(+)-Pinoresinol is a putative hypoglycemic agent in defatted sesame (Sesamum indicum) seeds though inhibiting α-glucosidase

Medicinal plants of Southeast Asia with anti-α-glucosidase activity as potential source for type-2 diabetes mellitus treatment

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetes mellitus, a widespread chronic illness, affects millions worldwide, and its incidence is increasing alarmingly, especially in developing nations. Current pharmacological treatments can be costly and have undesirable side effects. To address this, medicinal plants with antidiabetic effects, particularly targeting α-glucosidase for controlling hyperglycaemia in type-2 diabetes mellitus (T2DM), hold promise for drug development with reduced toxicity and adverse reactions.

AIM OF THIS REVIEW

This review aims to succinctly collect information about medicinal plant extracts that exhibit antidiabetic potential through α-glucosidase inhibition using acarbose as a standard reference in Southeast Asia. The characteristics of this inhibition are based on in vitro studies.

MATERIALS AND METHODS

Relevant information on medicinal plants in Southeast Asia, along with α-glucosidase inhibition studies using acarbose as a positive control, was gathered from various scientific databases, including Scopus, PubMed, Web of Science, and Google Scholar.

RESULTS

About 49 papers were found from specific counties in Southeast Asia demonstrated notable α-glucosidase inhibitory potential of their medicinal plants, with several plant extracts showcasing activity comparable to or surpassing that of acarbose. Notably, 19 active constituents were identified for their α-glucosidase inhibitory effects.

CONCLUSIONS

The findings underscore the antidiabetic potential of the tested medicinal plant extracts, indicating their promise as alternative treatments for T2DM. This review can aid in the development of potent therapeutic medicines with increased effectiveness and safety for the treatment of T2DM.

Lignans and coumarins from the stem bark of Alyxia fascicularis (Wall. ex G. Don) Benth. ex Hook. f.)

In the first phytochemical investigation of specialized metabolites from the stem bark of Alyxia fascicularis, which is used in different traditional medicines, including those of Myanmar and China, five lignans (1-5) and three coumarins (6-8) were isolated by semipreparative HPLC separations and identified mainly by 1D and 2D NMR spectral analysis. The radical scavenging activity of isolated compounds was tested using the DPPH method. Noteworthy, most lignans exhibited antiradical effects comparable to vitamin C and gallic acid. Instead, compounds 1-8 showed no cytotoxic effect on Hela cell line. A possible biosynthetic pathway to enantiomeric 3 and 4 is suggested.

Exploring the Pharmacological Potential of Onosma riedliana: Phenolic Compounds and Their Biological Activities

Onosma riedliana Binzet & Orcan, a traditionally used plant species, has been explored for its therapeutic potential in this study. The work presented here is the first report on the phenolic profile and biological activity of this species. Three extracts of varying polarity were prepared, with the methanolic extract containing the highest phenolic content (97.62 ± 0.20 mgGAE/g). Key phenolic compounds identified included pinoresinol, hesperidin, 4-hydroxybenzoic acid, and p-coumaric acid. The methanolic extract exhibited exceptional antioxidant properties, rivaling Trolox as a positive control, primarily attributed to hesperidin and luteolin. Moreover, the ethyl acetate extract demonstrated remarkable inhibition of cholinesterase and tyrosinase enzymes, while the methanolic extract displayed potent activity against carbohydrate hydrolytic enzymes, α-amylase and α-glucosidase. Again, phenolic compounds were shown to be responsible for the inhibition of cholinesterases and tyrosinase, but not for α-amylase and α-glucosidase. These findings underscore Onosma riedliana's potential for incorporation into diverse pharmaceutical formulations, given its multifaceted bioactivity.

Daraesoon (shoot of hardy kiwi) mitigates hyperglycemia in db/db mice by alleviating insulin resistance and inflammation

BACKGROUND/OBJECTIVES

Mitigating insulin resistance and hyperglycemia is associated with a decreased risk of diabetic complications. The effect of Daraesoon (shoot of hardy kiwi, Actinidia arguta) on hyperglycemia was investigated using a type 2 diabetes animal model.

MATERIALS/METHODS

Seven-week-old db/db mice were fed either an AIN-93G diet or a diet containing 0.4% of a 70% ethanol extract of Daraesoon, whereas db/+ mice were fed the AIN-93G diet for 7 weeks.

RESULTS

Consumption of Daraesoon significantly reduced serum glucose and blood glycated hemoglobin levels, along with homeostasis model assessment for insulin resistance in db/db mice. Conversely, Daraesoon elevated the serum adiponectin levels compared to the db/db control group. Furthermore, Daraesoon significantly decreased both serum and hepatic triglyceride levels, as well as serum total cholesterol levels. Additionally, consumption of Daraesoon resulted in decreased hepatic tumor necrosis factor-α and monocyte chemoattractant protein-1 expression.

CONCLUSIONS

These results suggest that hypoglycemic effect of Daraesoon is mediated through the improvement of insulin resistance and the downregulation of pro-inflammatory cytokine expression in db/db mice.

