Inhibitory effect on α-glucosidase by Adhatoda vasica Nees

Use of human Caco-2 cells and HPAE-PAD for α-glucosidase assay

To measure α-glucosidase activity, rat intestinal acetone powder is commonly used as a source of α-glucosidase, and the mutarotase-glucose oxidase (GOD) methods commonly used to quantitate glucose produced by enzymatic hydrolysis of the substrates. In this study, we compared human Caco-2 cell extracts with rat intestinal acetone powder extracts. We also compared high-performance anion-exchange chromatography with pulsed amperometric detection (HPAE-PAD) with the mutarotase-GOD method. The sensitivity of HPAE-PAD was higher than that of mutarotase-GOD. The glucose concentration quantified by HPAE-PAD was similar to that quantified using the mutarotase-GOD method. In the maltase reaction, 1-deoxynojirimycin (1-DNJ) exerted a more potent inhibitory effect on human enzymes than on rat enzymes. This order was reversed during the sucrase reaction. These results suggested that the combined use of Caco-2 cell extracts and HPAE-PAD is advantageous for use in α-glucosidase-related basic research.

Exploring the pharmacological and chemical aspects of pyrrolo-quinazoline derivatives in Adhatoda vasica

Adhatoda or Justicia is one of the biggest and complex genera of the Acanthaceae family. Adhatoda vasica is commonly known as 'Adosa'. It is an ayurvedic medicine with a medicinal history of more than a thousand years in India. Traditionally, it is used to treat cough, asthma, phlegm, bleeding hemorrhoids, for both adults and youth. This plant possesses antiarthritis, antiseptic, antimicrobial, anti-tuberculosis, anti-inflammatory and abortifacient properties. Alkaloids are the major phytoconstituents present in the plant in the form of pyrrolo-quinazoline derivatives viz vasicine, vasicinone, vasicinol, adhatodine, adhatodinine, adhavasinone and anisotine etc. The asserted objectives are to conduct a systematic review on the phytochemistry, pharmacology and traditional uses of A. vasica, as well as highlighting the challenges found in the research. This will promote the utilization of A. vasica at extract level and further development of new drug leads based on the compounds isolated and used for treatment of various ailments. The present review covers the literature survey from 1888 to 2023. The relevant data has been collected from various peer-reviwed journals, and books via Sci-Finder, PubMed, Science Direct, Google Scholar, EBSCO, online electronic journals, SpringerLink and Wiley. This paper aims to present a systematic review of known traditional applications, pharmacological and chemical aspects in Adhatoda vasica.

Beneficial Effects of Natural Alkaloids from Berberis glaucocarpa as Antidiabetic Agents: An In Vitro, In Silico, and In Vivo Approach

Diabetes, also known as diabetes mellitus (DM), is a metabolic disorder characterized by an abnormal rise in blood sugar (glucose) levels brought on by a complete or partial lack of insulin secretion along with corresponding changes in the metabolism of lipids, proteins, and carbohydrates. It has been reported that medicinal plants play a pivotal role in the treatment of various ailments such as diabetes mellitus, dyslipidemia, and hypertension. The current study involved exploring the acute toxicity and in vivo antidiabetic activity of berberine (WA1), palmatine (WA2), and 8-trichloromethyl dihydroberberine (WA3) previously isolated from Berberis glaucocarpa Stapf using a streptozotocin (STZ)-induced diabetic rat model. Body weight and blood glucose level were assessed on a day interval for 4 weeks. Biochemical parameters, antioxidant enzymes, and oxidative stress markers were also determined. In an acute toxicity profile, the WA1, WA2, and WA3 were determined to be nontoxic up to 500 mg/kg (b.w). After the second and third weeks of treatment (14 and 21 days), the blood glucose levels in the WA1-, WA2-, and WA3-treated groups were significantly lower than those in the diabetic control group (476.81 ± 8.65 mg/dL, n = 8, P < 0.001). On the 21st day, there was a decrease in the blood glucose level and the results obtained were 176.33 ± 4.69, 197.21 ± 4.80, and 161.99 ± 4.75 mg/dL (n = 8, P < 0.001) for WA1, WA2, and WA3 at 12 mg/kg, respectively, as opposed to the diabetic control group (482.87 ± 7.11 mg/dL, n = 8, P < 0.001). Upon comparison with the diabetic group at the end of the study (28 days), a substantial drop in the glucose level of WA3 at 12 mg/kg (110.56 ± 4.11 mg/dL, n = 8, P < 0.001) was observed that was almost near the values of the normal control group. The treated groups (WA1, WA2, and WA3) treated with the samples displayed a significant decline in the levels of HbA1c. Treatment of the samples dramatically lowered the lipid level profile. In groups treated with samples, plasma levels of triglycerides, total cholesterol, and LDL were significantly lowered [F (5, 42) = 100.6, n = 8, P < 0.001]; these levels were also significantly decreased [F (5, 42) = 129.6 and 91.17, n = 8, P < 0.001]. In contrast to the diabetes group, all treated groups had significantly higher HDL levels [F (5, 42) = 15.46, n = 8, P < 0.001]. As a result, hypolipidemic activity was anticipated in the samples. In addition to that, the activity of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) was considerably elevated in the groups treated with the sample compared to the diabetic control group (n = 8, P < 0.001).

