In vitro and in vivo evaluation of the antidiabetic activity of ursolic acid derivatives

Recent progress in the development of ursolic acid derivatives as anti-diabetes and anti-cardiovascular agents

Ursolic acid (UA) is a pentacyclic triterpenoid, which exhibits many biological activities, particularly in anti-cardiovascular and anti-diabetes. The further application of UA is greatly limited due to its low bioavailability and poor water solubility. Up to date, various UA derivatives have been designed to overcome these shortcomings. In this paper, the authors reviewed the development of UA derivatives as the anti-diabetes anti-cardiovascular reagents.

Synthesis of novel coumarin-based thiosemicarbazones and their implications in diabetic management via in-vitro and in-silico approaches

Diabetes mellitus has a high prevalence rate and it has been deemed a severe chronic metabolic disorder with long-term complications. This research aimed to identify compounds that could potentially inhibit the vital metabolic enzyme α-glucosidase and thereby exert an anti-hyperglycemic effect. The main goal was to establish an effective approach to control diabetes. To proceed with this study, a series of novel coumarin-derived thiosemicarbazones 3a-3m was synthesized and examined using a variety of spectroscopic methods. Moreover, all the compounds were subjected to α-glucosidase inhibition bioassay to evaluate their antidiabetic potential. Fortunately, all the compounds exhibited several folds potent α-glucosidase inhibitory activities with IC50 values ranging from 2.33 to 22.11 µM, in comparison to the standard drug acarbose (IC50 = 873.34 ± 1.67 µM). The kinetic studies of compound 3c displayed concentration-dependent inhibition. Furthermore, the binding modes of these molecules were elucidated through a molecular docking strategy which depicted that the thiosemicarbazide moiety of these molecules plays a significant role in the interaction with different residues of the α-glucosidase enzyme. However, their conformational difference is responsible for their varied inhibitory potential. The molecular dynamics simulations suggested that the top-ranked compounds (3c, 3g and 3i) have a substantial effect on the protein dynamics which alter the protein function and have stable attachment in the protein active pocket. The findings suggest that these molecules have the potential to be investigated further as novel antidiabetic medications.

Lavandula stoechas L. subsp. stoechas, a New Herbal Source for Ursolic Acid: Quantitative Analysis, Purification and Bioactivity Studies

In this study, methanol, ethanol, methanol-dichloromethane (1 : 1, v/v), acetone, ethyl acetate, diethyl ether, and chloroform extracts of lavender (Lavandula stoechas L. subsp. stoechas) were prepared by maceration, and the ursolic acid contents in the extracts were determined quantitatively by HPLC analyses. The present results show that the methanol-dichloromethane (1 : 1, v/v) solvent system is the most efficient solvent system for the extraction of ursolic acid from the plant sample with the highest yield (2.22 g/100 g plant sample). In the present study, a new practical method for the isolation of ursolic acid from polar extracts was also demonstrated for the first time. The inhibition effects of the extracts and ursolic acid were also revealed on α-glycosidase, acetylcholinesterase, butyrylcholinesterase, and human carbonic anhydrase I and II enzymes by determining IC50 values for the first time. The extracts and ursolic acid acted as potent antidiabetic agents by strongly inhibiting the α-glycosidase activity, whereas they were found to be very weak neuroprotective agents. In view of the present results, L. stoechas and its major metabolite, ursolic acid, can be recommended as a herbal source to control postprandial blood sugar levels and prevent diabetes by delaying the digestion of starch in food.

Semisynthesis, in silico study and in vitro antibacterial evaluation of fucosterol derivatives

Thirteen fucosterol derivatives were prepared by structural modification at the hydroxyl group in C-3 and catalytic hydrogenation at the carbon-carbon double bond in C-5(6) and C-24(28). The structures of all compounds were established based on their spectral data (IR, MS, and NMR). Fucosterol (1) and its derivatives (2-12, and a mixture of 13a and 13b) were evaluated for their in vitro antibacterial activity against Klebsiella pneumoniae (ATCC 10031), Escherichia coli (ATCC 10536), Pseudomonas aeruginosa (ATCC 15442), Streptococcus mutans (ATCC 0046) and Staphylococcus aureus using the microdilution method. Among them, 1, 8, 9, 10, and a mixture of 13a and 13b exhibited the best antibacterial activity. The derivative 7 was inactive against all bacterial strains evaluated (MIC ≥ 2.327 mM). In addition, the investigation of binding interactions of more active compounds (1, 8, 9, 10, and mixture of 13a and 13b) to appropriate proteins was performed using molecular docking. This paper registers for the first time the in silico studies on the antibacterial activity of compounds 1, 8, 9, 10, and mixture of 13a/13b, and the spectral data of compounds 4, 6, and 7.

Inhibitory Effects of Ursolic Acid on the Stemness and Progression of Human Breast Cancer Cells by Modulating Argonaute-2

The stemness and metastasis of cancer cells are crucial features in determining cancer progression. Argonaute-2 (AGO2) overexpression was reported to be associated with microRNA (miRNA) biogenesis, supporting the self-renewal and differentiation characteristics of cancer stem cells (CSCs). Ursolic acid (UA), a triterpene compound, has multiple biological functions, including anticancer activity. In this study, we find that UA inhibits the proliferation of MDA-MB-231 and MCF-7 breast cancer cell lines using the CCK-8 assay. UA induced a significant decrease in the fraction of CSC in which it was examined by changes in the expression of stemness biomarkers, including the Nanog and Oct4 genes. UA altered invasion and migration capacities by significant decreases in the levels of epithelial-to-mesenchymal transition (EMT) proteins of slug and vimentin. Furthermore, the co-reduction in oncogenic miRNA levels (miR-9 and miR-221) was a result of the down-modulation in AGO2 in breast cancer cells in vitro. Mechanically, UA increases PTEN expression to inactivate the FAK/PI3K/Akt/mTOR signaling pathway and the decreased level of c-Myc in quantitative RT-PCR and Western blot imaging analyses. Our current understanding of the anticancer potential of UA in interrupting between EMT programming and the state of CSC suggests that UA can contribute to improvements in the clinical practice of breast cancer.

