Identification and Characterization of a Streptomyces albus Strain and Its Secondary Metabolite Organophosphate against Charcoal Rot of Sorghum.

Streptomycesalbus strain CAI-21 has been previously reported to have plant growth-promotion abilities in chickpea, pigeonpea, rice, and sorghum. The strain CAI-21 and its secondary metabolite were evaluated for their biocontrol potential against charcoal rot disease in sorghum caused by Macrophomina phaseolina. Results exhibited that CAI-21 significantly inhibited the growth of the pathogen, M. phaseolina, in dual-culture (15 mm; zone of inhibition), metabolite production (74% inhibition), and blotter paper (90% inhibition) assays. When CAI-21 was tested for its biocontrol potential under greenhouse and field conditions following inoculation of M. phaseolina by toothpick method, it significantly reduced the number of internodes infected (75% and 45% less, respectively) and length of infection (75% and 51% less, respectively) over the positive control (only M. phaseolina inoculated) plants. Under greenhouse conditions, scanning electron microscopic analysis showed that the phloem and xylem tissues of the CAI-21-treated shoot samples were intact compared to those of the diseased stem samples. The culture filtrate of the CAI-21 was purified by various chromatographic techniques, and the active compound was identified as "organophosphate" by NMR and MS. The efficacy of organophosphate was found to inhibit the growth of M. phaseolina in the poisoned food technique. This study indicates that S.albus CAI-21 and its active metabolite organophosphate have the potential to control charcoal rot in sorghum.

Chiral 6-aryl-furo[2,3-d]pyrimidin-4-amines as EGFR inhibitors.

Epidermal growth factor receptor inhibitors are of importance in cancer therapy and possibly in the management of pain. Herein, we report a structure-activity relationship study with 29 new 6-aryl-furo[2,3-d]pyrimidin-4-amines, involving modification of the 4-amino group and 6-aryl function. The EGFR activity was especially dependent on having a chiral 4-benzylamino group with correct stereochemistry. Molecular dynamics indicate this to be due to favourable cation-π interactions. The most active inhibitor identified, equipotent to Erlotinib, was substituted with (R)-1-phenylethylamine at C-4 and a N(1), N(1)-dimethyl-1,2-diamine group in para position of the 6-aryl moiety. These new furopyrimidines had a different off-target kinase profile when compared to Erlotinib, and also possessed high activity towards Ba/F3 EGFR(L858R) reporter cells. Further, comparing the EGFR data of the furo[2,3-d]pyrimidin-4-amines with that of the corresponding thieno- and pyrrolopyrimidines concludes the furopyrimidine scaffold to be highly useful for development of new epidermal growth factor receptor antagonists.