4-Hydroxyderricin Isolated from the Sap of Angelica keiskei Koidzumi: Evaluation of Its Inhibitory Activity towards Dipeptidyl Peptidase-IV

Nephroprotective Activity of Angelica keiskei (Miq). Koidz. on Cisplatin-Induced Rats: Reducing Serum Creatinine, Urea Nitrogen, KIM-1, and Suppressing NF-kappaB p65 and COX-2

Background

The sap of Angelica keiskei (Miq). Koidz. has been reported for its abundance of chalcone contents. Chalcones have been known for their effective nephroprotective activity toward cisplatin-induced renal cells and mice.

Purpose

To investigate the effect of A. keiskei sap extract (ASEE) on kidney function parameters (serum creatinine, urea nitrogen, and kidney injury molecule-1) and the expression of NF-kappaB p65 and COX-2 in cisplatin-induced Wistar rats.

Methods

In vivo nephroprotective activity of ASEE at 1000 and 1500 mg/kg BW/day doses for 10 days on cisplatin (5 mg/kg BW) induced nephrotoxicity was evaluated on Wistar rats. Quercetin 20 mg/kg BW/day was used as the control drug. Cisplatin inducement was given on day 7. The BW was measured every day. On day 11, the rats were euthanized, and their blood was taken intracardially for creatinine and urea nitrogen analysis. Histopathological analysis was carried out on the right kidney, and KIM-1 levels in the left kidney were measured. The Western blot technique evaluated the NF-kappaB p65 and COX-2 expression in the kidney. All data obtained were compared to the cisplatin group (negative control). The total flavonoids and chalcones in ASEE were also determined.

Results

Pretreatment with ASEE reduces the BW of Wistar rats, and significantly reduces creatinine and KIM-1 levels, but does not significantly reduce the levels of urea nitrogen, the expression of NF-kappaB p65, and COX-2 in the kidney of cisplatin-induced Wistar rats. The total flavonoid content in ASEE is 8.755 g QE/100 g extract and the total chalcone content is 5.532 g IBCE/100 g extract.

Conclusion

The sap of Angelica keiskei (Miq). Koidz. reveal the potential to protect the kidneys against cisplatin-induced toxicity. The nephroprotective activity may be attributed to the antioxidant and anti-inflammatory properties of the flavonoids and the chalcones contained in the sap of Angelica keiskei (Miq). Koidz.

Identifying Potential Human Monoacylglycerol Lipase Inhibitors from the Phytoconstituents of Morinda Citrifolia L. Fruits by in silico Pharmacology and in vitro Study

Background

Human monoacylglycerol lipase (MGL) is accountable for the hydrolysis of 2-arachidonoylglycerol (2-AG), thus contributing pivotally to neuroprotection because 2-AG is the main source of arachidonic acid, the precursor of prostaglandins production. Inhibiting MGL reduces inflammatory damage in the ischemic brain and enhances cerebral blood flow. Plants have been reported for their neuroprotective effect, such as Morinda citrifolia on pentylenetetrazol (PTZ)-induced kindling seizures in mice, by reducing the seizures and restoring behavioral and biochemical changes, although the mechanism is not described.

Purpose

To evaluate the binding affinity and stability of phytoconstituents in M. citrifolia fruits toward human MGL (PDB ID 3PE6), compared to the known MGL inhibitors (JZL195 and ZYH). The in silico pharmacology study was validated by an in vitro study of the phytosterols and the ethanol extract of M. citrifolia fruits (EEMC) towards MGL.

Methods

Initially, nine phytoconstituents of M. citrifolia fruits were docked to the catalytic pocket of human MGL (PDB ID: 3PE6), and compounds with the best affinity were subjected to a molecular dynamic (MD) simulation. The in vitro study was performed using the MGL inhibitor screening assay kit.

Results

The best binding affinity and stability toward human MGL were shown by stigmasterol and beta-sitosterol, and the MM-PBSA total binding energy of stigmasterol and beta-sitosterol to MGL is stronger than that of JZL195 and ZYH. Moreover, beta-sitosterol and EEMC inhibit MGL with an IC50 value of, respectively, 8.10 μg/mL and 196.20 μg/mL, while JZL195 shows an IC50 of 0.028 μg/mL.