Synthesis and Biological Evaluation of 5-Fluoro-2-Oxindole Derivatives as Potential α-Glucosidase Inhibitors

α-Glucosidase inhibitors are known to prevent the digestion of carbohydrates and reduce the impact of carbohydrates on blood glucose. To develop novel α-glucosidase inhibitors, a series of 5-fluoro-2-oxindole derivatives (3a ∼ 3v) were synthesized, and their α-glucosidase inhibitory activities were investigated. Biological assessment results showed that most synthesized compounds presented potential inhibition on α-glucosidase. Among them, compounds 3d, 3f, and 3i exhibited much better inhibitory activity with IC50 values of 49.89 ± 1.16 μM, 35.83 ± 0.98 μM, and 56.87 ± 0.42 μM, respectively, which were about 10 ∼ 15 folds higher than acarbose (IC50 = 569.43 ± 43.72 μM). A kinetic mechanism study revealed that compounds 3d, 3f, and 3i inhibited the α-glucosidase in a reversible and mixed manner. Molecular docking was carried out to simulate the affinity between the compound and α-glucosidase.

Evaluation of the biological activities of β-glucan isolated from Lentinula edodes

Lentinula edodes (shiitake) is an edible mushroom that contains many constituents and β-glucan is considered a major polysaccharide. This study, therefore, aimed to characterize β-glucan and evaluate its activities. Fresh fruit bodies of L. edodes were used for β-glucan extraction and followed by analyses via Fourier transform infrared, Nuclear magnetic resonance, and High Performance Liquid Chromatography confirming its characteristic structure. For evaluating biological activities of β-glucan, different concentrations (0.1-3.5 mg ml^-1 ) were assessed. The optimal dose was 3.5 mg ml^-1 that showed the highest scavenging radical ability (75.3%) confirms antioxidant activity, strong inhibition of the peroxyl radical (80.9%) to inhibit lipid peroxidation, elevation the inhibition percentage of both α-amylase (73.4%) and α-glucosidase (70.3%) indicates the antidiabetic properties, and highest AFB1 reduction (88%) which ensured the aflatoxin-detoxifying ability. In addition, antifungal activity of β-glucan was evaluated to inhibit sporulation process in Aspergillus niger and recorded with minimum inhibitory concentration of 2.5 mg ml^-1 and minimum fungicidal concentration of 3 mg ml^-1 . In a dose-dependent manner, higher concentration of β-glucan affects viability of tumor cells concomitant induces potent anti-cancer immune responses and inhibited the activity of topoisomerase I which are considered an important target for cancer chemotherapy. Therefore, L. edodes-β-glucan has the potential to act as a suggestive agent for antioxidant, antidiabetic, antifungal activity, and aflatoxin detoxification.

Aspulvinones Suppress Postprandial Hyperglycemia as Potent α-Glucosidase Inhibitors From Aspergillus terreus ASM-1

Chemical investigation of Aspergillus terreus ASM-1 fermentation resulted in the isolation of three new prenylated aspulvinones V–X (1–3), together with the previously reported analogs, aspulvinone H (4), J-CR (5), and R (6). Their structures were elucidated by various spectroscopic methods including HRESIMS and NMR, and the absolute configurations of 2 and 3 were determined by ECD comparison. Compounds 1–6 were evaluated for α-glucosidase inhibitory effects with acarbose as positive control. As a result, compounds 1 and 4 exhibited potent α-glucosidase inhibitory activities with IC₅₀ values of 2.2 and 4.6 µM in mixed-type manners. The thermodynamic constants recognized the interaction between inhibitors and α-glucosidase was hydrophobic force-driven spontaneous exothermic reaction. The CD spectra also indicate that the compounds 1 and 4 changed the enzyme conformation. Furthermore, compound 4 significantly suppressed the increases in postprandial blood glucose levels in the C57BL/6J mice.

Anti-MRSA Constituents from Ruta chalepensis (Rutaceae) Grown in Iraq, and In Silico Studies on Two of Most Active Compounds, Chalepensin and 6-Hydroxy-rutin 3',7-Dimethyl ether

Ruta chalepensis L. (Rutaceae), a perennial herb with wild and cultivated habitats, is well known for its traditional uses as an anti-inflammatory, analgesic, antipyretic agent, and in the treatment of rheumatism, nerve diseases, neuralgia, dropsy, convulsions and mental disorders. The antimicrobial activities of the crude extracts from the fruits, leaves, stem and roots of R. chalepensis were initially evaluated against two Gram-positive and two Gram-negative bacterial strains and a strain of the fungus Candida albicans. Phytochemical investigation afforded 19 compounds, including alkaloids, coumarins, flavonoid glycosides, a cinnamic acid derivative and a long-chain alkane. These compounds were tested against a panel of methicillin-resistant Staphylococcus aureus (MRSA) strains, i.e., ATCC 25923, SA-1199B, XU212, MRSA-274819 and EMRSA-15. The MIC values of the active compounds, chalepin (9), chalepensin (10), rutamarin (11), rutin 3′-methyl ether (14), rutin 7,4′-dimethyl ether (15), 6-hydroxy-rutin 3′,7-dimethyl ether (16) and arborinine (18) were in the range of 32–128 µg/mL against the tested MRSA strains. Compounds 10 and 16 were the most active compounds from R. chalepensis, and were active against four out of six tested MRSA strains, and in silico studies were performed on these compounds. The anti-MRSA activity of compound 16 was comparable to that of the positive control norfloxacin (MICs 32 vs 16 μg/mL, respectively) against the MRSA strain XU212, which is a Kuwaiti hospital isolate that possesses the TetK tetracycline efflux pump. This is the first report on the anti-MRSA property of compounds isolated from R. chalepensis and relevant in silico studies on the most active compounds.