α-Glucosidase Inhibitors from Cold-Pressed Black Sesame (Sesamum indicum) Meal: Characterization of New Furofuran Lignans, Kinetic Study, and In Vitro Gastrointestinal Digestion

Black sesame (Sesamum indicum) meal is an agricultural waste obtained after oil extraction. It is used as a key protein source in animal feed. Previous investigations have indicated that its health benefits, such as antidiabetic activity, are mainly due to its high lignan content. In the present study, we applied α-glucosidase inhibitory guided isolation to identify the active components responsible for the above claim. Twenty-nine compounds, mostly lignans, were isolated and identified, of which five (2-3, 12-13, and 28) were newly isolated. Of the isolated compounds, 20 and 21 were the most potent inhibitors, retarding enzyme function in noncompetitive and uncompetitive manners. Structure-activity relationship analysis suggested that the number of phenolic hydroxyl groups in the structures was significantly related to the inhibitory effect against α-glucosidase. A gastrointestinal digestion study of the major lignan sesaminol triglucoside (STG, 9) suggested that the transformation of dioxymethylene and glucoside moieties gradually began in the late process, thus enhancing the α-glucosidase inhibitory effect.

New prenyl flavanone and diarylbutanol from Uvaria siamensis stem bark and their α-glucosidase inhibitory activity

One new prenyl flavanone (1), (2S)-8-prenyl-5,6-dihydroxy-7-methoxyflavanone, and one new diarylbutanol (2), (7'S)-3'-hydroxy-linderagatin-A, were isolated from the stem bark of Uvaria siamensis (Annonaceae), along with five known compounds, eriodictyol (3), quercetin (4), paprazine (5), N-trans-caffeoyltyramine (6), and N-trans-feruloyltyramine (7). Their structures were determined through extensive spectroscopic analyses and comparison with the literature. The α-glucosidase inhibitory potential of 1-7 was evaluated. Compound 6 showed the highest inhibitory activity against α-glucosidase and exhibited superior potency compared to the positive control, with an IC50 value of 0.12 μM.

Antioxidant and Wound Healing Bioactive Potential of Extracts Obtained from Bark and Needles of Softwood Species

Interest in the extraction of phytochemical bioactive compounds, especially polyphenols from biomass, has recently increased due to their valuable biological potential as natural sources of antioxidants, which could be used in a wide range of applications, from foods and pharmaceuticals to green polymers and bio-based materials. The present research study aimed to provide a comprehensive chemical characterization of the phytochemical composition of forest biomass (bark and needles) of softwood species (Picea abies L., H. Karst., and Abies alba Mill.) and to investigate their in vitro antioxidant and antimicrobial activities to assess their potential in treating and healing infected chronic wounds. The DPPH radical-scavenging method and P-LD were used for a mechanistic explanation of the biomolecular effects of the investigated bioactive compounds. (+)-Catechin, epicatechin, rutin, myricetin, 4 hydroxybenzoic and p-cumaric acids, kaempherol, and apigenin were the main quantified polyphenols in coniferous biomass (in quantities around 100 µg/g). Also, numerous phenolic acids, flavonoids, stilbenes, terpenes, lignans, secoiridoids, and indanes with antioxidant, antimicrobial, anti-inflammatory, antihemolytic, and anti-carcinogenic potential were identified. The Abies alba needle extract was more toxic to microbial strains than the eukaryotic cells that provide its active wound healing principles. In this context, developing industrial upscaling strategies is imperative for the long-term success of biorefineries and incorporating them as part of a circular bio-economy.

The Potential of Ginkgo biloba as a Source of Biologically Active Compounds-A Review of the Recent Literature and Patents

Ginkgo biloba is a relict tree species showing high resistance to adverse biotic and abiotic environmental factors. Its fruits and leaves have high medicinal value due to the presence of flavonoids, terpene trilactones and phenolic compounds. However, ginkgo seeds contain toxic and allergenic alkylphenols. The publication revises the latest research results (mainly from 2018-2022) regarding the chemical composition of extracts obtained from this plant and provides information on the use of extracts or their selected ingredients in medicine and food production. A very important section of the publication is the part in which the results of the review of patents concerning the use of Ginkgo biloba and its selected ingredients in food production are presented. Despite the constantly growing number of studies on its toxicity and interactions with synthetic drugs, its health-promoting properties are the reason for the interest of scientists and motivation to create new food products.

Phytochemical investigation, molecular docking studies and DFT calculations on the antidiabetic and cytotoxic activities of Gmelina philippensis CHAM

ETHNOPHARMACOLOGICAL RELEVANCE

Gmelina philippensis CHAM is an ornamental plant that is distributed in South Asia and warm regions of the Mediterranean area. The plant is traditionally applied in folk medicine for the treatment of diabetes.

AIM OF THE STUDY

To evaluate the cytotoxic and the antidiabetic activities of the ethanolic extract of G. philippensis aerial parts. To isolate the metabolite(s) responsible for these activities and to elucidate the mechanism of action by molecular docking study.

MATERIALS AND METHODS

Compounds (1-11) were isolated using various chromatographic techniques and their structures were determined by NMR spectroscopic and mass spectrometric analysis. The cytotoxic effect was tested using viability test and MTT assay. Antidiabetic activity was evaluated by measuring the inhibitory activity of the ethanolic extracts and compounds against α-glucosidase and α-amylase activities. Modeling and docking simulations were performed using Molecular Operating Environment software and the crystal structure of protein kinases CDK2, (1PYE) and AKT1 (4GV1), in addition to α-glucosidase (3TOP) and α-amylase (2QV4).

