Bioassay-guided isolation of novel and selective urease inhibitors from Diospyros lotus / 中国天然药物

Two new dimeric naphthoquinones, 5',8'-dihydroxy-6,6'-dimethyl-7,3'-binaphthyl-1,4,1',4'-tetraone (1; Di-naphthodiospyrol D) and 5',8'-dihydroxy-5,8-dimethoxy-6,6'-dimethyl-7,3'-binaphthyl-1,4,1',4'-tetraone (2; Di-naphthodiospyrol E), along with known naphthoquinones diospyrin (3) and 8-hydroxy diospyrin (4) were isolated from the chloroform fraction of extract of Diospyros lotus roots. Their structures were elucidated by advanced spectroscopic analyses, including HSQC, HMBC, NOESY, and J-resolved NMR experiments. The fractions and compounds 1-4 were evaluated for urease activity and phosphodiesterase-I, carbonic anhydrase-II and α-chymotrypsin enzyme inhibitory activities. Compounds 1 and 2 and their corresponding fractions showed significant and selective inhibitory effects on urease activities. The IC values of 1 and 2 were 260.4 ± 6.37 and 381.4 ± 4.80 µmol·L, respectively, using thiourea (IC = 21 ± 0.11 µmol·L) as the standard inhibitor. This was the first report demonstrating that the naphthoquinones class showed urease inhibition.

Antipyretic and antinociceptive activity of Diospyros lotus L. in animals

<p><b>OBJECTIVE</b>To evaluate pharmacologically the traditional use of Diospyros lotus as antipyretic and antinociceptive in various animal models.</p><p><b>METHODS</b>In vivo experimental models were used in this study. Antipyretic activity of extract/fractions was evaluated in brewer's yeast induced hyperthermic mice while antinociceptive activity was studied in acetic acid induced writhing test at 50 and 100 mg/kg i.p.</p><p><b>RESULTS</b>The crude extract strongly ameliorated the induced pyrexia during various assessment times. Upon fractionation, the antipyretic effects were strongly augmented by the chloroform and ethyl acetate fractions of the plant. However, hexane and butanol fractions were insignificant in their effect as antipyretic. The extract showed marked inhibition on the noxious simulation induced by post acetic acid injection. The effect was strongly supported by other fraction expect hexane.</p><p><b>CONCLUSIONS</b>In short, our study scientifically validated the traditional use of the plant as antipyretic.</p>