13C NMR spectra of pentacyclic triterpenoids--a compilation and some salient features
TL;DR: In this paper, a compilation of the 13C NMR data of a selected variety of naturally occurring pentacyclic triterpenoids, arranged skeletonwise, is provided.
About: This article is published in Phytochemistry.The article was published on 1994-12-01. It has received 1251 citations till now.
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TL;DR: Results revealed that the oleanolic acid and ursolic acid (2:1) mixture was a potent alpha-amylase inhibitor with IC(50)=2.01 microg/ml (4.41 microM) and that it contributes significantly to the alpha-AMylase inhibition activity of the extract.
679 citations
TL;DR: Because of its selective cytotoxicity against tumor cells and favorable therapeutic index, even at doses up to 500 mg/kg body weight, betulinic acid is a very promising new chemotherapeutic agent for the treatment of HIV infection and cancer.
Abstract: 3beta-Hydroxy-lup-20(29)-en-28-oic acid (betulinic acid) is a pentacyclic lupane-type triterpene that is widely distributed throughout the plant kingdom. A variety of biological activities have been ascribed to betulinic acid including anti-inflammatory and in vitro antimalarial effects. However, betulinic acid is most highly regarded for its anti-HIV-1 activity and specific cytotoxicity against a variety of tumor cell lines. Interest in developing even more potent anti-HIV agents based on betulinic acid has led to the discovery of a host of highly active derivatives exhibiting greater potencies and better therapeutic indices than some current clinical anti-HIV agents. While its mechanism of action has not been fully determined, it has been shown that some betulinic acid analogs disrupt viral fusion to the cell in a post-binding step through interaction with the viral glycoprotein gp41 whereas others disrupt assembly and budding of the HIV-1 virus. With regard to its anticancer properties, betulinic acid was previously reported to exhibit selective cytotoxicity against several melanoma-derived cell lines. However, more recent work has demonstrated that betulinic acid is cytotoxic against other non-melanoma (neuroectodermal and malignant brain tumor) human tumor varieties. Betulinic acid appears to function by means of inducing apoptosis in cells irrespective of their p53 status. Because of its selective cytotoxicity against tumor cells and favorable therapeutic index, even at doses up to 500 mg/kg body weight, betulinic acid is a very promising new chemotherapeutic agent for the treatment of HIV infection and cancer.
459 citations
TL;DR: This review deals with secondary metabolites isolated from Ganoderma and their biological significance and could lead to the discovery of hitherto unknown biologically active secondary metabolites.
240 citations
TL;DR: Evidence is provided that the studied plants extract, as well as some of the isolated compounds might be potential sources of new antimicrobial drug.
186 citations
TL;DR: Both bidesmosides and derived monodesmosides showed little or no antifungal activity, whereas a comparatively higher degree of hemolytic activity could be determined for monodesMosides.
Abstract: At least 16 saponins were detected in the seeds of Chenopodium quinoa. The 5 previously isolated major saponins, 3-O-beta-D-glucuronopyranosyl oleanolic acid 28-O-beta-D-glucopyranosyl ester, 3-O-alpha-L-arabinopyranosyl hederagenin 28-O-beta-D-glucopyranosyl ester, 3-O-beta-D-glucopyranosyl-(1-->3)-alpha-L-arabinopyranosyl hederagenin 28-O-beta-D-glucopyranosyl ester, 3-O-alpha-L-arabinopyranosyl phytolaccagenic acid 28-O-beta-D-glucopyranosyl ester, 3-O-beta-D-glucopyranosyl-(1-->3)-alpha-L-arabinopyranosyl phytolaccagenic acid 28-O-beta-D-glucopyranosyl ester, and the new saponin 3-O-beta-D-glucopyranosyl-(1-->3)-alpha-L-arabinopyranosyl phytolaccagenic acid were isolated and characterized using mainly NMR spectroscopy, mass spectrometry, and chemical methods. The antifungal activity against Candida albicans and hemolytic activity on erythrocytes of these compounds and derived monodesmosides were evaluated. Both bidesmosides and derived monodesmosides showed little or no antifungal activity, whereas a comparatively higher degree of hemolytic activity could be determined for monodesmosides.
184 citations
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TL;DR: In this paper, a general technique for the investigation of exchange processes in molecular systems is proposed and demonstrated and applications include the study of chemical exchange, of magnetization transfer by inter-and intramolecular relaxation in liquids, and of spin diffusion and cross-relaxation processes in solids.
Abstract: A new general technique for the investigation of exchange processes in molecular systems is proposed and demonstrated. Applications comprise the study of chemical exchange, of magnetization transfer by inter‐ and intramolecular relaxation in liquids, and of spin diffusion and cross‐relaxation processes in solids.
4,534 citations
TL;DR: In this article, the possibilities for the extension of spectroscopy to two dimensions are discussed, including the elucidation of energy level diagrams, the observation of multiple quantum transitions, and the recording of high-resolution spectra in inhomogenous magnetic fields.
Abstract: The possibilities for the extension of spectroscopy to two dimensions are discussed. Applications to nuclear magnetic resonance are described. The basic theory of two‐dimensional spectroscopy is developed. Numerous possible applications are mentioned and some of them treated in detail, including the elucidation of energy level diagrams, the observation of multiple quantum transitions, and the recording of high‐resolution spectra in inhomogenous magnetic fields. Experimental results are presented for some simple spin systems.
2,968 citations
2,600 citations
TL;DR: In this article, the detection of NMR spectra of less sensitive nuclei coupled to protons was improved by a 2-dimensional Fourier transform technique involving a double transfer of polarization.
2,449 citations