Antidiabetic Stilbenes from Peony Seeds with PTP1B, α-Glucosidase, and DPPIV Inhibitory Activities

Chemistry and biology of natural stilbenes: an update

Covering: 2009 up to the end of 2023Stilbenes, an emblematic group of polyphenols, have attracted the attention of numerous researchers owing to their intriguing polycyclic architectures and diverse bioactivities. In this updated review, natural stilbenes were analysed, especially oligomeric stilbenes, which are an emblematic group of polyphenols that harbor intriguing polycyclic architectures and diverse bioactivities compared with those previously anticipated. Oligomeric stilbenes with unique skeletons comprise a large majority of natural stilbenes owing to their structural changes and different substitutions on the phenyl rings. These compounds can be promising sources of lead compounds for studying new drugs and medicines. In addition, the exploration of unusual structures of oligomeric stilbenes such as polyflavanostilbenes A and B, analysing their absolute stereochemistry, and improving their yield using synthetic biology methods have recently gained interest. This review provides a systematic overview of 409 new stilbenes, which were isolated and identified over time from January 2009 to December 2023, focusing on the classification and biomimetic syntheses of oligomeric stilbenes, in addition to presenting meaningful insights into their structural diversity and biological activities, which will inspire further investigations of biological activities, structure-activity relationships, and screening of drug candidates.

Protective Role of Dietary Polyphenols in the Management and Treatment of Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM), a serious metabolic disorder, is a worldwide health problem due to the alarming rise in prevalence and elevated morbidity and mortality. Chronic hyperglycemia, insulin resistance, and ineffective insulin effect and secretion are hallmarks of T2DM, leading to many serious secondary complications. These include, in particular, cardiovascular disorders, diabetic neuropathy, nephropathy and retinopathy, diabetic foot, osteoporosis, liver damage, susceptibility to infections and some cancers. Polyphenols such as flavonoids, phenolic acids, stilbenes, tannins, and lignans constitute an extensive and heterogeneous group of phytochemicals in fresh fruits, vegetables and their products. Various in vitro studies, animal model studies and available clinical trials revealed that flavonoids (e.g., quercetin, kaempferol, rutin, epicatechin, genistein, daidzein, anthocyanins), phenolic acids (e.g., chlorogenic, caffeic, ellagic, gallic acids, curcumin), stilbenes (e.g., resveratrol), tannins (e.g., procyanidin B2, seaweed phlorotannins), lignans (e.g., pinoresinol) have the ability to lower hyperglycemia, enhance insulin sensitivity and improve insulin secretion, scavenge reactive oxygen species, reduce chronic inflammation, modulate gut microbiota, and alleviate secondary complications of T2DM. The interaction between polyphenols and conventional antidiabetic drugs offers a promising strategy in the management and treatment of T2DM, especially in advanced disease stages. Synergistic effects of polyphenols with antidiabetic drugs have been documented, but also antagonistic interactions that may impair drug efficacy. Therefore, additional research is required to clarify mutual interactions in order to use the knowledge in clinical applications. Nevertheless, dietary polyphenols can be successfully applied as part of supportive treatment for T2DM, as they reduce both obvious clinical symptoms and secondary complications.

A review of the ethnopharmacology, phytochemistry, pharmacology, pharmacokinetics and quality control of Paeonia lactiflora Pall

ETHNOPHARMACOLOGICAL RELEVANCE

Paeonia lactiflora Pall. (called Shaoyao in China) is a common herb cultivated all over the world. In some Asian and European countries, such as China, Japan, South Korea and Britain, P. lactiflora has a long history of ethnomedical uses, which is widely used to relieve pain, treat gynecological diseases, anti-infection and so on. It is attributed to the extensive pharmacological activities of total glucosides of P. lactiflora. Up to now, it is still commonly used in clinical medicine.

THE AIM OF THE REVIEW

The paper aims to make a comprehensive review on the botanical characterization and distribution, ethnopharmacology, phytochemistry, biosynthesis pathway, pharmacology, pharmacokinetics and quality control of P. lactiflora, so as to provide new insights and scientific evidence for the subsequent research.

MATERIALS AND METHODS

The information of P. lactiflora was obtained from books related to traditional Chinese medicine and electronic databases, including Scifinder, PubMed, Web of Science, CNKI and Google Scholar.

RESULTS

P. lactiflora is a kind of herb with a long history and it is used for medicine, food and ornamental, and shows high utilization value. There are 200 compounds have been identified from it, including terpenoids, flavonoids, polyphenols, organic acids and others, among those paeoniflorin, a monoterpenoid glycoside, has multiple activities and is currently the focus of pharmacological research. A great deal of pharmacological experiments supported the anti-inflammatory, anti-oxidant, hepatoprotective, neuroprotective, antibacterial, antitumor, dermatosis treating and other effects of P. lactiflora. In addition, evaluating the quality of P. lactiflora is essential to safe use of drug in humans.

CONCLUSIONS

The chemical components of P. lactiflora are diverse and have a wide range of activities. Modern pharmacological studies have provided reliable evidence for the traditional efficacy, such as suppressing liver yang, regulating menstruation and relieving pain. However, there are still some problems to be solved, such as part of the pharmacological mechanism has not been clarified and the biosynthetic pathway of cage-like monoterpenoids remains poorly defined. In addition, further studies on compounds other than paeoniflorin are clearly warranted. It is hoped that P. lactiflora will serve the clinic better in the future.