In Vitro Anti-Diabetic, Anti-Inflammatory, Antioxidant Activities and Toxicological Study of Optimized Psychotria malayana Jack Leaves Extract

Psychotria malayana Jack (Family: Rubiaceae, local name: Salung) is a traditional herb used to treat diabetes. A previous study by our research group demonstrated that P. malayana methanolic and water extract exhibits significant potential as an effective agent for managing diabetes. Further research has been performed on the extraction optimization of this plant to enhance its inhibitory activity against α-glucosidase, a key enzyme associated with diabetes, and to reduce its toxicity. The objectives of this study are to evaluate the anti-diabetic, anti-inflammatory, and antioxidant properties of the optimized P. malayana leaf extract (OE), to evaluate its toxicity using a zebrafish embryo/larvae model, and to analyze its metabolites. The anti-diabetic effects were assessed by investigating α-glucosidase inhibition (AGI), while the inflammation inhibitory activity was performed using the soybean lipoxygenase inhibitory (SLOXI) test. The assessment of antioxidant activity was performed utilizing FRAP and DPPH assays. The toxicology study was conducted using the zebrafish embryo/larvae (Danio rerio) model. The metabolites present in the extracts were analyzed using GC-MS and LC-MS. OE demonstrated significant AGI and SLOXI activities, represented as 2.02 and 4.92 µg/mL for IC50 values, respectively. It exhibited potent antioxidant activities as determined by IC50 values of 13.08 µg/mL (using the DPPH assay) and 95.44 mmol TE/mg DW (using the FRAP assay), and also demonstrated an LC50 value of 224.29 µg/mL, which surpasses its therapeutic index of 111.03. OE exhibited a higher therapeutic index compared to that of the methanol extract (13.84) stated in the previous state of the art. This suggests that OE exhibits a lower level of toxicity, making it safer for use, and has the potential to be highly effective in its anti-diabetic activity. Liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) demonstrated the presence of several constituents in this extract. Among them, several compounds, such as propanoic acid, succinic acid, D-tagatose, myo-inositol, isorhamnetin, moracin M-3'-O-β-D-glucopyranoside, procyanidin B3, and leucopelargonidin, have been reported as possessing anti-diabetic and antioxidant activities. This finding offers great potential for future research in diabetes treatment.

Alkaloidal Phytoconstituents for Diabetes Management: Exploring the Unrevealed Potential

The main characteristic feature of diabetes mellitus is the disturbance of carbohydrate, lipid, and protein metabolism, which results in insulin insufficiency and can also lead to insulin resistance. Both the acute and chronic diabetic cases are increasing at an exponential rate, which is also flagged by the World Health Organization (WHO) and the International Diabetes Federation (IDF). Treatment of diabetes mellitus with synthetic drugs often fails to provide desired results and limits its use to symptomatic treatment only. This has resulted in the exploration of alternative medicine, of which herbal treatment is gaining popularity these days. Owing to their safety benefits, treatment compliance, and ability to exhibit effects without disturbing internal homeostasis, research in the field of herbal and ayurvedic treatments has gained importance. Medicinal phytoconstituents include micronutrients, amino acids, proteins, mucilage, critical oils, triterpenoids, saponins, carotenoids, alkaloids, flavonoids, phenolic acids, tannins, and coumarins, which play a dynamic function in the prevention and treatment of diabetes mellitus. Alkaloids found in medicinal plants represent an intriguing potential for the inception of novel approaches to diabetes mellitus therapies. Thus, this review article highlights detailed information on alkaloidal phytoconstituents, which includes sources and structures of alkaloids along with the associated mechanism involved in the management of diabetes mellitus. From the available literature and data presented, it can be concluded that these compounds hold tremendous potential for use as monotherapies or in combination with current treatments, which can result in the development of better efficacy and safety profiles.

Anti-diabetic Potential of Indigenous Medicinal Plants of Cholistan Desert, Pakistan: A Review

Cholistan Desert is a sandy desert located in southern Punjab, Pakistan. The area is rich in more than 64 medicinal plants among 138 plant species. It is noteworthy that this remote desert lacks modern health care facilities and its inhabitants are dependent on locally-available plant species for the treatment of acute and chronic illnesses. Medicinal plants, traditionally have been ideal sources of remedies for the management of many non-communicable diseases; most modern prescriptions drugs have their origins from plants. Diabetes is increasing at an alarming rate in the past few decades. Whereas medicinal plants are used globally, the specific properties of only a few have been identifies scientifically. Similarly, little scientific evidence exists that confirms the efficacy of the medicinal plants of this region for diabetes management. Ethnobotanical studies show that locally-available medicinal plants do have anti-diabetic potential. We reviewed the medicinal properties of 36 of these plants. Several ingredients derived from these plants have chemical constituents that demonstrate anti-diabetic activity, thereby validating their importance for the management of diabetes.

Roles of Alkaloids from Medicinal Plants in the Management of Diabetes Mellitus

Medicinal plants play a fundamental part in health sectors via the management of different infectious diseases because of their wide plenitude wellspring of bioactive phytochemicals. Research activities on them have got attention throughout the world in the present days in search of low-cost and safe compounds for the management of diabetes. This is the literature-based analysis of alkaloids from medicinal plants in preventive or treatment approaches to diabetes. The most abundant and diversified group of secondary metabolites, i.e., alkaloids, show antidiabetic activity through the inhibition of enzymes (α-amylase, α-glucosidase, aldose reductase, dipeptidyl peptidase-IV, and protein tyrosine phosphatase-1B); inhibition of advanced glycation end products; increment of insulin secretion and its sensitivity; enhancement of glucose uptake; and their antioxidant ability. The study is useful for the examination of dynamic alkaloids for the advancement of a new medication for mankind.

Phenolics from Physalis peruviana fruits ameliorate streptozotocin-induced diabetes and diabetic nephropathy in rats via induction of autophagy and apoptosis regression

The objective of our study was to evaluate the effect of Physalis peruviana L. fruits in the management of diabetes and diabetic nephropathy in relation to its metabolic profile. In-vitro α-amylase, β-glucosidase, and lipase inhibition activities were assessed for the ethanolic extract (EtOH) and its subfractions. Ethyl acetate (EtOAc) fraction showed the highest α-amylase, β-glucosidase, and lipase inhibition effect. In vivo antihyperglycemic testing of EtOAc in streptozotocin (STZ)-induced diabetic rats showed that it decreased the blood glucose level, prevented the reduction in body weight, improved serum indicators of kidney injury (urea, uric acid, creatinine), and function (albumin and total protein). EtOAc increased autophagic parameters (LC3B, AMPK) and depressed mTOR contents. Histopathology revealed that EtOAc ameliorated the pathological features and decreased the glycogen content induced by STZ. The immunohistochemical analysis showed that EtOAc reduced P53 expression as compared to the STZ-diabetic group. UPLC-ESI-MS/MS metabolite profiling of EtOAc allowed the identification of several phenolic compounds. Among the isolated compounds, gallic acid, its methylated dimer and the glycosides of quercetin had promising α-amylase and β-glucosidase inhibition activity. The results suggest that the phenolic-rich fraction has a protective effects against diabetic nephropathy presumably via enhancing autophagy (AMPK/mTOR pathway) and prevention of apoptosis (P53 suppression).

