Aromatic-ring-functionalised benzoxazinones in the system Oryza sativa-Echinochloa crus-galli as biorational herbicide models.

Full Abstract

BACKGROUND: Barnyardgrass, Echinochloa crus-galli (L.) Beauv., is one of the most problematic weeds occurring in rice crops. Although efficient chemical control is provided by herbicides available on the market, resistant biotypes provoked by pressure selection have appeared in recent times. This emphasises the need for alternative treatments in which herbicidal compounds from a natural origin could be included. RESULTS: A number of chemicals with a [2H]-1,4-benzoxazin-3(4H)-one (D-DIBOA) skeleton were tested on this weed, and also in rice, in order to achieve an optimal lead for herbicide composition development by taking into consideration phytotoxic effects and selectivity on the weed. 6-Cl-D-DIBOA causes the same effect as the commercial herbicide propanil at a concentration 15 times lower, while 6-F-D-DIBOA causes this inhibition at a dose 30 times lower. The phytotoxicities caused by 8-Cl-D-DIBOA (IC50 = 44 microM, R2 = 0.866) and 7,8-diF-D-DIBOA (IC50 = 52 microM, R2 = 0.9067) are also remarkable. 8-Cl-D-DIBOA was the compound that presented the highest selectivity on Echinochloa crus-galli. The structural requirements for optimal phytotoxicity and selectivity were elucidated by means of QSAR methodology, considering electronic and steric factors. One of the most important descriptors influencing the bioactivity was the dipole moment modulus. This was successfully correlated by employing a second-order polynomial model. CONCLUSION: The in vitro phytotoxic profiles and selectivities shown for these chemicals make them truly promising candidates for higher-level studies. 6F- and 6Cl-D-DIBOA, for their high phytotoxicities, and 8-Cl-D-DIBOA, because of its high selectivity, were found to be the most interesting compounds from this point of view. Copyright 2009 Society of Chemical Industry.

Author information

Author/s: Macías, Francisco A (FA); Chinchilla, Nuria (N); Varela, Rosa M (RM); Molinillo, José Mg (JM); Marín, David (D); de Siqueira, Joao M (JM);

Affiliation: Allelopathy Group, Department of Organic Chemistry, University of Cádiz, Avda. República Saharaui, s/n, 11510 Puerto Real, Cádiz, Spain. famacias(-atsign-)uca.es

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: Pest management science (Pest Manag Sci), published in England. (Language: eng)

Reference: 2009-Oct; vol 65 (issue 10) : pp 1104-13

Dates: Created 2009/09/09; Completed 2009/11/03;

PMID: 19551813, status: MEDLINE (last retrieval date: 11/3/2009, IMS Date: )

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