Produção de biomassa e atividade antioxidante e antitumoral de Hibiscus sabdariffa L. cultivada com adubação orgânica

Abstract

Roselle (Hibiscus sabdariffa L., Malvaceae) is a medicinal plant with several uses and benefits, grown in different regions of the world, the stem is a source of fibers for textile and paper industry and calyxes are rich in substances with antioxidant activity and antitumor. The aim of this work was to evaluate the effect of poultry litter and organosuper® under three application modes in the biomass production and nutrient content in leaves, phenol and flavonoids content, antioxidant and antitumor activity of nine human cell lines in the methanol extract of leaves and calyxes. To this end, two experiments were performed with roselle: one in the agricultural year of 2008/2009 and another in 2009/2010. Treatments in each crop cycle were arranged in a factorial 2 x 3+1, being composed of combinations of two organic compounds poultry litter (10 t ha-1) and organosuper® (10 t ha-1) and three application modes (surface, incorporated and surface + incorporated) plus the control, in randomized block design with four replicates. The fresh and dry weight production of the leaves, stems, roots and calyxes, number of calyxes, leaf area and percentage of crude fiber in the stems, nitrogen, phosphorus, potassium, calcium, magnesium, iron, copper, manganese and zinc concentrations, concentrations of phenol and flavonoids in methanol extract of leaves and calyces, antioxidant and anticancer property in methanol extract of leaves and calyces were determined. Higher productions of fresh and dry weight of calyx, leaves, stems and roots, calyxes number, leaf area and fibers in the agricultural year 2008/2009 obtained with the poultry litter. Application mode of organic waste was not statistically different for any of the characteristics evaluated in two agricultural years. Leaves Nutrients contents were not affected by organic waste or by application mode. The highest contents of phenol and flavonoids were observed in leaf extract and calyces of plants cultivated with organosuper® incorporated. The IC50 average demonstrated that leaves (43,48 μg mL-1) and calyces (37,15 μg mL-1) have substances that may contribute to free radical scavenging action, compared to positive control BHT (16.7 mg mL-1). Furthermore, the methanol extract of calyces showed significant selective activity for leukemia lineage (K-562), concentration dependent, cytotoxic and cytocide effects. Under the conditions of the experiment was conducted, it was concluded that to obtain higher yields of biomass plants should be grown rosella with poultry litter semidecomposta, independently of the application of the residue. The incorporated poultry litter semidecomposta and organosuper® provided the highest concentrations of phenols and flavonoids in methanolic extract of leaves and calyxes of rosella, as well as, enhance the activity of the methanol extract of calyxes of rosella for leukemic cell line (K -562), with IC50 values of 1.16 and 0.12 mg mL-1, respectively.