Stevia rebaudiana Bertoni is a shrub having a high content of sweet diterpenoid glycosides in its leaves, mainly stevioside and rebaudioside A, which are used as noncaloric, natural sweeteners. The aim of this study was to deepen the knowledge about the insulin-mimetic effect exerted by four different mixtures of steviol glycosides, rich in stevioside and rebaudioside A, in neonatal rat cardiac fibroblasts. The potential antioxidant activity of these steviol glycosides was also assessed, as oxidative stress is associated with diabetes. Likewise the insulin effect, steviol glycosides caused an increase in glucose uptake into rat fibroblasts by activating the PI3K/Akt pathway, thus inducing Glut4 translocation to the plasma membrane. The presence of S961, an insulin antagonist, completely abolished these effects, allowing to hypothesize that steviol glycosides could act as ligands of the same receptor engaged by insulin. Moreover, steviol glycosides counteracted oxidative stress by increasing reduced glutathione intracellular levels and upregulating expression and activity of the two antioxidant enzymes superoxide dismutase and catalase. The present work unravels the insulin-mimetic effect and the antioxidant property exerted by steviol glycosides, suggesting their potential beneficial role in the cotreatment of diabetes and in health maintenance.

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Glycosides from Stevia rebaudiana Bertoni Possess Insulin-Mimetic and Antioxidant Activities in Rat Cardiac Fibroblasts.

Many fungi, lichens, and bacteria produce xanthones (derivatives of 9H-xanthen-9-one, “xanthone” from the Greek “xanthos”, for “yellow”) as secondary metabolites. Xanthones are typically polysubstituted and occur as either fully aromatized, dihydro-, tetrahydro-, or, more rarely, hexahydro-derivatives. This family of compounds appeals to medicinal chemists because of their pronounced biological activity within a notably broad spectrum of disease states, a result of their interaction with a correspondingly diverse range of target biomolecules. This has led to the description of xanthones as “privileged structures”.(1) Historically, the total synthesis of the natural products has mostly been limited to fully aromatized targets. Syntheses of the more challenging partially saturated xanthones have less frequently been reported, although the development in recent times of novel and reliable methods for the construction of the (polysubstituted) unsaturated xanthone core holds promise for future endeavors. In particular, the fascinating structural and biological properties of xanthone dimers and heterodimers may excite the synthetic or natural product chemist.

Xanthones from Fungi, Lichens, and Bacteria: The Natural Products and Their Synthesis

Xanthones from fungi, lichens, and bacteria : the natural products and their synthesis

Safety evaluation of certain food additives

In the quest for new medicines, the methanolic, hexanic, and aqueous extracts of Adiantum caudatum leaves, obtained by Soxhlet extraction, were analyzed for phenolic and flavonoid contents, and antioxidant and antimicrobial potential. TPCs (total phenolic content) of the methanolic, aqueous and hexanic extracts were 27.7, 21.1, and 16.7 μg of gallic acid equivalents per mL, respectively, while TFCs (total flavonoid content) were 13.2, 11.6, and 10.0 μg of rutin equivalents per mL, respectively. Antioxidant activities of the extracts in reducing power, FRAP (ferric reducing antioxidant power), phosphomolybdate and ABTS assays follow the same order of methanolic ˃ aqueous ˃ hexanic. In the DPPH assay, however, the aqueous extract exhibited a slightly higher antioxidant activity than the methanolic one. Methanol is therefore a better solvent to extract most of the antioxidant components from A. caudatum leaves. In lipid peroxidation inhibitory assay, the extracts showed almost similar behavior and their activity decreased gradually with time. The aqueous extract was the strongest inhibitor after two days, but the hexanic became the most potent after about three days. The antibacterial potential of the extracts was determined against Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa. Towards all the microbes, the aqueous extract was the most potent and the hexanic the least. P. aeruginosa was the most susceptible strain, while the aqueous and methanolic extracts exhibited a slightly higher efficacy against this pathogen than the drug amoxicillin. In conclusion, A. caudatum can potentially provide a remedy against disorders caused by oxidative stress and infections.

https://www.mdpi.com/2076-3921/4/2/394/pdf

Comparative Analysis of Phenolics, Flavonoids, and Antioxidant and Antibacterial Potential of Methanolic, Hexanic and Aqueous Extracts from Adiantum caudatum Leaves

Stevioside, an ent-kaurene type of diterpenoid glycoside, is a natural sweetener extracted from leaves of Stevia rebaudiana (Bertoni) Bertoni. Stevioside and a few related compounds are regarded as the most common active principles of the plant. Such phytochemicals have not only been established as non-caloric sweeteners, but reported to exhibit some other pharmacological activities also. In this article, natural distribution of stevioside and related compounds, their structural features, plausible biosynthetic pathways along with an insight into the structure-sweetness relationship are presented. Besides, the pharmacokinetics, wide-range of pharmacological potentials, safety evaluation and clinical trials of these ent-kaurene glycosides are revisited.

Stevioside and related compounds - molecules of pharmaceutical promise: a critical overview.

A compilation of the constituents isolated from Swertia species covering the literature up to December 2003 is presented. The botanical classification and ethno-pharmacology of Swertia plants, as well as the biological activities and pharmacological applications of both distinct phytochemicals and medicinally acitve plant materials (formulations, extracts, etc.) are discussed in detail.

Swertia (Gentianaceae): chemical and pharmacological aspects.

Stevioside and Related Compounds — Molecules of Pharmaceutical Promise: A Critical Overview

The present rev iew deals with traditi onal uses of Adianlw n species in the treatment o f va ri o us ailments a lo ng with the stud ies of biological activit y and phytochemistry o f the plant species reportin g up to 2002. Till date, no t muc h of work has been done on these pla nt species. He nce the review anticipates to provoke keen interest o f various o f workers to undertake work s on genu s Adiallfum th e majo r portion of whi c h remain s unex pl ored. K eywords: Adianl wn species, Trad iti o nal uses, Bi ological acti vit y, Phytochemi cal constituents

http://nopr.niscair.res.in/bitstream/123456789/17638/1/JSIR%2062%2812%29%201119-1130.pdf

Arun K. Brahmachari

Papers

Stevioside and related compounds - molecules of pharmaceutical promise: a critical overview.

Swertia (Gentianaceae): chemical and pharmacological aspects.

Stevioside and Related Compounds — Molecules of Pharmaceutical Promise: A Critical Overview

Phytochemicals and Biological Activities of Adiantum Species