Innovative Statistical Model Uncover Effective Herbal Medicines Among Personalized Treatment Plans in Persian Medicine: A Small-Scale Study in Type 2 Diabetes

Objectives: In holistic medicine, developing personalized treatment plans is challenging due to the multitude of possible therapy combinations. This study introduces the use of a statistical approach to identify the most effective herbal medicines prescribed in Persian medicine (PM) in a small-scale sample of patients with type 2 diabetes mellitus (T2DM). Methods: This prospective observational cohort study was conducted with 47 patients with T2DM referred to Behesht Clinic in Tehran, Iran. A physician prescribed individualized PM treatment for T2DM and related systemic issues. The fasting blood sugar (FBS) level of each patient was recorded at initial and two follow-up visits, with visit intervals and treatment modifications determined by patient health status. Patients who completed two follow-up visits were included in the final analysis (n = 27). Data were analyzed using R software. A general linear model was assumed for the mean response, along with an exponential covariance pattern model, to manage irregularly timed measurements. Results: Two fitted models showed that, after adjusting for confounders, the use of the "Diabetes Capsule" significantly reduced the average FBS by 17.14 mmol/L (p = 0.046). For each unit increase in the consumption of "Diabetes Capsule" or "Hab-e-Amber Momiai," the average FBS decreased by 15.22 mmol/L (p = 0.015) and 14.14 mmol/L (p = 0.047), respectively. Conclusion: It is possible to observe which medications are most effective, even when treatments are applied in a holistic and personalized fashion. Preliminary studies such as these may identify promising products for testing in clinical trials conducted under standardized conditions, to inform initial choices for future personalized treatments.

Effect of Mono- and Polysaccharide on the Structure and Property of Soy Protein Isolate during Maillard Reaction

As a protein extracted from soybeans, soy protein isolate (SPI) may undergo the Maillard reaction (MR) with co-existing saccharides during the processing of soy-containing foods, potentially altering its structural and functional properties. This work aimed to investigate the effect of mono- and polysaccharides on the structure and functional properties of SPI during MR. The study found that compared to oat β-glucan, the reaction rate between SPI and D-galactose was faster, leading to a higher degree of glycosylation in the SPI-galactose conjugate. D-galactose and oat β-glucan showed different influences on the secondary structure of SPI and the microenvironment of its hydrophobic amino acids. These structural variations subsequently impact a variety of the properties of the SPI conjugates. The SPI-galactose conjugate exhibited superior solubility, surface hydrophobicity, and viscosity. Meanwhile, the SPI-galactose conjugate possessed better emulsifying stability, capability to produce foam, and stability of foam than the SPI-β-glucan conjugate. Interestingly, the SPI-β-glucan conjugate, despite its lower viscosity, showed stronger hypoglycemic activity, potentially due to the inherent activity of oat β-glucan. The SPI-galactose conjugate exhibited superior antioxidant properties due to its higher content of hydroxyl groups on its molecules. These results showed that the type of saccharides had significant influences on the SPI during MR.

Identification of a novel hypoglycemic small molecule, trans-2, 4-dimethoxystilbene by rectifying gut microbiota and activating hepatic AMPKα-PPARγ pathway through gut-liver axis

With the increasing prevalence of metabolic disorders, hyperglycemia has become a common risk factor that endangers people's lives and the need for new drug solutions is burgeoning. Trans-2, 4-dimethoxystilbene (TDMS), a synthetic stilbene, has been found as a novel hypoglycemic small molecule from glucose consumption test. Normal C57BL/6 J mice, mouse models of type 1 diabetes mellitus and diet-induced obesity subjected to TDMS gavage were found with lower glycemic levels and better glycemic control. TDMS significantly improved the symptoms of polydipsia and wasting in type 1 diabetic mice, and could rise their body temperature at the same time. It was found that TDMS could promote the expression of key genes of glucose metabolism in HepG2, as do in TDMS-treated liver, while it could improve the intestinal flora and relieve intestinal metabolic dysbiosis in hyperglycemic models, which in turn affected its function in the liver, forming the gut-liver axis. We further fished PPARγ by virtual screening that could be promoted by TDMS both in-vitro and in-vivo, which was regulated by upstream signaling of AMPKα phosphorylation. As a novel hypoglycemic small molecule, TDMS was proven to be promising with its glycemic improvements and amelioration of diabetes symptoms. It promoted glucose absorption and utilization by the liver and improved the intestinal flora of diabetic mice. Therefore, TDMS is expected to become a new hypoglycemic drug that acts through gut-liver axis via AMPKα-PPARγ signaling pathway in improving glycemic metabolism, bringing new hope to patients with diabetes and glucose metabolism disorders.

Integrated Metabolomics Approach Reveals the Dynamic Variations of Metabolites and Bioactivities in Paeonia ostii 'Feng Dan' Leaves during Development

Paeonia ostii 'Feng Dan' is widely cultivated in China for its ornamental, medicinal, and edible properties. The whole plant of tree peony is rich in bioactive substances, while the comprehensive understanding of metabolites in the leaves is limited. In this study, an untargeted metabolomics strategy based on UPLC-ESI-TOF-MS was conducted to analyze the dynamic variations of bioactive metabolites in P. ostii 'Feng Dan' leaves during development. A total of 321 metabolites were rapidly annotated based on the GNPS platform, in-house database, and publications. To accurately quantify the selected metabolites, a targeted method of HPLC-ESI-QQQ-MS was used. Albiflorin, paeoniflorin, pentagalloylglucose, luteolin 7-glucoside, and benzoylpaeoniflorin were recognized as the dominant bioactive compounds with significant content variations during leaf development. Metabolite variations during the development of P. ostii 'Feng Dan' leaves are greatly attributed to the variations in antioxidant activities. Among all tested bacteria, the leaf extract exhibited exceptional inhibitory effects against Streptococcus hemolytis-β. This research firstly provides new insights into tree peony leaves during development. The stages of S1-S2 may be the most promising harvesting time for potential use in food or pharmaceutical purposes.

