Avaliação farmacobotânica e farmacológica de Cuphea calophylla Cham. & Schtdl. subsp. mesostemon (KOEHNE) LOURTEIG

Abstract

Cuphea P. Browne is the largest genus of the family Lythraceae, represented by about 260 species. Several species of Cuphea are used medicinally and are reported to have anti-inflammatory, diaphoretic, diuretic, antihypertensive and cardioprotective properties. Cuphea calophylla subsp. mesostemon (Koehne) Lourteig is an herbaceous plant growing naturally in the fields, forest edges and along roadsides in Brazil. It shares similar morphological features with several other species of Cuphea creating confusions in the species identification. Due to the morphological similarity, different species known as seven-sangrias in Brazil are used interchangeably for the same therapeutic purposes. The main objectives of the present work were i) to characterize the morpho-anatomy of leaves and stems of C. calophylla subsp. mesostemon; ii) to evaluate the safety of ethanol-soluble fraction from Cuphea calophylla (ESCC) of the taxon in relation to its toxicity; and iii) to investigate the diuretic, hypotensive, vasodilatory and antioxidant effects of ESCC at 30, 100 and 300 mg/kg doses. For the botanical analysis, the plant materials were analyzed by light and scanning electron microscopy. Morphologically, the leaves of C. calophylla subsp. mesostemon are opposite, ovate in shape with a rounded base, acute apex and smooth margins. The petioles and stems are cylindrical. Anatomically, the leaf is amphistomatic, with uniseriate epidermis and dorsiventral mesophyll containing oil droplets. Two types of stomata, namely anomocytic and diacytic, are present. The trichomes are of three types: a) glandular, multicellular, multiseriate; b) non-glandular, warty, adpressed; and c) non-glandular, multicellular, uniseriate. In cross-section, the midrib is slightly concave-convex in outline and possesses a central beam of bicollateral vascular system in open arch. The stem is circular in shape and covered by a uniseriate epidermis. Elemental analysis of the crystals shows that they are of calcium oxalate. The histochemical tests indicate the presence of lipophilic, lignified, phenolic compounds and starch grains in various tissues of the plant. For the pharmacological evaluation, the ESCC was obtained by infusion using standard methods with some modifications. Male and female Wistar rats of 8 to 12 weeks old were used for biological studies. In the tests for toxicity, the ESCC (2000 mg/kg) showed no acute toxic effects and therefore the estimated LD50 was above 2000 mg/kg. In the evaluation for diuretic activity, the ESCC (30, 100 and 300 mg/kg) did not present significant diuretic effect. However, on prolonged diuresis at the dose of 30 mg/kg on day 7, a significant difference was observed. In the tests for hypotensive activity, none of the treatments was able to promote a significant change in blood pressure levels or heart rate. The ESCC was then evaluated for vasodilator effects in isolated and perfused mesenteric bed, but no vasodilator action was observed. For the valuation of the antioxidant potential, in the cardiac tissue the groups treated with the ESCC in the three doses (30, 100 and 300 mg / kg) presented significant differences in relation to the control group on activity of the superoxide dismutase (SOD).