Toxicity and Anticancer Potential of Karwinskia: A Review.

Karwinskia genus consists of shrubs and small trees. Four toxic compounds have been isolated from Karwinskia plants, which were typified as dimeric anthracenones and named T496, T514, T516, and T544. Moreover, several related compounds have been isolated and characterized. Here we review the toxicity of the fruit of Karwinskia plants when ingested (accidentally or experimentally), as well as the toxicity of its isolated compounds. Additionally, we analyze the probable antineoplastic effect of T514. Toxins cause damage mainly to nervous system, liver, lung, and kidney. The pathophysiological mechanism has not been fully understood but includes metabolic and structural alterations that can lead cells to apoptosis or necrosis. T514 has shown selective toxicity in vitro against human cancer cells. T514 causes selective and irreversible damage to peroxisomes; for this reason, it was renamed peroxisomicine A1 (PA1). Since a significant number of malignant cell types contain fewer peroxisomes than normal cells, tumor cells would be more easily destroyed by PA1 than healthy cells. Inhibition of topoisomerase II has also been suggested to play a role in the effect of PA1 on malignant cells. More research is needed, but the evidence obtained so far indicates that PA1 could be an effective anticancer agent.

Vitamin D receptor polymorphisms and bone mineral density in Mexican women without osteoporosis.

Polymorphisms corresponding to Apa I, Bsm I, and Taq I restriction endonucleases at the vitamin D receptor (VDR) gene and bone mineral density (BMD) at lumbar spine (L2-L4) and proximal femur (neck, Ward's triangle and trochanteric region) sites were examined in a sample of 98 Mexican women (age 55 +/- 10 years). None of the subjects were pregnant or nursing and none had a previous diagnosis of osteoporosis. Polymorphisms were assessed by the restriction fragment length polymorphism - polymerase chain reaction (RFLP-PCR) technique. Alleles were denoted with capital letters for the absence of the RFLP site (A, B, or T) and with small letters for its presence (a, b, or t). BMD was assessed by dual energy X-ray absorptiometry (DXA). A structured, self-administrated questionnaire was used to obtain data on age, menopause, number of pregnancies, breast-feeding, fractures, exercise, smoking, alcohol, estrogens, calcium supplement, height, weight, and BMI. There were no differences between BMD at the skeletal sites and the genotypes disclosed by Apa I (Allele A = 0.43), Bsm I (Allele B = 0.26) and Taq I (Allele T = 0.76). The present study provides data for comparison with other studies to determine the possible value of genotyping VDR to predict predisposition for osteoporosis in Mexican or Mexican-American women. Am. J. Hum. Biol. 11:793-797, 1999. Copyright 1999 Wiley-Liss, Inc.