinetics of two strong flavonoid-type UGT1A1 inhibitors, acacetin and kaempferol, yielded interesting results. Both flavonoids were competitive inhibitors against UGT1A1-mediated NHPN-O-glucuronidation, but were mixed and competitive inhibitors toward UGT1A1-mediated NCHN-O-glucuronidation, respectively. Furthermore, docking simulations showed that the binding areas of NHPN, kaempferol and acacetin on UGT1A1 were highly overlapping, and convergence with the binding area of bilirubin within UGT1A1. In summary, detailed structure-inhibition relationships of flavonoids as UGT1A1 inhibitors were investigated carefully and the findings shed new light on the interactions between flavonoids and UGT1A1, and will contribute considerably to the development of flavonoid-type drugs without strong UGT1A1 inhibition.