Actividad antitumoral de compuestos naturales: lectinas y azafrán / Antitumor activity of natural substances: lectins and saffron

El problema principal en el uso de agentes quimioprotectores en tratamiento de cáncer es la toxicidad potencial de estos medicamentos a células. Una manera de resolver este problema es el empleo de inhibidores de tumorogénesis que sean de origen natural. Recientemente se ha tenido mucho interés en buscar, entre varios extractos naturales de plantas, aquellos que posean actividades antitumorales y anticarcinigénicas, así como también en compuestos naturales presentes en productos alimenticios. Los extractos naturales o sus compuestos purificados han sido de interés en el estudio de algunos aspectos referentes al cáncer. El descubrimiento acerca de que las lectinas de plantas presentan actividad biológica sobre células transformadas, especialmente en relación con un efecto antitumoral, ha aumentado el interés en este campo. Otra especie natural con efecto antitumoral es el azafrán. En la presente revisión se comentan algunas investigaciones acerca de los efectos antitumorogénicos y anticarcinogénicos de las lectinas y el azafrán, así como de alguno de sus componentes, Asimismo se discute también el posible mecanismo por el cual las lectinas y el azagrán puede actuar como antitumorogénicos

Inflammatory cutaneous reaction induced by the lectin of Dioclea grandiflora (Mart.)

The lectin from Dioclea grandiflora (Mart.) that selectively binds glucose and mannose, when subcutaneously injected in mouse induces an inflammatory cutaneous reaction whose histological analysis reveals an hemorrhagic ulceration with exudative reaction accompanied by an influx of polymorphonuclear leukocytes and giant cells. The presence of lymphocytes and plasma cells in the lesion was insignificant. In order to characterize the in vivo action of inflammatory factors generated by this lesion, distinct lines of mice were used: high and low antibody responder mice; the genetically selected mice to the acute phase of inflammatory reaction; lines of mice deficient in C5, a protein of the complement system. It is shown that the lectin of D. grandiflora acts as an inflammatory agent probably promoting exocytosis and release of mediators

Intracerebroventricular administration of canatoxin to rats increases the circulating levels of luteinizing hormone

Recent evidence has implicated the central nervous system as a target organ for canatoxin, a toxic protein present in Canavalia ensiformis seeds. This toxin activates the lipoxygenase pathway of arachidonic acid metabolism and can thus induce the release of substances mediated by lipoxygenase products. In the present study, the circulating levels of luteinizing hormone (LH) were measured by RIA in male Wistar rats (200-240 g) after the administration of canatoxin into the lateral cerebral ventricle. Canatoxin (0.5-2 micrograms in 2 microliters daily for 3 days) caused a dose- and time-dependent increase in the plasma levels of LH. The total dose of canatoxin used is subconvulsive. At 2, 4 and 24 h after 2 micrograms of canatoxin LH levels were increased by 10 per cent , 43 per cent and 61 per cent , respectively, compared to vehicle-injected animals (0.18 +/- 0.03 ng/ml). This response to 2 micrograms of canatoxin was not attenuated by pretreatment with two different lipoxygenase inhibitors, nordihydroguaiaretic acid (NDGA, 125 mg/kg) or esculetin (ECLT, 125 mg/kg), ip, 1 h before each canatoxin (CNTX) injection; per cent increase in LH with CNTX alone: 61 per cent ; CNTX+NDGA: 54 per cent ; CNTX+ECLT:76 per cent ; N = 5/group. These data show that intracerebral injection of CNTX in rats increases circulating levels of LH via a mechanism that is independent of the lipoxygenase pathway

Intraperitoneal toxicity of pea and lentil lectins in albino rats--effect on growth and osmotic fragility of erythrocytes.

Lectins from peas and lentils when injected to rats apparently appeared to be non toxic but they caused growth depression. The organ weights were not affected except spleen enlargement. The lectins also caused increased osmotic fragility of erythrocytes without affecting other hematological parameters such as haemoglobin, packed cell volume, and RBC count.

Sex-related canatoxin-induced blood glucose alterations in the rat

The present study was designed to characterize sex-related canatoxin-induced blood glucose alterations in rats. Chronic administration of canatoxin (50 mU, ip, daily for 3 days) induced hypoglycemia in female rats (N = 6) (-36.54 + or - 3.24%, P<0.05). The response of pregnant rats (N = 8) was similar to that observed for male rats (+29.57 + or - 4.70%). Administration of canatoxin did not modify blood glucose levels of gonadectomized male or female rats. Similarly, pretreatment of intact male or female rats with human chorionic gonadotropin (40 IU/kg, im) blocked the effect of canatoxin on blood glucose levels. Gonadal steroid replacement (testosterone, 10 mg/kg,im) for gonadectomized male rats did not reverse the inhibition of canatoxin-induced blood glucose alterations, whereas pretreatment of intact female rats (N = 6) with tetosterone (10 mg/kg, im) significantly attenuated the canatoxin-induced hypoglycemia. These data indicate that the blood glucose alterations produced by canatoxin in rats are under hormonal regulation