Vitisin B, a resveratrol tetramer from Vitis thunbergii var. taiwaniana, ameliorates impaired glucose regulations in nicotinamide/streptozotocin-induced type 2 diabetic mice

Background and aim

In Taiwan, Vitis thunbergii var. taiwaniana (VTT) is used in traditional medicine and as a local tea. VTT rich in resveratrol and resveratrol oligomers have been reported to exhibit anti-obesity and anti-hypertensive activities in animal models; however, no studies have investigated type 2 diabetes mellitus (T2DM) treatments. This study aimed to investigate the anti-T2DM effects of resveratrol tetramers isolated from the VTT in nicotinamide/streptozotocin (STZ)-induced Institute of Cancer Research (ICR) mice.

Experimental procedure

The oral glucose tolerance test (OGTT) was used to imitate postprandial blood glucose (BG) regulations in mice by pre-treatment with VTT extracts, resveratrol tetramers of vitisin A, vitisin B, and hopeaphenol 30 min before glucose loads. Vitisin B (50 mg/kg) was administered to treat T2DM-ICR mice once daily for 28 days to investigate its hypoglycemic activity.

Results and conclusion

Mice pre-treated with VTT-S-95EE, or vitisin B (100 mg/kg) 30-min before glucose loading showed significant reductions (P < 0.001) in the area under the curve at 120-min (BG-AUC0-120) than those without pre-treatment with VTT-S-95 E E or vitisin B. Vitisin B-treated T2DM mice showed hypoglycemic activities via a reduction in plasma dipeptidyl peptidase (DPP)-IV activities to maintain insulin actions and differed significantly than those of untreated T2DM mice (P < 0.05), and also reduced BG-AUC0-120 and insulin-AUC0-120 in the OGTT.These in vivo results showed that VTT containing vitisin B would be beneficial for developing nutraceuticals and/or functional foods for glycemic control in patients with T2DM, which should be investigated further.

Structurally Diverse Phenolic Amides from the Fruits of Lycium barbarum with Potent α-Glucosidase, Dipeptidyl Peptidase-4 Inhibitory, and PPAR-γ Agonistic Activities

A total of nine new phenolic amides (1-9), including four pairs of enantiomeric mixtures (3-5 and 8), along with ten known analogues (10-19) were identified from the fruits of Lycium barbarum using bioassay-guided chromatographic fractionation. Their structures were elucidated by comprehensive spectroscopic and spectrometric analyses, chiral HPLC analyses, and quantum NMR, and electronic circular dichroism calculations. Compounds 5-7 are the first example of feruloyl tyramine dimers fused through a cyclobutane ring. The activity results indicated that compounds 1, 11, and 13-17 exhibited remarkable inhibition against α-glucosidase with IC₅₀ of 1.11-33.53 μM, 5-150 times stronger than acarbose (IC₅₀ = 169.78 μM). Meanwhile, compounds 4a, 4b, 5a, 5b, 13, and 14 exerted moderate agonistic activities for peroxisome proliferator-activated receptor (PPAR-γ), with EC₅₀ values of 10.09-44.26 μM. Especially,compound 14 also presented inhibitory activity on dipeptidyl peptidase-4 (DPPIV), with an IC₅₀ value of 47.13 μM. Furthermore, the banding manner of compounds 14 and 17 with the active site of α-glucosidase, DPPIV, and PPAR-γ was explored by employing molecular docking analysis.

Phytochemical Study on Seeds of Paeonia clusii subsp. rhodia-Antioxidant and Anti-Tyrosinase Properties

In this study, the black fertile (BSs) and the red unfertile seeds (RSs) of the Greek endemic Paeonia clusii subsp. rhodia (Stearn) Tzanoud were studied for the first time. Nine phenolic derivatives, trans-resveratol, trans-resveratrol-4'-O-β-d-glucopyranoside, trans-ε-viniferin, trans-gnetin H, luteolin, luteolin 3'-O-β-d-glucoside, luteolin 3',4'-di-O-β-d-glucopyranoside, and benzoic acid, along with the monoterpene glycoside paeoniflorin, have been isolated and structurally elucidated. Furthermore, 33 metabolites have been identified from BSs through UHPLC-HRMS, including 6 monoterpene glycosides of the paeoniflorin type with the characteristic cage-like terpenic skeleton found only in plants of the genus Paeonia, 6 gallic acid derivatives, 10 oligostilbene compounds, and 11 flavonoid derivatives. From the RSs, through HS-SPME and GC-MS, 19 metabolites were identified, among which nopinone, myrtanal, and cis-myrtanol have been reported only in peonies' roots and flowers to date. The total phenolic content of both seed extracts (BS and RS) was extremely high (up to 289.97 mg GAE/g) and, moreover, they showed interesting antioxidative activity and anti-tyrosinase properties. The isolated compounds were also biologically evaluated. Especially in the case of trans-gnetin H, the expressed anti-tyrosinase activity was higher than that of kojic acid, which is a well-known whitening agent standard.

