No abstract

The antidiarrhoeal effects of the aqueous root extract of Terminalia avicennoides were evaluated in rodents. Studies were carried out on the isolated rabbit jejunum, gastrointestinal motility in vivo and on castor oil-induced diarrhoea in mice. The results revealed that the extract exhibited a concentration-dependent inhibition of the spontaneous pendular movement of the isolated rabbit jejunum and attenuated acetylcholine induced contractions. The extract (100, 200 and 400 mg/kg) also caused a dose-dependent decrease of gastrointestinal transit and markedly protected mice against castor oil-induced diarrhoea. The intraperitoneal LD(50) of the extract was found to be 871.4-917.4 mg/kg in mice (95% confidence). A preliminary phytochemical screening of the aqueous extract of T. avicennoides roots revealed the presence of tannins, saponins and flavonoids. The results obtained showed that the water extract of T. avicennoides roots may contain some biologically active principles that may be active against diarrhoea and this may be the basis for its use traditionally for gastrointestinal disorders.

No abstract

The reaction of diphenyl‐, dichloro‐, and chloroketenes with several siloxy dienes results in (4 + 2) and/or (2 + 2) cycloaddition products depending primarily on Substitution in the diene. The (4 + 2) cycloaddition products are easily hydrolyzed to pyranones. These results are discussed in terms of a dipolar intermediate.

ABSTRACTwere synthesized by reactions o? methyl 2-bromo-2-phmylethanorrte 1 with oFthosubstituted arylaminea 2a -2c. Subsequent reductive alkylationofthe lactams with aodium hydride and-iodobthane afforded only the N-alkylated quinoxalinone 4a and benzothiazinone 4b. Lithium aluminium hydride reduction of the lactams 3 8 -3~ gave the dihydro-aerivatives 5a, 5b and 5c while similar reduction of the A-aIkylated lactams 4a and 4b yieldzd tlie unsafurated quinoxaline 6a and benzothiazine 6b respectively. Lead tetraacetate oxidation of the quinsxalinone 3a furnished-the unsaturated quinoxalinone 9 which was N-alkylated using sodiumborohydride in formic acid to give 10. Treatment of the 1actm.w 3a, 3b and 3c with phosphorus pentasulphide produGd only the quinoxalinethiol f l aEd benzsthiazinethione 12. dium ethoxide t b g i v e the S-al&latedTroducta 2 urd 2 respectively. The lactam quinoxalinone 3a, benzothiazinone 3b and benzothiazinone 3cCompounds 11 and 12 were alkylated with iodomzhane and so-

The generation of diphenyl-, phenyl-, phenoxy-, and chloroketenes by treatment of the corresponding acid chlorides with triethylamine in the presence of 2-aminophenol resulted in good yields of 2-substituted benzoxazoles.

The generation of phenyl‐, diphenyl‐, phenoxy‐, and chloroketenes, by the dehydrochlorination of the corresponding acid chlorides with triethylamine, in the presence of 2‐aminothiophenol 1 gave 2‐substituted benzothiazoles 3 in good yields.

The cycloaddition of diphenyl-and various chloroketenes to /3-methoxy ,/3-unsaturated ketones afforded (4 + 2) cycloaddition products. The cycloadducts resulting from the choroketenes were converted to 2-pyranones on treatment with zinc in moist acetic acid. The cycloaddition products from chloroketenes and /3-(methoxymethylene)-a-tetralone were readily converted to substituted benzocoumarins.