Subcritical water extraction of steviol glycosides from Stevia rebaudiana leaves and characterization of the raffinate phase

WOS: 000347360800048The objectives of this work were to obtain steviol glycosides of S. rebaudiana leaves, possessing natural and noncaloric sweetener properties, using subcritical water extraction; to assess optimum extraction conditions; to determine biological activities of Stevia extracts and to characterize the raffinate phase. A Box-"Bhenken" statistical design was used to evaluate the effects of various values of temperature (100-150 degrees C), time (30-60 min) and flow rate (2-6 ml/min) at a pressure of 230 bar applying a solid/liquid ratio of 1:10 (m:v). The most effective parameter was temperature (p < 0.005). Optimum extraction conditions were elicited as 125 degrees C, 45 min, 4 ml/min flow rate which yielded 38.67 mg/g stevioside and 35.68 mg/g rebaudioside A. The total phenolic, flavonoid contents and DPPH free radical scavenging activity were found as 48.63 mg gallic acid/g extract, 29.81 mg quercetin/g extract and 92.50%, respectively. After extraction, total chlorophyll, carotenoid contents and dietary fibers were quantified as 31.91 mg/100g, 5.71 mg/100g and 4.98% in the raffinate phase. Hence, both extract and raffinate phases of S. rebaudiana leaves can be utilized as sources of natural sweeteners, fibers and coloring agents in the industry. (C) 2014 Elsevier B.V. All rights reserved.Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK)This study was supported by a grant from the Scientific and Technological Research Council of Turkey (TUBITAK) 2210-C National Graduate Scholarship Programme. The authors are thankful to the Natural Product Chemistry Laboratory of Bioengineering Department for access to the facilities

Cleavage of ring A and formation of an unusual nor-triterpene skeleton via the Baeyer-Villiger reaction

WOS: 000310170300012With the aim to generate a compound library for our biological screening studies, cycloastragenol was subjected to chemical transformation studies. The Baeyer-Villiger oxidation experiments provided an interesting 3,5-seco-4-nor-triterpene skeleton via ring opening followed by an unusual rearrangement. A new methodology is described for transforming triterpenoids into 3,5-seco-4-nor derivatives. (C) 2012 Elsevier Ltd. All rights reserved,TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [109S345]; COST ActionEuropean Cooperation in Science and Technology (COST) [CM 0804]; Global Research Network for Medicinal Plants (GRNMP); King Saud UniversityKing Saud UniversityThis work is supported by TUBITAK (109S345) and COST Action CM 0804. We are very grateful to Dr. Markus Ganzera and Dr. Bharathi Avula for their help in mass measurements. We also acknowledge partial support from the Global Research Network for Medicinal Plants (GRNMP) and King Saud University

Effect of a New Sapogenol Derivative (AG-07) on Cell Death via Necrosis

Saponins, plant secondary metabolites with high molecular weight, carry sugar groups on the triterpenic or steroidal skeleton. They exhibit biological activities such as anti-HIV, immunoadjuvant, analgesic and anticancer. Saponins have been reported to induce apoptosis, autophagy, stress responses and also inhibit cell cycle and invasion-migration in cancer cells. As saponins have partially weaker anti-cancer properties, they are often used as starting compounds for semi-synthesis of biologically more active molecules. With the same aim, we have focused on cycloartane-type saponins from Astragalus species to prepare potent compounds with cytotoxic activity. Cycloastragenol, a major sapogenol encountered only in Astragalus genus, was used to synthesize astragenol (AG) and then AG-07, a novel compound. Herein, we report the anticancer activities of AG and AG-07 against HCC1937 and HeLa cells by WST-1 assay. Additionally, levels of proteins associated with cell death are examined by immunoblotting. Cell death was also evaluated using flow cytometry and AO/EB staining. In comparison to AG, our results show that AG-07 is more cytotoxic. Furthermore, it induces formation of necrosis-associated protein fragments and necrosis-mediated cell death. In conclusion, AG-07, has a lethal effect on cancer cells through non-apoptotic cell death mechanism