Efficient discovery of potent α-glucosidase inhibitors from Paeoniae lactiflora using enzyme-MOF nanocomposites and competitive indicators

A great deal of attention has been paid to the seeds of Paeoniae lactiflora pall., an underutilized food resource, since its extract exhibits excellent α-glucosidase (GAA) inhibitory activity. In the present study, to gain further insight into this plant and find out potent GAA inhibitors, we established a novel ligand fishing strategy by introducing a competitive inhibitor as an indicator. After the successful establishment of this approach was verified by a series of methods, including kinetic assay, fluorescence determination, and HPLC, the newly developed ligand fishing method was applied to acquire potent GAA inhibitors from P. lactiflora seeds. Nine bioactive compounds were captured, and seven of them were identified as suffruticosol A, suffruticosol B, resveratrol, vitisin E, luteolin, trans-δ-viniferin, and ampelopsin E. The data of their GAA inhibitory activity demonstrated that these constituents were vigorously active against GAA with IC₅₀ values of 1.67-30.47 μM, while such value of 1-DNJ was 228.77 μM. Among them, vitisin E and ampelopsin E were reported to show such inhibitory activity for the first time. Collectively, our findings provide valuable clues for the further utilization of P. lactiflora seeds as a functional food, and offer a new avenue for acquiring potent inhibitors from natural resources.

The Influence of Different Extraction Techniques on the Chemical Profile and Biological Properties of Oroxylum indicum: Multifunctional Aspects for Potential Pharmaceutical Applications

Oroxylum indicum (L.) Kurz (Bignoniaceae), a traditional Chinese herbal medicine, possesses various biological activities including antioxidant, anti-inflammatory, antibacterial, and anticancer. In order to guide the practical application of O. indicum in the pharmaceutical, food, and cosmetic industries, we evaluated the effects of five different extraction techniques (maceration extraction (ME), oxhlet extraction (SOXE), ultrasound-assisted extraction (UAE), tissue-smashing extraction (TSE), and accelerated-solvent extraction (ASE)) with 70% ethanol as the solvent on the phytochemical properties and biological potential. The UHPLC-DAD Orbitrap Elite MS technique was applied to characterize the main flavonoids in the extracts. Simultaneously, the antioxidant and enzyme inhibitory activities of the tested extracts were analyzed. SOXE extract showed the highest total phenolic content (TPC, 50.99 ± 1.78 mg GAE/g extract), while ASE extract displayed the highest total flavonoid content (TFC, 34.92 ± 0.38 mg RE/g extract), which displayed significant correlation with antioxidant activity. The extract obtained using UAE was the most potent inhibitor of tyrosinase (IC50: 16.57 ± 0.53 mg·mL-1), while SOXE extract showed the highest activity against α-glucosidase (IC50: 1.23 ± 0.09 mg·mL-1), succeeded by UAE, ME, ASE, and TSE extract. In addition, multivariate analysis suggested that different extraction techniques could significantly affect the phytochemical properties and biological activities of O. indicum. To sum up, O. indicum displayed expected biological potential and the data collected in this study could provide an experimental basis for further investigation in practical applications.

Norlignans as potent GLP-1 secretagogues from the fruits of Amomum villosum

The dried fruit of Amomum villosum (Amomi Fructus) is an important spices and traditional Chinese medicine. In this study, the EtOH extract of Amomi Fructus was revealed with hypoglycemic effects on db/db mice by increasing plasma insulin levels. After extracted with EtOAc, the EtOAc fraction showed increased activity in stimulating glucagon-like peptide-1 (GLP-1) secretion compared with the EtOH extract. In order to clarify the antidiabetic constituents, four undescribed norlignans, amovillosumins A‒D, were isolated from the EtOAc fraction, and the subsequent chiral resolution yielded three pairs of enantiomers. Their structures were determined by extensive spectroscopic data (1D and 2D NMR, HRESIMS, IR, UV and [α]_D) and ECD calculations. Amovillosumins A and B significantly stimulated GLP-1 secretion by 375.1% and 222.7% at 25.0 μM, and 166.9% and 62.7% at 12.5 μM, representing a new type of GLP-1 secretagogues.

The antioxidant activity, α-glucosidase and acetylcholinesterase inhibition activity, and chemical composition of Paeonia delavayi petal

Objectives

This study aimed to evaluate the functional activity and phytochemical compositions in the flower petals of Paeonia delavayi with different colors.

Materials and Methods

P. delavayi petal extracts were prepared by maceration in methanol, including purple petal extract (PPE), red petal extract (RPE) and yellow petal extract (YPE), and their antioxidant activity, α-glucosidase and acetylcholinesterase inhibition activities were evaluated. To correlate these measured activities to phytochemicals in the petals, UPLC-MS/MS-based metabolomics method was applied to profile the compositions in the petals of different colors. Finally, the KEGG metabolic pathways database was used to identify the related metabolic pathways that are responsible for the production of these polyphenolic phytochemicals in the petals.

Results

The results showed that PPE had the highest total phenolic content (TPC), total flavonoid content (TFC), and the strongest ABTS· + scavenging ability, ferric reducing antioxidant power, and acetylcholinesterase inhibition ability in all three samples, while YPE showed the strongest DPPH· scavenging activity and α-glucosidase inhibition ability. A total of 232 metabolites were detected in the metabolomic analysis, 198 of which were flavonoids, chalcones, flavonols, and anthocyanins. Correlation analysis indicated that Peonidin-3-O-arabinoside and cyanidin-3-O-arabinoside were the major contributors to their antioxidant activity. Principal component analysis showed a clear separation between these three petals. In addition, a total of 38, 98, and 96 differential metabolites were identified in PPE, RPE, and YPE, respectively. Pathway enrichment revealed 6 KEGG pathways displayed significant enrichment differences, of which the anthocyanin biosynthesis, flavone and flavonol biosynthesis were the most enriched signaling pathways. It revealed the potential reason for the differences in metabolic and functional levels between different colors of P. delavayi petals.