Conclusion

Beta-sitosterol of Morinda citrifolia fruits may have the potential to protect human neurons by occupying the catalytic site of human MGL, thus competitively inhibiting the substrate of the enzyme. However, the inhibitory activity towards human MGL is lower than JZL195.

The pharmacology activities of Angelica keiskei Koidzumi and its efficacy and safety in humans

Chronic exposure to elevated levels of pro-oxidant factors may cause structural failings at the mitochondrial DNA level and alteration of antioxidant enzymes (glutathione peroxidase, catalase, and superoxide dismutase). Oxidative stress is an imbalance between the capacity of endogenous non-enzymatic antioxidants (glutathione, alpha-lipoic acid, uric acid, ferritin, metallothionein, melatonin, and bilirubin) and the occurrence of pro-oxidant factors which may lead to the pathogenesis of various diseases that affects the kidneys, pancreas, central nervous system, and cardiovascular system. Therefore, the utilization of medicinal plants with antioxidant activity, e.g., Angelica keiskei Koidzumi which contains chalcones, is interesting to be explored. Chalcones exhibit direct and indirect antioxidant activity and prevent oxidative stress by decreasing ROS, RNS, and superoxide production. In this review, we discuss the pharmacology activities of A. keiskei Koidzumi and its efficacy in humans. The articles were explored on PubMed and Google Scholar databases and based on the titles and abstracts related to the topic of interest, and 55 articles were selected. Two main chalcones of this plant, 4-hydroxyderricin and xanthoangelol, have been reported for their various pharmacology activities. The efficacy of A. keiskei was confirmed in anti-obesity, hepatoprotective, anti-diabetes mellitus, and increasing plasma antioxidants in patients with metabolic syndrome. A keiskei is safe as proven by only mild or no adverse events reported, thus it is prospective to be further developed as an antioxidant nutraceutical.

Pharmacological and Clinical Studies of Medicinal Plants That Inhibit Dipeptidyl Peptidase-IV

Dipeptidyl peptidase IV (DPP-IV) is an enzyme responsible for the degradation of the incretin hormone glucagon-like peptide-1 (GLP-1). DPP-IV plays a significant role in regulating blood glucose levels by modulating the activity of GLP-1. In the context of diabetes, DPP-IV inhibitors effectively block the activity of DPP-IV, hence mitigating the degradation of GLP-1. This, in turn, leads to an extension of GLP-1's duration of action, prolongs gastric emptying, enhances insulin sensitivity, and ultimately results in the reduction of blood glucose levels. Nonetheless, reported adverse events of DPP-IV inhibitors on T2DM patients make it essential to understand the activity and mechanism of these drugs, particularly viewed from the perspective of finding the effective and safe add-on medicinal plants, to be implemented in clinical practice. This review is intended to bring forth a thorough overview of plants that work by reducing DPP-IV activity, from computational technique, enzymatic study, animal experiments, and studies in humans. The articles were searched on PubMed using "Plants", "DPP-IV", "DPP-IV inhibitor", "GLP-1", "Type 2 diabetes", "diabetes", "in silico", "in vitro", "in vivo", "studies in human", "clinical study" as the query words, and filtered for ten years of publication period. Eighteen plants showed inhibition against DPP-IV as proven by in silico, in vitro, and in vivo studies; however, only ten plants were reported for efficacy in clinical studies. Several plant-based DPP-IV inhibitors, eg, Allium sativum, Morus Alba, Curcuma longa, Pterocarpus marsupium, and Taraxacum officinale, have established their functional role in inhibiting DPP-IV and have proven their effectiveness through studies in humans earning them a prominent place in therapeutic discovery.

Inhibitory activity of xanthoangelol isolated from Ashitaba (Angelica keiskei Koidzumi) towards α-glucosidase and dipeptidyl peptidase-IV: in silico and in vitro studies

