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-methoxyindolealkylamines. 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-hydroxyand 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 forma tion of 5-hydroxytryptophan, aromatic L-aminoacid decarboxylase producing the de carboxylation 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.

Occurrence of bombesin and alytesin in extracts of the skin of three European discoglossid frogs and pharmacological actions of bombesin on extravascular smooth muscle

“…Threshold amounts of the polypeptides were of the order of 20-30 ,ug. The qualitative detection and semiquantitative estimation of aromatic amines by paper chromatography has been described previously (Erspamer, Vitali, Roseghini & Cei, 1967;Erspamer, Roseghini & Cei, 1964).…”

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

“…The content of caerulein in different batches of Leptodactylus pentadactylus labyrinthicus skin is shown in Table 2, which also gives the content of biogenic amines; some of the latter data have already been reported by Cei, Erspamer & Roseghini (1967).…”

“…In order to obtain a better separation of the biogenic amines and facilitate their detection when occurring in small amounts, crude skin extracts were passed through a column of alkaline alumina which was then eluted with descending concentrations of ethanol (Erspamer, Vitali, Roseghini & Cei, 1967). An alumina column was unsuitable for purification of caerulein-like polypeptides.…”

Toxins and pharmacologically active compounds from species of the family Bufonidae (Amphibia, Anura)

“…In addition to species from the genera Bufo, Bufotes, and Duttaphrynus, most of the American toads contain alkaloid 111 except those from the genera Nannophryne, Epidalea and Incilius (Cei et al, 1968). Possible derivatives of alkaloids 104 and 106, containing sulfate attached to the indole nitrogen, have been detected in some species of Incilius (Erspamer et al, 1967).…”