Biotransformation of Neoruscogenin by the Endophytic Fungus Alternaria eureka

WOS: 000436527100006PubMed ID: 29893560Biotransformation of neoruscogenin (NR, 1, spirosta-5,25(27)-diene-1 beta,3 beta-diol), the major bioactive sapogenin of Ruscus preparations, was carried out with the endophytic fungus Alternaria eureka. Fourteen new biotransformation products (2-15) were isolated, and their structures were elucidated by NMR and HRESIMS data analyses. A. eureka affected mainly oxygenation, oxidation, and epoxidation reactions on the B and C rings of the sapogenin to afford compounds 8-15. In addition to these, cleavage of the spiroketal system as in compounds 2-7 and subsequent transformations provided unusual metabolites. This is the first study reporting conversion of the spirostanol skeleton to cholestane-type metabolites 2-5. Additionally, the cleavage of the C-22/C-26 oxygen bridge yielding a furostanol-type steroidal framework and subsequent formation of the epoxy bridge between C-18 and C-22 in 7 was encountered for the first time in steroid chemistry.Ege University Scientific Research ProjectEge University [15ECZ9011]; TUBITAKTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [114Z958]This project was supported by Ege University Scientific Research Project 15ECZ9011 and partly by TUBITAK (Project No: 114Z958). We are very grateful to Bionorm Natural Products for providing neoruscogenin, and special thanks to NMR operator Anzarulhaque Anwarulhaque of Prince Sattam bin Abdulaziz University, Al-Kharj, Saudi Arabia

Identification of a Noncanonical Necrotic Cell Death Triggered via Enhanced Proteolysis by a Novel Sapogenol Derivative

Kirmizibayrak, Petek Ballar/0000-0002-6189-1818; Bedir, Erdal/0000-0003-1262-063XWOS:000599310100019PubMed: 33136369Small molecules which activate distinct cell death pathways have promising high potential for anticancer drug research. Especially, regulated necrosis draws attention as an alternative cell death mechanism to overcome the drug resistance. Here, we report that a new semisynthetic saponin analogue (AG-08) triggers necrotic cell death with unprecedented pathways. AG-08-mediated necrosis depends on enhanced global proteolysis involving calpains, cathepsins, and caspases. Moreover, AG-08 generates several alterations in lysosomal function and physiology including membrane permeabilization, redistribution toward the perinuclear area, and lastly excessive tubulation. As a consequence of lysosomal impairment, the autophagic process was abolished via AG-08 treatment. Collectively, in addition to its ability to induce necrotic cell death, which makes AG-08 a promising candidate to cope with drug resistance, its unique activity mechanisms including autophagy/lysosome impairment and enhancement of proteolysis leading a strong death capacity emphasizes its potential for anticancer drug research.Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [118S709, 109S345]This project was supported by The Scientific and Technological Research Council of Turkey (TUBITAK, Project No: 118S709) as a continuation of a prior project (TUBITAK, Project No: 109S345)

Microbial transformation of Astragalus sapogenins using Cunninghamella blakesleeana NRRL 1369 and Glomerella fusarioides ATCC 9552

WOS: 000353599300005The microbial transformation of Astragalus sp. derived sapogenins, namely cycloastragenol, astragenol and cyclocanthogenol, by Cunninghamella blakesleeana NRRL 1369 and Glomerella fusarioides ATCC 9552 were investigated. The unique enzyme system of both fungi resulted hydroxylation, cyclization, dehydrogenation and oxidation reactions. Structures of the new metabolites were elucidated by 1-D (H-1, C-13, NOESY), 2-D NMR (DQF-COSY, HMBC, HMQC, NOESY) and HR-MS analyses. (C) 2015 Elsevier B.V. All rights reserved.Scientific and Technological Research Council of Turkey (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [109S345]; European Cooperation in Science and Technology (COST, Action)European Cooperation in Science and Technology (COST) [CM0804]This work is supported by The Scientific and Technological Research Council of Turkey (TUBITAK, Project No: 109S345) and European Cooperation in Science and Technology (COST, Action No: CM0804). The fungi, Cunninghamella blakesleeana NRRL 1369 was obtained from the ARS Culture Collection, USA, and Glomerealla fusarioides ATCC 9552 was obtained from LGC Standards-ATCC Culture Collection. Finally, we are very greatful to Biological Mass Spectrometry and Proteomics Facility, Izmir Institute of Technology, Department of Chemistry for obtaining mass spectra