In Indonesia, the sap of Angelica keiskei Koidzumi has been utilized traditionally as a blood-sugar reducer, nonetheless, its molecular mechanism still needs to be studied. This study aimed to isolate xanthoangelol (XA) from the yellow sap of A. keiskei planted in Mount Rinjani, Indonesia, and to investigate its mechanism by in silico and in vitro methods towards α-glucosidase and dipeptidyl peptidase-IV (DPP-IV). The dried yellow sap was macerated using ethanol, subjected to liquid-liquid extraction using a different polarity of solvents, further gradient-eluted with column chromatography. The isolated compound, formed as yellow crystals, melting point 114–114.4 °C, λ_max 368 nm, m/z 393.20 [M + H]⁺, was confirmed as XA. Acarbose, an α-glucosidase inhibitor, and sitagliptin, a DPP-IV inhibitor, respectively, were employed as the reference drugs for both the in silico and in vitro studies. XA interacts with essential amino acid residues 232–237 in the N-terminal N-loop of α-glucosidase by forming a hydrogen bond with Ala234, a salt-bridge with Asp232, and 9 hydrophobic interactions (binding energy -7.81 kcal/mol; Ki = 1.99 μM). These binding modes resemble those of acarbose. Moreover, XA forms hydrogen bonds with Glu205 and Glu206 in the subsite S2 and π-π interaction with Phe357 in the extensive subsite S2 of DPP-IV (binding energy -8.34 kcal/mol; Ki = 0.873 μM), which are similar to those of sitagliptin. XA inhibits both α-glucosidase (IC₅₀ XA = 14.45 μM; IC₅₀ acarbose = 207 μM) and DPP-IV (IC₅₀ XA = 10.49 μM; IC₅₀ sitagliptin = 0.87 μM). Taken together, XA isolated from the yellow sap of A. keiskei Koidzumi might possess the potential to be further developed as an inhibitor of α-glucosidase and DPP-IV.

The Cytotoxicity and Nephroprotective Activity of the Ethanol Extracts of Angelica keiskei Koidzumi Stems and Leaves against the NAPQI-Induced Human Embryonic Kidney (HEK293) Cell Line

Materials and Methods

A. keiskei Koidzumi plant was collected from Mount Rinjani, Lombok, Indonesia, and was identified at the School of Biology Sciences and Technology, Bandung Institute of Technology, Indonesia. Extraction of the stems (ASE) and leaves (ALE) was performed by employing ethanol 70% for 3 × 24 h at 26°C. The cytotoxicity study of the extracts was assessed using the water-soluble tetrazolium salt-8 (WST-8) reagent on the HEK293 cell line, while the nephroprotective activity assay was determined on the NAPQI-induced HEK293 cell line.

Results

The WST-8 assay showed that the cytotoxicity IC₅₀ of ASE = 2322 μg/mL and IC₅₀ of ALE = 2283 μg/mL. The nephroprotective activity assay revealed that ASE possesses nephroprotective activity against the NAPQI-induced HEK293 cell line at 1161 μg/mL, while ALE does not show the nephroprotective activity.

Conclusion

Taken together, lower concentrations of ASE and ALE (<2000 μg/mL) are not toxic to the HEK293 cell line, and only ASE indicates the activity to protect the HEK293 cell line against NAPQI damage. This Japanese celery could be further explored for its potential as a plant-based nephroprotective drug.

Advance in dietary polyphenols as dipeptidyl peptidase-IV inhibitors to alleviate type 2 diabetes mellitus: aspects from structure-activity relationship and characterization methods

Dietary polyphenols with great antidiabetic effects are the most abundant components in edible products. Dietary polyphenols have attracted attention as dipeptidyl peptidase-IV (DPP-IV) inhibitors and indirectly improve insulin secretion. The DPP-IV inhibitory activities of dietary polyphenols depend on their structural diversity. Screening methods that can be used to rapidly and accurately identify potential polyphenol DPP-IV inhibitors are urgently needed. This review focuses on the relationship between the structures of dietary polyphenols and their DPP-IV inhibitory effects. Different characterization methods used for polyphenols as DPP-IV inhibitors have been summarized and compared. We conclude that the position and number of hydroxyl groups, methoxy groups, glycosylated groups, and the extent of conjugation influence the efficiency of inhibition of DPP-IV. Various combinations of methods, such as in-vitro enzymatic inhibition, ex-vivo/in-vivo enzymatic inhibition, cell-based in situ, and in-silico virtual screening, are used to evaluate the DPP-IV inhibitory effects of dietary polyphenols. Further investigations of polyphenol DPP-IV inhibitors will improve the bioaccessibility and bioavailability of these bioactive compounds. Exploration of (i) dietary polyphenols derived from multiple targets, that can prevent diabetes, and (ii) actual binding interactions via multispectral analysis, to understand the binding interactions in the complexes, is required.

