The Triterpenes 3β-Lup-20(29)-en-3-ol and 3β-Lup-20(29)-en-3-yl Acetate and the Carbohydrate 1,2,3,4,5,6-Hexa-O-acetyl-dulcitol as Photosynthesis Light Reactions Inhibitors

Abstract

Three compounds were isolated from Maytenus acanthophylla Reissek (Celastraceae): the pentacyclic triterpenes lup-20(29)-en-3β-ol (lupeol, 1) and 3β-lup-20(29)-en-3-yl acetate (2) and the carbohydrate 1,2,3,4,5,6-hexa-O-acetyldulcitol (3);lupeol was also isolated from Xylosma flexuosa. The compounds’ structures were elucidated by spectroscopic and spectrometric analysis. Compound 1 acts as an energy transfer inhibitor, interacting with isolated CF1 bound to thylakoid membrane, and dulcitol hexaacetate 3 behaves as a Hill reaction inhibitor and as an uncoupler, as determined by polarography. Chlorophyll a (Chl a) fluorescence induction kinetics from the minimum yield F0 to the maximum yield FM provides information of the filling up from electrons coming from water to plastoquinone pool with reducing equivalents. In this paper we have examined the effects of compounds 1 and 3 on spinach leaf discs. Compound 1 induces the appearance of a K-band, which indicates that it inhibits the water splitting enzyme. In vivo assays measuring the fluorescence of chl a in P. ixocarpa leaves sprayed with compound 1, showed the appearance of the K-band and the PSII reaction centers was transformed to “heat sinks” or silent reaction centers unable to reduce QA. However, 3 also induced the appearance of a K band and a new band I appears in P. ixocarpa plants, therefore it inhibits at the water splitting enzyme complex and at the PQH2 site on b6f complex. Compounds 1 and 3 did not affect chlorophyll a fluorescence of L. perenne plants.

Chemical profiling and antioxidant activity of Bolivian propolis

“…The spectral data are in agreement with literature. 42 The compound 33 was identified as -amyrin by GC-MS analysis. The occurrence of triterpenes in propolis was reported for samples from Brazil, Myanmar, Saudi Arabia and Cameroon.…”

Evaluation of Alkaloids Isolated from Ruta graveolens as Photosynthesis Inhibitors

“…Ruta graveolens L. (Rutaceae) is a medicinal plant whose roots and aerial parts contain more than 120 special metabolites as coumarins, flavonoids, acridones, and furoquinoline alkaloids [ 1 , 2 ]. Many of these metabolites have attracted biological and pharmacological interest, demonstrating antifungal, phytotoxic, and antidotal activities [ 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. In this context, the effect of the natural products as photosynthesis inhibitors has been efficiently evaluated [ 10 , 11 , 12 ].…”

Two New Triterpenoids from Gelsemium Elegans and Aglaia odorata

“…In our previous studies, some Gelsemium alkaloids with either anticancer or immunosuppressive activity have been reported from the stems and leaves of G. elegans [4]. Herein we report the isolation from the stems and leaves of G. elegans and structural elucidation of a new triterpenoid saponin, odoratanone A (1) together with twelve known compounds 2--D-glucopyranosyloxy-5-methoxy methyl benzoate (2) [5], paeonol (3) [6], ethyl vanillate (4) [7], ethyl caffeate (5) [8], stigmastane-3,6-dione (6) [9], β-sitosterol (7), β-daucosterol (8), 24-hydroperoxy-24-vinylcholesterol (9) [10], lupeol (10) [11], α-amyrin (11) [12], ursolic acid (12) [12], α-amyrin margarate (13) [13], and a mixture of cerebrosides (14) [14].…”