1,721,020 research outputs found
Hotoda’s Sequence and Anti-HIV Activity: Where Are We Now?
Full text linkThe pharmacological relevance of ODNs forming G-quadruplexes as anti-HIV agents has been extensively reported in the literature over the last few years. Recent detailed studies have elucidated the peculiar arrangement adopted by many G-quadruplex-based aptamers and provided insight into their mechanism of action. In this review, we have reported the history of a strong anti-HIV agent: the 6-mer d(TGGGAG) sequence, commonly called “Hotoda’s sequence„. In particular, all findings reported on this sequence and its modified sequences have been discussed considering the following research phases: (i) discovery of the first 5′-modified active d(TGGGAG) sequences; (ii) synthesis of a variety of end-modified d(TGGGAG) sequences; (iii) biophysical and NMR investigations of natural and modified Hotoda’s sequences; (iv); kinetic studies on the most active 5′-modified d(TGGGAG) sequences; and (v) extensive anti-HIV screening of G-quadruplexes formed by d(TGGGAG) sequences. This review aims to clarify all results obtained over the years on Hotoda’s sequence, revealing its potentiality as a strong anti-HIV agent (EC50 = 14 nM)
New silibinin glyco-conjugates: Synthesis and evaluation of antioxidant properties
Full text linkNew silibinin glyco-conjugates have been synthesized by efficient method and in short time. Exploiting our solution phase strategy, several structurally diverse silibinin glyco-conjugates (gluco, manno, galacto, and lacto-) were successfully realized in very good yields and in short time. In preliminary study to evaluate their antioxidant and neuroprotective activities new derivatives were subjected to DPPH free radical scavenging assay and the Xanthine oxidase (XO) inhibition models assay. Irrespective of the sugar moiety examined, new glyco-conjugates are more than 50 times water-soluble of silibinin. In the other hand they exhibit a radical scavenging activities slightly higher than to silibinin and XO inhibition at least as silibinin. (C) 2014 Elsevier Ltd. All rights reserved
History of gymnemic acid, a molecule that does not exist
No full textIn the literature there are hundreds of articles, the first dating back to 1866 and the last to 2014, on gymnemic acid, isolated from Gymnema sylvestre, from its
isolation to the determination of its biological activities. Gymnemic acid has a CAS number but its structure is not specified. Studies during the second half of
the 1970s clearly demonstrated that what was being referred to as gymnemic acid is actually a very complex mixture of dozens of substances, belonging to
different classes of natural compounds. This plant, whose infusions or complex mixtures of its metabolites are the basis for many formulas sold in pharmacies
and by herbalists, has anti-diabetic and slimming effects. It is certainly misleading to talk about gymnemic acid as a specific molecule. There may be doubts
about the exact composition of the products, and consequently about their origin and the claimed effect
Toxin levels in different variety of potatoes: Alarming contents of α-chaconine
No full textPotato (Solanum tuberosum), which belongs to the family Solanaceae, is a native of South America and was introduced in Europe in the sixteenth century by the Spanish at first as a botanical curiosity and subsequently as a food plant. Potato cultivation has spread worldwide, with a high concentration of cropland in Europe. For many people, it serves as a staple food in place of bread. Potatoes are used in the food industry to produce starch, dextrin, and glucose; it is also used in distillation and in animal feed. The market also requires appropriate potato product for canning and for the production of French fries. Potato leaves and fruits can be poisonous because they are rich in alpha-solanine and alpha-chaconine, toxic alkaloids that can cause serious damages if consumed in large quantities. There are many varieties of potatoes, which differ in the shape of the tuber and the color of the flesh and skin. This study measures the content of the two toxic alkaloids in 15 different varieties of potatoes considered important for a commercial use; measurements were taken immediately following the collection and after 20 days. The data show that after 20 days the alpha-solanine content decreases (with the exception of only four varieties), whereas the alpha-chaconine content increases to alarming levels
Gymnema sylvestre R. Br., an Indian medicinal herb: traditional uses, chemical composition, and biological activity
Full text linkGymnema sylvestre R. Br. is one of the most important medicinal plants that grows in tropical forests in India and South East Asia. Its active ingredients and extracts of leaves and roots are used in traditional medicine to treat various ailments and they are present in the market for pharmaceutical and parapharmaceutical products. Commercial products based on substances of plant origin that are generally connoted as natural have to be subjected to monitoring and evaluation by health authorities for their potential impacts on public health. The monitoring and evaluation of these products are critical because the boundary between a therapeutic action and a functional or healthy activity has not yet been defined in a clear and unambiguous way. Therefore, these products are considered borderline products, and they require careful and rigorous studies, in order to use them as complement and/or even replacement of synthetic drugs that are characterized by side effects and high economic costs. This review explores the traditional uses, chemical composition and biological activity of G. sylvestre extracts, providing a general framework on the most interesting extracts and what are the necessary studies for a complete definition of the range of activities
Synthesis of β-l-2′-Fluoro-3′-thiacytidine (F-3TC) Stereoisomers: Toward a New Class of Oxathiolanyl Nucleosides?