Benzenesulfonamide derivatives as potent acetylcholinesterase, α-glycosidase, and glutathione S-transferase inhibitors: biological evaluation and molecular docking studies

Sulfonamide derivatives exhibit a wide biological activity and can function as potential medical molecules in the development of a drug. Studies have reported that the compounds have an effect on many enzymes. In this study, the derivatives of amine sulfonamide (1i-11i) were prepared with reduced imine compounds (1-11) with NaBH4 in methanol. The synthesized compounds were fully characterized by spectral data and analytical. The effect of the synthesized derivatives on acetylcholinesterase (AChE), glutathione S-transferase (GST) and α-glycosidase (α-GLY) enzymes were determined. For the AChE and α-GLY, the most powerful inhibition was observed on 10 and 10i series with KI value in the range 2.26 ± 0.45-3.57 ± 0.97 and 95.73 ± 13.67-102.45 ± 11.72 µM, respectively. KI values of the series for GST were found in the range of 22.76 ± 1.23-49.29 ± 4.49. Finally, the compounds have a stronger inhibitor in lower concentrations by the attachment of functional electronegative groups such as two halogens (-Br and -CI), -OH to the benzene ring and -SO2NH2. The crystal structures of AChE, α-GLY, and GST in complex with selected derivatives 4 and 10 show the importance of the functional moieties in the binding modes within the receptors.Communicated by Ramaswamy H. Sarma.

Antidiabetic Activity of Extract Combination of Orthosiphon aristatus and Oryza sativa L. var glutinosa

Traditionally and scientifically, research has shown that Orthosiphon aristatus and Oryza sativa L. var. glutinosa have antidiabetic activity. The combination of two medicinal plants can increase their biological activity. This study aimed to determine the antidiabetic activity of O. aristatus and O. sativa L. var. glutinosa on single and combined extracts. Phytochemical screening of the single extract was done qualitatively. The α-glucosidase inhibitory method was used as an antidiabetic activity. The results showed that every extract contained alkaloids, steroids/triterpenoids, flavonoids, tannins, quinones, and coumarins. A single extract of O. sativa L. var glutinosa, O. aristatus, and their combinations (1:1, 1:2, and 2:1) had an α-glucosidase enzyme inhibitory activity with an IC50 value of 67.82, 80.93, 73.81, 88.72, and 61.51 µg/ml, respectively. The combination shows that the ratio of 1:1 was nearly additive, 1:2 was slight to moderate antagonism, and 2:1 was moderate to slight synergism. The combination of 96% ethanol extract of O. sativa L. var. glutinosa and O. aristatus in a ratio of 2:1 was the most effective in increasing its inhibitory activity.

Phytochemical, antimicrobial, antioxidant and enzyme inhibitory potential of medicinal plant Dryopteris ramosa (Hope) C. Chr

Background

Dryopteris ramosa has numerous potentials uses in the treatment of different maladies as old traditional medication. The fronds of D. ramose are edible and orally administered for producing antibiotic effect. They are also used as astringent and febrifuge, and as a pesticide.

Methods

Extraction of fronds of D. ramosa using solvents of increasing polarity, namely, ethyl acetate, methanol and water were tested for phytochemical (qualitative tests, GC-MS), antimicrobial (well method), antioxidant (DPPH), antifungal (tube dilution), cytotoxic activity (brine shrimps lethality assay) and LOX and COX inhibitory activities were performed using standard methods.

Results

The phytochemical analysis of the crude methanolic extract revealed that the fronds are rich in flavonoids, alkaloids, saponins, tannins, glycosides and triterpenoids. The total flavonoid content of the ethyl acetate fraction was 46.28 μg QE/mg extract. The GC-MS analysis revealed nine major compounds that constituted the crude drug and potentially had a role in reported activities. The crude extract was the most active amongst all the fractions against the bacterial and fungal strains used such that it inhibited the growth of P. aeruginosa with a zone of 13 mm and a MIC value of 16 μg/ml as compared to the standard cefixime, which inhibited the zone by only 10 mm and a MIC value of 32 μg/ml. The highest antioxidant potential in DPPH assay was shown by the crude extract with 91.948% free radical scavenging activity. The bring shrimps lethality potential of the crude extract was the highest, with a LD₅₀ value of 47.635 μg/ml. The ethyl acetate fraction inhibits 91.36% of alpha glucosidase enzyme at a concentration of 0.5 mg/ml. In case of acetylcholine esterase inhibition assay, the methanol fraction inhibits 58.26% of the enzyme activity. Similarly, for butyrylcholine esterase inhibition, the maximum inhibitory effect was seen in the methanol fraction, with a percentage inhibition of 47.32%.

Conclusion

These test results support traditional medicinal uses of the plant. Dryopteris ramosa could be imperative for being used as a therapeutic agent and the medicinal importance of this plant should be further investigated.