Synthesis and biological evaluation of pentacyclic triterpenoid derivatives as potential novel antibacterial agents

A series of ursolic acid (UA), oleanolic acid (OA) and 18β-glycyrrhetinic acid (GA) derivatives were synthesized by introducing a range of substituted aromatic side-chains at the C-2 position after the hydroxyl group at C-3 position was oxidized. Their antibacterial activities were evaluated in vitro against a panel of four Staphylococcus spp. The results revealed that the introduction of aromatic side-chains at the C-2 position of GA led to the discovery of potent triterpenoid derivatives for inhibition of both drug sensitive and resistant S. aureus, while the other two series derivatives of UA and OA showed no significant antibacterial activity even at high concentrations. In particular, GA derivative 33 showed good potency against all four Staphylococcus spp. (MIC = 1.25-5 μmol/L) with acceptable pharmacokinetics properties and low cytotoxicity in vitro. Molecular docking was also performed using S. aureus DNA gyrase to rationalize the observed antibacterial activity. This series of GA derivatives has strong potential for the development of a new type of triterpenoid antibacterial agent.

Potential Application of Some Lamiaceae Species in the Management of Diabetes

Diabetes is one of the most dangerous metabolic disorders, with high rates of mortality worldwide. Since ancient times, medicinal plants have been used in traditional medicine to treat many diseases, including diabetes and its related complications. Plants are widely accepted, affordable, and perceived to have minimal adverse side effects. The Lamiaceae family is a potential source of therapeutic agents for the management of metabolic disorders, including diabetes. Hence, this review paper summarizes the antidiabetic use of Lamiaceae species in folk medicine globally. Furthermore, we present the antidiabetic activities and phytochemical constituents of twenty-three (23) Lamiaceae species and the antidiabetic activity of some notable chemical constituents isolated from some of these Lamiaceae species.

Modulatory effect of ursolic acid on neurodegenerative activities in oxidative brain injury: An ex vivo study

Natural products-based antioxidants have been well reported for their therapeutic benefits in the treatment and management of neurodegenerative diseases. The neuroprotective effect of ursolic acid (UA) against oxidative injury was investigated in isolated rat brain. Induction of oxidative injury in isolated rat brains with 0.1 mM FeSO4 led to depleted levels of glutathione, superoxide dismutase, catalase, and ENTPDase activities, with concomitant exacerbation of malondialdehyde and nitric oxide levels, α-chymotrypsin, ATPase, and acetylcholinesterase activities. These levels and activities were significantly reversed following treatment of the brain tissues with UA. Molecular docking studies revealed strong molecular interactions between UA, catalase, and ATPase. Overall, these results indicate the neuroprotective effect of UA against oxidative injury in isolated rat brains as depicted by their ability to mitigate oxidative stress, purinergic, and cholinergic dysfunctions, with concomitant suppression of proteolytic activity. PRACTICAL APPLICATIONS: Neurodegenerative diseases are among the common diseases associated with aging and has been implicated as oxidative mediated. Natural products have received increasing recognition in their use as treatment remedy for various oxidative-mediated diseases including neurodegeneration. These natural products include plant secondary metabolites commonly known as phytochemicals. Ursolic acid is a phytochemical usually present in leafy vegetables and fruits. The present study describes the possible therapeutic mechanism of ursolic acid in the amelioration of complications linked to neurodegeneration in oxidative-mediated brain injury. These findings thus give insights into the use of natural products of plant origin in treating and managing neurodegenerative diseases, which may have little or no side effects.

Design, synthesis and α-glucosidase inhibition study of novel embelin derivatives

Embelin is a naturally occurring para-benzoquinone isolated from Embelia ribes (Burm. f.) of the Myrsinaceae family. It was first discovered to have potent inhibitory activity (IC50 = 4.2 μM) against α-glucosidase in this study. Then, four series of novel embelin derivatives were designed, prepared and evaluated in α-glucosidase inhibition assays. The results show that most of the embelin derivatives synthesised are effective α-glucosidase inhibitors, with IC50 values at the micromolar level, especially 10d, 12d, and 15d, the IC50 values of which are 1.8, 3.3, and 3.6 μM, respectively. Structure-activity relationship (SAR) studies suggest that hydroxyl groups in the 2/5-position of para-benzoquinone are very important, and long-chain substituents in the 3-position are highly preferred. Moreover, the inhibition mechanism and kinetics studies reveal that all of 10d, 12d, 15d, and embelin are reversible and mixed-type inhibitors. Furthermore, docking experiments were carried out to study the interactions between 10d and 15d with α-glucosidase.

Ursolic Acid-Based Derivatives as Potential Anti-Cancer Agents: An Update

Ursolic acid is a pharmacologically active pentacyclic triterpenoid derived from medicinal plants, fruit, and vegetables. The pharmacological activities of ursolic acid have been extensively studied over the past few years and various reports have revealed that ursolic acid has multiple biological activities, which include anti-inflammatory, antioxidant, anti-cancer, etc. In terms of cancer treatment, ursolic acid interacts with a number of molecular targets that play an essential role in many cell signaling pathways. It suppresses transformation, inhibits proliferation, and induces apoptosis of tumor cells. Although ursolic acid has many benefits, its therapeutic applications in clinical medicine are limited by its poor bioavailability and absorption. To overcome such disadvantages, researchers around the globe have designed and developed synthetic ursolic acid derivatives with enhanced therapeutic effects by structurally modifying the parent skeleton of ursolic acid. These structurally modified compounds display enhanced therapeutic effects when compared to ursolic acid. This present review summarizes various synthesized derivatives of ursolic acid with anti-cancer activity which were reported from 2015 to date.