No full textThe synthesis of (1'S,2'S,4'R) and (1'S,2'R,4'R) stereoisomers of 2'-fluoro-3'-thiacytidine [(2' S)-F-3TC and (2' R)-F-3TC], the earliest examples of oxathiolanyl nucleosides with a fluorine atom in the 'sugar' backbone, is herein reported. From of a variety of synthetic routes devised for their preparation, the Pummerer rearrangement of protected lamivudine sulfoxides was successfully exploited for fluorine atom introduction. Despite the presence of three potentially labile stereocenters in such a small molecule, the (2'R)-isomer of F-3TC exhibited good chemical stability after protective group cleavage. Conversely, the (2'S)-epimer suffered from weak stability, owing to the formation of an undesired cyclization product. Based on the remarkable antiviral efficacy of the parent drugs, the access to 2'-fluorinated oxathiolanyl nucleosides (and more generally, 2'-fluorinated heterocyclic nucleosides) may provide a new source of candidates with antiviral potential
Evaluation of new strategies to reduce the total content of α-solanine and α- chaconine in potatoes.
No full textPotatoes are a staple food for over a billion people worldwide, a primary dietary source of carbohydrates, and a vital crop to the agricultural economy of South America, Africa, East Asia and Central Asia. Potatoes occupy third place (after rice and wheat) on the list of foods on which the world depends for food security. In particular,
glyco-alkaloids contents in potatoes are potentially toxic and secondary metabolites such as α-solanine and α- chaconine are reported to be dangerous to human health. This paper describes new methods for α-solanine and
α-chaconine reduction in the potato cultivar known as Marabel. The potatoes were incubated at room tem- perature in the dark for 24 h and the optimal experimental condition was achieved with NaOH solution at pH 12.
In the assayed samples, α-solanine and α-chaconine reduction was 43% and 27% respectively. The process proposed here allows to minimize the total content of glyco-alkaloids, with respect to mode of collection, storage and cleaning of Marabel potatoes
Scavenging Effect of Various Extracts of the Gymnema sylvestre R. Br. and Antioxidant Activity of the Isolated Triterpenes
Full text linkGymnema sylvestre has been used in Asian traditional medicine for its anti-microbial, antihypercholesterolemic, hepatoprotective and sweet suppressing properties and activities. G. sylvestre has also been used extensively in chewing gum, as a health food for preventing obesity and diabetes, and as a tea. This study has evaluated the total phenolic content and antioxidant activity of the aqueous and organic G. sylvestre extracts and their sub-fractions for the initial characterization of the biological properties of the isolated compounds. An in vivo cell model was used to calculate the concentration inhibiting cell growth by 50% and the ability to exert antioxidant activity. All compounds inhibit cell growth in a dose-dependent manner, with an IC50 value ranging between 29 and 1462 μM. The effects on intracellular ROS levels are extremely variable, but it is of interest that some of the compounds appear to display an antioxidant effect
A rapid and simple chromatographic separation of diastereomers of silibinin and their oxidation to produce 2,3-dehydrosilybin enantiomers in an optically pure form
No full textSilybin A and B were separated from commercial silibinin using the preparative HPLC method. The described method is rapid and effective in obtaining gram-scale amounts of two diastereoisomers with minimal effort. In our approach, silibinin was dissolved in THF (solubility greater than 100 mg/mL), an alternative solvent to H2O or MeOH in which silibinin has a very low solubility (ca 0.05-1.5 mg/mL), and then separated into its two components using preparative RP-HPLC. By starting with purified diastereoisomers, it was possible to obtain the two enantiomers of 2,3-dehydrosilybin in good yields and optically pure using an efficient oxidation procedure. All of the purified products were fully characterised using NMR (1H, 13C), CD, [??]D, and ESI MS analyses. The purities of the products, which were evaluated using analytical HPLC, were greater than 98 % in all cases
Traditional uses, chemical composition and biological activities of Sideritis raeseri Boiss. & Heldr
No full textSideritis species have been used in folk medicine for their antimicrobial, antiulcerogenic, digestive and anti-inflammatory properties. Over the years, the phytochemistry of the genus Sideritis has been studied, and various terpenoids, sterols, coumarins and especially flavonoid aglycones and glycosides have been identified. In particular, species from the Balkan Peninsula have been studied and were found to be rich in flavonoids, with valuable antioxidant activity. In the folk medicine of the Balkan countries, Sideritis raeseri is used as a herbal tea in the treatment of inflammation, gastrointestinal disorders and coughs, and also as a tonic, whereas extracts are used as a component of dietary supplements for anaemia. Its dried inflorescences are used to prepare a beverage called ‘mountain tea’. In light of the considerable interest generated in the chemistry, pharmacological properties and commercial value of S. raeseri Boiss. & Heldr., we review and summarise the available literature on these plants. The review details the chemical composition of the essential oil, its mineral and polyphenol contents, the naming of these plants and their physicochemical characterisation, and the nuclear magnetic resonance spectral data and biological properties associated with the plant extracts, with a focus on their potential chemotherapeutic applications
- …
