Strigolactones in chemical ecology: waste products or vital allelochemicals?
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Biomedical subjects
Publications and source records attributed to Andrew J Humphrey.
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The role played by molecules of the strigolactone family in stimulating the germination of seeds of parasitic weeds of the genera Striga, Orobanche and Alectra has never been clearly elucidated. The biogenesis of these unusual terpenoid lactones, originally identified in minute quantities in the root exudates of a small number of host plants and two or three "false hosts", also remains obscure. These lactones, as the chemical signals which initiate the life cycle of Striga, are consequently at the forefront of the Striga research effort. This paper reviews recent key discoveries relating to the biosynthesis and mode of action of strigolactones, and summarises the evidence suggesting that these molecules may be far more widely distributed and have a greater physiological significance than has hitherto been appreciated.
Several unnatural N-acyl neuraminic acids (N-propionyl, N-hexanoyl, N-benzoyl, N-trifluoroacetyl, N-chloroacetyl, N-difluoroacetyl) were prepared enzymatically using immobilised sialic acid aldolase. N-Trifluoroacetyl-, N-chloroacetyl- and N-difluoroacetyl neuraminic acids were shown to enhance up to 10-fold the rate of association of influenza virus A to a sialoglycolipid neomembrane by surface plasmon resonance, and were found to act as weak inhibitors (K(iapp) 0.45-2.0 mM) of influenza virus neuraminidase. The N-propionyl, N-chloroacetyl- and N-difluoroacetyl neuraminic acids were found to be substrates for recombinant Escherichia coli CMP sialate synthase, to give the corresponding CMP-N-acyl-neuraminic acids. CMP-N-propionyl neuraminic acid was found not to be a substrate for CMP-N-acetyl neuraminic acid hydroxylase from pig submandibular gland.