Pre-emergent evaluation of Croton ehrenbergii (Euphorbiaceae) and characterization of L-quebrachitol and flavones

Euphorbiaceae family is one of the most diverse and numerous of angiosperms, containing around 1300 species grouped in 300 genus [1]. Croton is the most important genus studied of this family and it has been used in traditional medicine to treat malaria, abscess, inflammation, cancer, diabetes, among others [2 – 3]. Some Euphorbiaceae species had been reported to exhibit herbicidal properties [4 – 5]. Thus the aim of present work was to evaluate its herbicidal activity and carry out the first phytochemical study of Croton ehrenbergii. Methanol, acetone and hexane extracts of aereal parts (separated leaves and stems) were obtained. Herbicidal assay was performed in vivo on Lalium perene and Lactuca sativa as mono and dicotyledonous models, respectively [5]. Extracts were assayed at 50 and 100 µg/mL on DMSO. Germination further root and stem elongation were registered (Table 1). Methanol extracts were found to be the most active inhibiting L. sativa germination in 96 and 100% (leaves) along with 85 and 100% (stems) at the concentrations tested, respectively. No significant effect was observed on root and stem elongation. Structural determination of the active metabolites was carried out by NMR spectroscopy (1 and 2D) after chromatographic process. Secondary metabolites from methanol extract were establish as L-quebrachitol (1), and four flavones tiliroside (2), kaempferol (3), kaempferol-7-O-rhamnoside (4), quercitin-3-O-rhamnoside (5). C. ehrenbergii could be a good candidate to be used for undergrowth control useful in agriculture.

Tab. 1: Germination of Lactuca sativa (dicotyledonous).

[ppm]	Control	E. Hexane		E. Acetone		E. methanol
		a	b	a	b	a	b
50	100	65	40	80	65	96	85
100	100	100	100	72	55	100	100
a =% Inhibition leaves b =% Inhibition stem

Acknowledgements: CONACyT (Grant number 241044) financed this work.

Keywords: Croton ehrenbergii, herbicidal activity, flavones, pre-emergent, NMR.

References:

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[4] Morales FF, King DB, Lotina HB. Natural diterpenes from Croton ciliatoglanduliferus as photosystem II and phothosystem I inhinitors in spicnach chloroplast. 2007. Photosynth Res. 91:71 – 80

[5] Islam AKMM and Kato-Noguchi H. Allelopathic prospective of Ricinus communis and Jatropha curcas for bio-control of weeds. Acta Agriculturae Scandinavica, Section B: Soil & Plant Science 2013; 63: 731 – 739

No conflict of interest has been declared by the author(s).