RESULTS

Compounds 2, 3 and 8 were isolated for the first time from the plant and identified as: gmelinol (2), apigenin (3) and tyrosol (8). While β-sitosterol-3-O- β-D-glucopyranoside (4) vicenin-II (7), rhoifolin (9), isorhoifolin (11) were isolated for the first time from the genus, along with and the new iridoid 6-O-α-L-(2″-O-benzoyl-4″-O-trans-p-methoxycinnamoyl)rhamnopyranosyl-1α- β-D-glucopyranoside catalpolgenin (6). In addition, to the previously reported compounds: mixture of β -sitosterol and stigmasterol (1), and 6- O- α-L-(2″,3″,4″-tri-O -benzoyl)rhamnopyranosylcatalpol (5) and 6-O-α-L-(2″-O-trans-p-methoxycinnamoyl)rhamnopyranosylcatalpol (10). The cytotoxic activity against hepatocellular carcinoma (HepG-2) cell lines for compounds 2, 5, 7, 9 and 11 was conducted using cisplatin as a standard. Gmelinol (2) exhibited strong cytotoxic activity against HepG-2 cell lines with IC ₅₀ value of 3.6 ± 0.1 μg/ml which is more potent than the standard cisplatin IC ₅₀ = 8.7 ± 0.9 μg/ml. Molecular modeling of 2 against diverse targets of protein kinases suggested that CDK-2 and AKT-1 could be the dual probable kinase targets for its cytotoxic action. Compound 2 showed α-amylase inhibition activity with IC ₅₀ value of 60.9 (μg/ml) while, compounds 5 showed strong α-glucosidase inhibition activity with IC ₅₀ values of 41.7 (μg/ml) compared to acarbose with IC ₅₀ value of 34.7, 30.6 (μg/ml). Molecular docking of compounds 2 and 5 on α-glucosidase (3TOP) and α-amylase (2QV4) enzymes revealed high binding affinity and active site interactions comparable to native ligand acarbose.

CONCLUSION

The ethanolic extract of G. philippensis CHAM aerial parts is effective against HepG-2 cell lines, α-amylase and α-glucocidase activities. Biologically guided isolation indicated that compounds 2 and 5 are responsible for these activities. These results were supported by DMF calculations that detected the molecular areas responsible for protein interactions shown via docking studies.

New Anti-Glycative Lignans from the Defatted Seeds of Sesamum indicum

Seven known analogs, along with two previously undescribed lignan derivatives sesamlignans A (1) and B (2), were isolated from a water-soluble extract of the defatted sesame seeds (Sesamum indicum L.) by applying the chromatographic separation method. Structures of compounds 1 and 2 were elucidated based on extensive interpretation of 1D, 2D NMR, and HRFABMS spectroscopic data. The absolute configurations were established by analyzing the optical rotation and circular dichroism (CD) spectrum. Inhibitory effects against the formation of advanced glycation end products (AGEs) and peroxynitrite (ONOO^-) scavenging assays were performed to evaluate the anti-glycation effects of all isolated compounds. Among the isolated compounds, (1) and (2) showed potent inhibition towards AGEs formation, with IC₅₀ values of 7.5 ± 0.3 and 9.8 ± 0.5 μM, respectively. Furthermore, the new aryltetralin-type lignan 1 exhibited the most potent activity when tested in the in vitro ONOO^- scavenging assay.

Food and nutraceutical functions of sesame oil: An underutilized crop for nutritional and health benefits

Sesame is the oldest oilseed crop known to humanity, though it contributes a small share in the global vegetable oil production. Sesame oil contains nutrients, including lignans, tocopherols, phytosterols, natural antioxidants, and bioactive compounds. It provides various health benefits such as anti-lipogenic, hypo-cholesterolemic, anti-degenerative, and neural health-promoting properties. Being an under-utilized minor crop, it has not received enough research attention for its food and nutraceutical potential. The sesame crop is a potential candidate to maintain the diversity of food oils and harness its benefits for improving human health. The present review will provide detailed research on sesame oil contents, health effects, nutraceuticals, oil quality, and value addition strategies. Also, the sesame oil nutritional quality was compared with other vegetable oils, highlighting the potential health and nutrition-related benefits. The way forward for further sesame improvement through value addition traits was also discussed.

Effect of Pinoresinol and Vanillic Acid Isolated from Catalpa bignonioides on Mouse Myoblast Proliferation via the Akt/mTOR Signaling Pathway

Growth and maintenance of skeletal muscle is essential for athletic performance and a healthy life. Stimulating the proliferation and differentiation of muscle cells may help prevent loss of muscle mass. To discover effective natural substances enabling to mitigate muscle loss without side effects, we evaluated muscle growth with several compounds extracted from Catalpa bignonioides Walt. Among these compounds, pinoresinol and vanillic acid increased C2C12, a mouse myoblast cell line, proliferation being the most without cytotoxicity. These substances activated the Akt/mammalian target of the rapamycin (mTOR) pathway, which positively regulates the proliferation of muscle cells. In addition, the results of in silico molecular docking study showed that they may bind to the active site of insulin-like growth factor 1 receptor (IGF-1R), which is an upstream of the Akt/mTOR pathway, indicating that both pinoresinol and vanillic acid stimulate myoblast proliferation through direct interaction with IGF-1R. These results suggest that pinoresinol and vanillic acid may be a natural supplement to improve the proliferation of skeletal muscle via IGF-1R/Akt/mTOR signaling and thus strengthen muscles.

