Igor Lemus

Hypoglycaemic activity of four plants used in Chilean popular medicine

The hypoglycaemic activity of a 20% dried leaf infusion of Bauhinia candicans Benth. (Leguminosae), Galega officinalis L. (Leguminosae), Morus alba L. (Moraceae) and Rubus ulmifolius Schott. (Rosaceae), used for diabetes in Chilean popular medicine, was evaluated in alloxan and streptozotocin induced hyperglycaemic rats.

Development and validation of an UV derivative spectrophotometric determination of Losartan potassium in tablets

Development and validation of an analytical UV derivative spectrophotometric method to quantify Losartan potassium used as a single active principle in pharmaceutical forms were done. Pharmacopeias have not yet provided an official method for its quantification. A study was carried out of all the parameters established by USP XXIV to validate an analytical method for a solid pharmaceutical form, i.e. linearity, range, accuracy, precision and specificity. All these parameters were found in accordance with the acceptance criteria of Comité de Guías Oficiales de Validación de la Dirección General de Control de Insumos para la Salud de México. Based on the spectrophotometric characteristics of Losartan potassium, a signal at 234 nm of the first derivative spectrum (1D234) was found adequate for quantification. The linearity between signal 1D234 and concentration of Losartan potassium in the range of 4.00-6.00 mg l(-1) in aqueous solutions presents a square correlation coefficient (r2) of 0.9938. The mean recovery percentage was 100.7+/-1.1% and the precision expressed as relative standard deviation (R.S.D.) 0.88%. In addition, the proposed method is simple, easy to apply, low-cost, does not use polluting reagents and requires relatively inexpensive instruments. Then, it is a good alternative to existing methods for determining Losartan potassium in tablets provided that the pharmaceutical dosage form does not contain hydrochlorothiazide as second drug.

Daidzein–Estrogen Interaction in the Rat Uterus and Its Effect on Human Breast Cancer Cell Growth

Sex hormone replacement therapy provides several advantages in the quality of life for climacteric women. However, estrogen-induced cell proliferation in the uterus and mammary gland increases the risk of cancer development in these organs. The lower incidence of mammary cancer in Asian women as compared with Western women has been attributed to high intake of soy isoflavones, including genistein. We have previously shown that genistein induces an estradiol-like hypertrophy of uterine cells, but does not induce cell proliferation, uterine eosinophilia, or endometrial edema. It also inhibits estradiol-induced mitosis in uterine cells and hormone-induced uterine eosinophilia and endometrial edema. Nevertheless, genistein stimulates growth of human breast cancer cells in culture; therefore, it is not an ideal estrogen for use in hormone replacement therapy (HRD). The present study investigated the effect of another soy isoflavone, daidzein (subcutaneous, 0.066 mg/kg body weight), in the same animal model, and its effect on responses induced by subsequent treatment (1 h later) with estradiol-17β (E(2); subcutaneous, 0.33 mg/kg body weight). In addition, we investigated the effects of daidzein (1 μg/mL) or E(2) on the growth of human breast cancer cells in culture. Results indicate that daidzein stimulates growth of breast cancer cells and potentiates estrogen-induced cell proliferation in the uterus. We suggest caution for the use of daidzein or formulas containing this compound in HRD. Future research strategies should be addressed in the search for new phytoestrogens that selectively inhibit cell proliferation in the uterus and breast.

Differential pulse voltammetric determination of famotidine

A differential pulse voltammetric method for the determination of famotidine in pharmaceutical preparations is described. The method is based on electrochemical oxidation of famotidine at a glassy carbon or platinum electrode. The proposed method shows good reproducibility, and sample preparation is simple.

Genistein Selectively Inhibits Estrogen-Induced Cell Proliferation and Other Responses to Hormone Stimulation in the Prepubertal Rat Uterus

Sex hormone replacement therapy helps improve quality of life in climacteric women. However, estrogen-induced cell proliferation in the uterus and mammary gland increases the risk for cancer in these organs. The lower incidence of mammary cancer in Asian women than in western women has been attributed to high intake of soy isoflavones, including genistein. Our previous work in the prepubertal rat uterus model showed that genistein (0.5 mg/kg body weight subcutaneously) caused an estradiol-like hypertrophy in myometrial and uterine luminal epithelial cells and an increase in RNA content in luminal epithelium; however, it did not induce cell proliferation, uterine eosinophilia, or endometrial edema. The present study investigated, in the same animal model, the effect of genistein administration (0.5 mg/kg body weight subcutaneously) before treatment with estradiol-17β (0.33 mg/kg body weight subcutaneously) on uterine responses that were not induced by genistein. Pretreatment with this phytoestrogen completely inhibited estradiol-induced mitoses in uterine luminal epithelium, endometrial stroma, and myometrium and partially inhibited estradiol-induced uterine eosinophilia and endometrial edema. These findings indicate that genistein protects against estrogen-induced cell proliferation in the uterus and suggest that future studies should investigate the possibility of using this agent to decrease the risk for uterine cancer after hormone replacement therapy in climacteric women.

Biological and chemical study of paico (Chenopodium chilense, Chenopodiaceae)

The methanolic extract of the aerial portion of Chenopodium chilense Schrad., used in Chilean traditional medicine as a remedy for stomach-ache, has been found to exert the major spasmolytic activity in acetylcholine contracted rat ileum. This extract, with a complex flavonoid patterns on thin layer chromatography (TLC) analysis, is practically non-toxic both for rats and brine shrimp Artemia salina in acute toxicity test.

Voltammetric behaviour of ketorolac and its HPLC-EC determination in tablets

Ketorolac is an antiinflammatory-analgesic agent that is oxidizable at the glassy carbon electrode. The voltammetric oxidation produces two well resolved pH-dependent peaks, that are overlapped at pH>10. Using this voltammetric response a HPLC procedure with electrochemical detection in order to quantify ketorolac in pharmaceutical dosage forms is presented. Furthermore comparative methods using UV spectrophotometry and HPLC with photodiode array detector were used.