V. Erspamer

ISOLATION AND AMINO ACID SEQUENCE OF PHYSALAEMIN, THE MAIN ACTIVE POLYPEPTIDE OF THE SKIN OF PHYSALAEMUS FUSCUMACULATUS.

Abstract Crude methanol extracts of fresh and dried skins of Physalaemus fuscumaculatus , a South American amphibian, were subjected successively to chromatography on alkaline alumina and to countercurrent distribution. The main active constituent of these extracts, the polypeptide physalaemin , was thus obtained in a pure form. Total and partial acid hydrolysis, fission with trypsin and chymotrypsin, and end-group determination experiments demonstrated that physalaemin is an endecapeptide having the following amino acid composition and sequence: Pyr-Ala-Asp(OH)-Pro-Asp(NH 2 )-Lys-Phe-Tyr-Gly-Leu-Met-NH 2 Some anomalies in the trypsin and chymotrypsin fission of physalaemin are discussed, and the strict chemical resemblance between physalaemin and eledoisin is pointed out.

Synthetic peptides related to caerulein. Note 2

Vengono descritte le proprietà di una serie di peptidi sintetici affini alla ceruleina e si discutono brevemente i rapporti fra attività e struttura.

Presence of caerulein in extracts of the skin of Leptodactylus pentadactylus labyrinthicus and of Xenopus laevis

1 The South American amphibian Leptodactylus pentadactylus labyrinthicus and the South African amphibian Xenopus laevis contain in their skin a polypeptide indistinguishable from caerulein prepared from the Australian amphibian Hyla caerulea. 2 The caerulein content of different batches of Leptodactylus pentadactylus labyrinthicus skins varies from 10 to 500–600 μg/g tissue. Drying of the skin causes either a moderate decrease or a slight increase in the caerulein content. Methanol extraction gives considerably higher yields of caerulein than acetone extraction. 3 Caerulein or caerulein‐like polypeptides also occur in the skin of several other species of Leptodactylus together with 5‐hydroxyindole alkylamines and imidazole alkylamines. Yet other species of Leptodactylus lack caerulein‐like polypeptides and 5‐hydroxyindole alkylamines. 4 It is suggested that caerulein and caerulein‐like polypeptides may have some function either in the regulation of secretory processes of the skin or in the exchange of water and electrolytes through the skin, or in both.

THE IDENTIFICATION OF NEW HISTAMINE DERIVATIVES IN THE SKIN OF LEPTODACTYLUS.

Abstract Extracts of the skin of some South American amphibians belonging to the genus Leptodactylus contain, in addition to 5-hydroxyindolealkylamines and hydroxyphenylalkylamines, remarkable amounts of imidazolealkylamines. The species most rich in these compounds are Leptodactylus pentadactylus labyrinthicus and Leptodactylus laticeps . The skin of the former species contains not only histamine, N′ -methylhistamine and N′ , N′ -dimethylhistamine but also two imidazo- c -pyridine derivatives hitherto unknown in nature: spinaceamine and 6-methylspinaceamine . The new findings permit a notable enlargement of our knowledge in the field of biogenic imidazolealkylamines and illustrate new possible metabolic pathways for histamine.

Occurrence of new imidazolealkylamines (Spinaceamine and 6-Methylspinaceamine) in skin extracts ofLeptodactylus pentadactylus labyrinthicus

Estratti di pelle diLeptodactylus pentadactylus labyrinthicus contengono elevati quantitativi di imidazolalchilamine, fra cui due derivati imidazo-c-piridinici finora ignoti in natura: la spinaceamina e la 6-metilspinaceamina.