Synthesis and biological evaluation of ursolic acid derivatives bearing triazole moieties as potential anti-Toxoplasma gondii agents

Ursolic acid (UA), a plant-derived compound, has many properties beneficial to health. In the present study, we synthesised three series of novel UA derivatives and evaluated their anti-Toxoplasma gondii activity both in vitro and in vivo. Most derivatives exhibited an improved anti-T. gondii activity in vitro when compared with UA (parent compound), whereas compound 3d exhibited the most potent anti-T. gondii activity in vivo. Spiramycin served as the positive control. Additionally, determination of biochemical parameters, including the liver and spleen indexes, indicated compound 3d to effectively reduce hepatotoxicity and significantly enhance anti-oxidative effects, as compared with UA. Furthermore, our molecular docking study indicated compound 3d to possess a strong binding affinity for T. gondii calcium-dependent protein kinase 1 (TgCDPK1). Based on these findings, we conclude that compound 3d, a derivative of UA, could act as a potential inhibitor of TgCDPK1.

Effects of fermentation on structural characteristics and in vitro physiological activities of barley β-glucan

The effects of fermentation by Lactobacillus plantarum dy-1 on the main structural changes of barley β-glucan and their in vitro activities were studied. Molecular characteristics, infrared spectroscopy, monosaccharide composition, methylation, 1D and 2D-NMR analyses and scanning electron microscopy revealed that both (raw barley β-glucan) RBG and fermented barley β-glucan (FBG) are polysaccharides predominanted by β-(1→3) and β-(1→4) linked glucose. However, different molecular weight (decreasing from 1.13×10⁵ D to 6.35×10⁴ D), the ratio of the β-(1→3) residues to the β-(1→4) residues (ranging from 1:1.98-1:2.50 to 1:1.8-1:2.24) and microstructure features (transforming from a rod-like to sheet-like structure) were observed. Bioassay results showed that FBG exhibited improved inhibitory activities of α-amylase, α-glucosidase and lipase, as well as the adsorption of cholesterol under acidic conditions compared to RBG. These results suggested that fermentation may enhance in vitro physiological activities of barley β-glucan, especially related to glucose and lipid metabolism.

Bifunctional Hybrid Enzyme-Catalytic Metal Organic Framework Reactors for α-Glucosidase Inhibitor Screening

The screening strategy based on α-glucosidase inhibition has been widely employed for the discovery of antidiabetic drugs, but it still faces some challenges in practical applications, such as poor stability of enzyme, high consumption of test compounds, low sensitivity of screening methods and so on. In this work, a bifunctional hybrid enzyme-catalytic metal organic framework reactor (GAA@GOx@Cu-MOF) with a flower-shaped globular structure was innovatively prepared via self-assembling of α-glucosidase (GAA), glucose oxidase (GOx), Cu²⁺, and 4,4'-bipyridine. It was found that GAA@GOx@Cu-MOF not only enjoyed merits of high stability, selectivity, and sensitivity but also possessed the character of assembly line work, with about 4.58 times enhanced enzyme activity compared with the free enzyme system. Based on the above characteristics, a highly sensitive screening of GAA inhibitors could be achieved with the detection limit of 7.05 nM for acarbose. Furthermore, the proposed method was successfully applied to the screening of oleanolic acid derivatives as potential antidiabetic drugs. Therefore, it was expected that this work could provide new insights and inspirations for the screening of clinical antidiabetic drugs and for further exploration of functional MOF composites.

Ursolic Acid and Its Derivatives as Bioactive Agents

Non-communicable diseases (NCDs) such as cancer, diabetes, and chronic respiratory and cardiovascular diseases continue to be threatening and deadly to human kind. Resistance to and side effects of known drugs for treatment further increase the threat, while at the same time leaving scientists to search for alternative sources from nature, especially from plants. Pentacyclic triterpenoids (PT) from medicinal plants have been identified as one class of secondary metabolites that could play a critical role in the treatment and management of several NCDs. One of such PT is ursolic acid (UA, 3 β-hydroxy-urs-12-en-28-oic acid), which possesses important biological effects, including anti-inflammatory, anticancer, antidiabetic, antioxidant and antibacterial effects, but its bioavailability and solubility limits its clinical application. Mimusops caffra, Ilex paraguarieni, and Glechoma hederacea, have been reported as major sources of UA. The chemistry of UA has been studied extensively based on the literature, with modifications mostly having been made at positions C-3 (hydroxyl), C12-C13 (double bonds) and C-28 (carboxylic acid), leading to several UA derivatives (esters, amides, oxadiazole quinolone, etc.) with enhanced potency, bioavailability and water solubility. This article comprehensively reviews the information that has become available over the last decade with respect to the sources, chemistry, biological potency and clinical trials of UA and its derivatives as potential therapeutic agents, with a focus on addressing NCDs.

A Review Exploring Therapeutic Worth of 1,3,4-Oxadiazole Tailored Compounds

1,3,4-Oxadiazole, a five-membered aromatic ring can be seen in a number of synthetic molecules. The peculiar structural feature of 1,3,4-oxadiazole ring with pyridine type of nitrogen atom is beneficial for 1,3,4-oxadiazole derivatives to have effective binding with different enzymes and receptors in biological systems through numerous weak interactions, thereby eliciting an array of bioactivities. Research in the area of development of 1,3,4-oxadiazole-based derivatives has become an interesting topic for the scientists. A number of 1,3,4-oxadiazole based compounds with high therapeutic potency are being extensively used for the treatment of different ailments, contributing to enormous development value. This work provides a systematic and comprehensive review highlighting current developments of 1,3,4-oxadiazole based compounds in the entire range of medicinal chemistry such as anticancer, antifungal, antibacterial, antitubercular, anti-inflammatory, antineuropathic, antihypertensive, antihistaminic, antiparasitic, antiobesity, antiviral, and other medicinal agents. It is believed that this review will be of great help for new thoughts in the pursuit for rational designs for the development of more active and less toxic 1,3,4-oxadiazole based medicinal agents.

