Isolation and structural elucidation of potential allelopathic compounds from sugarcane leaves

SAMPIETRO, D.A.; ISLA, M. I.; VATTUONE, M.A.

Ciego de Avila (Cuba)

Congreso; V Congreso Internacional de Biotecnología y Agricultura; 2005

Centro de Bioplantas

Sugarcane is a traditional crop in the northwest of Argentina. Field experiments showed that sugarcane residues are able to inhibit the growth of some weeds. The aim of this work was: 1) the isolation and structural elucidation of potential allelopathic compounds from aqueous leachates of sugarcane leaves and 2) the evaluation of the phytotoxic potency of the purified compounds on weeds that usually are found in sugarcane fields. A bioassay guided isolation of phytotoxins was conducted on sugarcane leaf leachates. Radicle elongation of Lactuca sativa L. was used as indicator of phytotoxicity. The bioactive compounds were separated with organic solvents, gel filtration, silica gel column chromatography and semipreparative HPLC. Pure compounds were identified as ferulic acid, syringic acid and vanillic acid. The concentration of phenolic acids needed to produce 50% of inhibition on radicle elongation (IC50) was calculated for L. sativa and the weeds Sida rhombifolia L., Amaranthus quitensis L., Bidens subalternans L. and Brassica campestris L. Vanillic acid was the most phytotoxic, following by ferulic and syringic acids. Although the isolated compounds are involved in the phytotoxicity of sugarcane residues, other phytotoxins participate with the phenolic acids in the total inhibitory activity of the leachates from sugarcane leaves.