Mechanistic insights into the inhibitory activities of chemical constituents from the fruits of Terminalia boivinii on α-glucosidase

Regulation of key digestive enzymes is currently considered an effective remedy for diabetes mellitus. In this study, bioactive constituents were purified from Terminalia boivinii fruits and identified by 1 H NMR, 13 C NMR and EI-MS. In vitro and in silico methods were used to evaluate α-glucosidase, α-amylase, and lipase inhibition activities. Compounds 1 , 2 , and 4-7 with IC50 values between 89 and 445 µM showed stronger α-glucosidase inhibitory activities than the antihyperglycemic drug acarbose (IC 50 =1463.0 ± 29.5 µM). However, the compounds showed lower inhibitory effects against α-amylase and lipase with IC 50 values above 500 µM than acarbose (IC 50 = 16.7 ± 3.5 µM) and ursolic acid (IC 50 = 89.5 ± 5.6 µM), respectively. Lineweaver-Burk plots showed that compounds 1 , 2 , and 7 were non-competitive inhibitors, compounds 4 and 5 were competitive inhibitors and compound 6 was a mixed-type inhibitor. Fluorescence spectroscopic data showed that the compounds altered the microenvironment and conformation of α-glucosidase. Computer simulations indicated that the compounds and enzyme interacted primarily through hydrogen bonding. The findings indicated that the compounds were inhibitors of α-glucosidase and provided significant structural basis for understanding the binding activity of the compounds with α-glucosidase.

Investigation of the mechanism of Shen Qi Wan prescription in the treatment of T2DM via network pharmacology and molecular docking

Shen Qi Wan (SQW) prescription has been used to treat type 2 diabetes mellitus (T2DM) for thousands of years, but its pharmacological mechanism is still unclear. The network pharmacology method was used to reveal the potential pharmacological mechanism of SQW in the treatment of T2DM in this study. Nine core targets were identified through protein-protein interaction (PPI) network analysis and KEGG pathway enrichment analysis, which were AKT1, INSR, SLC2A1, EGFR, PPARG, PPARA, GCK, NOS3, and PTPN1. Besides, this study found that SQW treated the T2DM through insulin resistance (has04931), insulin signaling pathway (has04910), adipocytokine signaling pathway (has04920), AMPK signaling pathway (has04152) and FoxO signaling pathway (has04068) via ingredient-hub target-pathway network analysis. Finally, molecular docking was used to verify the drug-target interaction network in this research. This study provides a certain explanation for treating T2DM by SQW prescription, and provides a certain angle and method for researchers to study the mechanism of TCM in the treatment of complex diseases.

Supplementary information

The online version contains supplementary material available at 10.1007/s40203-022-00124-2.

Developmental effects of sesamolin on zebrafish (Danio rerio) embryos

Sesamolin is one of the major active compounds found in sesame seeds (Sesamum indicum L.) that are commonly and increasingly used as an ingredient in cuisines and various food products. The compound has been reported to have several pharmaceutical activities such as antioxidant, antimicrobial, neuroprotective, and anticancer. However, the toxicological profile of sesamolin does not currently include developmental toxicity. In this study, we assessed sesamolin toxicity to embryonic development of zebrafish by exposure for 72 h at concentrations ranging from 10 to 50 μM. The evaluation revealed that sesamolin did not affect survival and hatching rates. However, it did induce embryo malformations and reduced embryonic heart rates in a dose-dependent manner. By qRT-PCR analysis, it downregulated the expression of oxidative stress-related genes, including superoxide dismutase 1 (sod1), catalase (cat), and glutathione S-transferase pi 2 (gstp2). Alkaline phosphatase staining of embryos revealed that sesamolin inhibited the development of subintestinal vessels, and hemoglobin staining revealed a negative impact on embryonic erythropoiesis. These findings showed that sesamolin affected genes related to angiogenesis and erythropoiesis. The risks of sesamolin to embryonic development found in this study may imply similar effects in humans and other mammals.

Advances in Research on Chemical Constituents and Their Biological Activities of the Genus Actinidia

Kiwi, a fruit from plants of the genus Actinidia, is one of the famous fruits with thousand years of edible history. In the past twenty years, a great deal of research has been done on the chemical constituents of the Actinidia species. A large number of secondary metabolites including triterpenoids, flavonoids, phenols, etc. have been identified from differents parts of Actinidia plants, which exhibited significant in vitro and in vivo pharmacological activities including anticancer, anti-inflammatory, neuroprotective, anti-oxidative, anti-bacterial, and anti-diabetic activities. In order to fully understand the chemical components and biological activities of Actinidia plants, and to improve their further research, development and utilization, this review summarizes the compounds extracted from different parts of Actinidia plants since 1959 to 2020, classifies the types of constituents, reports on the pharmacological activities of relative compounds and medicinal potentials.

Antidiabetic Medicinal Plants Used in Democratic Republic of Congo: A Critical Review of Ethnopharmacology and Bioactivity Data

Several studies have been conducted and published on medicinal plants used to manage Diabetes Mellitus worldwide. It is of great interest to review available studies from a country or a region to resort to similarities/discrepancies and data quality. Here, we examined data related to ethnopharmacology and bioactivity of antidiabetic plants used in the Democratic Republic of Congo. Data were extracted from Google Scholar, Medline/PubMed, Scopus, ScienceDirect, the Wiley Online Library, Web of Science, and other documents focusing on ethnopharmacology, pharmacology, and phytochemistry antidiabetic plants used in the Democratic Republic of Congo from 2005 to September 2021. The Kew Botanic Royal Garden and Plants of the World Online web databases were consulted to verify the taxonomic information. CAMARADES checklist was used to assess the quality of animal studies and Jadad scores for clinical trials. In total, 213 plant species belonging to 72 botanical families were reported. Only one plant, Droogmansia munamensis, is typically native to the DRC flora; 117 species are growing in the DRC and neighboring countries; 31 species are either introduced from other regions, and 64 are not specified. Alongside the treatment of Diabetes, about 78.13% of plants have multiple therapeutic uses, depending on the study sites. Experimental studies explored the antidiabetic activity of 133 plants, mainly in mice, rats, guinea pigs, and rabbits. Several chemical classes of antidiabetic compounds isolated from 67 plant species have been documented. Rare phase II clinical trials have been conducted. Critical issues included poor quality methodological protocols, author name incorrectly written (16.16%) or absent (14.25%) or confused with a synonym (4.69%), family name revised (17.26%) or missing (1.10%), voucher number not available 336(92.05%), ecological information not reported (49.59%). Most plant species have been identified and authenticated (89.32%). Hundreds of plants are used to treat Diabetes by traditional healers in DRC. However, most plants are not exclusively native to the local flora and have multiple therapeutic uses. The analysis showed the scarcity or absence of high-quality, in-depth pharmacological studies. There is a need to conduct further studies of locally specific species to fill the gap before their introduction into the national pharmacopeia.

