Australian myobatrachid frogs of the genus Pseudophryne have only two classes of alkaloids in skin extracts, pseudophrynamines (PSs) and pumiliotoxins (PTXs). The former are unique to such Australian frogs, while the PTXs occur worldwide in all other genera of frogs/toads that contain lipophilic alkaloids. The major alkaloid of wild-caught frogs from one population of Pseudophryne semimarmorata was PTX 267C, while PSs were only minor or trace alkaloids. Captive-raised frogs from the same parental stock had no PTXs, but had larger amounts of PSs. A PTX fed to captive-raised frogs accumulated into skin along with dihydro and hydroxy metabolites. Thus, Pseudophryne frogs appear to biosynthesize PSs, but to sequester into skin dietary PTXs. In addition, biosynthesis of PSs appears reduced when high levels of dietary PTXs have accumulated into skin. This is the first evidence indicating that certain frogs are capable of synthesizing rather than merely sequestering alkaloids. A wide range of PSs, including many with molecular weights >500, were detected using both GC-mass spectral and LC-mass spectral analysis.
We investigated the potential of red algae cultivated with deep-sea water (D) as dietary anti-oxidants to ameliorate the redox levels in the main organs and in bone metabolism using SAMP1 and its control SAMR1, in comparison with the same algae cultivated with surface seawater. Only the D group showed marked increases of glutathione (GSH) levels in the liver (R1, 134%) and brain (R1, 128% and P1, 126%) as well as activities of GSH non-dependent peroxidase in the liver (R1, 138%) and the brain (R1, 117% and P1, 112%) but not GSH-dependent peroxidase. The D diet also exhibited beneficial effects on bone metabolism; elevations of femoral calcium, phosphorus, hydroxyproline for collagen, hexosamine for polysaccharides, and suppression of urinary excretion of hydroxyproline as an index of increased bone resorption. A three-point bending test showed that the D diet increased the stiffness and the strength of the femur, which correlated with increases in femoral calcium and phosphorus contents. The results suggest that red algae of the Gracilaria sp. cultivated with deep-sea water has the potential to ameliorate degenerative diseases of aging.
The structure of alkaloid 223A (1), the first member of a new class of amphibian alkaloids, purified by HPLC from a skin extract of a Panamanian population of the frog Dendrobates pumilio Schmidt (Dendrobatidae) has been established as (5R,6S,8R,9S)- or (5S,6R,8S,9R)-6,8-diethyl-5-propylindolizidine, based on GC-MS, GC-FTIR, and 1H-NMR spectral studies. Three higher homologs of 223A, namely alkaloids 237L (2), 251M (3), and 267J (4), have been detected in other extracts, and tentative structures are proposed.
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