Corosolic acid isolated from Eriobotrya japonica leaves reduces glucose level in human hepatocellular carcinoma cells, zebrafish and rats

Type 2 diabetes (T2D) with high morbidity and mortality is characterized by abnormal glucose and lipid metabolism due in part to insulin resistance in liver, which lead to elevated hyperglycemia and hyperlipidemia. This study sough to explore the effects of corosolic acid (CA) in different T2D models and explored the underlying mechanism. Separated from Eriobotrya japonica leaves, CA purity was above 95% measured by a HPLC method. Compared with cAMP and DEX induced T2D HepG2 model, CA significantly stimulated glucose consumption and improved glycogen accumulation by inhibiting PEPCK mRNA expression. And in cAMP and DEX induced T2D zebrafish model, CA reduced glycogen degradation and increased glucose consumption by regulating some key enzymes in carbon metabolism including GLUT1, GLUT2, GLUT3, LDHA, LDHB, GP, G6Pase, GYS1, and PFKFB3. In addition, insulin receptor signals were also involved in CA-regulated hypoglycemic action. Furthermore, in STZ-induced T2D rat model, compared with diabetic control groups, CA remarkably downregulated the levels of serum lipid, blood glucose, ICAM-1, malonaldehyde and insulin resistance index, while upregulated SOD activity and impaired glucose tolerance. In a conclusion, CA can regulate glucose and lipid metabolic adaptation in T2D like HepG2, zebrafish and rat models partly through reducing inflammation and oxidative stress and suppressing PEPCK.

Synthesis and biological evaluation of novel oleanolic acid analogues as potential α-glucosidase inhibitors

Considerable interest has been attracted in oleanolic acid and its analogues because of their hypoglycemic activity. In this study, a series of novel oleanolic acid analogues against α-glucosidase were synthesized and their biological activities were evaluated in vitro and in vivo. In vitro α-glucosidase inhibition activity results indicated that most of the designed analogues exhibited prominent inhibition activities, especially compounds 10, 15, 16 and 26 which with the IC₅₀ values of 0.33 ± 0.01, 0.98 ± 0.06, 0.69 ± 0.01 and 0.72 ± 0.21 μM, respectively. Enzyme kinetic studies on the most potent compounds reveled that derivatives 10, 15, 16 and 26 were noncompetitive inhibitors. Moreover, the docking studies were carried out to prove that the four compounds could interact with the hydrophobic region of the active pocket and form hydrogen bonds to enhance the binding affinity of them with the α-glucosidase. Cytotoxicity evaluation assay demonstrated a high level of safety profile of the active compounds (10, 15, 16 and 26) against normal 3T3 cell line. Furthermore, the in vivo actual pharmacological potential studies on derivatives 10, 15, 16 and 26 showed that the hypoglycemic effects of them were comparable to that of positive control, acarbose.

Carrier-Free, Pure Nanodrug Formed by the Self-Assembly of an Anticancer Drug for Cancer Immune Therapy

Ursolic acid (UA) is a food-plant-derived natural product which has good anticancer activities and low toxicity. However, the poor water solubility of UA limits its application in clinic. To address this issue, we developed a carrier-free nanodrug by self-assembly of UA. Here, we showed that UA nanoparticles (NPs) have a near-spherical shape with a diameter of ∼150 nm. UA NPs exhibited higher antiproliferative activity; significantly caused apoptosis; decreased the expression of COX-2/VEGFR2/VEGFA; and increased the immunostimulatory activity of TNF-α, IL-6, and IFN-β and decreased the activity of STAT-3 in A549 cells in vitro. Furthermore, UA NPs could inhibit tumor growth and have the ability of liver protection in vivo. More importantly, UA NPs could significantly improve the activation of CD4+ T-cells, which indicated that UA NPs have the potential for immunotherapy. Overall, a carrier-free UA nanodrug may be a promising drug to further enhance their anticancer efficacy and immune function.

Design, synthesis, evaluation, and molecular docking of ursolic acid derivatives containing a nitrogen heterocycle as anti-inflammatory agents

Ursolic acid derivatives containing oxadiazole, triazolone, and piperazine moieties were synthesized in an attempt to develop potent anti-inflammatory agents. Structures of the synthesized compounds were elucidated by 1H NMR, 13C NMR, and HRMS. Most of the synthesized compounds showed pronounced anti-inflammatory effects at 100 mg/kg. In particular, compound 11b, which displayed the most potent anti-inflammatory activity of all of the compounds prepared, with 69.76% inhibition after intraperitoneal administration, was more potent than the reference drugs indomethacin and ibuprofen. The cytotoxicity of the compounds was also assessed by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay, and no compounds showed any appreciable cytotoxic activity (IC50 >100 μmol/L). Furthermore, molecular docking studies of the synthesized compounds were performed to rationalize the obtained biological results. Overall, the results indicate that compound 11b could be a therapeutic candidate for the treatment of inflammation.

