- Dendrimer-inspired nanomaterials for the in vivo delivery of siRNA to lung vasculature
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Targeted RNA delivery to lung endothelial cells has the potential to treat conditions that involve inflammation, such as chronic asthma and obstructive pulmonary disease. To this end, chemically modified dendrimer nanomaterials were synthesized and optimized for targeted small interfering RNA (siRNA) delivery to lung vasculature. Using a combinatorial approach, the free amines on multigenerational poly(amido amine) and poly(propylenimine) dendrimers were substituted with alkyl chains of increasing length. The top performing materials from in vivo screens were found to primarily target Tie2-expressing lung endothelial cells. At high doses, the dendrimer-lipid derivatives did not cause chronic increases in proinflammatory cytokines, and animals did not suffer weight loss due to toxicity. We believe these materials have potential as agents for the pulmonary delivery of RNA therapeutics.
- Khan, Omar F.,Zaia, Edmond W.,Jhunjhunwala, Siddharth,Xue, Wen,Cai, Wenxin,Yun, Dong Soo,Barnes, Carmen M.,Dahlman, James E.,Dong, Yizhou,Pelet, Jeisa M.,Webber, Matthew J.,Tsosie, Jonathan K.,Jacks, Tyler E.,Langer, Robert,Anderson, Daniel G.
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- Mechanistic insights from reaction of α-oxiranyl-aldehydes with cyanobacterial aldehyde deformylating oxygenase
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The biosynthesis of long-chain aliphatic hydrocarbons, which are derived from fatty acids, is widespread in Nature. The last step in this pathway involves the decarbonylation of fatty aldehydes to the corresponding alkanes or alkenes. In cyanobacteria, this is catalyzed by an aldehyde deformylating oxygenase. We have investigated the mechanism of this enzyme using substrates bearing an oxirane ring adjacent to the aldehyde carbon. The enzyme catalyzed the deformylation of these substrates to produce the corresponding oxiranes. Performing the reaction in D2O allowed the facial selectivity of proton addition to be examined by 1H NMR spectroscopy. The proton is delivered with equal probability to either face of the oxirane ring, indicating the formation of an oxiranyl radical intermediate that is free to rotate during the reaction. Unexpectedly, the enzyme also catalyzes a side reaction in which oxiranyl-aldehydes undergo tandem deformylation to furnish alkanes two carbons shorter. We present evidence that this involves the rearrangement of the intermediate oxiranyl radical formed in the first step, resulting in aldehyde that is further deformylated in a second step. These observations provide support for a radical mechanism for deformylation and, furthermore, allow the lifetime of the radical intermediate to be estimated based on prior measurements of rate constants for the rearrangement of oxiranyl radicals.
- Das, Debasis,Ellington, Benjamin,Paul, Bishwajit,Marsh, E. Neil G.
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p. 570 - 577
(2014/03/21)
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- Ketoalkylphospholipids
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Novel ketoalkylphospholipids, inclusive of salts thereof, of the formula STR1 wherein R1 is an aliphatic hydrocarbon residue containing 10 to 20 carbon atoms, R2 is hydrogen or methoxy, and R3, R4 and R5 are independently hydrogen or C1-5 alkyl, or STR2 represents a cyclic ammonio group, exhibit inhibitory activity against multiplication of tumor cells and antifungal activity.
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