Xanthones are one of the biggest classes of compounds in natural product chemistry. A number of xanthones have been isolated from natural sources of higher plants, fungi, ferns, and lichens. They have gradually risen to great importance because of their medicinal properties. This review focuses on the types, isolation, characterization, biological applications, and biosynthesis of naturally occurring xanthones isolated so far. Different physicochemical and instrumental methods such as liquid-solid and liquid-liquid extraction, TLC, flash chromatography, column chromatography, IR, 1H NMR and 13C NMR spectroscopy, GLC, HPLC, GC, and LCMS have been widely used for isolation and structural elucidation of xanthones. Hepatoprotective, anticarcinogenic, antileprosy, antimalarial, antioxidant, anticholinergic, mutagenicity, radioprotective, immunomodulatory, antibone resorption, antiparasitic, neuraminidase inhibitory, anticomplement, antibacterial, antifungal, algicidal, anti-HIV, cardioprotective, antitumoral, antidiabetes, antihyperlipidemic, antiatherogenic, anti-inflammatory, antiulcer, antidiabetic, hypolipidemic, analgesic, antiasthmatic, antihistaminic, antiamoebic, diuretic, antidiarrheal, larvicidal, and ovicidal activities have been reported for natural occurring xanthones. To a certain extent, this review provides necessary foundation for further research and development of new medicines.

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Naturally Occurring Xanthones: Chemistry and Biology

Identification and characterization of chemical compounds in different crude extracts from leaves of Omani neem

Diabetes has caused a major burden to the health sector in the developing countries and has shown an increasing trend among the urban population. It is estimated that most patients are with type II diabetes which could be easily treated with dietary changes, exercise, and medication. Sri Lanka carries a long history ayurvedic medicine where it uses the plant for treating many diseases. Therefore it is important to screen medicinal plants scientifically so they could be used safely and effectively in the traditional medical system and also be used for further investigations. Adenanthera pavonina is a plant used in the Ayurvedic medical system in Sri Lanka for treating many diseases including diabetics. We evaluated the anti-diabetic properties and the antioxidant properties of Adenanthera pavonina leaves. The methanol extract of the leaves was sequentially extracted with petroleum ether and thereafter was partitioned between EtOAc, and water. The α-amylase inhibition assay was performed using the 3,5- dinitrosalicylic acid method. The antioxidant activities were measured using the DPPH free radical scavenging activity and the total phenolic content using Folin-Ciocalteu’s reagent. The cytotoxicity of the extract was evaluated using the Brine shrimp bioassay. The IC50 values of α amylase inhibitory activity of MeOH, EtOAc, petroleum ether, and water were 16.16 ± 2.23, 59.93 ± 0.25, 145.49 ± 4.86 and 214.85 ± 9.72 μg/ml respectively and was similar to that of Acarbose (18.63 ± 1.21 (μg/ml). Antioxidant activities were also determined and the EtOAc fraction showed the highest total phenolic content (34. 62 ± 1.14 mg/g extract) and the highest DPPH scavenging activity with an IC50 of 249.92 ± 3.35 μg/ml. The leaf extracts of Adenanthera pavonina exhibit remarkable α-amylase inhibitory activity in the crude methanolic extract. Hence leaves of Adenanthera pavonina has a potential to be used as a regular green vegetable and also be investigated further in isolating pure compounds with anti-diabetic activity.

https://link.springer.com/content/pdf/10.1186/s12906-016-1452-y.pdf

In-vitro alpha amylase inhibitory activity of the leaf extracts of Adenanthera pavonina.

Saponins: Anti-diabetic principles from medicinal plants - A review.