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.

Lignans of Sesame (Sesamum indicum L.): A Comprehensive Review

Major lignans of sesame sesamin and sesamolin are benzodioxol--substituted furofurans. Sesamol, sesaminol, its epimers, and episesamin are transformation products found in processed products. Synthetic routes to all lignans are known but only sesamol is synthesized industrially. Biosynthesis of furofuran lignans begins with the dimerization of coniferyl alcohol, followed by the formation of dioxoles, oxidation, and glycosylation. Most genes of the lignan pathway in sesame have been identified but the inheritance of lignan content is poorly understood. Health-promoting properties make lignans attractive components of functional food. Lignans enhance the efficiency of insecticides and possess antifeedant activity, but their biological function in plants remains hypothetical. In this work, extensive literature including historical texts is reviewed, controversial issues are critically examined, and errors perpetuated in literature are corrected. The following aspects are covered: chemical properties and transformations of lignans; analysis, purification, and total synthesis; occurrence in Seseamum indicum and related plants; biosynthesis and genetics; biological activities; health-promoting properties; and biological functions. Finally, the improvement of lignan content in sesame seeds by breeding and biotechnology and the potential of hairy roots for manufacturing lignans in vitro are outlined.

Pinoresinol-4-O-β-D-glucopyranoside: a lignan from prunes (Prunus domestica) attenuates oxidative stress, hyperglycaemia and hepatic toxicity in vitro and in vivo

OBJECTIVES

This study aimed to explore the pharmacological properties of pinoresinol-4-O-β-D-glucopyranoside (PG), isolated from prunes.

METHODS

In-vitro antioxidant activity was assessed using ferric reducing antioxidant power (FRAP) and 2,2'-azino-bis [3-ethylbenzothiazoline-6-sulfonic acid]-diammonium salt (ABTS) assays. In-vivo hepatoprotective activity was evaluated using CCl₄ -induced hepatotoxicity mouse model. The antihyperglycaemic activity was determined in vitro using α-glucosidase and α-amylase inhibiting activity and in vivo using streptozotocin-treated model. Molecular modelling was done on α-amylase, α-glucosidase, aldose reductase and peroxisome proliferator-activated receptor gamma.

KEY FINDINGS

Pinoresinol-4-O-β-D-glucopyranoside showed promising antioxidant activity in FRAP and ABTS assays with total antioxidant capacity equal 418.47 and 1091.3 µmol/g in terms of ascorbic acid, respectively. PG (50 mg/kg b.w.) exhibited a hepatoprotective activity in vivo as it lowered AST and ALT levels. PG showed a potent in-vitro antihyperglycaemic activity as it inhibited α-glucosidase with an IC₅₀ value of 48.13 μg/ml. PG caused a prominent decline in serum glucose level by 37.83% in streptozotocin-treated mice with promising elevation in insulin level of 25.37%. Oxidative stress markers were reduced by PG, and it showed a high fitting on α-amylase and α-glucosidase active sites.

CONCLUSIONS

Pinoresinol-4-O-β-D-glucopyranoside is a natural entity combating oxidative stress, hepatic damage and diabetes.

Lignans' Potential in Pre and Post-onset Type 2 Diabetes Management

INTRODUCTION

Type 2 Diabetes (T2D) cases continue to rise dramatically despite efforts to get people to exercise and eat with a view to health and combatting the cluster of 7 issues (central obesity (elevated waist circumference), hyperglycaemia, hypertension, dyslipidemia, pro-thrombotic state, increased oxidation (including Low-density Lipoprotein (LDL)) and the pro-inflammatory state associated with pre- and post-onset T2D.

BACKGROUND

There are numerous medications available to deal with these seven major issues. However, each medication currently available manages a maximum of two cluster members at a time. Consequently, polypharmacy is frequently required to manage the cluster of seven. Polypharmacy brings with it high financial costs for numerous medications, the risk of poor compliance (particularly so in older patients), side effects and drug interactions. Thus, there is a search for new agents that reduce the high costs and risks of polypharmacy while at the same time combatting three or more of the cluster of seven. There is very limited evidence to suggest that one or more lignans may efficaciously and safely, in the short and long term, manage at least three of the cluster of seven, pre- and post-T2D onset, thus reducing polypharmacy. However, multi-centre, large clinical trials are required before any definitive conclusions about these lignans can be reached regarding their safe and efficacious polypharmacy reduction potential, both long and short-term, in pre and post-onset T2D management.

CONCLUSION

It is concluded that some lignans appear to have the potential to manage at least three members of the cluster of seven in pre- or post-T2D onset and hence reduce polypharmacy but much more investigation is required to confirm if such is the case. At the moment, there is not enough evidence that any of the lignans will, in the long or short term, safely and efficaciously manage the cluster of seven via polypharmacy reduction.

