New linear polyamine derivatives in spider venoms.

Linear free polyamines were characterized in the venom of the spiders Agelenopsis aperta, Hololena curta, and Paracoelotes birulai by RP-HPLC coupled to mass spectrometry. The several linear polyamines found were tetramine, pentamine, and hexamine derivatives. Some of these natural products were identified as N-hydroxylated, guanidylated, or acetylated compounds. In addition, the biosynthetical pathway leading to the formation of acylpolyamines in spider venoms is discussed.

Macrocyclic polyamines deplete cellular ATP levels and inhibit cell growth in human prostate cancer cells.

In solid tumors, when O(2) partial pressure drops below 10 mmHg, ATP levels rapidly decrease due to the Warburg effect. It is known that certain macrocyclic polyamines catalyze the chemical hydrolysis of ATP with release of inorganic phosphate. Since tumor cells have diminished ATP levels as compared to normal cells, we attempted to deplete cellular ATP with macrocyclic polyamines in an effort to inhibit tumor cell proliferation. Five macrocyclic polyamines, related to the budmunchamine family of alkaloids, were prepared by total synthesis. They were the [17]-N(4) macrocycle 1, the [16]-N(4) macrocycle 20, the [18]-N(4) macrocycle 13, the [20]-N(5) macrocycle 8, and the [13]-N(3) macrocycle 17. Each one of them hydrolyzed ATP in vitro with release of P(i); the largest ring macrocycle 8 was the most efficient catalyst, while the smallest ring macrocycle 17 was the least efficient (P(i) released in these runs was on the order of 40-100 microM). The linear polyamine spermine had no hydrolytic effect on ATP. The macrocycles were found to be cytotoxic when assessed by means of a MTT assay against two human prostate cell lines, DuPro and PC-3, with resultant ID(50) values ranging between 0.5 and 1.8 microM. Colony forming efficiency (CFE) assays performed on DuPro cells, where the macrocycles were used in a concentration range of 1-8 microM, confirmed the cytotoxic effect of each macrocycle. Each killed 3-4 log of DuPro cells. The smallest ring 17 was the least cytotoxic after 24 h of incubation, although after 144 h of incubation it showed significant cytotoxicity at 8 microM. The macrocycles were equally efficient in depleting the intracellular ATP pools; after a 24 h incubation with each macrocycle other than 17 at 1-8 microM concentrations, cellular ATP concentrations were decreased by 3 orders of magnitude. The decrease in ATP levels was more pronounced after a 72 h incubation, when even 17 reduced ATP by 2 orders of magnitude. A linear pentamine of established cytotoxicity was without effect on the ATP pools. The macrocycles depleted almost entirely the intracellular pools of polyamines and were efficiently taken up by cells. A rough correlation could be established between the cytotoxic effect of the macrocyclic polyamines and their ATP-ase like activity in the DuPro cell line. As ATP is a scarce metabolite in cancer cells, where it can only be replenished through the very ATP-inefficient glycolytic pathway; macrocyclic polyamines appear to be promising new anticancer agents.

Hydroxylated 2-amino-3H-phenoxazin-3-one derivatives as products of 2-hydroxy-1,4-benzoxazin-3-one (HBOA) biotransformation by Chaetosphaeria sp., an endophytic fungus from Aphelandra tetragona.

The biotransformation of the phytoanticipin HBOA and its major degradation metabolites 2-hydroxy-N-(2-hydroxyphenyl)acetamide (7) and N-(2-hydroxyphenyl)acetamide (8) by Chaetosphaeria sp., an endophytic fungus isolated from Aphelandra tetragona, was studied. Three new metabolites could be identified as 2-amino-7-hydroxy-3H-phenoxazin-3-one (12), 2-acetylamino-7-hydroxy-3H-phenoxazin-3-one (13) and 7-hydroxy-2-(2-hydroxyacetyl)-amino-3H-phenoxazin-3-one (14). Structure elucidation of 12 and 13 was performed by MS, 1H, 13C NMR and 2D NMR techniques and confirmed by chemical transformation.