Ursolic acid derivatives as potential antidiabetic agents: In vitro, in vivo, and in silico studies

Hit, Lead & Candidate Discovery Protein tyrosine phosphatase 1B (PTP-1B) has attracted interest as a novel target for the treatment of type 2 diabetes, this because its role in the insulin-signaling pathway as a negative regulator. Thus, the aim of current work was to obtain seven ursolic acid derivatives as potential antidiabetic agents with PTP-1B inhibition as main mechanism of action. Furthermore, derivatives 1-7 were submitted in vitro to enzymatic PTP-1B inhibition being 3, 5, and 7 the most active compounds (IC50  = 5.6, 4.7, and 4.6 μM, respectively). In addition, results were corroborated with in silico docking studies with PTP-1B orthosteric site A and extended binding site B, showed that 3 had polar and Van der Waals interactions in both sites with Lys120, Tyr46, Ser216, Ala217, Ile219, Asp181, Phe182, Gln262, Val49, Met258, and Gly259, showing a docking score value of -7.48 Kcal/mol, being more specific for site A. Moreover, compound 7 showed polar interaction with Gln262 and Van der Waals interactions with Ala217, Phe182, Ile219, Arg45, Tyr46, Arg47, Asp48, and Val49 with a predictive docking score of -6.43 kcal/mol, suggesting that the potential binding site could be localized in the site B adjacent to the catalytic site A. Finally, derivatives 2 and 7 (50 mg/kg) were selected to establish their in vivo antidiabetic effect using a noninsulin-dependent diabetes mice model, showing significant blood glucose lowering compared with control group (p < .05).

α-Glucosidase Inhibition and Antibacterial Activity of Secondary Metabolites from the Ecuadorian Species Clinopodium taxifolium (Kunth) Govaerts

The phytochemical investigation of both volatile and fixed metabolites of Clinopodium taxifolium (Kunth) Govaerts (Lamiaceae) was performed for the first time. It allowed the isolation and characterization of the essential oil and six known compounds: carvacrol (1), squalane (2), uvaol (3), erythrodiol (4), ursolic acid (5), and salvigenin (6). Their structures were identified and characterized by Nuclear Magnetic Resonance (NMR) and Gas Chromatography coupled to Mass Spectroscopy (GC-MS), and corroborated by literature. The essential oil of the leaves was obtained by hydrodistillation in two different periods and analyzed by GC-MS and GC coupled to Flame Ionization Detector (GC-FID). A total of 54 compounds were detected, of which 42 were identified (including trace constituents). The major constituents were carvacrol methyl ether (18.9-23.2%), carvacrol (13.8-16.3%) and, carvacryl acetate (11.4-4.8%). The antibacterial activities were determined as Minimum Inhibition Concentration (MIC) against Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Pseudomonas aeruginosa and Micrococcus luteus. The hexane and methanol extracts exhibited activity only against Klebsiella pneumoniae (250 and 500 μg/mL respectively), while the ethyl acetate extract was inactive. The hypoglycemic activity was evaluated by the in vitro inhibition of α-glucosidase. The ethyl acetate (EtOAc) extract showed strong inhibitory activity with IC50 = 24.88 µg/mL, however methanolic and hexanic extracts showed weak activity. As a pure compound, only ursolic acid showed a strong inhibitory activity, with IC50 = 72.71 μM.

Synthesis and biological evaluation of novel ursolic acid analogues as potential α-glucosidase inhibitors

Ursolic acid (UA) is a major pentacyclic triterpenoid in plants, vegetables and fruits, which has been reported to have a potential anti-diabetic activity. Despite various semi-synthetic ursolic acid derivatives already described, new derivatives still need to be designed and synthesized to further improve the anti-diabetic activity. In the present study, two series of novel UA derivatives, were synthesized and their structures were confirmed. The enzyme inhibition activities of semi-synthesized analogues against α-glucosidase were screened in vitro. The results indicated that most of UA derivatives showed a significant inhibitory activity, especially analogues UA-O-i with the IC50 values of 0.71 ± 0.27 μM, which was more potential than other analogues and the positive control. Furthermore, molecular docking studies were also investigated to verify the in vitro study. Structure modification at the C-3 and C-2 positions of UA was an effective approach to obtain the desired ligand from UA, whose structure was in accordance with the active pocket. Besides, suitable hydrophobic group at the position of C-2 might play an important role for the docking selectivity and binding affinity between the ligand and the homology modelling protein. These results could be helpful for designing more potential α-glucosidase inhibitors from UA in the future.

Acute and Subacute Oral Toxicity Evaluation of Eriobotrya japonica Leaf Triterpene Acids in ICR Mice

The interest focusing on Eriobotrya japonica leaf triterpene acid (ELTA) has increased recently because of its beneficial effects on health. However, there has been a lack of experimental data on its toxicity. The present study therefore was conducted to evaluate its toxicity in ICR mice. The results showed that ELTA produced neither mortality nor toxicity of the main organs in ICR male and female mice in both acute (0.30, 0.65, 1.39, and 3.00 g·kg⁻¹ body weight) and subacute (150, 300, and 600 mg·kg⁻¹ BW) 28-day toxicity studies. Because of lacking apparently adverse effects found in the hematology, clinical biochemistry, and histopathology evaluation, results of the present study together with the beneficial effects make ELTA as a promising dietary supplement and indicated that ELTA administered orally might have a large safety margin for human.

Evaluation of Ursolic Acid as the Main Component Isolated from Catharanthus roseus against Hyperglycemia

Ursolic acid with large amount (0.67% of dried plant weight) along with 7 compounds, namely as spatozoate (1), kaurenoic acid (2), ursonic acid (3), 3-hydroxy-11-ursen-28,13-olide (4), ursolic acid (5), vindoline (6) and mixture of β-sitosterol and stigmasterol were isolated from dichloromethane and ethyl acetate extracts which have shown anti-glucosidase activity of the whole plant of C.roseus. Some isolated compounds and their derivatives were also tested for anti-glucosidase and cytotoxicity.Ursolic acid was examined for hypoglycemic activity inalloxan-induced diabetic micewith dose of 200 and 300 mg/kg/day, respectively. The results have shown that the blood glucose level were reduced by 45.75% and 51.31% to compare with the control group. This study has confirmed that the main component of Vietnamese C. roseus has had significant anti-hyperglycemia activity.

