Indonesian tea mistletoe (Scurrula oortiana) stem extract increases tumour cell sensitivity to tumour necrosis factor alpha (TNFalpha).

The water extract of Indonesian tea mistletoe, Scurrula oortiana ('benalu teh'), has been used for generations to treat tumours, however, little is known of its biological action. In the present study the stem and leaf extracts of S. oortiana were investigated for their modulation of tumour cell sensitivity toward TNFalpha, a potent anti-tumour cytokine. WEHI-164 cells which are known to be sensitive to TNFalpha, were used as a model. The assay results showed that either the stem or leaf extract of S. oortiana increased the sensitivity or susceptibility of WEHI-164 cells to TNFalpha as shown by decreases in LD(50) values in the TNFalpha sensitivity assay. The stem extract showed a greater increase than the leaf extract, increasing the sensitivity more than 160 times compared with the normal untreated tumour cells. This study showed for the fi rst time that water extracts of S. oortiana were significantly cytotoxic to the WEHI-164 tumour cell line and increased tumour cell sensitivity to TNFalpha mediated lysis.