Mangifera indica (family Anacardiaceae), commonly known as mango, is a pharmacologically, ethnomedically, and phytochemically diverse plant. Various parts of M. indica tree have been used in traditional medicine for the treatment of different ailments, and a number of bioactive phytochemical constituents of M. indica have been reported, namely, polyphenols, terpenes, sterols, carotenoids, vitamins, and amino acids, and so forth. Several studies have proven the pharmacological potential of different parts of mango trees such as leaves, bark, fruit peel and flesh, roots, and flowers as anticancer, anti-inflammatory, antidiabetic, antioxidant, antibacterial, antifungal, anthelmintic, gastroprotective, hepatoprotective, immunomodulatory, antiplasmodial, and antihyperlipemic. In the present review, a comprehensive study on ethnopharmacological applications, pharmacological activities, and bioactive compounds of M. indica has been described.

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A Review on Ethnopharmacological Applications, Pharmacological Activities, and Bioactive Compounds of Mangifera indica (Mango)

Context: Mangifera indica (Anacardiaceae) stem bark contains a rich content of mangiferin and is used traditionally in Indian Ayurvedic system to treat diabetes. Purpose of the study: To investigate anti-diabetic and hypolipidemic effects of mangiferin in type 1 and type 2 diabetic rats models. Streptozotocin was used to induce type 1 and type 2 diabetic rats. Mangiferin (at a dose 10 and 20mg/kg) was administrated intra-peritoneally in type 1 and type 2 diabetic rats daily up to 30 days. Biochemical parameters notably fasting blood sugar, total cholesterol, triglycerides, low-density lipoprotein, very low-density lipoprotein and high-density lipoprotein were estimated. In addition, in vitro alpha amylase and alpha glucosidase inhibitory effects of mangiferin were performed and IC50 values were determined. Results: Mangiferin exhibited significant (P<0.05) anti-diabetic as well as hypolipidemic effects by lowering FBS, TC, TG, LDL, and VLDL levels; but also with elevation of HDL level in type 2 diabetic model rats. In addition, mangiferin showed appreciable alpha amylase inhibitory effect (IC50 value 74.35±1.9µg/ml) and alpha glucosidase inhibitory effect (IC50 41.88±3.9µg/ml) when compared with standard drug acarbose (IC50 83.33±1.2µg/ml). Conclusions: Mangiferin showed anti-diabetic as well as hypolipidemic potentials in type 2 diabetic model rats. Therefore, mangiferin possess beneficial effects in the management of type 2 diabetes with hyperlipidemia.

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Studies on the anti-diabetic and hypolipidemic potentials of mangiferin (Xanthone Glucoside) in streptozotocin-induced Type 1 and Type 2 diabetic model rats

In India, the prevalence of diabetes mellitus is on the increase and needs to be addressed appropriately. In this study area, herbal remedies are considered convenient for management of Type 2 diabetes with postprandial hyperglycemia due to their traditional acceptability and availability, low costs, lesser side effects. Comparative evaluation of alpha amylase inhibitory activities of selected plants extracts. Kharagpur is situated in the Midnapur West district of West Bengal in India. In this district, diabetes prevalence is comparatively high. Ten common plants in IIT Kharagpur 1 Block namely, Acalypha indica, Allium cepa, Allium sativum, Azadirachta indica, Musa sapientum, Mangifera indica, Murraya, Ocimum sanctum, Phyllanthus amarus and Tinospora cordifolia were tested for their alpha amylase inhibitory activities to establish anti-diabetic potentials. The plant extracts were prepared sequentially with petroleum ether, hexane, chloroform, ethanol and aqueous. The extracts obtained were subjected to in vitro alpha amylase inhibitory assay using starch azure as a substrate and porcine pancreatic amylase as the enzyme. Statistical difference and linear regression analysis were performed by using Graphpad prism 5 statistical software. Ethanol extracts of Mangifera indica, Azadirachta indica and petroleum ether extract of Murraya koenigii (at a concentrations 10-100μg/ml) showed maximum percentage inhibition on alpha amylase activity with an IC50 value of 37.86 ± 0.32μg/ml, 62.99 ± 1.20μg/ml and 59.0 ± 0.51μg/ml respectively when compared with acarbose (IC50 value 83.33 ± 0.75μg/ml). The results showing that Mangifera indica, Azadirachta indica and Murraya koenigii might be effective in lowering post prandial hyperglycemia. Key words: Alpha amylase inhibition, plant extracts, postprandial hyperglycemia

