The present invention generally relates to novel synthetic methods, systems, kits, salts, and precursors useful in medical imaging. In some embodiments, the present invention provides compositions comprising an imaging agent precursor, which may be formed using the synthetic methods described herein. An imaging agent may be converted to an imaging agent using the methods described herein. In some cases, the imaging agent is enriched in .sup.18F. In some cases, an imaging agent including salt forms (e.g., ascorbate salt) may be used to image an area of interest in a subject, including, but not limited to, the heart, cardiovascular system, cardiac vessels, brain, and other organs.

The present invention generally relates to novel synthetic methods, systems, kits, salts, and precursors useful in medical imaging. In some embodiments, the present invention provides compositions comprising an imaging agent precursor, which may be formed using the synthetic methods described herein. An imaging agent may be converted to an imaging agent using the methods described herein. In some cases, the imaging agent is enriched in .sup.18F. In some cases, an imaging agent including salt forms (e.g., ascorbate salt) may be used to image an area of interest in a subject, including, but not limited to, the heart, cardiovascular system, cardiac vessels, brain, and other organs.

The invention describes membrane permeable creatine prodrugs, pharmaceutical compositions comprising membrane permeable creatine prodrugs, and methods of treating diseases such as ischemia, heart failure, neurodegenerative disorders and genetic disorders affecting the creatine kinase system comprising administering creatine prodrugs or pharmaceutical compositions thereof. The invention also describes treating a genetic disease affecting the creatine kinase system, such as, for example, a creatine transporter disorder or a creatine synthesis disorder comprising administering creatine prodrugs or pharmaceutical compositions thereof.

The invention describes membrane permeable creatine prodrugs, pharmaceutical compositions comprising membrane permeable creatine prodrugs, and methods of treating diseases such as ischemia, heart failure, neurodegenerative disorders and genetic disorders affecting the creatine kinase system comprising administering creatine prodrugs or pharmaceutical compositions thereof. The invention also describes treating a genetic disease affecting the creatine kinase system, such as, for example, a creatine transporter disorder or a creatine synthesis disorder comprising administering creatine prodrugs or pharmaceutical compositions thereof.

The disclosure features novel lipids and compositions involving the same. Nanoparticle compositions include a novel lipid as well as additional lipids such as phospholipids, structural lipids, and PEG lipids. Nanoparticle compositions further including therapeutic and/or prophylactics such as RNA are useful in the delivery of therapeutic and/or prophylactics to mammalian cells or organs to, for example, regulate polypeptide, protein, or gene expression.

The disclosure features novel lipids and compositions involving the same. Nanoparticle compositions include a novel lipid as well as additional lipids such as phospholipids, structural lipids, and PEG lipids. Nanoparticle compositions further including therapeutic and/or prophylactics such as RNA are useful in the delivery of therapeutic and/or prophylactics to mammalian cells or organs to, for example, regulate polypeptide, protein, or gene expression.

The disclosure features novel lipids and compositions involving the same. Nanoparticle compositions include a novel lipid as well as additional lipids such as phospholipids, structural lipids, and PEG lipids. Nanoparticle compositions further including therapeutic and/or prophylactics such as RNA are useful in the delivery of therapeutic and/or prophylactics to mammalian cells or organs to, for example, regulate polypeptide, protein, or gene expression.

The disclosure features novel lipids and compositions involving the same. Nanoparticle compositions include a novel lipid as well as additional lipids such as phospholipids, structural lipids, and PEG lipids. Nanoparticle compositions further including therapeutic and/or prophylactics such as RNA are useful in the delivery of therapeutic and/or prophylactics to mammalian cells or organs to, for example, regulate polypeptide, protein, or gene expression.

A tri-carbobenzoxy-arginine represented by the following formula (2):

##STR00001##

is produced by carbobenzoxylating the arginine or arginine derivative (1) represented by the following formula (1), or a salt thereof:

##STR00002##

by adding carbobenzoxy chloride and a base in a water/organic solvent bilayer system to an arginine or arginine derivative (1) represented by the formula (1), or a salt thereof.

A tri-carbobenzoxy-arginine represented by the following formula (2):

##STR00001##

is produced by carbobenzoxylating the arginine or arginine derivative (1) represented by the following formula (1), or a salt thereof:

##STR00002##

by adding carbobenzoxy chloride and a base in a water/organic solvent bilayer system to an arginine or arginine derivative (1) represented by the formula (1), or a salt thereof.