4-Hydroxyderricin Promotes Apoptosis and Cell Cycle Arrest through Regulating PI3K/AKT/mTOR Pathway in Hepatocellular Cells

4-hydroxyderricin (4-HD), as a natural flavonoid compound derived from Angelica keiskei, has largely unknown inhibition and mechanisms on liver cancer. Herein, we investigated the inhibitory effects of 4-HD on hepatocellular carcinoma (HCC) cells and clarified the potential mechanisms by exploring apoptosis and cell cycle arrest mediated via the PI3K/AKT/mTOR signaling pathway. Our results show that 4-HD treatment dramatically decreased the survival rate and activities of HepG2 and Huh7 cells. The protein expressions of apoptosis-related genes significantly increased, while those related to the cell cycle were decreased by 4-HD. 4-HD also down-regulated PI3K, p-PI3K, p-AKT, and p-mTOR protein expression. Moreover, PI3K inhibitor (LY294002) enhanced the promoting effect of 4-HD on apoptosis and cell cycle arrest in HCC cells. Consequently, we demonstrate that 4-HD can suppress the proliferation of HCC cells by promoting the PI3K/AKT/mTOR signaling pathway mediated apoptosis and cell cycle arrest.

Molecular docking and molecular dynamics studies of bioactive compounds contained in noni fruit (Morinda citrifolia L.) against human pancreatic α-amylase

Human pancreatic α-amylase inhibition is currently a promising therapeutic target against type 2 diabetes (DMT2) because it can reduce aggressive digestion of carbohydrates into absorbable monosaccharides. In Indonesia, medicinal plants, e.g. Morinda citrifolia fruit, have been empirically utilized as a blood-sugar reducer, however, the inhibitory activity of compounds in this plant against human pancreatic α-amylase is still limited or none. Therefore, this study aimed to test the interaction of 7 compounds (americanin, asperulosidic acid, damnacanthal, quercetin, rutin, scopoletin, and ursolic acid) contained in noni fruit against human pancreatic α-amylase by molecular docking and molecular dynamics and compared their binding modes with that of acarbose. Results of the molecular docking simulation indicated that the ursolic acid compound possesses the best binding energy (-8.58 kcal/mol) and comparable to that of acarbose (-8.59 kcal/mol). The molecular dynamics study at 100 ns simulation, the values of RMSD, RMSF, the radius of gyration (Rg), the solvent-accessible surface area (SASA), principal component analysis (PCA), and MM-PBSA binding free energy were stable and identical to those of acarbose. It could be concluded that ursolic acid might be potential in inhibiting human pancreatic α-amylase, thus, potential to be developed as an anti-DMT2 drug candidate. Communicated by Ramaswamy H. Sarma.

Novel Potent and Selective DPP-4 Inhibitors: Design, Synthesis and Molecular Docking Study of Dihydropyrimidine Phthalimide Hybrids

BACKGROUND

Dipeptidyl peptidase-4 (DPP-4) inhibitors have emerged as anti-hyperglycemic agents that improve glycemic control in type 2 diabetic patients, either as monotherapy or in combination with other antidiabetic drugs.

METHODS

A novel series of dihydropyrimidine phthalimide hybrids was synthesized and evaluated for their in vitro and in vivo DPP-4 inhibition activity and selectivity using alogliptin as reference. Oral glucose tolerance test was assessed in type 2 diabetic rats after chronic treatment with the synthesized hybrids ± metformin. Cytotoxicity and antioxidant assays were performed. Additionally, molecular docking study with DPP-4 and structure activity relationship of the novel hybrids were also studied.

RESULTS

Among the synthesized hybrids, 10g, 10i, 10e, 10d and 10b had stronger in vitro DPP-4 inhibitory activity than alogliptin. Moreover, an in vivo DPP-4 inhibition assay revealed that 10g and 10i have the strongest and the most extended blood DPP-4 inhibitory activity compared to alogliptin. In type 2 diabetic rats, hybrids 10g, 10i and 10e exhibited better glycemic control than alogliptin, an effect that further supported by metformin combination. Finally, 10j, 10e, 10h and 10d had the highest radical scavenging activity in DPPH assay.

CONCLUSIONS

Hybrids 10g, 10i and 10e are potent DPP-4 inhibitors which may be beneficial for T2DM treatment.