Strategies to enhance the production of pinoresinol and its glucosides by endophytic fungus (Phomopsis sp. XP-8) isolated from Tu-chung bark

To improve the production yield of (+)-pinoresinol (Pin), (+)-pinoresinol monoglucoside (PMG), and (+)-pinoresinol diglucoside (PDG), different methods were conducted, including co-culture with resveratrol-producing Alternaria sp. MG1 spores and addition of Tu-chung in a medium at the start of cultivation, ultrasound treatment (40 kHZ, 10 min) on 5-day culture, and addition of ethanol and sodium butyrate on Day 3, followed by cultivation for an additional period of 2 days. At the end of the cultivation period (5 days), the liquid phase was collected for product analysis. Cells were collected for the determination of gene expression levels and then used in bioconversion using resting cells for another period of 2 days. The liquid phase was measured to determine the output of the target products and the expression levels of the key genes related to the biosynthesis of these compounds. Consequently, co-culture with Alternaria MG1 and addition of Tu-chung bark in the medium efficiently increased Pin, PMG, and PDG production yield in the biosynthesis systems using potato dextrose broth medium and resting cells of Phomopsis sp. XP-8. The key genes related to the biosynthesis of these compounds were significantly upregulated. However, in the majority of cases, the addition of ethanol and sodium butyrate, and ultrasound treatment decreased the production yield of Pin, PMG, and PDG. The change in production yield was not consistently accompanied by a change in gene expression.

Naphthalene glycosides in the Thai medicinal plant Diospyros mollis

This study evaluated methanol extracts from the leaves and branches of the Thai medicinal plant Diospyros mollis (Ebenaceae). Seven triterpenes and 22 aromatic compounds, including five new compounds, were isolated, and their structures were determined. The new compounds had the following structures: diospyrol glycoside (makluoside A, 1), 8,8'-di-O-6-β-D-apiofuranosyl-β-D-glucopyranosyl-6,6'-dimethyl-2,3'-binaphthalene-1-ol-1',4'- dione (makluoside B, 2), and 3-methyl-1,8- naphthalenediol glycosides (makluosides C-E, 3-5). Makluoside B is the first example of a naphthoquinone glycoside that has both a 3-methyl-1,8-naphthalenediol unit and a 5-hydroxy-7-methyl-1,4-naphthoquinone unit. The hyaluronidase inhibitory activity of the isolates was evaluated, revealing that one of the triterpene derivatives possessed moderate inhibitory activity.

Engineering of an H2 O2 auto-scavenging in vivo cascade for pinoresinol production

Pinoresinol is a natural lignan with a high market value that has potential pharmacological and food supplement applications. Pinoresinol is currently isolated from plants, which suffers from low efficiency and yield. To produce pinoresinol from inexpensive and industrially available eugenol, an in vivo enzymatic cascade composed of vanillyl alcohol oxidase and peroxidase was designed, which scavenges H₂ O₂ automatically and eliminates protein purification and cofactor addition. Two peroxidases were screened and identified from Escherichia coli BL21 (DE3), and tested in the enzymatic cascade. To balance the flux, different genetic architectures were constructed by using ePathBrick and fusion gene approaches. Scavenging H₂ O₂ alleviated by-product toxicity and enzyme inhibition, and led to efficient pinoresinol production. Optimization of the reaction conditions achieved a titer of 11.29 g/L pinoresinol. The molar yield and productivity were 52.77% and 1.03 g/(L × h), respectively. The elegant strategy developed herein utilizes the harmful by-product to drive the biosynthetic reaction forward and simultaneously detoxify cells, thereby preventing enzyme inhibition. Biotechnol. Bioeng. 2017;114: 2066-2074. © 2017 Wiley Periodicals, Inc.

Antihyperglycaemic activity of the methanol extract from leaves of Eremophila maculata (Scrophulariaceae) in streptozotocin-induced diabetic rats

OBJECTIVES

This study was designed to evaluate the antihyperglycaemic activity of the methanol leaf extract of Eremophila maculata (EMM) both in vitro and in vivo.

METHODS

The antihyperglycaemic activity was assessed in vitro using differentiated 3T3-L1 adipocytes, whereas in-vivo effect was evaluated in streptozotocin-induced diabetic rats. Chemical profiling of EMM was done using LC-ESI-MS techniques. Molecular modelling experiments of the identified compounds were performed using C-Docker protocol.

KEY FINDINGS

Eremophila maculata slightly enhanced cellular glucose uptake and utilization in vitro by 3.92% relative to the untreated control. A stronger in-vivo effect was observed for EMM and its dichloromethane fraction. A pronounced elevation in serum insulin by 88.89 and 66.67%, respectively, accompanied by an apparent decline in fasting blood glucose (FBG) level by 65.60 and 70.37% comparable to streptozotocin-induced diabetic rats was observed. This effect was stronger than that of the reference drug glibenclamide (GLB). Chemical profiling of EMM revealed that leucoseptoside A, verbascoside, syringaresinol-4-O-β-D-glucopyranoside, pinoresinol-4-O-β-D-glucopyranoside and pinoresinol-4-O-[6″-O-(E)-feruloyl]-β-D-glucopyranoside are the major compounds. Molecular modelling showed that martynoside, verbascoside and phillygenin exhibited the highest inhibition to human pancreatic α-amylase (HPA), maltase glucoamylase (MGAM) and aldose reductase (AR), respectively.

CONCLUSION

Eremophila maculata offers an interesting relatively safer antihyperglycaemic candidate comparable to synthetic analogues.

Phytoestrogen (+)-pinoresinol exerts antitumor activity in breast cancer cells with different oestrogen receptor statuses

Background

Consumption of virgin olive oil (VOO) has been associated with a low breast cancer incidence. Pinoresinol is a phytoestrogen that is typically found in VOO. Considering the role of oestrogen in breast cancer development and progression, we investigated the potential antitumor activity of pinoresinol in breast cancer cells.

