title: Antiplasmodial activity of extracts of 25 cyanobacterial species from coastal regions of Tamil Nadu.
abstract: BACKGROUND
  Marine cyanobacteria offer considerable potential to isolate new antimalarials to meet a pressing need of our times.
  
  
  OBJECTIVE
  To explore the antiplasmodial properties of marine cyanobacteria.
  
  
  METHODS
  Cyanobacterial samples collected from the coastal regions of Tamil Nadu were identified using light microscopy, and the strains were cultivated in ASN-III medium. Organic extracts (0-100 µg mL(-1)) of 25 in vitro mass-cultivated cyanobacteria, prepared using methanol: chloroform mixture (1:1 v/v) were evaluated for their antiplasmodial activity against chloroquine-sensitive and -resistant strains of Plasmodium falciparum by fluorescence-based SYBR Green I assay where chloroquine was used as a control. To detect the toxic effects of cyanobacterial extracts against red blood cells, the invasion, maturation, and growth rate of malarial parasites in cyanobacterial extracts pre-treated versus untreated erythrocytes were quantified microscopically. Mammalian cell line (HeLa) was used to determine cyanobacterial extract toxicity using the MTT assay.
  
  
  RESULTS
  The extracts of Lyngbya aestuarii Liebm. ex Gomont CNP 1005 (C12) Oscillatoria boryana BDU 91451 (C22) and Oscillatoria boryana Bory ex Gomont BDU 141071 (C18) showed promising antiplasmodial activity (IC50 = 18, 18, and 51 μg mL(-1) respectively) against Pf3D7. Pretreatment of red blood cells with IC100 of C12, C18, and C22 (40, 100, and 40 µgmL(-1), respectively) did not significantly influence the invasion, maturation, and growth rate of malarial parasites in comparison with untreated RBC controls suggesting a lack of toxicity to host cells. MTT assay based IC50 (>200 μg mL(-1)) of these extracts against HeLa cell line also indicates their high selectivity against the malaria parasite.
  
  
  CONCLUSIONS
  These exploratory studies suggest the possibilities of development of new antimalarial compounds from marine cyanobacteria.
authors.affiliation: Department of Marine Biotechnology, National Facility for Marine Cyanobacteria, Bharathidasan University , Tiruchirappalli, Tamil Nadu , India and.
authors.forename: Maruthanayagam
authors.initials: M
authors.lastname: Veerabadhran
authors.forename: Nagarajan
authors.initials: N
authors.lastname: Manivel
authors.forename: Dinesh
authors.initials: D
authors.lastname: Mohanakrishnan
authors.forename: Dinkar
authors.initials: D
authors.lastname: Sahal
authors.forename: Sundararaman
authors.initials: S
authors.lastname: Muthuraman
mesh_terms: D000962:Antimalarials / Q000302:isolation & purification / Q000494:pharmacology*; D001483:Base Sequence; D000458:Cyanobacteria / Q000235:genetics / Q000302:isolation & purification*; D004912:Erythrocytes / Q000187:drug effects / Q000502:physiology; D006367:HeLa Cells; D006801:Humans; D007194:India; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000187:drug effects* / Q000502:physiology
chemical_list: D000962:Antimalarials
keywords: Bioactivity; Lyngbya; Oscillatoria; cytotoxicity