Deoxycalyciphylline B, a Hepatotoxic Alkaloid from Daphniphyllum calycinum
Daphniphyllum calycinum (DC), a main component of Chinese patent drug Fengliao-Changweikang, is effectively used to cure bowel disease in the clinic. It was recorded that DC possessed slight toxicity, which was caused by the alkaloids existing in its extract. Unfortunately, to date the toxicity level and toxic constituents are still unclear. The present study is designed to illustrate the acute toxicity and induced organ damages of the total alkaloids as well as to determine the toxic constituents. Based on the above studies, not only was the acute toxicity determined but also hepatic toxicity was characterized by increased plasma biomarkers of ALT and AST and liver cell inflammatory infiltrate as well necrosis that was firstly observed. Significantly, deoxycalyciphylline B exhibited exactly the same hepatic toxicity so it was identified as the main toxic constituent in DC. An obvious dose-effect relationship between the toxic compound and induced hepatic injuries was also observed. Moreover, the Chinese patent drug Fengliao-Changweikang contained low levels of the toxic compound, compared with the total alkaloids. Therefore, this Chinese patent drug could be regarded to be safe in this point of view.
Harnessing Radical Reactivity For The Construction Of Natural Product Frameworks And Transition Metal Catalyst Stability In A Modified Kochi Coupling Reaction
HARNESSING RADICAL REACTIVITY FOR THE CONSTRUCTION OF NATURAL PRODUCT FRAMEWORKS AND TRANSITION METAL CATALYST STABILITY IN A MODIFIED KOCHI COUPLING REACTION Advisor: Dr. Jennifer L. Stockdill Major: Organic Chemistry Degree: Doctor or Philosophy Polycyclic N-containing heterocycles play an important role in therapeutic applications and as molecular tools in studying biological processes, making them important synthetic targets. Current synthetic approaches are too lengthy, use toxic reagents or are limited to accessing a particular framework and hence, their syntheses warrant further study. The Stockdill research group have recently developed conditions to avoid both reduction and slow addition in aminyl radical cyclizations in our venture to access the constrained ABC core of calyciphilline A, a Daphniphyllum alkaloid. An electron deficient enone with a pendent internal alkyne as the neutral aminyl radical precursor was used for radical cyclization. Based on these results on enone reactivity, it was hypothesized that the rate of the tandem cyclization over reduction can be significantly increased by introducing electron-deficient substituents on the olefin. This hypothesis was tested on simple substrates, and surprisingly, experimental data revealed that regardless of the presence or absence of electron withdrawing substituents on the olefin, all substrates work approximately the same resulting similar yields. Cross coupling-reactions using transition metals have played a vital role in the synthesis of active pharmaceutical ingredients via C-C and C-heteroatom bond formation,
Treatment of oily wastewater by organic–inorganic composite tubular ultrafiltration (UF) membranes
A tubular UF module equipped with polyvinylidene fluoride membranes modified by inorganic nano-sized alumina particles was used to purify oily wastewater from an oil field. The membrane water permeations of the UF process were analyzed. Retentions of chemical oxygen demand and total organic carbon were more than 90% and 98%, respectively. The results indicate that after UF treatment, oil content was below 1 mg/L, suspended solids content was below 1 mg/L, and solid particle median diameters were less than 2 μm. The quality of the permeation water met the requirement by oilfield injection or drainage. Fouled membranes and washed membranes were analyzed by scanning electron microscopy, and fouled membranes were backwashed with different solutions. Results show that the addition of nanosized alumina particles improved membrane antifouling performance, and the flux recovery ratio of modified membranes reached 100% washing with 1 wt% of OP-10 surfactant solution (pH 10).