CYTOTOXIC EFFECT AGAINST HELA-CELLS OF POLYSACCHARIDES FROM THE LICHEN RAMALINA-CELASTRI

The most active polysaccharides which show anti-tumoral activity are ( 1-->3)-beta-D-glucans, branched or not at O-6. Since these structures are sometimes poorly soluble in aqueous media, oc-D-glucans and their chemical derivatives, which are more soluble, were also studied. The p resent object is to observe morphological alterations in HeLa cells ca used by two different polysaccharides obtained from the lichen Ramalin a celastri, which are (1-->3), (1-->4)-linked alpha-D-glucan and its s ulphated derivative. The cells were incubated in Eagle's medium in the absence or presence of each polysaccharide and routinely processed an d analysed by light and electron microscopy. Even though the cc-D-gluc an altered the cellular volume, cytoplasmic densities, and mitosis, th e resulting monolayer was similar to the control. TEM analysis showed cytoplasmic blebbing and the presence of an amorphous electron-dense m aterial free in the cytoplasm and interior membranes. The enhanced inj ury caused by the sulphated derivative was apparent, altering cell adh esion and causing cell aggregation. Nuclear modifications such as frag mentation and condensation of chromatin under the nuclear envelope, wh ich showed to be convoluted, suggested the occurrence of cell death by apoptosis.