Glycoside Hydrolases and Non-Enzymatic Glycation Inhibitory Potential of Viburnum opulus L. Fruit-In Vitro Studies

Phytochemicals of various origins are of great interest for their antidiabetic potential. In the present study, the inhibitory effects against carbohydrate digestive enzymes and non-enzymatic glycation, antioxidant capacity, and phenolic compounds composition of Viburnum opulus L. fruits have been studied. Crude extract (CE), purified extract (PE), and ethyl acetate (PEAF) and water (PEWF) fractions of PE were used in enzymatic assays to evaluate their inhibitory potential against α-amylase with potato and rice starch as substrate, α-glucosidase using maltose and sucrose as substrate, the antioxidant capacity (ABTS, ORAC and FRAP assays), antiglycation (BSA-fructose and BSA-glucose model) properties. Among four tested samples, PEAF not only had the highest content of total phenolics, but also possessed the strongest α-glucosidase inhibition, antiglycation and antioxidant activities. UPLC analysis revealed that this fraction contained mainly chlorogenic acid, proanthocyanidin oligomers and flavalignans. Contrary, the anti-amylase activity of V. opulus fruits probably occurs due to the presence of proanthocyanidin polymers and chlorogenic acids, especially dicaffeoylquinic acids present in PEWF. All V. opulus samples have an uncompetitive and mixed type inhibition against α-amylase and α-glucosidase, respectively. Considering strong anti-glucosidase, antioxidant and antiglycation activities, V. opulus fruits may find promising applications in nutraceuticals and functional foods with antidiabetic activity.

Anti-inflammatory effect of herbal traditional medicine extract on molecular regulation in allergic asthma

Asthma is an important global health problem, and the main cause of asthma is allergic reaction and immune system dysregulation. Airway inflammation causes bronchial narrowing, and goblet cell hyperplasia leads to mucus hypersecretion that leads to airflow obstruction and difficulty breathing. The Th2 cytokines can induce allergic asthma. Camellia, Adhatoda, and Glycyrrhiza are the traditional medicines that are used in some countries. In the current study, we evaluated three herbal extracts on airway inflammatory responses in asthmatic mice. The asthma model was induced in mice that were divided into 6 groups: Phosphate-buffered saline (PBS) group, ovalbumin (OVA) group, OVA-budesonide group, OVA-Glycyrrhiza group, OVA-Camellia group, and OVA-Adhatoda group. Measurements of IL-4, IL-5, IL-13, glutamate oxaloacetate transaminase (GOT), glutamic pyruvic transaminase (GPT), IgE, histamine, percentages of eosinophils in bronchoalveolar lavage fluid (BALf), gene expression of COX-2, CCL24, CCL11, eotaxin, and histopathological study of lung were done. Adhatoda significantly attenuated the IL-4, IgE, and histamine levels. Glycyrrhiza attenuated the levels of IL-5, IL-13, GTP, GOT (on day 51), mRNA expression of eotaxin, CCL24, CCL11, and COX-2, eosinophil infiltration, mucus secretion, and goblet cell hyperplasia. Camellia decreased IL-13, GTP, COX-2 mRNA expression, mucus secretion, and goblet cell hyperplasia on day 31 and 51. We evaluated effect of three plants on allergic bio-factors. Glycyrrhiza as main anti-inflammatory treatment, Adhatoda as anti-allergic, and Camellia as anti-mucus releasing treatment can be used in attacks of allergic asthma.

Kinetic analysis of inhibition of α-glucosidase by leaf powder from Morus australis and its component iminosugars

Abbreviations

1-DNJ: 1-deoxynojirimycin; GAL-DNJ: 2-O-α-D-galactopyranosyl-DNJ

Indian Traditional medicinal plants as a source of potent Anti-diabetic agents: A Review

Objective

The present review aims to provide an overview of traditional medicinal plants known to be of anti-diabetic potential.

Methods

A literature search was conducted using the scientific databases including PubMed, EMBASE and google scholar and a total of fifty herbs have been described and their possible mechanism of anti-diabetic action has been mentioned. Among them, in-depth discussion on five most potent anti-diabetic herbs has been provided with respect to their mechanism of action, in-vivo studies and clinical efficacies.

Results

The present review has highlighted the usefulness of the herbal source for the treatment and management of diabetes mellitus. With the help of previous literature published on In-vivo animal studies and human clinical studies; the effectiveness of Gymnema sylvestre, Momordica charantia, Trigonella foenum graecum, Tinospora cordifolia and Curcuma longa in the treatment and management of Diabetes has been proved.

Conclusion

Based on this review it can be concluded that herbs can serve as more efficient, safer, and cost-effective adjuvant therapy in the management and treatment of diabetes. Further investigations mainly focusing on the isolation of phytocompounds from these herbs can lead to the discovery of newer antidiabetic agents.

Enhancement of biochemical aspects of lipase adsorbed on halloysite nanotubes and entrapped in a polyvinyl alcohol/alginate hydrogel: strategies to reuse the most stable lipase

Entrapment of halloysite nanotubes (HNTs) loaded with enzyme, into a polymer matrix (PVA/Alg), is a way to produce an environment surrounding the adsorbed enzyme molecules which improves the enzyme properties such as storage and operational stability. Hence, in this study, we optimised the factors affecting lipase adsorption onto halloysite nanotubes including halloysite amounts (5, 42.5 and 80 mg), lipase concentrations (30, 90 and 150 µg/ml), temperatures (5, 20 and 35 °C) and adsorption times (30, 165 and 300 min). The optimal conditions were determined as an halloysite amount of 50 to 80 mg, a lipase concentration of 30 to 57 μg/ml, an adsorption temperature of 20 °C and an adsorption time of 165 min, which resulted in a specific activity and adsorption efficiency of 15,000 (U/g protein) and 70%, respectively. Then, lipase adsorbed under optimal conditions was entrapped in a PVA/Alg hydrogel. The formation mechanism of immobilized lipase was investigated by FESEM and FTIR. Subsequent entrapment of adsorbed lipase improved the lipase storage and operational stability. K_m, V_max, K_cat and K_cat/K_m values showed an increase in the entrapped HNT-lipase performance in comparison with the free and adsorbed lipase.

