TRYPANOCIDAL, ANTI-LEISHMANIAL, AND CYTOTOXIC ACTIVITY OF MUEHLENBECKIA TAMNIFOLIA (KUNTH) MEINS (POLYGONACEAE)

Objective: The objective of this study was to evaluate the activity against amastigotes of Leishmania panamensis and epimastigotes of Trypanosoma cruzi (Chagas), extracts and fractions obtained from leaves and stems of Muehlenbeckia tamnifolia. Methods: Plant material was collected during the flowering, in the town of La Calera (Cundinamarca), at a height of 2746 m above sea level, 4°43’11”N, 3°58’12”W. Leaves and stems were extracted with light petroleum and then with ethanol. The extracts were fractionated by column chromatography on silica gel with petrol; CH2Cl2, AcOEt, and MeOH. The activity against epimastigotes and cytotoxicity was evaluated by the enzymatic micromethod with MTT. The active extracts against epimastigotes and with low cytotoxicity were also evaluated in trypomastigotes and intracellular amastigotes. Results: The dichloromethane fraction from leaves and stems of M. tamnifolia showed the highest activity against Leishmania panamensis with an 50% of the effective concentration of 0.006 (μg/ml) and a selectivity index of 4.16. In U937 cells, six of the extracts and fractions tested showed high cytotoxicity, 50 inhibitory concentration <50 μg/ml. Conclusions: The extracts obtained from leaves and stems of different polarities of M. tamnifolia (Kunth) Meins, revealed a moderate effect against amastigotes of L. panamensis (Leishmaniosis) (low polarity fractions) and a low effect against epimastigotes of T. cruzi (Chagas).

Direct enzymatic determination of urea in plasma and urine with a centrifugal analyzer.

A direct enzymatic micromethod (sample volume, 3mul) has been adapted to the centrifugal analyzer (ENI-GEMSAEC) for measurement of urea in plasma and urine. The method is based on urease (urea amidohydrolase, EC3.5.1.5)/glutamate dehydrogenase [l-glutamate:NAD(P)+oxidoreductase (deaminating), EC1.41.3] coupled reactions, and uses a two-point fixed-time (t(1)=20s,t(2)=50s)kinetic scheme for monitoring the rate of comsumption of NADH at 340 nm. Sensitivity and precision of the method are excellent,and results compare well with those from a commonly used continuous-flow method.

Automated Enzymatic Micromethod for Determination of Uric Acid in Serum and Urine with a Centrifugal Analyzer

Uric acid is determined in serum and urine by an enzymatic method on a centrifugal analyzer. The sample (8 µl) is mixed with the enzyme uricase in a sodium borate buffer. The resulting decrease in absorbance at 292 nm is linearly proportional to the concentration of uric acid from 1 to 75 mg of uric acid per deciliter. Use of a centrifugal analyzer eliminates measurement of a separate serum blank. Recovery of uric acid added to serum and urine averaged 100% (range: 97-110%). Within-run precision (CV) on a serum pool for which the mean value was 5.96 mg/dl was 2.52%; day-to-day precision, measured on the same serum pool over a seven-day period, was 2.81% (mean: 6.05 mg/dl). Results obtained for serum with the uricase method on a centrifugal analyzer and with the uricase method on the Du Pont aca yielded a correlation coefficient of 0.99.