Characterization of Cycloartane-Type Sapogenol Derivatives for Prostate Cancer Chemoprevention

Inhibition of inflammation-induced carcinogenesis is an efficient therapeutic strategy for cancer chemoprevention as use of anti-inflammatories was reported to decrease the cancer risk. In this study, we aimed to investigate the inhibition potential of semi-synthetic derivations of cycloartane-type sapogenol molecules on inflammation-related tumorigenic mechanisms in LNCaP prostate cancer cells. Inflammatory microenvironment was stimulated by TNFα/inflammatory conditioned media (CM). WST1/Xcelligence (proliferation), luciferase reporter (NFkB activity), immunoblotting, DCFH (ROS) and Griess (NO release) methods were used. It has been found that TNFα-induced NFkB activation was suppressed by both astragenol and cycloastragenol derivatives through inhibition of IkB phosphorylation. Further, the loss of Androgen Receptor, NKX3.1 and p53 due to inflammatory microenvironment was partially restored. In addition, tumorigenic cellular events such as increased NO release and intracellular ROS levels were both suppressed by the molecules. Inhibition of B-catenin pathway at anti-inflammatory concentrations was determined through decreased levels of pAkt(S473), total B-catenin and B-catenin(S552) induced by both lipopolysaccharide and CM treatments in inflammatory microenvironment. Finally, saponin molecules were found to suppress the proliferation and migration of prostate cancer cells at apoptotic concentrations. Therefore, it is suggested that anti-inflammatory activity of these sapogenol derivatives through NFkB inhibition make them promising agents for chemoprevention of inflammation-related prostate carcinogenesis

Cycloartane-type sapogenol derivatives inhibit NF kappa B activation as chemopreventive strategy for inflammation-induced prostate carcinogenesis

WOS: 000434746900002PubMed ID: 29678446Chronic inflammation is associated to 25% of cancer cases according to epidemiological data. Therefore, inhibition of inflammation-induced carcinogenesis can be an efficient therapeutic approach for cancer chemoprevention in drug development studies. It is also determined that anti-inflammatory drugs reduce cancer incidence. Cell culture-based in vitro screening methods are used as a fast and efficient method to investigate the biological activities of the biomolecules. In addition, saponins are molecules that are isolated from natural sources and are known to have potential for tumor inhibition. Studies on the preparation of analogues of cycloartane-type sapogenols (9,19-cyclolanostanes) have so far been limited. Therefore we have decided to direct our efforts toward the exploration of new anti-tumor agents prepared from cycloastragenol and its production artifact astragenol. The semi-synthetic derivatives were prepared mainly by oxidation, condensation, alkylation, acylation, and elimination reactions. After preliminary studies, five sapogenol analogues, two of which were new compounds (2 and 3), were selected and screened for their inhibitory activity on cell viability and NF kappa B signaling pathway activity in LNCaP prostate cancer cells. We found that the astragenol derivatives 1 and 2 as well as cycloastragenol derivatives 3, 4, and 5 exhibited strong inhibitory activity on NF kappa B signaling leading the repression of NF kappa B transcriptional activation and suppressed cell proliferation. The results suggested that these molecules might have significant potential for chemoprevention of prostate carcinogenesis induced by inflammatory NF kappa B signaling pathway.Turkish Scientific and Technological Research Council (TUBITAK)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [113Z078]This work was supported by Turkish Scientific and Technological Research Council (TUBITAK) with the project number 113Z078 to BDB