Methods

To address this question, we treated MDA-MB-231 (oestrogen receptor [ER] negative) and MCF7 (ER+) human breast tumour cells and MCF10A human mammary epithelial cells (ER-) with different concentrations of pinoresinol. The cytotoxic activity, cell proliferation, cell cycle profile, apoptosis induction, reactive oxygen species production and DNA damage were assessed.

Results

Pinoresinol showed cytotoxic, anti-proliferative and pro-oxidant activity in human breast tumour cells, independent of their oestrogen receptor status. In addition, pinoresinol exerted antioxidant activity and prevented DNA damage associated with oxidative stress in human mammary epithelial cells.

Conclusions

Overall, the results suggest that pinoresinol may have antitumor activity in human breast cancer cells independently of oestrogen receptor status. Furthermore, the results show that the pinoresinol has the typical characteristics of a chemopreventive compound.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-016-1233-7) contains supplementary material, which is available to authorized users.

Three-steps in one-pot: whole-cell biocatalytic synthesis of enantiopure (+)- and (-)-pinoresinol via kinetic resolution

Background

Pinoresinol is a high-value plant-derived lignan with multiple health supporting effects. Enantiomerically pure pinoresinol can be isolated from natural sources, but with low efficiency. Most chemical and biocatalytic approaches that have been described for the synthesis of pinoresinol furnish the racemic mixture. In this study we devised a three-step biocatalytic cascade for the production of enantiomerically pure pinoresinol from the cheap compound eugenol. Two consecutive oxidations of eugenol through vanillyl-alcohol oxidase and laccase are followed by kinetic resolution of racemic pinoresinol by enantiospecific pinoresinol reductases.

Results

The addition of the enantiospecific pinoresinol reductase from Arabidopsis thaliana for kinetic resolution of (±)-pinoresinol to an in vitro cascade involving the vanillyl-alcohol oxidase from Penicillium simplicissimum and the bacterial laccase CgL1 from Corynebacterium glutamicum resulted in increasing ee values for (+)-pinoresinol; however, an ee value of 34 % was achieved in the best case. The ee value could be increased up to ≥99 % by applying Escherichia coli-based whole-cell biocatalysts. The optimized process operated in a one-pot “two-cell” sequential mode and yielded 876 µM (+)-pinoresinol with an ee value of 98 %. Switching the reductase to the enantiospecific pinoresinol lariciresinol reductase from Forsythia intermedia enabled the production of 610 µM (−)-pinoresinol with an ee value of 97 %.

Conclusion

A new approach for the synthesis of enantiomerically pure (+)- and (−)-pinoresinol is described that combines three biotransformation steps in one pot. By switching the reductase in the last step, the whole-cell biocatalysts can be directed to produce either (+)- or (−)-pinoresinol. The products of the reductases’ activity, (−)-lariciresinol and (−)-secoisolariciresinol, are valuable precursors that can also be applied for the synthesis of further lignans.

Electronic supplementary material

The online version of this article (doi:10.1186/s12934-016-0472-0) contains supplementary material, which is available to authorized users.

Bioconversion of Pinoresinol Diglucoside and Pinoresinol from Substrates in the Phenylpropanoid Pathway by Resting Cells of Phomopsis sp.XP-8

Pinoresinol diglucoside (PDG) and pinoresinol (Pin) are normally produced by plant cells via the phenylpropanoid pathway. This study reveals the existence of a related pathway in Phomopsis sp. XP-8, a PDG-producing fungal strain isolated from the bark of the Tu-chung tree (Eucommiaulmoides Oliv.). After addition of 0.15 g/L glucose to Phomopsis sp. XP-8, PDG and Pin formed when phenylalanine, tyrosine, leucine, cinnamic acid, and p-coumaric acid were used as the substrates respectively. No PDG formed in the absence of glucose, but Pin was detected after addition of all these substrates except leucine. In all systems in the presence of glucose, production of PDG and/or Pin and the accumulation of phenylalanine, cinnamic acid, or p-coumaric acid correlated directly with added substrate in a time- and substrate concentration- dependent manner. After analysis of products produced after addition of each substrate, the mass flow sequence for PDG and Pin biosynthesis was defined as: glucose to phenylalanine, phenylalanine to cinnamic acid, then to p-coumaric acid, and finally to Pin or PDG. During the bioconversion, the activities of four key enzymes in the phenylpropanoid pathway were also determined and correlated with accumulation of their corresponding products. PDG production by Phomopsis sp. exhibits greater efficiency and cost effectiveness than the currently-used plant-based system and will pave the way for large scale production of PDG and/or Pin for medical applications.

The Lignan Pinoresinol Induces Nuclear Translocation of DAF-16 in Caenorhabditis elegans but has No Effect on Life Span

The lignan pinoresinol is a constituent of flaxseed, sesame seeds and olive oil. Because of different molecular effects reported for this compound, e.g. antioxidative activity, pinoresinol is suggested to cause positive effects on humans. Because experimental data are limited, we have analysed the effects of the lignan on the nematode Caenorhabditis elegans: in spite of a strong antioxidative capacity detected in an in vitro assay, no antioxidative effects were detectable in vivo. In analogy to this result, no modulation of the sensitivity against thermal stress was detectable. However, incubation with pinoresinol caused an enhanced nuclear accumulation of the transcription factor DAF-16 (insulin/IGF-like signalling pathway). Using a strain with an enhanced oxidative stress level (mev-1 mutant), we clearly see an increase in stress resistance caused by this lignan, but no change in reactive oxygen species. Furthermore, we investigated the effects of pinoresinol on the life span of the nematode, but no modulation was found, neither in wild-type nor in mev-1 mutant nematodes. These results suggest that pinoresinol may exert pharmacologically interesting effects via modulation of the insulin-like signalling pathway in C. elegans as well as in other species like mammals due to the evolutionary conservation of this signalling pathway.

