title: Multifunctionalised benzoxazinones in the systems Oryza sativa-Echinochloa crus-galli and Triticum aestivum-Avena fatua as natural-product-based herbicide leads.
abstract: BACKGROUND
  Fifteen novel derivatives of D-DIBOA, including aromatic ring modifications and the addition of side chains in positions C-2 and N-4, had previously been synthesised and their phytotoxicity on standard target species (STS) evaluated. This strategy combined steric, electronic, solubility and lipophilicity requirements to achieve the maximum phytotoxic activity. An evaluation of the bioactivity of these compounds on the systems Oryza sativa-Echinochloa crus-galli and Triticum aestivum-Avena fatua is reported here.
  
  
  RESULTS
  All compounds showed inhibition profiles on the two species Echinochloa crus-galli (L.) Beauv. and Avena fatua L. The most marked effects were caused by 6F-4Pr-D-DIBOA, 6F-4Val-D-DIBOA, 6Cl-4Pr-D-DIBOA and 6Cl-4Val-D-DIBOA. The IC(50) values for the systems Echinochloa crus-galli-Oryza sativa and Avena fatua-Triticum aestivum for all compounds were compared. The compound that showed the greatest selectivity for the system Echinochloa crus-galli-Oryza sativa was 8Cl-4Pr-D-DIBOA, which was 15 times more selective than the commercial herbicide propanil (Cotanil-35). With regard to the system Avena fatua-Triticum aestivum, the compounds that showed the highest selectivities were 8Cl-4Val-D-DIBOA and 6F-4Pr-D-DIBOA. The results obtained for 6F-4Pr-D-DIBOA are of great interest because of the high phytotoxicity to Avena fatua (IC(50) = 6 µM, r(2) = 0.9616).
  
  
  CONCLUSIONS
  The in vitro phytotoxicity profiles and selectivities shown by the compounds described here make them candidates for higher-level studies. 8Cl-4Pr-D-DIBOA for the system Echinochloa crus-galli-Oryza sativa and 6F-4Pr-D-DIBOA for Avena fatua-Triticum aestivum were the most interesting compounds.
authors.affiliation: Department of Organic Chemistry, University of Cádiz, Puerto Real, Cádiz, Spain. famacias@uca.es
authors.forename: Francisco A
authors.initials: FA
authors.lastname: Macías
authors.forename: Nuria
authors.initials: N
authors.lastname: Chinchilla
authors.forename: Elena
authors.initials: E
authors.lastname: Arroyo
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Varela
authors.forename: José M G
authors.initials: JM
authors.lastname: Molinillo
authors.forename: David
authors.initials: D
authors.lastname: Marín
mesh_terms: D018554:Avena / Q000187:drug effects*; D048588:Benzoxazines / Q000737:chemistry / Q000494:pharmacology*; D031747:Echinochloa / Q000187:drug effects*; D006540:Herbicides / Q000737:chemistry / Q000494:pharmacology*; D012275:Oryza / Q000187:drug effects*; D013329:Structure-Activity Relationship; D014908:Triticum / Q000187:drug effects*
chemical_list: D048588:Benzoxazines; D006540:Herbicides