Search

Abstract: The development of antioxidants as useful drugs for the treatment of neurodegenerative diseases such as Alzheimer’s is extremely challenging in medicinal chemistry. Coumarins have attracted great attention as possible therapeutic tools against oxygen radicals in human degenerative diseases. In order to establish the possible structure-antioxidant activity relationship, a series of twenty four 4-methylcoumarin derivatives were examined by employing reducing power measurements, and comparison with bond dissociation enthalpy and ionization potential calculations. Based on the reducing potency of 4-methylcoumarin derivatives with respect to trolox, these compounds were classified into five groups as “most active”, “more active”, “moderately active”, “less active” and “inactive” derivatives. The presence of hydroxyl groups is an essential requirement for the activity, and substitution of hydroxyl groups by methoxy groups leads to non-active derivatives. The results revealed that dihydroxyl groups in the ortho position show a better antioxidant activity with respect to dihydroxyl groups in the meta position. This is ascribed to the ability to construct more stable 4-methylcoumarin radical intermediates by rearrangement of intra-molecular hydrogen bonding. Our findings indicate that other important factors to enhance the antioxidant activity of coumarins are the number of hydroxyl groups, the presence of ester substitutions and a thiono functional group on the pyrone ring. However, bond dissociation enthalpy and ionization potential calculations alone are not sufficient to identify the best antioxidant structures. As a result, chemical and functional properties of molecules such as 4-methylcoumarins should be examined as a whole entity, considering all substitutions versus a single substitution to design functional compounds with good antioxidant activity.

We have recently reported that about 30-40% of female breast tumours produce prostate-specific antigen (PSA) and that PSA production is associated with the presence of oestrogen (ER) and progesterone (PR) receptors. We have now developed a tissue culture system to study the regulation of the PSA gene in breast cancer. The breast carcinoma cell line T-47D produces PSA when stimulated by androgens, progestins and glucocorticoids/mineralocorticoids but not oestrogens. PSA mRNA appears approximately 2 h after stimulation; PSA protein appears after 4-8 h. Among 38 compounds tested, only androgens and progestins were able to stimulate PSA production at concentrations below 10(-9) M. Evidence that the progesterone and androgen receptors can regulate the PSA gene independently was provided as follows: (a) the progestin norgestimate, which does not bind to the androgen receptor, up-regulates the PSA gene at concentrations as low as 10(-10) M; (b) triamicinolone acetonide, which does not bind to the androgen receptor (AR) but binds to the PR, acts similarly to norgestimate; (c) the antiandrogen cyproterone acetate, which blocks the androgen receptor but has progestational activity, up-regulates the PSA gene at concentrations as low as 10(-10) M; (d) the antiprogestine mifepristone completely blocks the stimulation of the specific progestin norgestimate. Our tissue culture system identified androgen-progestin agonist activities of 17 alpha-ethinyloestradiol, the antioestrogen RU56, 187 and the antiprogestin mifepristone. Our data suggest that the expression of the PSA gene in the female breast is under the control of androgens and progestins. Our tissue culture system is a highly sensitive in vitro method for evaluating the biological activity of candidate compounds having agonist and antagonist steroid hormone activity.

Creatinine kinase BB (CK-BB) is elevated in many tumours including those of the breast. We have recently described a new, highly sensitive and specific method for measuring CK-BB, based on monoclonal antibodies and time-resolved fluorometry. Using this method, we quantitated CK-BB in 172 breast tumour cytosols and examined the associations between CK-BB and other clinicopathological variables and patient survival. High CK-BB levels were seen more frequently in tumours from patients who were younger (age < 50 years), patients who qualified for chemotherapy and patients with oestrogen receptor-positive tumours. No association was seen between CK-BB and tumour stage, grade, size, histological type or the progesterone receptor. In univariate analysis, the risk of relapse or death was higher in the group with tumours containing high CK-BB levels but the difference did not reach statistical significance. In multivariate analysis, the risk of death was statistically significantly higher in the high-CK-BB group. Analysis of subsets of patients revealed that patients with oestrogen receptor-negative cancer have higher risk of death if their tumours contain high levels of CK-BB. Our data suggest that, in general, CK-BB is associated with more aggressive tumours but its value as a prognostic indicator is limited. CK-BB content of breast tumours may be more useful as an aid in selecting therapy directed at inhibiting this enzyme activity and thus depriving tumour cells of their energy source.

Asmundson and Julian (1,2) reported the presence of a recessive autosomal gene (am) in New Hampshire chickens which produces in the homozygous bird a condition quite similar to certain forms of muscular dystrophy in man(3). The superficial pectoral muscles of such adult birds contained considerably more fat than those of normal birds (4,5). Elevated fat content has also been found in certain muscles of mice with muscular dystrophy by Shull and Alfm-Slater(6) and in some types of muscular dystrophy in man (3).This investigation was undertaken to determine the nature of the fat deposited intramuscularly in chickens with inherited muscular dystrophy. An increase in the triglyceride fraction and a decrease in the phospholipid fraction relative to other lipids constitute the major differences in the dystrophic muscle when compared with the normal muscle.Methods.Seven pairs of 36-week-old normal and muscular dystrophic female New Hampshire birds were used in the study. The animals were sacrificed and the left superficial pectoral muscles were excised, quick-frozen in a dry ice-acetone bath and stored at —20°C. They were thawed and used as needed.A 0.5-0.8 sample g of wet muscle was placed in a vacuum oven at 70° for 12 hours to determine the moisture content by weight difference. Protein was determined by the Kjeldahl method (N × 6.25) and hydroxyproline was determined by the technique of Neuman and Logan(7). The hydroxyproline content was used as a measure of collagen or connective tissue.The fat was extracted from the muscle by the CHCl3:CH3OH:H2O method of Bligh and Dyer(8). The CHCl3layer containing the lipid, was evaporated in a 60° C water bath under a stream of N2. Approximately 70 mg of this fat was chromatographed on a 3.0 g silicic acid-Hiflo Supercell column (70: 30 w/w), and eluted by the scheme of Barron and Hanahan(9).