Conclusions

P. delavayi petals of different colors have different metabolite contents and functional activities, of which the anthocyanin, flavone, and flavonol metabolites are critical in its functional activities, suggesting the anthocyanin biosynthesis, flavone and flavonol biosynthesis pathways be the key pathways responsible for both the petal color and bioactive phytochemicals in P. delavayi flowers.

Synthesis and biological evaluation of (20S,24R)-epoxy-dammarane-3β,12β,25-triol derivatives as α-glucosidase and PTP1B inhibitors

The dammarane triterpenoid (20S,24R)-epoxy-dammarane-3β,12β,25-triol obtained from Cyclocarya paliurus in our previous study showed inhibitory activity on α-glucosidase in vitro with an inhibitory ratio of 32.2% at the concentration of 200 μM. In order to reveal the structure-activity relationships (SARs) and get more active compounds, 42 derivatives of (20S,24R)-epoxy-dammarane-3β,12β,25-triol were synthesized by chemical modification on the hydroxyls (C-3 and C-12), rings A and E, and assayed for their α-glucosidase and PTP1B inhibitory activities. Two compounds (8, 26) increased activity against α-glucosidase, and four compounds (8, 15, 26, 42) significantly inhibited PTP1B. It was noted that compounds 8 and 26 could inhibit both α-glucosidase and PTP1B as dual-target inhibitors with IC₅₀ values of 489.8, 467.7 μM (α-glucosidase) and 319.7, 269.1 μM (PTP1B). Compound 26 was revealed to be a mix-type inhibitor on α-glucosidase and a noncompetitive-type inhibitor on PTP1B based on enzyme kinetic study. Furthermore, compound 42 could selectively inhibited PTP1B as a mix-type inhibitor with IC₅₀ value of 134.9 μM, which was 2.5-fold higher than the positive control, suramin sodium (IC₅₀ 339.0 μM), but not inhibit α-glucosidase.

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.

Six New 3,5-Dimethylcoumarins from Chelonopsis praecox, Chelonopsis odontochila and Chelonopsis pseudobracteata

Ten 3,5-dimethylcoumarins (1-6 and 8‒11) involving six new ones (1-6), together with a known 3-methylcoumarin (7), were isolated from the aerial parts of three Chelonopsis plants, C. praecox, C. odontochila, and C. pseudobracteata. The structures of the new compounds were determined by extensive HRESIMS, 1D and 2D NMR spectroscopic analyses. According to the substitution at C-5, these coumarins were classified into 5-methyl, 5-hydroxymethyl, 5-formyl, and 5-nor types. All the isolates were assayed for their inhibition on α-glucosidase, protein tyrosine phosphatase 1B, and T-cell protein tyrosine phosphatase in vitro.

Bioactive-guided isolation and identification of oligostilbenes as anti-rheumatoid arthritis constituents from the roots of Caragana stenophylla

ETHNOPHARMACOLOGICAL RELEVANCE

The roots of Caragana stenophylla have been used as folk medicine due to the functions of activating blood, diuresis, analgesic and tonicity, especially in treating rheumatoid arthritis and hypertension. However, the anti-rheumatoid arthritis mechanisms and bioactive ingredients have not previously been fully investigated.

AIM OF THE STUDY

The aim of this study was to assess the anti-rheumatoid arthritis effects of the roots of Caragana stenophylla ethanol extract (EC), elucidate its mechanism of action and identify its active substances.

MATERIALS AND METHODS

Anti-rheumatoid arthritis activity of EC was assessed using type II-collagen induced arthritis in rats. Arthritis severity was evaluated by foot paw volume, arthritis index, joint swelling degree and histopathology. The serum inflammatory cytokines and matrix metalloproteinases (MMPs) were also detected by immunohistochemical analysis. In addition, the protein expression of IκB, p-IκB, iNOS and COX-2 was analyzed by western blot. RAW 264.7 macrophage cells were employed to assess the anti-inflammatory effects of fractions and compounds in vitro. UPLC-Q-TOF-MS was adopted to appraise the ingredients of the active fraction of the roots of C. stenophylla. Furthermore, various chromatographic techniques and spectroscopic methods were used for isolation and structure elucidation of compounds.

RESULTS

The results showed that EC could reduce type II collagen-induced rheumatoid arthritis model arthritic score and histopathology markedly at dose of 240 mg/kg. Besides, EC could suppress the levels of pro-inflammatory cytokines (IL-1β, IL-6, IL-8, IL-17, and TNF-α) and matrix metalloproteinases (MMP-3, MMP-9), and the expression levels of COX-2, p-IκB and iNOS also were declined. While, the levels of IL-10 and IκB were increased. The ethyl acetate fraction exhibited potent inhibitory effects against nitric oxide production in RAW 264.7 macrophage cells. Eleven main components including 1 flavonoid and 10 oligostilbenes from active fraction were isolated by mass directed chromatographic techniques. Their structures were determined on the basis of various spectroscopic methods and by comparison with the published NMR data.

