In one aspect, the invention relates to compounds having the formula:

##STR00001##

where R.sup.1-R.sup.5 and X are as defined in the specification, or a pharmaceutically acceptable salt thereof. These compounds have neprilysin inhibition activity. In another aspect, the invention relates to pharmaceutical compositions comprising such compounds; methods of using such compounds; and processes and intermediates for preparing such compounds.

Methods of treating or suppressing mitochondrial diseases, such as Friedreich's ataxia (FRDA), Leber's Hereditary Optic Neuropathy (LHON), mitochondrial myopathy, encephalopathy, lactacidosis, and stroke (MELAS), Kearns-Sayre Syndrome (KSS), are disclosed, as well as compounds useful in the methods of the invention, such as 4-(p-quinolyl)-2-hydroxybutanamide derivatives. Methods and compounds useful in treating other disorders such as amyotrophic lateral sclerosis (ALS), Huntington's disease, Parkinson's disease, and pervasive developmental disorders such as autism are also disclosed. Energy biomarkers useful in assessing the metabolic state of a subject and the efficacy of treatment are also disclosed. Methods of modulating, normalizing, or enhancing energy biomarkers, as well as compounds useful for such methods, are also disclosed.

Methods of treating or suppressing mitochondrial diseases, such as Friedreich's ataxia (FRDA), Leber's Hereditary Optic Neuropathy (LHON), mitochondrial myopathy, encephalopathy, lactacidosis, and stroke (MELAS), Kearns-Sayre Syndrome (KSS), are disclosed, as well as compounds useful in the methods of the invention, such as 4-(p-quinolyl)-2-hydroxybutanamide derivatives. Methods and compounds useful in treating other disorders such as amyotrophic lateral sclerosis (ALS), Huntington's disease, Parkinson's disease, and pervasive developmental disorders such as autism are also disclosed. Energy biomarkers useful in assessing the metabolic state of a subject and the efficacy of treatment are also disclosed. Methods of modulating, normalizing, or enhancing energy biomarkers, as well as compounds useful for such methods, are also disclosed.

This document discloses molecules having the following formula (Formula One): ##STR00001##
and processes associated therewith.