Showing papers on "Polygonum published in 1992"

Emodin, a protein tyrosine kinase inhibitor from Polygonum cuspidatum.

Abstract: Bioassay-directed fractionation of a Chinese medicinal plant, Polygonum cuspidatum (Polygonaceae), has led to the discovery of an anthraquinone, emodin [1], as a strong inhibitor of a protein tyrosine kinase (p56lck) partially purified from bovine thymus. Comparison of the IC50 values of emodin for protein tyrosine kinase inhibitory activity with physcion [2] and emodin-O8-D-glucoside [3], also isolated from the same plant, reveal the importance of the hydroxyl groups at C-6 and C-8 for the observed activity.

Allelochemicals from Polygonum sachalinense Fr. Schm. (Polygonaceae)

Abstract: The root exudates fromPolygonum sachalinense in a recirculating system significantly inhibited lettuce seedling growth. The rhizomes and roots ofP. sachalinense were extracted with 80% acetone. Bioassay of the neutral-acidic fraction on the TLC agar plate showed the inhibitory activity corresponded to the two yellow pigment bands. Two orange needles were isolated and identified as anthraquinone compounds: emodin and physcion. Both compounds exhibited inhibitory activities against the seedling growth of several testing plant species. Glucosides were isolated fromP. sachalinense and were identified as emodin-1-O-β-D-glucoside and physcion-1-O-β-D-glucoside, respectively. On plant growth bioassay, these glucosides showed no phytotoxic activity against lettuce seedlings. The concentrations of emodin, physcion, and their glucosides from rhizome with roots, aerial parts, fallen leaves, and soil were determined. The rhizome with roots and fallen leaves contained emodin and physcion at relatively high concentrations. Emodin also occurs in the soil of this plant community with effective concentrations in the fall. The results indicate that these anthraquinones are responsible for the observed interference and are potent allelopathic substances.

Antioxidative substances in leaves of Polygonum hydropiper

Abstract: Antioxidative flavonoids and flavonoid glucoside were isolated from the leaves of Polygonum hydropiper, a culinary herb. The flavonoid Ia was identified as 7,4'-dimethylquercetin, Ib as 3'-methylquercetin, Ic as quercetin, and the flavonoid glucoside Id as isoquercitrin on the basis of chemical and spectroscopic evidence. The antioxidative activities measured by a ferric thiocyanate method were in the order Id>Ia>Ic>Ib

Physiological basis of achene dormancy in polygonum convolvulus (polygonaceae)

Abstract: Germination of dormant achenes of wild buckwheat (Polygonum convolvulus L.) was promoted at 25 C if they were stratified at low temperatures. Preincubation at either 2 C or 10 C promoted subsequent germination at 25 C equally, although the period of time to reach maximum germination was shorter for the 2 C treatment. Moreover, a preincubation treatment of a daily alternating cycle 2 C for 20 hr and 10 C for 4 hr promoted germination at 25 C more than either temperature alone. Removing portions of the hard pericarp and testa did not promote germination of dormant achenes at 25 C except when the portion of those structures covering the tip of the radicle was removed. This suggests that the structures covering the embryo do not prevent germination by restricting the movement of water or gases but rather restrict growth mechanically. Complete removal of the pericarp promoted germination, but much higher germination was obtained when the testa was also removed, indicating that the pericarp may not be the main factor in dormancy. Thus the role of low temperature in the loss of dormancy in wild buckwheat achenes may be to promote the production of hydrolytic enzymes that lower the mechanical resistance of pericarp and testa and/or increase the embryo growth potential beyond some threshold level and thereby enable the radicle to overcome the resistance to growth imposed by the structures covering the embryo. Wild buckwheat (Polygonum convolvulus) is a common annual weed in cultivated fields of North America. Its persistence as a weed has been attributed in part to dormancy of newly ripened achenes that allows germination to be spread over several subsequent seasons (Hume, Martinez, and Best, 1983).

Occurrence and Distribution of Polygonum Species in Ohio

Abstract: Study of herbarium specimens from 23 Ohio institutions revealed that there are 24 species of Polygonum in the state—sixteen native and eight alien. These species fall into six sections, all of which have been treated as genera by various authors in the past. They are treated here as part of Polygonum sensu lato. Some of the species have been documented in only two or three counties, while others are widely distributed in all 88 counties. At least one native species, P. careyi, is presumed extirpated from the state. A purpose of this paper is to develop a key to the identification of the species. Another purpose is to show their distribution in the state by county maps. Ohio J. Sci. 92 (4): 88-97, 1992

Effect of the root of Polygonum multiflorum Thunb. and its processed products on fat accumulation in the liver of mice

Abstract: Experiments have shown that the root of Polygonum multiflorum exhibits inhibitory effect on triglyceride (TG) accumulation in the liver of mice induced by CCl4, cortisone acetate and thioacetamide (TAA). Its processed products (I, II) were found to be effective in lowering the accumulated TG induced by cortisone acetate. The root of Polygonum multiflorum and its processed products also reduced the enlargement of liver by CCl4.