A comparative study of alpha amylase inhibitory activities of common anti-diabetic plants at Kharagpur 1 block

Many medicinal plants have been used for the treatment of diabetes mellitus in Indian system of medicine and in other ancient systems of the world. Medicinal plants are significant source of biological compounds and many of the currently available biological compounds have been derived directly or indirectly from them. The major focus of this review is on anti-diabetic activity of medicinal plants like Achillea ligutica, Aegles marmelos, Andrographis paniculata, Azadirachta indica, Allium sativum, Bergenia ciliata, Brassica juncea, Commelina communis, Euonymus alatus, Ficus bengalensis, Gymnema sylvestre, Mangifera indica, Medicago sativa, Momordica charantia, Murraya koenigii, Pterocarpus marsupium, Syzigium cumini, Trigonella foenum graecum, Tinospora cripa, Tournefortia haetwegiana (active constituents and crude extracts). These medicinal plants act on various mechanisms- either by acting directly on pancreas and stimulate insulin levels in blood or by altering the activities of regulatory enzymes in different pathways like glycolysis, gluconeogensis and thus producing effects on tissues like liver, muscle, adipose tissue etc. All medicinal plants, as specified, have shown different degrees of anti-diabetic activity.

In vitro and in vivo studies of antidiabetic indian medicinal plants: a review

Introduction: Azadirachta indica (Meliaceae) leaves are used traditionally in the Indian Ayurvedic medicinal system to treat diabetes. The aim of the present study is to investigate the effect of azadirachtolide (tetranortriterpenoid from Azadirachta indica leaves) on blood glucose and serum lipid profiles on streptozotocin-induced diabetic rats. Methods: Streptozotocin-induced diabetic rats were used for the study. Azadirachtolide (at a dose 50 and 100 mg/kg) was administrated intra-peritoneally in diabetic rats once a week for 30 days. Biochemical parameters notably fasting blood sugar, total cholesterol, triglycerides, low-density lipoprotein, very low-density lipoprotein and high-density lipoprotein were determined. The in vitro alpha amylase and alpha glucosidase inhibitory effects of azadirachtolide were measured and IC 50 values were determined. Results: Azadirachtolide exhibited significant (P < 0.05) anti-diabetic as well as hypolipidemic effects by lowering FBS, TC, TG, LDL, and VLDL levels; but also with elevation of HDL level in diabetic rats. Azadirachtolide showed appreciable alpha amylase (IC 50 value of 55.80 ± 1.7 µg/ml) and alpha glucosidase inhibitory effects (IC 50 value of 47.85 ± 1.4 µg/ ml) compared with acarbose (IC 50 value of 83.33 ± 1.8 µg/ml). Conclusion: The present study indicated that azadirachtolide possesses anti-hyperglycemic and anti-lipidemic effects. Thus, results suggested azadirachtolide has a beneficial effect in the management of diabetes associated with abnormal lipid profile and related cardiovascular complications.

M. Manjunatha

Papers

Studies on the anti-diabetic and hypolipidemic potentials of mangiferin (Xanthone Glucoside) in streptozotocin-induced Type 1 and Type 2 diabetic model rats

A comparative study of alpha amylase inhibitory activities of common anti-diabetic plants at Kharagpur 1 block

In vitro and in vivo studies of antidiabetic indian medicinal plants: a review

Azadirachtolide: An anti-diabetic and hypolipidemic effects from Azadirachta indica leaves

The Evaluation of Various Biological Properties for Bismuth Oxychloride Nanoparticles (BiOCl NPs)