Anti-diabetic potential of plant alkaloids: Revisiting current findings and future perspectives

Diabetes mellitus (DM) is a chronic metabolic disease which causes millions of death all over the world each year, and its incidence is on increase. The most prevalent form, type 2 DM, is characterized by insulin resistance and β-cell dysfunction, whereas type 1 DM is due to insulin deficiency as a result of β-cell destruction. Various classes of synthetic drugs have been developed to regulate glucose homeostasis and combat the development of late-diabetic complications. However, several of these chemical agents are either sub-optimal in their effect and/or may have side effects. Biologically, alkaloids unveiled a wide range of therapeutic effects including anti-diabetic properties. The chemical backbones of these compounds have the potential to interact with a wide range of proteins involved in glucose homeostasis, and thus they have received increasing attention as reliable candidates for drug development. This review sets out to investigate the anti-diabetic potential of plant alkaloids (PAs), and therefore, scientific databases were comprehensively screened to highlight the biological activity of 78 PAs with a considerable anti-diabetic profile. There are not enough clinical data available for these phytochemicals to follow their fingerprint in human, but current studies generally recommending PAs as potent α-glucosidase inhibitors. Except for some classes of monoterpene alkaloids, other compounds showed similar features as well as the presently available anti-diabetic drugs such as amino sugars and other relevant drugs. Moreover, the evidence suggests that PAs have the potential to be used as alternative additives for the treatment of DM, however, further in vitro and in vivo studies are needed to validate these findings.

Dietary Phytonutrients in the Prevention of Diabetes-related Complications

BACKGROUND

The increasing prevalence of reported cases of diabetes has evidently become a major global public health concern. Although diabetes management is possible by the administration of synthetic anti-diabetic agents, there are profound side-effects associated with their long-term usage. Hence there is a demand for safer alternatives which could be possibly formulated using specific yet common phytonutrients.

OBJECTIVES

The main objective of this review is to describe the cellular mechanisms of phytonutrients as an alternative to commercially available synthetic anti-diabetic agents in the management of diabetes and related complications. Furthermore, the clinical evidence that supports this view is also highlighted.

METHODOLOGY

An in-depth review of published literature was carried out to identify the most promising phytonutrients in the management of diabetes and related complications.

RESULTS

A number of phytonutrients are reported to be potential anti-diabetic agents. Few examples include biguanides, resveratrol, lycopene, thymoquinone and quercetin. However, suitable formulations using these phytonutrients and their clinical trials are still underway. Most of the reported findings focus on one aspect of several biochemical processes e.g. enhancement of glucose utilization, antioxidation, induction of insulin production, antiglycation, etc. An in-depth study of phytonutrients with respect to functional, immunological as well as biochemical factors suggesting their efficacy, as well as safety in the management of diabetes, is rarely reported.

CONCLUSION

Our study thus highlights the abundance of clinical evidence of the efficiency of phytonutrients, and at the same time, the scarcity of clinically approved and marketed phytonutrients, as drugs, for the management of diabetes and related complications.

Alpha Glucosidase Inhibitory Activities of Plants with Focus on Common Vegetables

Type-2 diabetes mellitus is one of the most prevalent metabolic diseases in the world, and is characterized by hyperglycemia (i.e., high levels of glucose in the blood). Alpha-glucosidases are enzymes in the digestive tract that hydrolyze carbohydrates into glucose. One strategy that has been developed to treat type-2 diabetes is inhibition of the activity of alpha-glucosidases using synthetic drugs. However, these inhibitors are usually associated with gastrointestinal side effects. Therefore, the development of inhibitors from natural products offers an alternative option for the control of hyperglycemia. In recent years, various studies have been conducted to identify alpha-glucosidases inhibitors from natural sources such as plants, and many candidates have transpired to be secondary metabolites including alkaloids, flavonoids, phenols, and terpenoids. In this review, we focus on the alpha-glucosidases inhibitors found in common vegetable crops and the major classes of phytochemicals responsible for the inhibitory activity, and also as potential/natural drug candidates for the treatment of type-2 diabetes mellitus. In addition, possible breeding strategies for production of improved vegetable crops with higher content of the inhibitors are also described.

Antidiabetic potential of Asparagus racemosus Willd leaf extracts through inhibition of α-amylase and α-glucosidase

The aim of this work was to evaluate the inhibitory activities of different extracts of Asparagus racemosus Willd on α - amylase and α - glucosidase at varying concentrations. Diabetes mellitus is a clinical condition characterized by hyperglycaemia in which an elevated amount of glucose circulates in the blood plasma. α - amylase and α - glucosidase inhibitors are used to achieve greater control over hyperglycemia in type 2 diabetes mellitus. This study is to treat the diabetes using natural resources. We aimed to evaluate of Asparagus racemosus Willd by digestive enzymes inhibitory activity. n-hexane, chloroform, ethyl acetate, methanol, and aqueous was used to extract the root of the Asparagus racemosus Willd. The different extracts were then used to study its digestives enzymes activity α-amylase and α - glucosidase inhibitory activity. The significant inhibitory effect of α-amylase and α - glucosidase enzyme and exhibited lower inhibitory activity than acarbose was extracted by the ethyl acetate and aqueous extracts of the plant. Flavonoids, Tannins and phenolic, Saponins, Amino acids, Protein are the major phytochemical constituents present. The total flavonoid content plant extracts of ethyl acetate and aqueous showed dose dependent 23.45 ± 1.33 mg rutin equivalent/g and 25.81 ± 0.82 mg rutin equivalent/g respectively. The total triterpenoids content plant extracts of ethyl acetate, aqueous showed dose dependent 109.8 ± 5.6 mg ursolic acid/g and 95.6 ± 7.5 mg ursolic acid/g respectively. The antidiabetic potential and to develop medicinal preparations and nutraceuticals and function foods for diabetes has revealed.

In vitro biotechnological advancements in Malabar nut (Adhatoda vasica Nees): Achievements, status and prospects

Adhatoda vasica Nees, belonging to family Acanthaceae, is a well-known medicinal plant. It is endorsed for its pyrroloquinazoline alkaloids and its derivatives, such as vasicine and vasicinone. Germinating A. vasica seeds is a tedious task; on that account, vegetative propagation is the preferred method for its multiplication. For rapid and large-scale multiplication, germplasm conservation as well as secondary metabolites production, in vitro culture of A. vasica was preferred over conventional propagation by several researchers; however, some major applications of this tissue culture technique are still awaiting to undergo extensive research. The present review, for the first time, illustrates all the major achievements associated with in vitro regeneration of A. vasica, reported till date and highlights the future prospects.

