ABSTRACT
Photodynamic therapy (PDT) is a treatment for superficial tumours involving the administration of a photosensitiser followed by irradiation. The potential of the natural anthraquinone parietin (PTN) in PDT is still relatively unexploited. In the present work, PTN isolated from the lichen Teoloschistes nodulifer (Nyl.) Hillman (Telochistaceae) was evaluated as a potential photosensitiser on tumour cells employing UVA-Vis and blue light. Blue light of 2 J/cm2 induced 50% death of K562 leukaemic cells treated 1 h with 30 µM PTN (Protocol a). Higher light doses (8 J/cm2) were needed to achieve the same percentage of cell death employing lower PTN concentrations (3 µM) and higher exposure times (24 h) (Protocol b). Cell cycle analysis after both protocols of PTN-PDT revealed a high percentage of sub-G1 cells. PTN was found to be taken up by K562 cells mainly by passive diffusion. Other tumour cells such as ovary cancer IGROV-1 and LM2 mammary carcinoma, as well as the normal keratinocytes HaCaT, were also photosensitised with PTN-PDT. We conclude that PTN is a promising photosensitiser for PDT of superficial malignancies and purging of leukaemic cells, when illuminated with blue light. Thus, this light wavelength is proposed to replace the Vis-UVA lamps generally employed for the photosensitisation of anthraquinones.
Subject(s)
Ascomycota/chemistry , Complex Mixtures/chemistry , Emodin/analogs & derivatives , Photochemotherapy/methods , Photosensitizing Agents/chemistry , Apoptosis/radiation effects , Cell Line, Tumor , Cell Membrane Permeability , Cell Proliferation/radiation effects , Complex Mixtures/pharmacology , Dose-Response Relationship, Radiation , Emodin/chemistry , Emodin/pharmacology , Humans , Light , Photosensitizing Agents/pharmacology , Radiation Exposure , Time FactorsABSTRACT
ABSTRACT Achyrocline satureioides (Lam.) DC. Asteraceae, ‘marcela del campo', possess several pharmacological properties. Previously we reported antiviral activity of an aqueous extract of A. satureioides against an alphavirus, Western Equine Encephalitis virus. Alphaviruses are highly virulent pathogens which cause encephalitis in humans and equines. There are no effective antiviral to treat its infections. The aim of this study was to evaluate in vitro cytotoxic and antiviral activities against Western Equine Encephalitis virus of five water extract chromatographic fractions from A. satureioides and identify the main compounds of the bioactive fraction. Also, it was to assess in vivo cytogenotoxic ability of the active fraction. Cytotoxicity studies revealed low toxicity of the most of fractions in Vero and in equine peripheral blood mononuclear cells. Antiviral studies showed that the water crude extract – Sephadex LH 20 – fraction 3 MeOH–H2O (Fraction 3) was active against Western Equine Encephalitis virus with Effective Concentration 50% = 5 µg/ml. Selectivity Indices were 126.0 on Vero and 133.6 on peripheral blood mononuclear cells, four times higher than aqueous extract selectivity index. Regarding the mechanism of action we demonstrated that F3 exerted its action in intracellular replication stages. Further, fraction 3 showed important virucidal action. Fraction 3 contains, in order of highest to lowest: chlorogenic acid, luteolin, 5,7,8-trimethoxyflavone, 3-O-methylquercetin and caffeic acid. Fraction 3 did not induce in vivo toxic nor mutagenic effect. Therefore, it is safe its application as antiviral potential. Further studies of antiviral activity in vivo will be developed using a murine model.
