Yasuko Tsujino

Potato tuber-inducing activities of jasmonic acid and related compounds

Salicylic acid (SA) induced potato tuberization in vitro at concentrations greater than 10−5 M. A comparison of the tuber-inducing activities of various related compounds suggested that derivatives of benzoic acid with a free carboxyl group and a substituent at the C-2 position of the benzene ring have this activity. Although SA had the strongest activity among the compounds tested, the activity was about one thousandth of that of natural jasmonic acid (1R,2S-jasmonic acid) in terms of the threshold concentration for activity. Spraying SA to leaves of plants grown under tuber-noninducing conditions (long days) induced tuberization. However, the natural occurrence of SA was not detected in the leaves of potato plants that had been grown under tuber-inducing conditions (short days) and had begun to form tubers. The results seem to exclude the possibility of the involvement of SA in the natural tuberization of potato plants.

Nigrosporins A and B, New Phytotoxic and Antibacterial Metabolites Produced by a Fungus Nigrospora oryzae

Nigrosporin A and B, two new phytotoxic and antibacterial metabolites were isolated from a culture filtrate of Nigrospora oryzae. The active principles were absorbed on XAD-2 resin and purified by successive ODS-HPLC. The structures were identified by spectroscopic and derivatization analysis as naphthoquinone derivatives. The substances showed phytotoxic activities, such as root elongation inhibition, necrotic effects, oxygen evolution inhibition, starch synthesis inhibition, and CO2 fixation inhibition at concentrations of 10-100 ppm. They also showed growth inhibition activity against Bacillus subtilis in a disc diffusion assay as well as when compared with streptomycin.

A malonylated anthocyanin and flavonols in the blue flowers of Meconopsis

Abstract The blue Himalayan poppies, Meconopsis horridula, M. grandis and M. betonicifolia, contain cyanidin 3-malonylsambubioside 7-glucoside as the anthocyanin. They also contain large amounts of kaempferol 3-gentiobioside and very small amounts of kaempferol 3-xylosylgentiobioside. The ratio of flavonol to anthocyanin was found to be 5.6:1, suggesting that the flavonol plays a role as a co-pigment in the blueing of Meconopsis flowers.

Buchaninoside, a steroidal glycoside from Elaeodendron buchananii

Abstract A novel steroidal glycoside was isolated from the fruit of a tropical tree, Elaeodendron buchananii , as an antifeedant substance for Spodoptera exempta . The structure of the compound was determined to be a glycoside of 2α,3β-14-trihydroxy-16α-acetoxy-14β-carda-4,20 (22)-dienolide-7β,8β-epoxide.

Conjugate of nicotine and cotinine to bovine serum albumin.

Abstract A new simple method for the conjugation of nicotine and cotinine to protein has been developed. The pyridine alkaloids were coupled with ethyleneimine to form their aminoethylpyridinium derivatives, which were conjugated to bovine serum albumin (BSA) in the presence of 1-cyclohexyl-3-(2-morpholinoethyl)-carbodiimide metho-p-toluenesulfonate. About forty molecules of S-nicotine and thirty-five of S-cotinine per molecule of starting BSA were respectively recognized to be present in the conjugates by determining the liberated aminoethylpyridinium compounds after hydrolysis.