Screening for microbial secondary metabolites for inhibitors of protein phosphatases and Photodynamic Therapy (PDT)

Siti Hasmiza Mahassan, (2007) Screening for microbial secondary metabolites for inhibitors of protein phosphatases and Photodynamic Therapy (PDT). University Malaysia Sabah. (Unpublished)


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This study was carried out to find the microbial secondary metabolites of actinomycetes that inhibited protein phosphatases, PP1 and PP2A, in eukaryotic signal transduction. The actinomycetes strains of H11825, H7352, H7520, H7775, H7786, H7891, H7959, H7979, H7984, H8632 and H8886 were isolated and grown aerobically to produce secondary metabolites. The actinomycetes strains under observation for the protein phosphatases screening, PP1 and PP2A were H7520, H11825 and H7891. The screening systems were done on the yeast, the Saccharomyces cerevisiae that encoded the GLC7 protein. The acetone extracts of H7520, H11825 and H7891 were used to show the inhibitory effects to the PPI and PP2A screening system. Three replicates of the screening were done and the results showed that H7520, H11825 and H7891 acetone extracts did not give any inhibition zone. The actinomycetes strains H11825, H7891 , H8632, H8886, H7775 and H7786 also were grown and tested for photocytotoxicity using a MIT assay. The crude freeze dried acetone extracts of these actinomycetes strains that produced the red pigmentation which were H11825, H7891, H8632, H8886, H7775 and H7786 were screened for photocytotoxicity against a human leukaemic cell line HL60 using MTT based cell viability assay. The highest percentage of photo cytotoxicity which the cells killed by red pigmented extract in the light treatment compared to the dark control was the H11825T2 at 20 μg/ml with the photocytotoxicity activity of 14.5 %, followed by H11825Tl (13.8 % at 20 μg/ml), H7786 (13.4 % at 20 μg/ml), H111 825T1 (10 % at 100 μg/ml), H111825T2 (8.7 % at 100 μg/ml), H8632 (8.6 % at 20 μg/ml), H11825 with acetic acid (7.4 % 20 μg/ml), H7891 (6.0 % at 100 μg/ml), H7891 (5.4 % at 20 μg/ml), H8886 (4.5 % at 20 μg/ml) and H7775 (1.3 % at 20 μg/ml). The photocytotoxic activities of these extracts warrant their future investigation as potential photosensitisers for PDT therapy and further experiment on the activity on semi-pure fractions and pure compound should be done.

Item Type: Academic Exercise
Uncontrolled Keywords: eukaryotic signal transduction, photocytotoxicity, PDT therapy, extracts warrant, semi-pure fractions, acetone extract, actinomycetes
Subjects: Q Science > QR Microbiology
Divisions: SCHOOL > School of Science and Technology
Date Deposited: 15 May 2014 03:09
Last Modified: 13 Oct 2017 03:59

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