Evidences for diabetes and insulin mimetic activity of medicinal plants: Present status and future prospects

Diabetes mellitus (DM) is a considerable systemic metabolic disorder to exhibit various metabolic and cardiovascular disorders, mainly hyperglycemia. The global projected estimate of diabetes in 2030 will be about 439 million adults, out of which 300 million expected are of type-2 diabetes mellitus (T2DM). The present knowledge revealed responsible factors, occurrence and mechanism of these factors involved in the DM diseases. Hence, the aim of this review is to address and summarize the causes, plant resources, importance, present status and future programmes for diabetes control. The present review answers the contemporary present questions raised in the scientific field on DM. Two major problems are explained in detail about the autoimmune attack or dysfunction of β-cell and insulin resistance involved for Type 1 and Type 2 DM, respectively. Though there are various approaches to reduce the ill effects of diabetes and its secondary complications, many preferred herbal formulations due to lesser side effects and low cost. For this reason still it is getting increased attention in searching antidiabetic medicinal plants for hot research and to develop targeted medicine. Recurrence of islet autoimmunity lesson from pancreatic islet cell transplantation to cure T1D was outlined. With these highlights, the review summarizes the current knowledge on diabetes occurrence, factors (environmental and genetics), and types (I, II, gestation, and secondary DM), antidiabetic plants, sources for insulin mimetic plant principle compounds and their target mechanism with current and future trusted research areas for controlling of DM.

Antidiabetic plant-derived nutraceuticals: a critical review

Diabetes mellitus (DM) is one of the major health problems in the world, especially amongst the urban population. Chemically synthesized drugs used to decrease the ill effects of DM and its secondary complications cause adverse side effects, viz., weight gain, gastrointestinal disturbances, and heart failure. Currently, various other approaches, viz., diet control, physical exercise and use of antidiabetic plant-derived molecules/foods are advocated to manage DM, as they are economical with fewer or no side effects. This review mainly focuses on antidiabetic plants, chemically characterized plant molecules and plant-based foods in the treatment of DM. Very little science-based evidence is available on the mechanism of action of plant-derived food molecules on the DM targets. Critical DM targets include α-amylase, α-glucosidase, DPP-IV, aldose reductase, PPAR-γ, AMP kinase and GLUT4. In-depth studies carried out on a few of those targets with specific mechanisms of action are addressed in this review. This review may help future researchers in identifying a right plant molecule to treat DM or to develop food formulations for DM management.

In Silico Study of Alkaloids as α-Glucosidase Inhibitors: Hope for the Discovery of Effective Lead Compounds

α-Glucosidase (extinction coefficient 3.2.1.20) is a primary carbohydrate metabolizing enzyme that acts on the 1-4 associated α-glucose residues. The inhibition of α-glucosidase slows down the process of carbohydrate digestion and avoids postprandial hyperglycemia, which is a major cause of chronic diabetes-associated complication. This study was designed to evaluate the binding capacity of isolated alkaloids with targeted receptor. For this purpose, the three-dimensional tertiary structure of the α-glucosidase was generated by using the Molecular Operating Environment (MOE). The generated model was then validated by using the RAMPAGE and ERRAT server. The molecular docking of 37 alkaloids along with standard acarbose and miglitol reported as a α-glucosidase inhibitor was performed via MOE-Dock implemented in MOE software to find the binding modes of these inhibitors. The results showed that compound 17 (oriciacridone F) and 24 (O-methylmahanine) demonstrated marked interaction with active residues and were comparable to standard inhibitors. In short, this study provided computational background to the reported α-glucosidase inhibitors and thus further detail studies could lead to novel effective compounds.

In vitro and in vivo metabolism and inhibitory activities of vasicine, a potent acetylcholinesterase and butyrylcholinesterase inhibitor

Vasicine (VAS), a potential natural cholinesterase inhibitor, exhibited promising anticholinesterase activity in preclinical models and has been in development for treatment of Alzheimer’s disease. This study systematically investigated the in vitro and in vivo metabolism of VAS in rat using ultra performance liquid chromatography combined with electrospray ionization quadrupole time-of-flight mass spectrometry. A total of 72 metabolites were found based on a detailed analysis of their ¹H- NMR and ¹³C NMR data. Six key metabolites were isolated from rat urine and elucidated as vasicinone, vasicinol, vasicinolone, 1,2,3,9-tetrahydropyrrolo [2,1-b] quinazolin-3-yl hydrogen sulfate, 9-oxo-1,2,3,9-tetrahydropyrrolo [2,1-b] quinazolin-3-yl hydrogen sulfate, and 1,2,3,9-tetrahydropyrrolo [2,1-b] quinazolin-3-β-D-glucuronide. The metabolic pathway of VAS in vivo and in vitro mainly involved monohydroxylation, dihydroxylation, trihydroxylation, oxidation, desaturation, sulfation, and glucuronidation. The main metabolic soft spots in the chemical structure of VAS were the 3-hydroxyl group and the C-9 site. All 72 metabolites were found in the urine sample, and 15, 25, 45, 18, and 11 metabolites were identified from rat feces, plasma, bile, rat liver microsomes, and rat primary hepatocyte incubations, respectively. Results indicated that renal clearance was the major excretion pathway of VAS. The acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities of VAS and its main metabolites were also evaluated. The results indicated that although most metabolites maintained potential inhibitory activity against AChE and BChE, but weaker than that of VAS. VAS undergoes metabolic inactivation process in vivo in respect to cholinesterase inhibitory activity.

