title: Cytotoxic and HIV-1 enzyme inhibitory activities of Red Sea marine organisms.
abstract: BACKGROUND
  Cancer and HIV/AIDS are two of the greatest public health and humanitarian challenges facing the world today. Infection with HIV not only weakens the immune system leading to AIDS and increasing the risk of opportunistic infections, but also increases the risk of several types of cancer. The enormous biodiversity of marine habitats is mirrored by the molecular diversity of secondary metabolites found in marine animals, plants and microbes which is why this work was designed to assess the anti-HIV and cytotoxic activities of some marine organisms of the Red Sea.
  
  
  METHODS
  The lipophilic fractions of methanolic extracts of thirteen marine organisms collected from the Red Sea (Egypt) were screened for cytotoxicity against two human cancer cell lines; leukaemia (U937) and cervical cancer (HeLa) cells. African green monkey kidney cells (Vero) were used as normal non-malignant control cells. The extracts were also tested for their inhibitory activity against HIV-1 enzymes, reverse transcriptase (RT) and protease (PR).
  
  
  RESULTS
  Cytotoxicity results showed strong activity of the Cnidarian Litophyton arboreum against U-937 (IC50; 6.5 μg/ml ±2.3) with a selectivity index (SI) of 6.45, while the Cnidarian Sarcophyton trochliophorum showed strong activity against HeLa cells (IC50; 5.2 μg/ml ±1.2) with an SI of 2.09. Other species showed moderate to weak cytotoxicity against both cell lines. Two extracts showed potent inhibitory activity against HIV-1 protease; these were the Cnidarian jelly fish Cassiopia andromeda (IC50; 0.84 μg/ml ±0.05) and the red algae Galaxura filamentosa (2.6 μg/ml ±1.29). It is interesting to note that the most active extracts against HIV-1 PR, C. andromeda and G. filamentosa showed no cytotoxicity in the three cell lines at the highest concentration tested (100 μg/ml).
  
  
  CONCLUSIONS
  The strong cytotoxicity of the soft corals L. arboreum and S. trochliophorum as well as the anti-PR activity of the jelly fish C. andromeda and the red algae G. filamentosa suggests the medicinal potential of crude extracts of these marine organisms.
authors.forename: Mona S
authors.initials: MS
authors.lastname: Ellithey
authors.forename: Namrita
authors.initials: N
authors.lastname: Lall
authors.forename: Ahmed A
authors.initials: AA
authors.lastname: Hussein
authors.affiliation: Department of Biochemistry, University of Pretoria, Pretoria, 0002, South Africa. Debra.Meyer@up.ac.za.
authors.forename: Debra
authors.initials: D
authors.lastname: Meyer
mesh_terms: D000818:Animals; D059001:Aquatic Organisms / Q000737:chemistry*; D001688:Biological Products / Q000494:pharmacology* / Q000633:toxicity*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D002522:Chlorocebus aethiops; D016333:HIV Protease / Q000378:metabolism*; D054303:HIV Reverse Transcriptase / Q000037:antagonists & inhibitors*; D015497:HIV-1 / Q000201:enzymology*; D006367:HeLa Cells; D006801:Humans; D019156:Indian Ocean; D014709:Vero Cells
chemical_list: D001688:Biological Products; C514824:reverse transcriptase, Human immunodeficiency virus 1; D054303:HIV Reverse Transcriptase; D016333:HIV Protease; C514803:p16 protease, Human immunodeficiency virus 1