CONCLUSION

The roots of C. stenophylla attenuated arthritis severity, restored serum cytokine imbalances by regulating NF-κB signaling pathway in type II collagen-induced rheumatoid arthritis model. Oligostilbenes were essential ingredients in ethyl acetate extract of C. stenophylla roots. Stilbenes and flavonoids should be responsible for its anti-rheumatoid arthritis activities.

Antidiabetic Activity of Ficusonolide, a Triterpene Lactone from Ficus foveolata (Wall. ex Miq.): In Vitro, In Vivo, and In Silico Approaches

Diabetes is a chronic condition which is locally managed through the stem of Ficus foveolata. To find the exact chemical constituent responsible for this activity, a triterpene lactone (ficusonolide) isolated from F. foveolata was studied for antidiabetic potential through the in vitro antidiabetic paradigm employing L-6 cells and an in vivo antidiabetic assay against non-insulin-dependent rats. The results on glucose uptake in the L-6 cell line indicated that ficusonolide has enhanced the uptake of glucose by 53.27% over control at a dose of 100 μg/mL, while at doses of 50 and 25 μg/mL, the glucose uptake was enhanced by 22.42 and 14.34%, respectively. The extract of F. foveolata (100 mg/kg) and ficusonolide (50 mg/kg) demonstrated a significant (p < 0.001) decline in streptozotocin-induced hyperglycemia of diabetic rats. Ficusonolide displayed conspicuous inhibitory activity against the molecular docking studies with proteins such as dipeptidyl peptidase-IV (DPP-IV), protein tyrosine phosphatase 1B (PTP-1B), α-glucosidase, and α-amylase subjected to molecular targets. Detailed computational and structural insights affirmed promising interactions between target proteins and ficusonolide. In conclusion, the plant and its isolated compound have significant antidiabetic activity with a possible mechanism of interaction with DPP-IV, PTP-1B, α-glucosidase, and α-amylase.

Comprehensive metabolite profile of multi-bioactive extract from tree peony (Paeonia ostii and Paeonia rockii) fruits based on MS/MS molecular networking

Tree peony seed, traditionally used for edible oil production, is rich in α-linolenic acid. However, little attention is given to the fruit by-products during seed oil production. The present work aimed to comprehensively investigate the phytochemical constituents and multiple biological activities of different parts of tree peony fruits harvested from Paeonia ostii and Paeonia rockii. 130 metabolites were rapidly identified through UPLC-Triple-TOF-MS on the basis of MS/MS molecular networking. Metabolite quantification was performed through the targeted approach of HPLC-ESI-QQQ-MS. Eight chemical markers were screened via principal component analysis (PCA) for distinguishing species and tissues. Interestingly, two dominant compounds, paeoniflorin and trans-resveratrol, are specially localized in seed kernel and seed coat, respectively. Unexpectedly, the extracts of fruit pod and seed coat showed significantly stronger antioxidant, antibacterial, and anti-neuroinflammatory activities than seed kernel from both P. ostii and P. rockii. Our work demonstrated that tree peony fruit is promising natural source of bioactive components and provided its potential utilization in food and pharmaceutical industries.

Natural α-Glucosidase and Protein Tyrosine Phosphatase 1B Inhibitors: A Source of Scaffold Molecules for Synthesis of New Multitarget Antidiabetic Drugs

Diabetes mellitus (DM) represents a group of metabolic disorders that leads to acute and long-term serious complications and is considered a worldwide sanitary emergence. Type 2 diabetes (T2D) represents about 90% of all cases of diabetes, and even if several drugs are actually available for its treatment, in the long term, they show limited effectiveness. Most traditional drugs are designed to act on a specific biological target, but the complexity of the current pathologies has demonstrated that molecules hitting more than one target may be safer and more effective. The purpose of this review is to shed light on the natural compounds known as α-glucosidase and Protein Tyrosine Phosphatase 1B (PTP1B) dual-inhibitors that could be used as lead compounds to generate new multitarget antidiabetic drugs for treatment of T2D.

Screening and tissue distribution of protein tyrosine phosphatase 1B inhibitors in mice following oral administration of Garcinia mangostana L. ethanolic extract

Garcinia mangostana L. (mangosteen) is a tropical fruit that is rich in xanthones and is thought to have an anti-diabetic effect. In this study, we screened for the xanthones in mangosteen that could inhibit the activity of protein tyrosine phosphatase 1B (PTP1B), an enzyme that is targeted by diabetic drugs. Mice were orally administered mangosteen extract and blood samples were screened for the presence of PTP1B-interacting xanthones. Six such compounds (1-6) were identified by UF-HPLC-QTOF-MS and their inhibition against PTP1B was confirmed by activity assay. Among them, garcinone E (5) was found to be the most effective PTP1B inhibitor (IC50 = 0.43 μM). Tissue distribution analysis showed that the six compounds were distributed in eleven tissues, including the liver, muscle, fat, stomach, large intestine, small intestine, brain, kidney, heart, lung, and spleen. The results demonstrated that mangosteen might be a promising source of natural compounds with high PTP1B-inhibitory activity.

