Abstract:A new series of the 0-pyrimidinylsalicylates was synthesized and their herbicidal activity was examined. Some of these compounds showed very strong herbicidal activity under pre-and post-emergent treatment conditions against various kinds of grass and broadleaf weeds. Among these compounds, 0-(4, 6-dimethoxypyrimidin-2-yl) salicylic acid and its methyl ester were found to exhibit the highest activity. The herbicidal symptoms observed after the treatments included early cessation of plant growth followed by chlorosis, necrosis and plant death. The symptoms were similar to those caused by sulfonylureas and imidazolinones, which inhibit branched-chain amino acid biosynthesis.Key words: pyrimidinyl salicylates, methyl 0-(4-chloro-6-methoxypyrimidin-2-yl) salicylate, 2-alkanesulfonylpyrimidines, methyl 0-(4, 6-dimethoxypyrimidin-2-yl) salicylate, methyl 0-(4, 6-dimethoxy-s-triazin-2-yl) salicylate, acetolactate synthase, sulfonylureas.
An aqueous methanol/water extract of the Oriental crude drug "ninjin" (ginseng), Panax ginseng roots from Korea, showed a remarkable hypoglycaemic activity on administration to mice. Fractionation of the extract, along with the pharmacological assays, led to isolation of five glycans, panaxans A, B, C, D and E. These constituents exhibited significant hypoglycaemic actions in normal and alloxan-induced hyperglycaemic mice.
A number of 6-(4-phenoxyphenoxy)pyrimidines and triazines were synthesized and their herbicidal activity was measured. Compounds with the methoxy groups at the 2-and 4-positions on the pyrimidine and triazine rings exhibited high herbicidal activity. Introduction of a substituent into the 5-position of the pyrimidine ring diminished the activity. In the phenoxyphenoxy substructure at the 6-position, the central ether bond can be replaced by a methylene group without loss of activity. The optimum substituent on the terminal phenyl ring was 3-trifluoromethyl. The compounds showed a strong Hill reaction inhibition, but unfortunately showed poor selectivity between weeds and crops.
tracted with MeOH-water (1: 1, 501 x 4) for 4 days (each extraction) at room temperature. The aqueous MeOH solution was concentrated under reduced pressure to give the extract (2.7 kg) which was chromatographed over cellulose (5.0 kg). The active water eluate (410 g) was dialyzed with cellulose tubings (Visking, 36/32) against water for 10 days to afford the non-dialyzable portion (69.6 g). Successive chromatography of the nondialyzable portion over DEAE-cellulose (4.0 ID x 45 cm) with water, over Sepharose 6B (4.0 ID x 95 cm) with 0.1 N NaCI, over DEAE-Toyopearl 650M (4.0 ID x 45 cm) with water containing NaCl (0-* 1 M120 h) and over Sephacryl S-200 (4.0 ID x 95 cm) with 0.1 M Tris-HC1 buffer (pH 8.0) containing 0.5 M NaCI yielded moran A.
A hypoglycaemic constituent, panaxan A, isolated from the roots of Panax ginseng, was revealed to be a glycan with molecular weight of Ca. 14000. Spectroscopic and degradative studies demonstrated that panaxan A is mainly composed of a-1-.+ 6 linked nglucopyranose residues having branching at the C-3 position, the ratio of terminals, branching positions and intermediate units being Ca. 1:1:2.
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