Enzyme inhibition, antioxidant and immunomodulatory activities, and brine shrimp toxicity of extracts from the root bark, stem bark and leaves of Terminalia macroptera

ETHNOPHARMACOLOGICAL RELEVANCE

The root bark, stem bark and leaves of Terminalia macroptera have been traditionally used against a variety of ailments such as wounds, hepatitis, malaria, fever, cough, and diarrhea as well as tuberculosis and skin diseases in African folk medicine. Boiling water extracts of Terminalia macroptera, administered orally, are the most common preparations of this plant used by the traditional healers in Mali. This study aimed to investigate the inhibition of the activities of α-glucosidase, 15-lipoxygenase and xanthine oxidase, DPPH scavenging activity, complement fixation activity and brine shrimp toxicity of different extracts obtained by boiling water extraction (BWE) and by ASE (accelerated solvent extraction) with ethanol, ethanol-water and water as extractants from different plant parts of Terminalia macroptera.

MATERIALS AND METHODS

27 different crude extracts were obtained by BWE and ASE from root bark, stem bark and leaves of Terminalia macroptera. The total phenolic and carbohydrate contents, enzyme inhibition activities (α-glucosidase, 15-lipoxygenase and xanthine oxidase), DPPH scavenging activity, complement fixation activity and brine shrimp toxicity of these extracts were evaluated. Principal component analysis (PCA) was applied for total biological activities evaluation.

RESULTS

Several of the extracts from root bark, stem bark and leaves of Terminalia macroptera obtained by BWE and ASE showed potent enzyme inhibition activities, radical-scavenging properties and complement fixation activities. None of the extracts are toxic against brine shrimp larvae in the test concentration. Based on the results from PCA, the ASE ethanol extracts of root bark and stem bark and the low molecular weight fraction of the 50% ethanol-water extract of leaves showed the highest total biological activities. The boiling water extracts were less active, but the bark extracts showed activity as α-glucosidase inhibitors and radical scavengers, the leaf extract being less active.

CONCLUSION

The observed enzyme inhibition activities, radical scavenging properties and complement fixation activities may explain some of the traditional uses of this medicinal tree, such as in wound healing and against diabetes.

α-Glucosidase inhibition, 15-lipoxygenase inhibition, and brine shrimp toxicity of extracts and isolated compounds from Terminalia macroptera leaves

CONTEXT

Terminalia macroptera Guill. & Perr. (Combretaceae), a tree that grows in West Africa, has been used in traditional medicine against a variety of diseases such as hepatitis, gonorrhea, skin diseases, and diabetes.

OBJECTIVE

To investigate enzyme inhibitory activity against α-glucosidase and 15-lipoxygenase (15-LO) and toxicity against brine shrimp of extracts and compounds from T. macroptera leaves.

MATERIALS AND METHODS

Methanol extract, ethyl acetate, and butanol extracts obtained from the methanol extract, six isolated polyphenols (chebulagic acid, chebulic acid trimethyl ester, corilagin, methyl gallate, narcissin, and rutin), and shikimic acid were evaluated for enzyme inhibition and toxicity.

RESULTS

In enzyme inhibition assays, all extracts showed high or very high activity. Chebulagic acid showed an IC50 value of 0.05 µM towards α-glucosidase and 24.9 ± 0.4 µM towards 15-LO, in contrast to positive controls (acarbose: IC50 201 ± 28 µM towards α-glucosidase, quercetin: 93 ± 3 µM towards 15-LO). Corilagin and narcissin were good 15-LO and α-glucosidase inhibitors, as well, while shikimic acid, methyl gallate, and chebulic acid trimethyl ester were less active or inactive. Rutin was a good α-glucosidase inhibitor (IC50 ca. 3 µM), but less active towards 15-LO. None of the extracts or the isolated compounds seemed to be very toxic in the brine shrimp assay compared with the positive control podophyllotoxin.

CONCLUSION

Inhibition of α-glucosidase in the gastrointestinal tract may be a rationale for the medicinal use of T. macroptera leaves against diabetes in traditional medicine in Mali. The plant extracts and its constituents show strong inhibition of the peroxidative enzyme 15-LO.

Shenzhu Tiaopi granule combined with lifestyle intervention therapy for impaired glucose tolerance: a randomized controlled trial

OBJECTIVE

The purpose of the study was to evaluate the clinical effects of the Shenzhu Tiaopi granule (SZTP) combined with a lifestyle intervention in patients with impaired glucose tolerance (IGT), who also had a spleen deficiency and damp overabundance syndrome (SDDOS).

METHODS

After a one-month washout period, a total of 514 patients were randomly assigned to the control (lifestyle intervention) and experimental (SZTP plus lifestyle intervention) groups, with 257 patients in each group. Patients in the control group received the lifestyle intervention (diet and exercise) for 12 months, while the patients in the experimental group were treated with SZTP plus the lifestyle intervention for 12 months. The Traditional Chinese Medicinal (TCM) symptom scores were observed in each group before and after treatment; the conversion rates from IGT to diabetes mellitus (DM) were also measured.

RESULTS

Following 12 months of treatment, the conversion rate from IGT to DM in the experimental group was significantly lower than in the control group (8.52% vs. 15.28%, P<0.05). A significantly higher number of patients with IGT reverted to normal blood glucose levels in the experimental group than in the control group (42.15% vs. 32.87%, P<0.05). In addition, after following the treatment for 12 months, the TCM symptoms of patients in the experimental group were markedly alleviated, as compared to the control group (P<0.01).

CONCLUSION

The combination of SZTP and lifestyle intervention showed a reduction in the conversion from IGT to DM, and an increase in the conversion from IGT to normal blood glucose levels.

