title: Systematic comparison of the functional physico-chemical characteristics and biocidal activity of microbial derived biosurfactants on blood-derived and breast cancer cells.
abstract: OBJECTIVE
  The cytotoxicity of biosurfactants on cell membranes may be influenced by composition of their hydrophilic head and hydrophobic tails. It is hypothesised that they form mixed micelles which exert a detergent-like effect that disrupts the plasma membrane. The functional physico-chemical and biocidal characteristics of four biosurfactants were concurrently investigated to determine which of their structural characteristics may be tuned for greater efficacy.
  
  
  METHODS
  Rhamnolipid-95, rhamnolipid-90, surfactin and sophorolipid were characterised using FTIR, LC-MS, HPLC, surface tension and critical micelle concentration. Their biocidal activity against HEK 293, MCF-7 and THP-1 cell lines were investigated by MTT assay, using doxorubicin as cytotoxic control. Growth curves were established for all cell lines using trypan blue (TB) and MTT assays, corresponding doubling time (DT) and growth rate were obtained and compared.
  
  
  RESULTS
  HEK 293 cell-line had the highest growth rate amongst the three cell lines. For TB assay, growth of HEK 293>THP-1 and for MTT, HEK 293>MCF-7 while the DT was in the order of THP-1>MCF-7>HEK 293. Sophorolipid showed anti-proliferative activity comparable to doxorubicin on THP-1>MCF-7>HEK 293. THP-1 showed high sensitivity to sophorolipid with IC50 of 10.50, 25.58 and 6.78(μg/ml) after 24, 48 and 72h respectively. However, sophorolipid was cytotoxic from 24 to 72h on HEK 293 cell lines with IC50 of 21.53, 40.57 and 27.53μg/ml respectively. Although, doxorubicin showed higher anti-proliferative activity than all biosurfactants, it had poorer selectivity index for the same time durations compared to the biosurfactants. This indicates that biosurfactants were more effective for slowing the growth of the tested cancer cell lines and hence may be potential candidates for use in human cancer therapy. Physico-chemical characteristics of the biosurfactants suggest that their mechanism of action may be due to activity on the cell membrane.
authors.affiliation: Faculty of Engineering and Science, University of Greenwich, Medway, Kent ME4 4TB, UK.
authors.forename: Olufunke
authors.initials: O
authors.lastname: Akiyode
authors.affiliation: Faculty of Engineering and Science, University of Greenwich, Medway, Kent ME4 4TB, UK.
authors.forename: Daliya
authors.initials: D
authors.lastname: George
authors.affiliation: Faculty of Engineering and Science, University of Greenwich, Medway, Kent ME4 4TB, UK.
authors.forename: Giulia
authors.initials: G
authors.lastname: Getti
authors.affiliation: Faculty of Engineering and Science, University of Greenwich, Medway, Kent ME4 4TB, UK. Electronic address: j.s.boateng@gre.ac.uk.
authors.forename: Joshua
authors.initials: J
authors.lastname: Boateng
mesh_terms: D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000097:blood* / Q000473:pathology*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002627:Chemistry, Physical; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology; D004354:Drug Screening Assays, Antitumor; D006017:Glycolipids / Q000737:chemistry / Q000494:pharmacology*; D057809:HEK293 Cells; D006801:Humans; D061986:MCF-7 Cells; D008968:Molecular Conformation; D013329:Structure-Activity Relationship; D013501:Surface-Active Agents / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000970:Antineoplastic Agents; D006017:Glycolipids; D013501:Surface-Active Agents; D004317:Doxorubicin
keywords: Biosurfactants; Cancer chemotherapy; Critical micelle concentration; Cytotoxicity; HEK 293; MCF-7; Rhamnolipid; Sophorolipid; Surfactin; THP-1