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.

Inhibition of insect glutathione S-transferase (GST) by conifer extracts

Insecticide synergists biochemically inhibit insect metabolic enzyme activity and are used both to increase the effectiveness of insecticides and as a diagnostic tool for resistance mechanisms. Considerable attention has been focused on identifying new synergists from phytochemicals with recognized biological activities, specifically enzyme inhibition. Jack pine (Pinus banksiana Lamb.), black spruce (Picea mariana (Mill.) BSP.), balsam fir (Abies balsamea (L.) Mill.), and tamarack larch (Larix laricina (Du Roi) Koch) have been used by native Canadians as traditional medicine, specifically for the anti-inflammatory and antioxidant properties based on enzyme inhibitory activity. To identify the potential allelochemicals with synergistic activity, ethanol crude extracts and methanol/water fractions were separated by Sephadex LH-20 chromatographic column and tested for in vitro glutathione S-transferase (GST) inhibition activity using insecticide-resistant Colorado potato beetle, Leptinotarsa decemlineata (Say) midgut and fat-body homogenate. The fractions showing similar activity were combined and analyzed by ultra pressure liquid chromatography-mass spectrometry. A lignan, (+)-lariciresinol 9'-p-coumarate, was identified from P. mariana cone extracts, and L. laricina and A. balsamea bark extracts. A flavonoid, taxifolin, was identified from P. mariana and P. banksiana cone extracts and L. laricina bark extracts. Both compounds inhibit GST activity with taxifolin showing greater activity compared to (+)-lariciresinol 9'-p-coumarate and the standard GST inhibitor, diethyl maleate. The results suggested that these compounds can be considered as potential new insecticide synergists.

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

In this study, a series of ursolic acid derivatives were synthesized, and their structures were confirmed. The activity of the synthesized compounds against α-glucosidase was determined in vitro. The results suggested that all compounds have significant inhibitory activity, especially compounds 3-5 and 8, the IC50 values of which were 2.66 ± 0.84, 1.01 ± 0.44, 3.26 ± 0.22, and 3.24 ± 0.21 μM. These compounds were more potent than acarbose (positive control) against α-glucosidase. Kinetic studies were performed to determine the mechanism of inhibition by compounds 3-5 and 8. The kinetic inhibition studies indicated that compound 3 was a non-competitive inhibitor, and the inhibition constant Ki was calculated to be 2.67 ± 0.19 μM. Moreover, the kinetic inhibition studies of compounds 4, 5 and 8 demonstrated that they were mixed-type inhibitors. Furthermore, the actual pharmacological potentials of synthesized compounds 3 and 4 were demonstrated by the reduction of postprandial blood glucose levels in normal Kunming mice. The hypoglycemic effects of these compounds were more evident 30 and 60 min after maltose ingestion (P < 0.05), which was similar to the effect displayed by the positive control, acarbose.

Orthosiphol A from the Aerial Parts of Orthosiphon aristatus is Putatively Responsible for Hypoglycemic Effect via α-Glucosidase Inhibition

An infusion of Orthosiphon aristatus has long been used for diabetes therapy; however, the active principles remained unknown. Herein, we report the identification of the putative agents responsible for this antidiabetic activity using an α-glucosidase-guided isolation. Four flavonoids named sinensetin (1), salvigenin (2), tetramethylscutellarein (3) and 3,7,4′-tri- O-methylkaempferol (4), together with a diterpenoid named orthosiphol A (5), were characterized, based on analysis of their spectroscopic data. Flavonoids 3 and 4 inhibited yeast α-glucosidase with IC50 values of 6.34 and 0.75 mM, respectively, whereas orthosiphol A (5) selectively inhibited intestinal maltase with an IC50 value of 6.54 mM. A kinetic investigation of 5 indicated that it retarded maltase function in a noncompetitive manner.

First Identification of α-Glucosidase Inhibitors from Okra (Abelmoschus Esculentus) Seeds

Infusion of roasted okra seeds has long been consumed in Turkey for diabetes mellitus therapy. Previous reports of a hypoglycemic effect observed in rats administrated with okra seed extract indicated a possible connection with inhibition of intestinal α-glucosidase. An attempt to identify active components was first herein conducted using α-glucosidase-inhibition-guided isolation, yielding two major flavonol glucosides named isoquercetin (2) and quercetin-3- O-β-glucopyranosyl-(1″′ →6″)-glucoside (3). They selectively inhibited rat intestinal maltase and sucrase, in which isoquercetin (2) was 6–10 times more potent than its related diglucoside 3. This result suggested that an increase in hydrophilicity by the additional glucose residue in 3 led to a significant decline in the inhibitory effect and raised the possible involvement of the free 3-OH in exerting the inhibition. Our postulation was evaluated by examining α-glucosidase inhibition of quercetin (1), and the aglycone of 2 and 3, whose 3-OH is free from any glucose moiety. Interestingly, 1 displayed a broad inhibitory effect toward rat intestinal and baker's yeast α-glucosidases, with improved potency. A kinetic study of 1 indicated that it inhibited maltase by two distinct mechanisms, in competitive ( K i 462 μM) and noncompetitive ( K i 2153 μM) manners, whereas the mechanism underlying the inhibition of sucrase was verified as being of a competitive behavior ( K i 218 μM).