Total Saponins from Dioscorea Septemloba Thunb Reduce Serum Uric Acid Levels in Rats with Hyperuricemia through OATP1A1 Up-regulation

The aim of this study is to evaluate the efficacy of total saponins of Dioscorea（TSD）, an extract of the Chinese herbal Bi Xie, on hyperuricemia and to elucidate the underlying mechanisms. The rat hyperuricemia model was established by administration of adenine. Thirty-two rats were randomly allocated into 4 groups： model group, low/high-dose TSD-treated groups, and allopurinol-treated group. Meanwhile, 8 rats were used as normal controls. Serum uric acid（UA）, blood urea nitrogen（BUN）, serum creatinine（Scr）, and organic anion transporting polypeptide 1A1（OATP1A1） levels were measured. Comparison between the model group and treatment（allopurinol and TSD） groups showed the serum UA levels were significantly decreased in treatment groups. TSD had similar effects to allopurinol. It was found that the OATP1A1 protein expression levels in treatment groups were higher than in model group and normal controls. And different from the allopurinol-treated groups, TSD-treated group had elevated OATP1A1 expression levels in the stomach, liver, small intestine and large intestine tissues. It was suggested that TSD may facilitate the excretion of UA and lower UA levels by up-regulating OATP1A1 expression.

Biology of Planococcus citri (Risso) (Hemiptera: Pseudococcidae) on Five Yam Varieties in Storage

Yam is an important staple cash crop, which constitutes 53% of total root and tuber consumption in West Africa. It is a cheap source of carbohydrate in the diets of millions of people worldwide and in tropical West Africa. However, attack by Planococcus citri results in shriveling of the tubers, making them become light and unpalatable. They also lose their market value. The total number of eggs laid, incubation period, developmental period and adult longevity of P. citri on stored yam Disocorea species were studied on five yam varieties namely Dioscorea rotundata var. Pona, Dioscorea rotundata var. Labreko, Dioscorea rotundata var. Muchumudu, Disocorea alata var. Matches and Dioscorea rotundata var. Dente in the laboratory with ambient temperatures of 26.0&#176C - 30.0&#176C and relative humidity of 70.0% - 75.0%. The mean life spans of the female insect that is from hatch to death on Dioscorea rotundata var. Pona, Dioscorea rotundata var. Labreko, Dioscorea rotundata var. Muchumudu, Disocorea alata var. Matches and Dioscorea rotundata var. Dente were 62.4, 63.5, 66.8, 67.3 and 69.8 days, respectively and those of the male were 23.8, 25.3, 29.6, 30.2 and 33.5 days, respectively. The adult female lived longer than the adult male. The findings showed that citrus mealybug preferred Dioscorea rotundata var. Pona to the rest of the varieties, as it developed faster and laid more eggs (497.0 eggs) on it than on the other varieties. This implies that citrus mealybug multiplies faster and destroys Dioscorea rotundata var. Pona tubers in storage faster than on the other varieties. Therefore, Dioscorea rotundata var. Dente should be the preferred yam for long-term storage.

Two new steroidal saponins from the rhizomes of Dioscorea zingiberensis

AIM: To investigate the chemical constituents of Dioscorea zingiberensis C. H. Wright. METHODS: The compounds were isolated by various chromatographic techniques, and the structures of the new steroidal saponins were elucidated by extensive 1D- and 2D-NMR, MS, and IR spectral analysis. RESULTS: The 70% EtOH extract of the rhizomes of Dioscorea zingiberensis afforded two new steroidal saponins, zingiberenosides A(1) and B(2), along with eight known analogues, 3β, 26-dihydroxy-25(R)-furosta-△5, 20(22)-diene-3-O-α-Lrhamnopyranosyl-(1→2)-O-β-D-glucopyranoside(3), methyl parvifloside(4), deltoside(5), methyl deltoside(6), zingiberensis new saponin(7), deltonin(8), progenin III(9) and diosgenin-diglucoside(10). CONCLUSION: Two new steroidal saponins were isolated from Dioscorea zingiberensis and their structures determined.

Panthogenins A and B,two novel norergostanol steroids from Dioscorea panthaica

Two novel 27-norergostanol steroids, panthogenins A （1） and B （2）, possessing unusual rings E and F featuring a ketal moiety at C-25 were isolated from rhizomes ofDioscorea panthaica. Their structures and relative configurations were elucidated by extensive spectroscopic methods including 1D and 2D NMR techniques, and the structure of panthogenin A was further confirmed by X-ray crystallography. Both compounds showed potent in vitro insulin sensitizing activity.