Inhibition of Alpha-Glucosidase by Synthetic Derivatives of Lupane, Oleanane, Ursane and Dammarane Triterpenoids

A variety of new and earlier synthesized lupane, oleanane, ursane and dammarane triterpenoids have been investigated for their inhibitory activity against α-glucosidase. 2,3-Indole-21β-acetyl-20β,28-epoxy-18α,19βH-ursane and 3-oxo-3A-homo-3a-aza-20( S)-hydroxydammar-24(25)-ene were synthesized for the first time. The compounds 3, 4, 8–11 and 14 demonstrated strong in vitro inhibitory activity towards α-glucosidase with IC50 values of 37.5–115.1 μM. 3-Deoxy-3a-homo-3a-aza-28-cinnamoyloxy-20(29)-lupene, with an IC50 of 6.67 μM was 60-fold more active than the market drug acarbose.

Betulinic acid and oleanolic acid, natural pentacyclic triterpenoids, interfere with N-linked glycan modifications to intercellular adhesion molecule-1, but not its intracellular transport to the cell surface

Betulinic acid (3β-hydroxy-20(29)-lupen-28-oic acid), oleanolic acid (3β-hydroxy-olean-12-en-28-oic acid), and ursolic acid (3β-hydroxy-urs-12-en-28-oic acid) are close structural isomers of natural pentacyclic triterpenoid carboxylic acids. We recently identified a unique biological effect of ursolic acid, its inhibition of the intracellular trafficking of glycoproteins. In the present study, we demonstrated that betulinic acid and oleanolic acid did not inhibit the interleukin-1α-induced expression of cell-surface intercellular adhesion molecule-1 (ICAM-1) in human lung carcinoma A549 cells. Nevertheless, betulinic acid and, to a lesser extent, oleanolic acid interfered with N-linked glycan modifications to ICAM-1 in a similar manner to castanospermine (an inhibitor of endoplasmic reticulum α-glucosidases I and II), but not swainsonine (an inhibitor of Golgi α-mannosidase II). Consistent with these results, betulinic acid and oleanolic acid inhibited yeast α-glucosidase activity, but not Jack bean α-mannosidase activity. Thus, to the best of our knowledge, this is the first study to show that betulinic acid and oleanolic acid interfere with N-linked glycan modifications to ICAM-1, but not its intracellular transport to the cell surface.

Synthesis and Evaluation of Novel Triterpene Analogues of Ursolic Acid as Potential Antidiabetic Agent

Ursolic acid (UA) is a naturally bioactive compound that possesses potential anti-diabetic activity. The relatively safe and effective molecule intrigued us to further explore and to improve its anti-diabetic activity. In the present study, a series of novel UA analogues was synthesized and their structures were characterized. Their bioactivities against the α-glucosidase from baker's yeast were determined in vitro. The results suggested that most of the analogues exhibited significant inhibitory activity, especially analogues 8b and 9b with the IC50 values of 1.27 ± 0.27 μM (8b) and 1.28 ± 0.27 μM (9b), which were lower than the other analogues and the positive control. The molecular docking and 2D-QSAR studies were carried out to prove that the C-3 hydroxyl could interact with the hydrophobic region of the active pocket and form hydrogen bonds to increase the binding affinity of ligand and the homology modelling protein. Thus, these results will be helpful for understanding the relationship between binding mode and bioactivity and for designing better inhibitors from UA analogues.

Design, synthesis and in vitro evaluation of novel ursolic acid derivatives as potential anticancer agents

A series of novel ursolic acid (UA) derivatives modified at the C-3 and the C-28 positions were designed and synthesized in an attempt to develop potential antitumor agents. The in vitro cytotoxicity were evaluated against five cancer cell lines (MGC-803, HCT-116, T24, HepG2 and A549 cell lines) and a normal cell (HL-7702) by MTT assay. The screening results indicated that some of these target compounds displayed moderate to high levels of antiproliferative activities compared with ursolic acid and 5-fluorouracil (5-FU), and exhibited much lower cytotoxicity than 5-FU, indicating that the targeted compounds had selective and significant effect on the cell lines. The induction of apoptosis and affects on the cell cycle distribution of compound 6r were investigated by acridine orange/ethidium bromide staining, Hoechst 33258 staining, JC-1 mitochondrial membrane potential staining and flow cytometry, which revealed that the antitumor activity of 6r was possibly achieved through the induction of cell apoptosis by G1 cell-cycle arrest. Western blot and qRT-PCR (quantitative real-time PCR) experiments demonstrated that compound 6r may induce apoptosis through both of intrinsic and extrinsic apoptosis pathway.

Evaluation of Antidiabetic and Antihyperlipidemic Effects of Hydroalcoholic Extract of Leaves of Ocimum tenuiflorum (Lamiaceae) and Prediction of Biological Activity of its Phytoconstituents

Objective:

The aim was to evaluate the anti-diabetic and anti-hyperlipidemic effects of hydroalcoholic extract of leaves of Ocimum tenuiflorum (Lamiaceae) and prediction of biological activities of its phytoconstituents using in vivo anti-diabetic model and in silico analysis respectively.

Materials and Methods:

The leaves of O. tenuiflorum were extracted with 60% ethanol, and the extract was used for further pharmacological screening. The acute toxicity of the extract was evaluated as per the guidelines set by the Organization for Economic Co-operation and Development, revised draft guidelines 423. The oral anti-diabetic activity of the hydroalcoholic extract of O. tenuiflorum (125, 250 and 500 mg/kg) was studied against streptozotocin (STZ) (50 mg/kg; i.p.) + nicotinamide (120 mg/kg; i.p.) induced diabetes mellitus. The animals were treated with the investigational plant extract and standard drug (glibenclamide) for 21 consecutive days and the effect of hydroalcoholic extract of O. tenuiflorum on blood glucose levels was measured at regular intervals. At the end of the study, blood samples were collected from all the animals for biochemical estimation, then the animals were sacrificed and the liver and kidney were collected for organ weight analysis. Prediction for pharmacological and toxicological properties of phytoconstituents of O. tenuiflorum was carried out using online web tools such as online pass prediction and lazar toxicity prediction.

