Tetra-glucopyranosyl Diterpene ent-Kaur-16-en-19-oic Acid and ent-13(S)-Hydroxyatisenoic Acid Derivatives from a Commercial Extract of Stevia rebaudiana (Bertoni) Bertoni

Stevia rebaudiana and its diterpene glycosides are one of the main focuses of food companies interested in developing novel zero calorie sugar substitutes since the recognition of steviol glycosides as Generally Recognized as Safe (GRAS) by the United States Food and Drug Administration. Rebaudioside A, one of the major steviol glycosides of the leaves is more than 200 times sweeter than sucrose. However, its lingering aftertaste makes it less attractive as a table-top sweetener, despite its human health benefits. Herein, we report the purification of two novel tetra-glucopyranosyl diterpene glycosides 1 and 3 (rebaudioside A isomers) from a commercial Stevia rebaudiana leaf extract compounds, their saponification products compounds 2 and 4, together with three known compounds isolated in gram quantities. Compound 1 was determined to be 13-[(2-O-β-d-glucopyranosyl-6-O-β-d-glucopyranosyl-β-d-glucopyranosyl) oxy]ent-kaur-16-en-19-oic acid-β-d-glucopyranosy ester (rebaudioside Z), whereas compound 3 was found to be 13-[(2-O-β-d-glucopyranosyl-3-O-β-d-glucopyranosyl-β-d-glucopyranosyl) oxy]ent-hydroxyatis-16-en-19-oic acid -β-d-glucopyranosy ester. Two new tetracyclic derivatives with no sugar at position C-19 were prepared from rebaudiosides 1 and 3 under mild alkaline hydrolysis to afford compounds 2 13-[(2-O-β-d-glucopyranosyl-6-O-β-d-glucopyranosyl-β-d-glucopyranosyl) oxy]ent-kaur-16-en-19-oic acid (rebaudioside Z1) and 4 13-[(2-O-β-d-glucopyranosyl-3-O-β-d-glucopyranosyl-β-d-glucopyranosyl) oxy]ent-hydroxyatis-16-en-19-oic acid. Three known compounds were purified in gram quantities and identified as rebaudiosides A (5), H (6) and J (7). Chemical structures were unambiguously elucidated using different approaches, namely HRESIMS, HRESI-MS/MS, and 1D-and 2D-NMR spectroscopic data. Additionally, a high-quality crystal of iso-stevioside was grown in methanol and its structure confirmed by X-ray diffraction.

Isolation and Structure Elucidation of a New Diterpene Glycoside from Stevia rebaudiana Bertoni

A new minor diterpene glycoside has been isolated from a commercial extract of the leaves of Stevia rebaudiana and its structure was identified as 13-[(2-O-β-D-glucopyranosyl-β-D-glucopyranosyl)oxy] ent-kaur-16-en-19-oic acid-[2-O-(2-O-β-D-glucopyranosyl)-β-D-glucopyranosyl-3-O-b-D-glucopyranosyl-β-D-glucopyranosyl] ester (1) based on extensive NMR (1D and 2D) and mass spectroscopic data, and hydrolysis studies.

Evaluation of efficacy of Carica papaya leaf extracts to increase platelet count in hydroxyurea induced thrombocytopenia in Albino rats

Background: Dengue is an infectious disease associated with high mortality and morbidity. Being a viral disease, there is no specific drug available for treatment. There are some reports that Carica papaya leaf extract may improve the clinical condition of dengue patients. However, to support this, at present, there is no systematically searched and synthesized evidence available. Hence this study was undertaken to compare the efficacy of commercial preparation of Carica papaya leaves with freshly prepared Carica papaya leaf extracted.Methods: 48 albino rats were randomly divided into eight groups of six each. Thrombocytopenia was induced by giving hydroxyurea (15mg/kg) orally. Group I and II served as saline and toxic control group respectively. Other six groups were given two different doses of either commercial extract or fresh extract orally for five days. 1ml of blood was withdrawn at baseline,3rd and 6th day of the study. Platelet, WBC, RBC count, clotting and bleeding time were determined.Results: Mean platelet count increased significantly on day 6 in both low dose (2.06 to 4.93lakh/mm3) and human equivalent dose (2.73 to 7.66lakh/mm3) of commercial extract groups compared to the toxic control group (p<0.05). Similarly, the mean platelet count increased significantly for human equivalent dose in fresh leaf extract group (3.17 to 4.69lakh/mm3) but the increase in low dose fresh extract (3.28 to 3.76lakh/mm3) was not significant. There was no significant rise in mean platelets count, mean RBC count, WBC count, decrease in mean bleeding and clotting time between commercial extract and fresh leaf extract group for both low dose and human equivalent dose.Conclusions: Efficacy of fresh leaf extract of Carica papaya was not inferior to commercial available preparation. Fresh Carica papaya leaf extract no doubt offers a potential therapeutic efficacy which is cost effective, more affordable and accessible treatment in patients with thrombocytopenia.