SF2487, a new polyether antibiotic produced by Actinomadura.

A new antibiotic SF2487 has been isolated from the culture broth of Actinomadura sp. SF2487. The structure of antibiotic SF2487 was determined by spectroscopic analyses of the sodium salt and X-ray diffraction analysis of the silver salt. The antibiotic represents a new member of polyether group antibiotics known as the acyltetronic acid type 4. The antibiotic is weakly active against Gram-positive bacteria and exhibits antiviral activity against influenza virus in vitro.

Regulation of saponin production in callus cultures of Panax ginseng [1].

It was shown that Panax ginseng callus produces the same kinds of saponins in considerable amounts as in intact plants, and the saponin content is significantly lower in habituated callus than in normal callus. Furthermore, it was found that semicarbazide and particularly thiosemicarbazide inhibit the production of phytosterols and promote the biosynthesis of saponins in the presence of mevalonic acid, also the biosyntheses of saponins and phytosterols are inhibited by the individual end products.

Effects of auxins on growth and saponin production in callus cultures of Panax ginseng.

A callus was induced from the petiole of Panax ginseng C. A. Meyer by treatment with 2,4-D. The callus has been maintained on the synthetic media containing 2,4-D as growth factor. Habituated ginseng callus which required no auxin for its growth was induced from a 2,4-D callus by successive treatments with a low concentration of 2,4-D. The fact that the process of habituation is reversible suggests that its mechanism is based upon adaptation rather than rare mutation followed by selection. It was also shown that the capacity of saponin production is significantly lower in habituated callus than in normal callus. Habituated callus which was maintained on 2,4-D media gradually recovered its capacity for saponin production and the degree of this capacity seemed to parallel the degree of its requirement for auxin.

Pharmacokinetics of neothramycin in animals and man.

The pharmacokinetics of neothramycin (NTM) was performed in mice, rabbits and man. Biological half-life of NTM in man after a 20 mg bolus injection produced an alpha phase half-life of 3.63 minutes, a beta phase half-life of 84.5 minutes and a volume of distribution at a steady state of 50.3 liters/body. Its human half-life was longer than those of adriamycin, mitomycin C and neocarzinostatin, and a little shorter than that of bleomycin. In mice and rabbits, NTM was well distributed in the kidney, urinary bladder, squamous tissues, lung, spleen and gastrointestinal tract and it was rapidly excreted in urine and bile. It was partially absorbed from the gastrointestinal tract. Concentrations of NTM in ascites and pleural fluids in man were also reported.

Determination of dihydroergot alkaloids in serum by radioimmunoassay.

A radioimmunoassay for dihydroergotoxine was developed using antiserum frm the rabbit injected with a dihydromethylergometrine-bovine serum albumin conjugate. The antiserum was found to be highly specific to dihydroergot alkaloids. The minimum detectable amount of dihydroergotoxine methanesulfonate with this assay system was about 100 pg/ml in serum. Practical applicability of the assay system was proved by measuring dog serum concentrations after oral administration of dihydroergotoxine methanesulfonate.