Twenty Traditional Algerian Plants Used in Diabetes Therapy as Strong Inhibitors of α-Amylase Activity

In the present work, we have studied the inhibitory effects of aqueous and alcoholic extracts of six Algerian medicinal plants known by their therapeutic virtues against diabetes. The total phenolic compounds content, assayed using Folin-Ciocalteu’s reagent, of the samples ranged from 0.183 mg/g to 43.088 mg/g and from 1.197 mg/g to 7.445 mg/g, expressed as gallic acid equivalent (GAE), for the, respectively, whereas the total flavonoids concentrations, detected using 2% of the aluminium chloride, ranged from 0.41 mg/g to 11.613 mg/g and from 0.0097 mg/g to 1.591 mg/g, expressed as rutin equivalents (RE), for the aqueous and methanolic extracts, respectively. The major plants were found to inhibit enzymatic activities of Aspergillus oryzae-amylase in a concentration dependent manner. The values of the inhibition constants (Ki) have been determined according to the Dixon and Lineweaver-Burk methods. The results showed that the Ki values were less than 55 ppm for the all extracts. A strong inhibition was found in the phenolic extract of Salvia officinalis with a Ki of 8 ppm.

Phytotherapy in diabetes: Review on potential mechanistic perspectives

Diabetes mellitus (DM) is a widely spread epidemic disease that results from the absence of insulin, decreased secretion and/or impaired function. Since DM is a multi-factorial disease, the available pharmaceuticals, despite their sensible treatment, target mostly one pathway to control hyperglycemia and encounter several side effects. Therefore, new therapeutic paradigms aim to hit several pathways using only one agent. Traditionally, antidiabetic plants and/or their active constituents may fulfill this need. More than 200 species of plants possess antidiabetic properties which were evaluated mostly by screening tests without digging far for the exact mode of action. Searching among the different literature resources and various database and in view of the above aspects, the present article provides a comprehensive review on the available antidiabetic plants that have been approved by pharmacological and clinical evaluations, and which their mechanism(s) of action is assured. These plants are categorized according to their proved mode of action and are classified into those that act by inhibiting glucose absorption from intestine, increasing insulin secretion from the pancreas, inhibiting glucose production from hepatocytes, or enhancing glucose uptake by adipose and muscle tissues. The current review also highlights those that mimic in their action the new peptide analogs, such as exenatide, liraglutide and dipeptidylpeptidase-4 inhibitors that increase glucagon-like peptide-1 serum concentration and slow down the gastric emptying.

Synthesis and structure elucidation of five new conjugates of oleanolic acid derivatives and chalcones using 1D and 2D NMR spectroscopy

Five new conjugates of oleanolic acid derivatives and chalcones have been designed and synthesized. The structure elucidation of these conjugates was accomplished by using extensive 1D ((1)H, (13)C) and 2D NMR spectroscopic studies (COSY, HSQC and HMBC); and α-glucosidase inhibitory activity is reported for these conjugates. Compound 2b (IC(50)  = 47.5 µm) displayed much stronger activity than oleanolic acid and acarbose.

α-glucosidase inhibitors from plants: A natural approach to treat diabetes

Diabetes is a common metabolic disease characterized by abnormally high plasma glucose levels, leading to major complications, such as diabetic neuropathy, retinopathy, and cardiovascular diseases. One of the effective managements of diabetes mellitus, in particular, non-insulin-dependent diabetes mellitus (NIDDM) to decrease postprandial hyperglycemia, is to retard the absorption of glucose by inhibition of carbohydrate hydrolyzing enzymes, such as α-glucosidase and α-amylase, in the digestive organs. α-Glucosidase is the key enzyme catalyzing the final step in the digestive process of carbohydrates. Hence, α-glucosidase inhibitors can retard the liberation of d-glucose from dietary complex carbohydrates and delay glucose absorption, resulting in reduced postprandial plasma glucose levels and suppression of postprandial hyperglycemia. In recent years, many efforts have been made to identify effective α-glucosidase inhibitors from natural sources in order to develop a physiologic functional food or lead compounds for use against diabetes. Many α-glucosidase inhibitors that are phytoconstituents, such as flavonoids, alkaloids, terpenoids,anthocyanins, glycosides, phenolic compounds, and so on, have been isolated from plants. In the present review, we focus on the constituents isolated from different plants having α-glucosidase inhibitory potency along with IC50 values.

An inventory of the ethnobotanicals used as anti-diabetic by a rural community of Dhemaji district of Assam, Northeast India

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional remedies used for treating diabetic ailments are very important in the primary health care of the people living in rural Dhemaji district of Assam, north-east India. Novel information gathered from the current survey is important in preserving folk indigenous knowledge.

MATERIALS AND METHODS

Interviews were conducted amongst 80 households comprising of 240 individuals using semi-structured questionnaires. The focus was on plants used in treating diabetes mellitus.

RESULTS

The current survey documented 21 plant species (20 families) which are reportedly used to treat diabetes mellitus by the rural people in the study area. To the best of our knowledge, Amomum linguiforme, Cinnamomum impressinervium, Colocasia esculenta, Dillenia indica, Euphorbia ligularia, Garcinia pedunculata, Solanum indicum, Sterculia villosa and Tabernaemontana divaricata are recorded for the first time based on globally published literature as medicinal plants used for treating diabetes mellitus and related symptoms.

CONCLUSIONS

The wide variety of plants that are used to treat diabetes mellitus in this area supports the traditional value that medicinal plants have in the primary health care system of the rural people of Dhemaji district of Assam. The finding of new plant uses in the current study reveals the importance of the documentation of such ethnobotanical knowledge.

Methyl caffeate as an alpha-glucosidase inhibitor from Solanum torvum fruits and the activity of related compounds

In screening experiments for rat intestinal alpha-glucosidase (sucrase and maltase) inhibitors in 325 plants cultivated in Japan's southern island, of Tanegashima, marked inhibition against both sucrase and maltase was found in the extract of the fruit of Solanum torvum. Enzyme-assay guided fractionation of the extract led to the isolation of methyl caffeate (1) as a rat intestinal sucrase and maltase inhibitor. We examined 13 caffeoyl derivatives for sucrase- and maltase-inhibitory activities. The results showed that methyl caffeate (1) had a most favorable structure for both sucrase and maltase inhibition, except for a higher activity of methyl 3,4,5-trihydroxycinnamate (14) against sucrase. Its moderate inhibitory action against alpha-glucosidase provides a prospect for antidiabetic usage of S. torvum fruit.