Results:

The hydroalcoholic extract of O. tenuiflorum showed significant anti-diabetic and anti-hyperlipidemic activity at 250 and 500 mg/kg, and this effect was comparable with that of glibenclamide. Predicted biological activities of phytoconstituents of O. tenuiflorum showed presence of various pharmacological actions, which includes anti-diabetic and anti-hyperlipidemic activities. Prediction of toxicological properties of phytoconstituents of O. tenuiflorum did not show any major toxic effects.

Conclusion:

The hydroalcoholic extract of O. tenuiflorum showed significant anti-diabetic and anti-hyperlipidemic activity against STZ + nicotinamide induced diabetes mellitus in rats. Further studies are required to confirm the anti-diabetic and anti-hyperlipidemic activities of individual phytoconstituents of O. tenuiflorum.

Synthesis, in vitro antimicrobial and cytotoxic activities of new carbazole derivatives of ursolic acid

A series of new carbazole derivatives of ursolic acid were designed and synthesized in an attempt to develop potent antimicrobial or antitumor agents. Their structures were confirmed by using IR, HRMS and (1)H NMR analysis. All the synthesized compounds were evaluated for their antimicrobial activity against four bacterial and three fungal strains using serial dilution method. Compounds 3a, 3b, 4a, 4b and 5a-f exhibited significant antibacterial activity against at least one tested bacteria with MIC values of 3.9-15.6μg/ml. In addition, the in vitro cytotoxicity of these compounds were also assayed against two human tumor cell lines (SMMC-7721 and HepG2) using MTT colorimetric method. From the results, compounds 5a-e and 5h displayed pronounced cytotoxic activity with IC50 values below 10μM. Specially, compound 5e was found to be the most potent compound with IC50 values of 1.08±0.22 and 1.26±0.17μM against SMMC-7721 and HepG2 cells, respectively, comparable to those of doxorubicin. In addition, compound 5e showed reduced cytotoxicity against noncancerous LO2 cells with IC50 value of 5.75±0.48μM.

UP12, a novel ursolic acid derivative with potential for targeting multiple signaling pathways in hepatocellular carcinoma

Targeting cancer cell glucose metabolism is a promising strategy for cancer therapy. In past approaches to cancer drug discovery, ursolic acid (UA) has been chemically modified to improve its antitumor activities and bioavailability. Here, a novel ursolic acid (UA) derivative UP12 was developed via computer-aided drug design to explore potent anti-cancer agents and to examine possible mechanisms. The structural docking analyses suggested that UP12 could bind to the active sites of glucokinase (GK), glucose transporter 1 (GLUT1) and ATPase, which are the main enzymes involved in cancer glucose metabolism. We further investigated the synergistic effect between UP12 and glycolysis inhibitor 2-deoxy-d-glucose (2-DG) in inhibiting glucose metabolism of cancer cells. The pharmacological results showed that the combination enhanced depletion of intracellular ATP and decrease in lactate production, and pushed more cancer cells arrested in the S and G2/M cycle phases. The combination selectively down-regulated the expression of Bcl-2 and HKII proteins, up-regulated the expression of Bax and p53, and collectively resulted in enhanced apoptosis related to caspase-3, -8, and -9 activities, in addition to inhibition on the cell mitochondrial membrane potential. The animal studies further demonstrated that the combination exhibited significant antitumor activity without obvious toxicity. In summary, UP12 can interfere cancer cell metabolism pathway and further enhance the therapeutic effects of 2-DG likely through synergistic suppression of cancer cell glucose metabolism, making UP12 a likely new candidate for anti-cancer drug development.

A hydrophilic conjugate approach toward the design and synthesis of ursolic acid derivatives as potential antidiabetic agent

In this study, a series of novel ursolic acid (UA) derivatives were designed and synthesized successfully via conjugation of hydrophilic and polar groups at 3-OH and/or 17-COOH position.

Effects of ursolic acid derivatives on Caco-2 cells and their alleviating role in streptozocin-induced type 2 diabetic rats

In this study, the effect and mechanism of a series of ursolic acid (UA) derivatives on glucose uptake were investigated in a Caco-2 cells model. Their effect on hyperglycemia, hyperlipidemia and oxidative stress were also demonstrated in streptozocin (STZ)-induced diabetic rats. 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxy-glucose (2-NBDG) was used as a fluorescein in Caco-2 cells model to screen UA derivatives by glucose uptake and expression of glucose transporter protein (SGLT-1, GLUT-2). Moreover, STZ-induced diabetic rats were administered with these derivatives for 4 weeks of treatment. The fasting blood glucose (FBG), insulin levels, biochemical parameters, lipid levels, and oxidative stress markers were finally evaluated. The results of this study indicated that compounds 10 and 11 significantly inhibited 2-NBDG uptake under both Na+-dependent and Na+-independent conditions by decreasing SGLT-1 and GLUT-2 expression in the Caco-2 cells model. Further in vivo studies revealed that compound 10 significantly reduced hyperglycemia by increasing levels of serum insulin, total protein, and albumin, while the fasting blood glucose, body weight and food intake were restored much closer to those of normal rats. Compounds 10 and 11 showed hypolipidemic activity by decreasing the total amounts of cholesterol (TC) and triglycerides (TG). Furthermore, compound 10 showed antioxidant potential which was confirmed by elevation of glutathione (GSH) and superoxide dismutase (SOD) and reduction of malondialdehyde (MDA) levels in the liver and kidney of diabetic rats. It was concluded that compound 10 caused an apparent inhibition of intestinal glucose uptake in Caco-2 cells and hypoglycemia, hypolipidemia and augmented oxidative stress in STZ-induced diabetic rats. Thus, compound 10 could be developed as a potentially complementary therapeutic or prophylactic agent for diabetics mellitus and its complications.