Chemical profiling and antidiabetic potency of Paeonia delavayi: Comparison between different parts and constituents

Paeonia delavayi (Paeoniaceae), an endemic plant mainly distributed in southwest China, is always used as the substitute of P. suffruticosa due to their morphological and pharmacological similarity. In the previous study, P. suffruticosa was revealed with antidiabetic potency, whereas the chemical difference and antidiabetic property between different parts of P. delavayi has not yet been studied. This paper was designed to clarify the chemical constituents and antidiabetic potency of P. delavayi by LCMS analysis and enzyme inhibition on α-glucosidase, PTP1B, TCPTP, and DPP4. By interpretation of their UV absorptions and MS fragmentations, and/or comparison with reference samples, 57 constituents comprising 15 flavonoids, 10 monoterpene glycosides, eight triterpenoids, seven galloyl glucoses, six N-containing compounds, five gallic acids, two acetophenones, and four other types of compounds were identified from the different parts of P. delavayi. Moreover, two new monoterpene aglycones (42 and 47) and one new noroleanane triterpenoid (51) were speculated by their MS/MS fragmentation rules. Principal component analysis (PCA) suggested the chemical resemblance between root core and root bark which could be well differentiated with the leaves and stems by their characteristic constituents (monoterpene glycosides, flavonoids, and acetophenones). All the four parts (200 μg/mL) showed obvious inhibition on α-glucosidase and PTP1B (81.2%-98.5%), but moderate to weak inhibition on TCPTP and DPP4 (19.5%-34.9%). Nine compounds representing five main types of constituents in Paeonia plants were assayed for their antidiabetic effects, indicating flavonoids and triterpenoids were the main active substances regarding to the four enzymes. Luteolin displayed obvious activity on α-glucosidase, PTP1B, and TCPTP with IC₅₀ values of 94.6, 136.3, and 157.3 μM, and akebonic acid could inhibit α-glucosidase and PTP1B with IC₅₀ values of 73.5 and 57.8 μM. Luteolin and akebonic acid were recognized as competitive inhibitors of α-glucosidase, but anticompetitive and mix-type inhibitors of PTP1B, respectively. Docking study demonstrated akebonic acid as PTP1B (over TCPTP) selective inhibitor by bonding to the catalytic sites (B/C) of PTP1B. This LCMS combined with enzymatic comparison opens new sights for recognizing the chemical profiles and antidiabetic potency of P. delavayi.

Diarylheptanoid-chalcone hybrids with PTP1B and α-glucosidase dual inhibition from Alpinia katsumadai

The EtOH extracts of the dried seeds of Alpinia katsumadai were revealed with hypoglycemic effects on db/db mice at the concentration of 200 mg/kg. In order to clarify the antidiabetic constituents, 16 new diarylheptanoid-chalcone hybrids, katsumadainols A₁-A₁₆ (1-16), together with 13 known analogues (17-29), were isolated from A. katsumadai under the guidance of bioassay. Most of the compounds showed α-glucosidase and PTP1B dual inhibition, among which compounds 1-3, 5-7, 11-14, 21-25, and 27 showed PTP1B/TCPTP selective inhibition with IC₅₀ values ranging from 22.0 to 96.7 μM, which were 2-10 times more active than sodium orthovanadate (IC₅₀, 215.7 μM). All compounds exhibited obvious inhibition against α-glucosidase with IC₅₀ values of 2.9-29.5 μM, indicating 6-59 times more active than acarbose (IC₅₀, 170.9 μM). Study of enzyme kinetics indicated compounds 1, 3, and 12 were PTP1B and α-glucosidase mixed-type inhibitors with K_i values of 13.1, 12.9, 21.6 μM, and 4.9, 7.4, 3.4 μM, respectively.

Bioactive components, antioxidant and antimicrobial activities of Paeonia rockii fruit during development

In last ten years, much attention focused on tree peony fruit (TPF) for edible oil production despite other potential utilization. The present study identified and quantified 29 bioactive components by liquid chromatography-electrospray ionization-triple quadrupole-mass spectrometry (LC-ESI-QqQ-MS) targeted approach during the development of TPF. Trans-resveratrol, benzoic acid, luteolin, and methyl gallate were selected as predominant chemical markers between seeds and pods through principal component analysis (PCA) and orthogonal partial least square-discriminant analysis (OPLS-DA). Extremely high levels of paeoniflorin (1893 mg/100 g) and trans-resveratrol (1793 mg/100 g) were observed at stage 2 (S2) and S6 in seeds, respectively. Antioxidant activities determined by ABTS^+•, DPPH^•, and FRAP assays showed significant correlations with total phenolic content (TPC) and total flavonoid content (TFC). The strongest antibacterial effects of pod and seed against Staphylococcus aureus and Proteus vulgaris occurred at initial stages and maturation stages. TPF could be a potential source of bioactive compounds with functional properties.

Nineteen New Flavanol-Fatty Alcohol Hybrids with α-Glucosidase and PTP1B Dual Inhibition: One Unusual Type of Antidiabetic Constituent from Amomum tsao-ko

The dried fruits of Amomum tsao-ko were first revealed to have hypoglycemic effects on db/db mice at a concentration of 200 mg/kg. In order to clarify the antidiabetic constituents, 19 new flavanol-fatty alcohol hybrids, tsaokoflavanols A-S (1-19), were isolated and determined by extensive spectroscopic data and ECD calculations. Most of the compounds showed α-glucosidase and PTP1B dual inhibition, among which 1, 2, 6, 11, and 18 exhibited obvious activity against α-glucosidase with IC₅₀ values of 5.2-9.0 μM, 20-35 times stronger than that of acarbose (IC₅₀, 180.0 μM); meanwhile, 6, 10-12, and 19 were PTP1B/TCPTP-selective inhibitors with IC₅₀ values of 56.4-80.4 μM, 2-4 times stronger than that of suramin sodium (IC₅₀, 200.5 μM). Enzyme kinetics study indicated that compounds 1, 2, 6, and 11 were α-glucosidase and PTP1B mixed-type inhibitors with K_i values of 13.0, 11.7, 2.9, and 5.3 μM and 142.3, 88.9, 39.2, and 40.8 μM, respectively. Docking simulations proved the importance of hemiacetal hydroxy, the orientation of 3,4-dihydroxyphenyl, and the length of alkyl in binding with α-glucosidase and PTP1B.

