Cytotoxic and antimicrobial activities of sterile culture supermatant of pigmented bacterial epibionts of corals and algae and the effects on expression of c-fox and e-jun early apoptotic genes

• Main Author: Antonio, Jayson M.
• Format: text
• Language: English
• Published: Animo Repository 2016
• Subjects: Marine organisms; Corals; Algae; Anti-infective agents
• Online Access: https://animorepository.dlsu.edu.ph/etd_masteral/5317
• Institution: De La Salle University

Marine epibionts participate on defense strategies of the host by deterring the growth of potentially invasive microorganisms. Secondary metabolites secreted by marine epibionts demonstrate wide array of bioefficacy. This study determined cytotoxicity and antimicrobial activities of 11 pigmented bacterial epibionts (PBEs) isolated from corals and algae. The filtered-sterilized supernatant (FSS) of PBEs were evaluated for cytotoxicity to breast cancer cells (MCF-7), colon cancer cells (HT-29 and HCT116), leukemia cells (THP-1), and normal human dermal fibroblasts (HDFn) using PrestoBlue™ resazurin assay. Bleomycin (Bleo) was the positive control while marine broth (MB) was the negative control. The FSS and ethyl acetate extracts of PBEs were also tested for antimicrobial activity against clinical isolates of multi-drug resistant pathogens. Isolated PBEs were molecular identified as belonging to class Actinobacteria, Bacilli, Alpha-proteobacteria and Gamma-proteobacteria. The FSS of PBEs Zooshikella isolated from Porites sp., Microbulbifer isolated from Fungia sp., Exiguobacterium isolated from Halymenia dilatata, Arthrobacter isolated from Caulerpa cupressoides, Dietzia and Paracoccus isolated from Galaxea facicularis showed dose dependent and selective cytotoxicity to the cells. Cytotoxicity index (CI%) profiles on HDFn and THP-1 of all FSS and MB suggest nontoxicity to the cells when compared to Bleo. However, the FSS of Dietza (IC50=18.46%), Paracoccus (IC50=23.24%), and Microbulbifer (IC50=26.46%) exhibited cytotoxicity for MCF-7. On the other hand, the FSS of Exiguobacterium and Arthrobacter were cytotoxic for HCT-116 in the concentration range of 23-25%. The CI% profiles of Zooshikella sp. (IC50=13.4%) and Dietzia (IC50=13.7%) for HT29 suggest toxicity for the cell line. None of the FSS were able to prevent the growth of the bacterial pathogens tested. However, ethyl acetate extract of Zooshiekella FSS exhibited anti-MRSA activity. The FSS of PBEs cytotoxic to tested cancer cells induced transcriptions of c-fos and c-jun pro-apoptotic genes. Overall, results showed that the cytotoxic and antimicrobial activities of PBEs are found in the secondary metabolites present in the supernatant.