(Phosphinyloxy)acyl amino acid inhibitors of angiotensin converting enzyme. 2. Terminal amino acid analogues of (S)-1-[6-amino-2 [[hydroxy(4-phenylbutyl)phosphinyl]oxy]-1-oxohexyl]-L-proline.

Analogues of (S)-1-[6-amino-2[[hydroxy(4-phenylbutyl)phosphinyl] oxy]-1-oxohexyl]-L-proline (1, SQ 29,852) in which the terminal proline residue has been replaced by a variety of substituted and heteroatom-substituted prolines, N-arylglycines, N-cycloalkylglycines, and bicyclic amino acids have been synthesized and evaluated as inhibitors of angiotensin converting enzyme in vitro and in vivo. In general, the addition of lipophilic substituents to the 4-position of proline of the parent phosphonate 1 resulted in substantial increases in in vitro activity. The largest improvements were observed in the case of cis-benzyl (36-fold) and dithioketal (24-fold) analogues 2r and 2x, respectively. These enhancements of in vitro activity were accompanied by modest increases (2-3.5-fold) in in vivo (iv) activity. Among the various terminal amino acid replacements examined in this study, the indoline-based analogue 2i was by far the most potent compound on iv administration in the normotensive rat.

(Phosphinyloxy)acyl amino acid inhibitors of angiotensin converting enzyme (ACE). 1. Discovery of (S)-1-[6-amino-2-[[hydroxy(4-phenylbutyl)phosphinyl]oxy]-1-oxohexyl]-L -proline a novel orally active inhibitor of ACE.

The synthesis of a series of orally active, phosphinyloxyacyl proline inhibitors of angiotensin converting enzyme (ACE) is described. The in vitro and in vivo ACE inhibitory activities are reported for each compound. The structure-activity relationship for this series of compounds in relation to the carboxyalkyl dipeptide ACE inhibitors as well as other types of hydroxyphosphinyl-containing ACE inhibitors (e.g., the corresponding nitrogen and carbon isosteres) is discussed. Within an isosteric series of phosphorus-containing inhibitors based on the lysylproline terminal dipeptide sequence, only the phosphonates (oxygen isosteres) show a high level of oral activity. Optimum potency and oral activity in the phosphonate series occurs with the (phenylbutyl)- and n-hexylphosphonate side chains. An aminobutyl side chain in the P1' residue is an absolute requirement for full expression of oral activity. The most potent of these compounds, 8b (SQ 29,852), has intravenous and oral activities superior in potency to those of captopril in the normotensive rat.

Antioxidant pathways in Alzheimer's disease: possibilities of intervention.

Alzheimer's disease (AD) is closely related to the occurrence of oxidative stress. It was claimed that all pathophysiological mechanisms involved in the onset and progression of AD are related to oxidative stress. Thus, it is important to evaluate if there is oxidative stress as well as the mechanism by which this happens in AD patients as well as in animal models of AD. Extracellular plaques of amyloid b peptides (Aß), a hallmark of the disease, have been postulated to be more protective than damaging in terms of oxidative stress because they may be chemical sinks in which heavy metals are placed. More than a decade ago we reasoned that damage due to Ab might be caused not by extracellular, but rather intracellular Ab peptide interacting with normal cell metabolism. Ab binds to mitochondrial membranes, interacts with heme and thus interferes with the normal electron flow through the respiratory chain. This results in a faulty mitochondrial energy metabolism and in an increased production of reactive oxygen species (ROS). The low mitochondrial energy metabolism may important to explain the hypo metabolism observed in AD patients in vivo (measured by positron emission tomography) and in isolated neurons incubated in the presence of Ab peptide. The increased ROS production results in oxidative stress. The occurrence of such stress provides the basis for a putative treatment of AD with antioxidants. Major efforts have been made to determine whether antioxidant supplementation could be a means of preventing, or even treating AD, but this idea is far from being well- established. We found that even though there is oxidative stress in AD, the administration of antioxidant vitamins, particularly vitamin E, is not effective in preventing the progression of the disease in all patients. We termed this the vitamin E paradox in AD. The paradox is the fact that for some patients, vitamin E could even be detrimental whereas for others vitamin E treatment partially prevents the loss memory associated with the progression of the disease. It is clear, however, that increasing the intake of fruits and vegetables rich in antioxidant vitamins, prevents or retards the onset of AD. Thus, the issue of whether antioxidant treatment is of use in AD is not settled and more research is warranted to clarify this point.

[Proteus syndrome with cerebral vascular malformations]. / Síndrome de Proteus con malformaciones vasculares cerebrales.

INTRODUCTION: Proteus syndrome is a congenital hamartomatous dysplasia. This sporadic disorder involves the skeletal system, soft tissues, skin and vascular system. The most likely pathogenesis involves somatic mosaicism. Main manifestations included soft-tissue and epidermal nevi, partial gigantism, hemihypertrophy, exostoses, lipomas and vascular anomalies. The most common brain abnormalities are hemimegencephaly and migrational disorders. We present a case of Proteus syndrome with cerebral vascular anomalies which are not described previously. CLINICAL CASE: Our patient is a 61 year-old male who has hypertrophy of the four limbs, macrodactyly and hypertrophy of chest and abdomen asymmetric with mild facial asymmetry. Prominent and abundant of the four extremities and trunk, also asymmetric. Vascular tumors in the skin of trunk and left limb. Cerebral MRI shows venous angiomas and multiple cavernous malformations. CONCLUSION: Clinical diagnostic criteria of Proteus syndrome are documented in our patient. He also has brain vascular malformations which are not described previously in the literature. We consider that both findings are not a product of causality due to the high prevalence of systemic vascular hamartomatous malformations in these patients. We hypothesize that a single mutation, probably involving genes in relation with apoptotic control will be responsible of Proteus syndrome and cerebral vascular anomalies in our patient, due to a defect of angiogenesis.

Design, synthesis and structure of non-macrocyclic inhibitors of FKBP12, the major binding protein for the immunosuppressant FK506.

We have synthesized a series of non-macrocyclic ligands to FKBP12 that are comparable in binding potency and peptidyl prolyl isomerase (PPIase) inhibition to FK506 itself. We have also solved the structure of one of these ligands in complex with FKBP12, and have compared that structure to the FK506-FKBP12 complex. Consistent with the observed inhibitory equipotency of these compounds, we observe a strong similarity in the conformation of the two ligands in the region of the protein that mediates PPIase activity. Our compounds, however, are not immunosuppressive. In the FKBP12-FK506 complex, a significant portion of the FK506 ligand, its 'effector domain', projects beyond the envelope of the binding protein in a manner that is suggestive of a potential interaction with a second protein, the calcium-dependent phosphatase, calcineurin, whose inhibition by the FKBP 12-FK506 complex interrupts the T-cell activation events leading to immunosuppression. In contrast, our compounds bind within the surface envelope of FKBP12, and induce significant changes in the structure of the FKBP12 protein which may also affect calcineurin binding indirectly.