The present invention relates to systems, compositions, and methods for the synthesis and use of imaging agents, or precursors thereof. An imaging agent precursor 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 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. In some embodiments, methods and compositions for assessing perfusion and innervation mismatch in a portion of a subject are provided.

Described herein are compounds and compositions characterized, in certain embodiments, by conjugation of various groups, such as lipophilic groups, to an amino or amide group of an amino acid, a linear or cyclic peptide, a linear or cyclic polypeptide, or structural isomer thereof, to provide compounds of the present invention, collectively referred to herein as “APPLs”. Such APPLs are deemed useful for a variety of applications, such as, for example, improved nucleotide delivery. Exemplary APPLs include, but are not limited to, compounds of Formula (I), (II), (III), (IV), (V), and (VI), and salts thereof, as described herein:

##STR00001##

wherein m, n, p, R′, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.8, Z, W, Y, and Z are as defined herein.

Described herein are compounds and compositions characterized, in certain embodiments, by conjugation of various groups, such as lipophilic groups, to an amino or amide group of an amino acid, a linear or cyclic peptide, a linear or cyclic polypeptide, or structural isomer thereof, to provide compounds of the present invention, collectively referred to herein as “APPLs”. Such APPLs are deemed useful for a variety of applications, such as, for example, improved nucleotide delivery. Exemplary APPLs include, but are not limited to, compounds of Formula (I), (II), (III), (IV), (V), and (VI), and salts thereof, as described herein:

##STR00001##

wherein m, n, p, R′, R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5, R.sup.8, Z, W, Y, and Z are as defined herein.

The present disclosure provides methadone prodrugs, pharmaceutical compositions, and their methods of use, where the pharmaceutical compositions comprise a methadone prodrug that provides enzymatically-controlled release of methadone, and an optional enzyme inhibitor that interacts with the enzyme(s) that mediates the enzymatically-controlled release of methadone from the prodrug so as to attenuate enzymatic cleavage of the prodrug.

Antiviral therapeutic compounds and compositions that may be used in methods of preventing and/or treating infection(s) caused by coronaviruses or influenza viruses. The present disclosure also relates to compounds for use in boosting cellular energy production and/or optimizing cellular energy homeostasis and incorporation of such compounds into compositions for administration. Also disclosed are methods of boosting cellular energy production and/or optimizing cellular energy homeostasis.

Methods of manufacturing inositol-stabilized arginine-silicate (“ASI”) complexes with reduced or eliminated clumping and with increased solubility.

Methods of manufacturing inositol-stabilized arginine-silicate (“ASI”) complexes with reduced or eliminated clumping and with increased solubility.

The present invention provides derivatives of glutamine of formula (I) and derivatives of arginine of formula (II), and the use of such compounds as flavor modifiers. The invention further provides the use of such derivatives of glutamine and arginine to enhance the salty and umami taste of ingestible compositions as ingestible compositions that include such derivatives of glutamine and arginine and bulking agents.

##STR00001##

The present invention provides derivatives of glutamine of formula (I) and derivatives of arginine of formula (II), and the use of such compounds as flavor modifiers. The invention further provides the use of such derivatives of glutamine and arginine to enhance the salty and umami taste of ingestible compositions as ingestible compositions that include such derivatives of glutamine and arginine and bulking agents.

##STR00001##

The object of the present invention is to provide a mitochondrial dysfunction improving agent comprising a vitamin K derivative having a high deliverability to mitochondria.

A mitochondrial dysfunction improving agent, neurodegeneration improving agent, amyotrophic lateral sclerosis improving agent, Alzheimer's disease improving agent, and Parkinson's disease improving agent comprising at least one of a carboxylic acid ester of an active vitamin K represented by a general formula (1) or a salt thereof, and

##STR00001##

(wherein, R.sub.1 and R.sub.2 are a hydrogen atom, respectively, or a substituent selected from glycine, N-acyl glycine, N-alkyl glycine, N,N-dialkyl glycine, N,N,N-trialkyl glycine, acyl, dicarboxylic acid hemiester, and salts thereof; and at least either of R.sub.1 and R.sub.2 is glycine, N-acyl glycine, N-alkyl glycine, N,N-dialkyl glycine, N,N,N-trialkyl glycine, acyl, dicarboxylic acid hemiester, and salts thereof. R.sub.3 is a group represented by a general formula (2), or a general formula (3). n is an integer of 1 to 7)

##STR00002##

a mitochondrial dysfunction improving agent, neurodegeneration improving agent, amyotrophic lateral sclerosis improving agent, Alzheimer's disease improving agent, and Parkinson's disease improving agent comprising a carboxylic acid ester of an active vitamin K or a salt thereof (in the general formula (1), R.sub.1 and R.sub.2 is a carboxylic acid residue selected from a group consisting of R.sub.4OOCCH.sub.2CH.sub.2CO— and R.sub.4OOCCH.sub.2CH.sub.2CH.sub.2CO—. R.sub.3 represents the above general formula (2) or (3). R.sub.4 is a C1-C3 alkyl group.).