Screening of red extracts from actinomycetes and fungi for photodynamic therapy

How S. E., . and Wong N. K., . and Teo S. H., . and Ong C. Y., . and Teoh H. H., . and S. H. Mahassan, . and Puah S. H., . and Ho A. S. H., . and Ho C. C., . and K. Suppayah, . and Lee H. B., . (2008) Screening of red extracts from actinomycetes and fungi for photodynamic therapy. [Proceedings Paper]

Photodynamic therapy PDT is a promising new modality for the treatment of cancer. This technique is based on the ability of photosensitisers to acumulate preferentially in tumor cells and to generate singlet oxygen 0‚‚ when activated by visible light of a specific wavelength to induce cellular toxicity. At present an ideal photosensitiser with respect to chemical purity tumor selectivity chemical and physical stability as well as rapid body clearance has not been found. In our screening program for bioactive compounds from actinomycetesandfungi inSabah purecultures ofactinomycetesH7891 andH11825andfungi H9010and H93l7 with orange to red extra-cellular pigment and non reddish actinomycetes H7372 H7530 H7667 H7763 and H11855 were successfully isolated mainly from soils collected from Maliau Basin and Danum Valley. These pure isolates were grown aerobically to produce secondary metabolites. The acetone extracts ofthese microbes were screened for photocytotoxic activity against a human leukaemic cell line HL60 using an MTf-based cell viability assay. The red actinomycetes and fungi crude freeze-dried acetone extracts were shown to have mild photocytotoxicity at 20 Ig/mL with no cytotoxicity when cells were kept in the dark. But surprisingly H1I855 a non reddish actinomycete also showed this mild photocytotoxicity. Extraction of H11825 that was cultured in a different medium solid oatmeal agar also yielded the same level of photocytotoxicity even though the extracts showed slightly different coloration. H7372 extract displayed a very interesting trend where the dark cytotoxicity was lost upon photo-irradiation. The photocytotoxic activity of these extracts warrants their further investigation as PDT photosensitisers and experiments are currently underway to evaluate the activity on semi-pure fractions and pure compounds.

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Abstract

Photodynamic therapy PDT is a promising new modality for the treatment of cancer. This technique is based on the ability of photosensitisers to acumulate preferentially in tumor cells and to generate singlet oxygen 0‚‚ when activated by visible light of a specific wavelength to induce cellular toxicity. At present an ideal photosensitiser with respect to chemical purity tumor selectivity chemical and physical stability as well as rapid body clearance has not been found. In our screening program for bioactive compounds from actinomycetesandfungi inSabah purecultures ofactinomycetesH7891 andH11825andfungi H9010and H93l7 with orange to red extra-cellular pigment and non reddish actinomycetes H7372 H7530 H7667 H7763 and H11855 were successfully isolated mainly from soils collected from Maliau Basin and Danum Valley. These pure isolates were grown aerobically to produce secondary metabolites. The acetone extracts ofthese microbes were screened for photocytotoxic activity against a human leukaemic cell line HL60 using an MTf-based cell viability assay. The red actinomycetes and fungi crude freeze-dried acetone extracts were shown to have mild photocytotoxicity at 20 Ig/mL with no cytotoxicity when cells were kept in the dark. But surprisingly H1I855 a non reddish actinomycete also showed this mild photocytotoxicity. Extraction of H11825 that was cultured in a different medium solid oatmeal agar also yielded the same level of photocytotoxicity even though the extracts showed slightly different coloration. H7372 extract displayed a very interesting trend where the dark cytotoxicity was lost upon photo-irradiation. The photocytotoxic activity of these extracts warrants their further investigation as PDT photosensitisers and experiments are currently underway to evaluate the activity on semi-pure fractions and pure compounds.

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Item Type:	Proceedings Paper
Additional Information:	Available at Perpustakaan Sultan Abdul Samad Universiti Putra Malaysia 43400 UPM Serdang Selangor Malaysia. mal RM666 H33 B573 Call Number
AGROVOC Term:	Actinomycetes
AGROVOC Term:	Fungi
AGROVOC Term:	Disease treatment
AGROVOC Term:	Human diseases
AGROVOC Term:	Screening tests
AGROVOC Term:	Acetone
AGROVOC Term:	Freeze drying
AGROVOC Term:	Absorbance
AGROVOC Term:	Microbes
AGROVOC Term:	Secondary metabolites
Geographical Term:	MALAYSIA
Depositing User:	Ms. Suzila Mohamad Kasim
Last Modified:	24 Apr 2025 05:15
URI:	http://webagris.upm.edu.my/id/eprint/12849

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