OBJECTIVEImpact of the presence of bacteria associated with a marine dinoflagellate, Alexandrium tamarense CI01, on the growth and toxin production of the algae in batch culture was investigated.

METHODSPronounced changes in the activities of the algal culture were observed when the culture was treated with different doses of a mixture of penicillin and streptomycin.

RESULTSIn the presence of antibiotics at the initial concentration of 100 u/mL in culture medium, both algal growth and toxin yield increased markedly. When the concentration of antibiotics was increased to 500 u/mL, the microalgal growth was inhibited, but resumed in a few days to eventually reach the same level of growth and toxin production as at the lower dose of the antibiotics. When the antibiotics were present at a concentration of 1 000 u/mL, the algal growth was inhibited permanently.

CONCLUSIONSThe results indicate that antibiotics can enhance algal growth and toxin production not only through their inhibition of the growth and hence competition for nutrients, but also through their effects on the physiology of the algae.

Animals ; Anti-Bacterial Agents ; pharmacology ; Bacteria ; Dinoflagellida ; microbiology ; pathogenicity ; Eutrophication ; Marine Toxins ; biosynthesis ; Penicillins ; pharmacology ; Saxitoxin ; Streptomycin ; pharmacology

OBJECTIVETo study the cytotoxicity of maitotoxin (MTX) and its protective effects on calcium-channel blocking agents, so as to provide the data for control and treatment of MTX poisoning.

METHODSCytotoxicity was measured by MTT detecting system, and cytoplasmic free [Ca(2+)]i was measured by F-4500 fluorometry.

RESULTSIncubation with 8 ng/ml MTX for 3 h reduced the survival ratio of LLC-PK(1) cells. The response was found in a time- and concentration-dependent manner, with significant differences as compared with the control group. The MTX-induced increase in [Ca(2+)]i was inhibited by Verapamil and Nifedipine at 5 x 10(-5) mol/L and 1 x 10(-4) mol/L respectively. Both of them significantly reduced the death of the LLC-PK(1) cells.

CONCLUSIONSCytotoxicity of MTX may be caused by the elevated intracellular [Ca(2+)]i. Calcium-channel blocking agents could protect LLC-PK(1) cells from injury by MTX.

Animals ; Calcium ; metabolism ; Calcium Channel Blockers ; pharmacology ; Drug Antagonism ; LLC-PK1 Cells ; Marine Toxins ; toxicity ; Nifedipine ; pharmacology ; Oxocins ; Swine ; Verapamil ; pharmacology

Ocean is a unique and excellent resource that provides a diverse array of intriguing natural products. Marine natural products have demonstrated significant and extremely potent biological activities and have captured the attention of natural products chemists in the past few decades. It is increasingly recognized that a wealth of fascinating natural products and novel chemical entities will play a dominant role in the discovery of useful leads for the development of pharmaceutical agents and provide useful probes to lead to breakthroughs in a variety of life-science fields. This article focused on the research progress of chemistry of marine natural products in recent five years.
Alkaloids ; chemistry ; isolation & purification ; pharmacology ; Animals ; Anti-Infective Agents ; chemistry ; isolation & purification ; pharmacology ; Antineoplastic Agents ; chemistry ; isolation & purification ; pharmacology ; Aquatic Organisms ; chemistry ; Biological Products ; chemistry ; isolation & purification ; pharmacology ; Humans ; Macrolides ; chemistry ; isolation & purification ; pharmacology ; Marine Biology ; Marine Toxins ; chemistry ; isolation & purification ; pharmacology ; Molecular Structure ; Peptides ; chemistry ; isolation & purification ; pharmacology ; Steroids ; chemistry ; isolation & purification ; pharmacology ; Terpenes ; chemistry ; isolation & purification ; pharmacology

Globally, peptide-based anticancer therapies have drawn much attention. Marine organisms are a reservoir of anticancer peptides that await discovery. In this study, we aimed to identify cytotoxic oligopeptides from Sarcophyton glaucum. Peptides were purified from among the S. glaucum hydrolysates produced by alcalase, chymotrypsin, papain, and trypsin, guided by a methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay on the human cervical cancer (HeLa) cell line for cytotoxicity evaluation. Purification techniques adopted were membrane ultrafiltration, gel filtration chromatography, solid phase extraction (SPE), and reversed-phase high-performance liquid chromatography (RP-HPLC). Purified peptides were identified by de novo peptide sequencing. From papain hydrolysate, three peptide sequences were identified: AGAPGG, AERQ, and RDTQ (428.45, 502.53, and 518.53 Da, respectively). Peptides synthesized from these sequences exhibited cytotoxicity on HeLa cells with median effect concentration (EC₅₀) values of 8.6, 4.9, and 5.6 mmol/L, respectively, up to 5.8-fold stronger than the anticancer drug 5-fluorouracil. When tested at their respective EC₅₀, AGAPGG, AERQ, and RDTQ showed only 16%, 25%, and 11% cytotoxicity to non-cancerous Hek293 cells, respectively. In conclusion, AERQ, AGAPGG, and RDTQ are promising candidates for future development as peptide-based anticancer drugs.
Amino Acid Sequence ; Animals ; Anthozoa/chemistry* ; Antineoplastic Agents/pharmacology* ; Chromatography, Gel ; Chromatography, High Pressure Liquid ; Chromatography, Reverse-Phase ; Cytotoxins/pharmacology* ; Drug Discovery ; HEK293 Cells ; HeLa Cells ; Humans ; Hydrolysis ; Marine Toxins/pharmacology* ; Oligopeptides/pharmacology* ; Solid Phase Extraction ; Tandem Mass Spectrometry