Seasonal variation of exudate ofCistus ladanifer

Abstract

The production of labdanum exudate byCistus ladanifer L. is highly seasonal, reaching a maximum concentration during summer and a minimum concentration in winter. Because this exudate strongly absorbs in the wavelength range of 260-400 nm (the near-UV-visible range), it may be important biologically as an UV-visible filter. Separation of exudate components has been achieved by reverse-phase high-performance liquid chromatography (HPLC).The retention times of HPLC chromatograms and the spectral characteristics (absorption and fluorescence) of the exudate identify flavonoids as the most relevant chromophores regarding the potency of the exudate as a UV-visible filter. HPLC studies show that kaempferol-3-(O)methyl, kaempferol-3,7-di(O)methyl, and apigenin-4'-(O)methyl are the most enriched flavonoids in the exudate.Other flavonoids [apigenin, apigenin-7-(O)methyl, apigenin-7,4'-di(O)methyl, kaempferol-3,4'-di(O)methyl and kaempferol-3,7,4'-tri(O)methyl] are present in the exudate as minor components, e.g., each contributes by less than 10% to total flavonoids.The ratio of kaempferols to apigenins of the exudate also shows seasonal variation (maximum value in summer and minimum in spring). However, due to the similar absorption spectra of both groups of flavonoids, this has a minor influence on the exudate's ability to filter near-UV-visible radiation.

A New Approach to Plant Diversity Assessment Combining HPLC Data, Simplex Mixture Design and Discriminant Analysis

“…in model II (Fig. 8), the predicted contributions of 2, 6 and 9 corresponded to the following ranges of true values: [0, 3], [3,7] and [7,10], respectively; these three ranges correspond to three distinct abundance states of chemotype II. These dispersion features give models II and IV better sensitivity in detecting high variations of relative frequency (e.g.…”

“…The 14 flavonol glycosides were identified as three principal categories: kaempferol glycosides (2,3,5,6,7,8,9,10), quercetin-based glycosides (1,4) and methylated forms at the 7′ position, namely rhamnetin (11), rhamnocitrin (12,13) and rhamnazin (14) glycosides [91][92][93]95]. The multivariate analyses of the HPLC database highlighted four distinct chemical taxons, or chemotypes (Fig.…”

“…-The HPLC pattern of chemotype I was characterized by numerous chemical compounds which were clearly either major (compounds 1,4,[11][12][13][14] or minor (2,(5)(6)(7)(8)(9)(10), leading to a strong taxonomic signature (Fig. 7).…”

Fitotoxicidad De Aceites Esenciales Y Extractos Acuosos De Plantas Mediterráneas Para El Control De Arvenses

“…Estos y otros trabajos posteriores (Ruiz de la Torre, 1981;López-González, 2001) concluyeron que el fenómeno puede ser atribuido a los efectos alelopáticos de C. ladanifer (Alías, 2006). Los exudados secretados por las hojas de C. ladanifer mostraron actividad inhibitoria de la germinación de especies herbáceas, que no se encuentran normalmente en los jarales (Chaves et al, 1993;Chaves y Escudero, 1997;Chaves et al, 2001a;Chaves et al, 2001b;Chaves et al, 2003). Extractos acuosos de hojas de C. ladanifer se ensayaron frente a la germinación de 20 especies que normalmente comparten su hábitat (Herranz et al, 2006 En diferentes poblaciones de C. ladanifer se estudió la variación cuantitativa y cualitativa del exudado de sus hojas y tallos, incluyendo el contenido en geninas de flavonoides (Sosa et al, 2005).…”

“…Depende del crecimiento de la planta y de las estaciones (Siegelman, 1964;Harborne, 1967;Graham, 1991;Chaves et al, 1993;Hare, 2002). Se ha propuesto que la síntesis de flavonoides debe ser considerada un mecanismo de defensa de las plantas contra el estrés (Bell, 1980;Chapell y Hahlbrock, 1984;Vogt et al, 1991;Panagopoulos et al, 1992;Ziska et al, 1993;Cen y Bornman, 1993;, y que desempeñan importante funciones ecológicas, como antimicrobianas, antifúngicas, antioxidantes, antiherbívoros, y como agentes alelopáticos (Pandji et al, 1993;Weidenborner y Jha, 1993;Ziska et al, 1993;Grayer y Harborne, 1994;Chaves y Escudero,1997;Chaves et al, 2001b;Kidd et al, 2001).…”