5-Methoxy- and 5-Hydroxyindoles in the skin of Bufo alvarius

Abstract The skin of Bufo alvarius, a desert toad of Arizona, contains a number of indolealkylamines and their metabolites belonging to the common series of 5-hydroxyindolealkylamines and to the unusual series of 5-methoxyindolealkyIamines. The most abundant representative of 5-hydroxyindolealkylamines is, as in numerous other toads, bufotenine (up to 3 mg per g dry skin), the most abundant representative of 5-methoxyindolealkylamines, O-methylbufotenine. In parotoid and coxal glands as much as 5–15 per cent of the dry weight is made up by this compound. Natural O-methylbufotenine has been isolated in a pure form and its identity with synthetic O-methylbufotenine definitely established. The B. alvarius skin presents three sulphur-containing indolealkylamines: one is bufoviridine, the well known O-sulphate of bufotenine, the other two are completely new compounds with sulphuric acid probably attached to the > NH group of the indole nucleus. All the hitherto described metabolites arising from the oxidative deamination of 5-hydroxy- and 5-methoxy-indolealkylamines may be found in the B. alvarius skin: 5-hydroxytryptophol, 5-hydroxyindoleacetic acid, 5-methoxytryptophol and 5-methoxyindoleacetic acid. The occurrence of the above compounds points to the necessary presence in B. alvarius skin of a number of enzymes: tryptophan 5-hydroxylase, catalysing the formation of 5-hydroxytryptophan, aromatic L-aminoacid decarboxylase producing the decarboxylation of 5-hydroxytryptophan to 5-hydroxytryptamine, N-methyl transferase and 5-hydroxyindole-O-methyl transferase giving origin to the N-methyl and O-methylindolealkylamines, and finally sulphoconjugases catalysing the linkage of sulphuric acid to the 5-hydroxy group and the > NH group of the indole nucleus. The exceptionally rich sample card of indolealkylamines in the skin of B. alvarius seems of interest not only from the point of view of comparative biochemistry, but also from that of comparative enzymology and biochemical taxonomy.

Indole-, imidazole-, and phenyl-alkylamines in the skin of thirteen Leptodactylus species

Abstract The skin of thirteen Leptodactylus species and sub-species has been examined in regard to its content in biogenic amines. This tissue presents, especially in Leptodactylus pentadactylus labyrinthicus and some other species, an unusually rich miscellany of amines, including at least two indolealkylamines (5-hydroxytryptamine and bufotenidine), three hydroxyphenylalkylamines (p-tyramine, candicine, leptodactyline) and five imidazolealkylamines (histamine, N-methylhistamine, N,N-dimethylhistamine, spinaceamine and 6-methylspinaceamine). It is concluded that the Leptodactylus skin must possess aromatic acid decarboxylase activity, tryptophan-5-hydroxylase activity and N-methyltransferase activity. The skin of nearly every Leptodactylus species and sub-species is characterized by a particular spectrum of amines, which evidently may help in systematies of these species.

OCCURRENCE AND DISTRIBUTION OF N-ACETYLHISTIDINE IN BRAIN AND EXTRACEREBRAL TISSUES OF POIKILOTHERMAL VERTEBRATES*

I N a recent paper the occurrence of large amounts of N-acetylhistidine in the brain and eye of Rana esculenta has been reported (ANASTASI, CORREALE and ERSPAMER, 1964). This communication describes the presence and distribution of the amino acid in the brain and extracerebral tissues of a number of poikilothermal vertebrates. It will be seen that the results of this research represent the necessary basis for studies intended to interpret the possible biological meaning of N-acetylhistidine.

5-Methoxy- and 5-hydroxy-indolealkylamines in the skin ofBufo alvarius

Gli estratti di pelle diBufo alvarius, rospo delle regioni desertiche del Nord America, contengono, oltre alle consuete 5-idrossiindolalchilamine (5-HT, N-metil-5-HT, bufotenina) enormi quantitativi di derivati 5-metossiindolici, rappresentati soprattutto daO-metilbufotenina. Questa può giungere a costituire fino il 16% del peso delle ghiandole cutanee secche. Si insiste sulla probabile presenza di 5-idrossiindolo-O-metiltransferasi nella pelle diBufo alvarius.

Action of reserpine on the 5-hydroxytryptamine (enteramine) biosynthesis and metabolism in dogs and rats

Wiederholte intraperitoneale Reserpindosen (0.1–1 mg/kg), die bei vielen Tieren tödlich wirken, sind beim Hund und bei der Ratte kaum imstande, die Biosynthese des 5-Oxytryptamins (Enteramin) zu beeinflussen, obwohl sie eine erhebliche Ausschüttung der Substanz aus einigen Körperdepots verursachen können.