Amomutsaokols A-K, diarylheptanoids from Amomum tsao-ko and their α-glucosidase inhibitory activity

Eleven undescribed diarylheptanoids, amomutsaokols A‒K (1-11), together with 13 known ones (13-24), were isolated from the active fraction of the fruits of Amomum tsao-ko. The structures of the undescribed compounds were determined by extensive 1D and 2D NMR, HRESIMS and ECD calculations. Compounds 3-5, 7, 8, 12, 14 and 19 showed obviously α-glucosidase inhibitory activity with IC₅₀ values ranging from 12.9 to 48.8 μM. An enzyme kinetic analysis indicated that compounds 8 and 9 were α-glucosidase noncompetitive inhibitors with K_i values of 18.5 and 213.0 μM, respectively. This study supported diarylheptanoids as the active constituents of A. tsao-ko with α-glucosidase inhibitory effects.

Aldose reductase and protein tyrosine phosphatase 1B inhibitors as a promising therapeutic approach for diabetes mellitus

Diabetes mellitus is a metabolic disease characterized by high blood glucose levels and usually associated with several chronic pathologies. Aldose reductase and protein tyrosine phosphatase 1B enzymes have identified as two novel molecular targets associated with the onset and progression of type II diabetes and related comorbidities. Although many inhibitors against these enzymes have already found in the field of diabetic mellitus, the research for discovering more effective and selective agents with optimal pharmacokinetic properties continues. In addition, dual inhibition of these target proteins has proved as a promising therapeutic approach. A variety of diverse scaffolds are presented in this review for the future design of potent and selective inhibitors of aldose reductase and protein tyrosine phosphatase 1B based on the most important structural features of both enzymes. The discovery of novel dual aldose reductase and protein tyrosine phosphatase 1B inhibitors could be effective therapeutic molecules for the treatment of insulin-resistant type II diabetes mellitus. The methods used comprise a literature survey and X-ray crystal structures derived from Protein Databank (PDB). Despite the available therapeutic options for type II diabetes mellitus, the inhibitors of aldose reductase and protein tyrosine phosphatase 1B could be two promising approaches for the effective treatment of hyperglycemia and diabetes-associated pathologies. Due to the poor pharmacokinetic profile and low in vivo efficacy of existing inhibitors of both targets, the research turned to more selective and cell-permeable agents as well as multi-target molecules.

Lactam ent-Kaurane Diterpene: A New Class of Diterpenoids Present in Roasted Beans of Coffea arabica

Seven new lactam ent-kaurane diterpenoids, cafemides A-G (1-7), were isolated from roasted beans of Coffea arabica. Their structures were elucidated by extensive spectroscopic analysis including 1D, 2D NMR (heteronuclear single quantum correlation (HSQC), heteronuclear multiple bond correlation (HMBC), ¹H-¹H correlation spectroscopy (COSY), and rotating frame Overhauser effect spectroscopy (ROESY)), high-resolution electrospray ionization mass spectrometry (HRESIMS), and IR spectra. They were divided into subtype I-III according to the structure. Further, with the aid of liquid chromatography-tandem mass spectrometry (LC-MS/MS) based molecular network, seven (8-14) subtype II diterpenoids were successfully identified. In addition, a variety of other subtypes of N-containing diterpenoids have been proven in roasted coffee. Compounds 1, 2, 3, 5, and 7 showed a moderate inhibitory effect on α-glucosidase with an IC₅₀ value of 8.28 ± 0.62 μM, 38.23 ± 8.87 μM, 28.94 ± 1.42 μM, 12.44 ± 1.37 μM, and 22.2 ± 5.34 μM, respectively. To the best of our knowledge, this is the first time that N-containing diterpenoids have been reported in coffee.

Preparative Isolation of Piceatannol Derivatives from Passion Fruit (Passiflora edulis) Seeds by High-Speed Countercurrent Chromatography Combined with High-Performance Liquid Chromatography and Screening for α-Glucosidase Inhibitory Activities

Passiflora edulis Sims (passion fruit) seeds are often discarded as byproducts during juice processing. In fact, the seeds are of considerable commercial value in the food and cosmetics industry because of their rich polyphenols, especially piceatannol. In this study, high-speed countercurrent chromatography (HSCCC) was applied for the separation of stilbene polyphenols from passion fruit seeds. The n-hexane-ethyl acetate-methanol-water (1:2:1:2.8, v/v) was found to be the optimum two-phase solvent for the preparation of two major stilbenes, scirpusin B (8) and piceatannol (9) with purities of 90.2% and 94.8%, respectively. In addition, a continuous semipreparative HPLC was applied to further purify the HSCCC fractions containing minor stilbenes and obtain four new piceatannol derivatives (1-4) along with three known ones (5-7). The structures of these new compounds were determined using spectroscopic methods, including NMR, high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), and circular dichroism (CD). The isolated compounds were evaluated for α-glucosidase inhibitory activities in vitro. The result suggested that all of them exhibited more significant activity than acarbose, and passiflorinol B (2) had the strongest activity, with a IC₅₀ value of 1.7 μM.