Frutas tropicais do Nordeste Brasileiro: estudo fitoquímico, potencial antioxidante e composição mineral

Abstract

Brazil has great importance in the fruits market, however, data about the composition of Brazilian tropical fruits, mainly of those produced on Northeast, is scarce. This work reports the investigation of mineral content and antioxidant potential of eleven tropical fruits cultivated in the Northeast of Brazil: Ananas comosus (L.) Merr. (pineapple), Annona muricata L. (soursop), Annona squamosa L. (sweetsop), Artocarpus integrifolia L. (jackfruit), Byrsonima crassifolia (L.) Kunth. (murici), Carica papaya L. (papaya), Hancornia speciosa Gomes (mangaba), Manilkara zapota (L.) P. Royen (sapodilla), Spondias purpurea L. (ciruela), Spondias tuberosa Arruda Camara (umbu) and Tamarindus indica L. (tamarind). The species M zapota, S. tuberosa and B. crassifolia were selected to conduct a phytochemical study focusing on the isolation and characterization of special metabolites, as well as the analysis of the profile of fatty acids. The following substances were isolated from the fresh pulp of M zapota: triterpenes (3-0-acetyl-a-amyrin and 3-0-acetyl-P-amyrin, 3-0- acetyllupeol, 3 -0-hexanoyl-a-amyrin and 3 - 0-hexanoyl-P-amyrin, 313 -hydroxyurs-12-ene and 313-hydroxyolean-12-ene), carbohydrate (D-glucose), cyclitol (proto-quercitol) and a polymer [poly(1,4-trans-isoprene)]. The constituents obtained from S. tuberosa were: a steroid (13- sitosterol), a carbohydrate (D-glucose) and a mixture of fatty acids (hexadecanoic and heneicosenoic acids). The special metabolites isolated from B. crassifolia were: a binary mixture of triterpenes (3 p-hydroxyurs-12-en-28-oic acid and 313 -hydroxyolean-12-en-28-oic acid) and a flavonoid (3,5,7,3',4'-pentahydroxyflavone). The study of the composition of fatty acids contained in the pulps of S. tuberosa and B. crassifolia revealed the presence of similar major constituents: palmitic and oleic acids. The main compounds identificated in the pulp of M zapota were palmitic, estearic and oleic acids. The investigation of lipids contained in seeds indicated oleic acid as the major substance in M zapota and S. tuberosa, while in B. crassifolia the main detected constituent was the linoleic acid. The evaluation of antioxidant activity and its correlation with phenolics, vitamin C and anthocyanins contents was studied in vitro, using both antioxidant systems DPPH and ABTS. The results reveal that, overall, the consumption of tropical fruits from the Northeast of Brazil may deliver great health benefits by supplying natural antioxidants, standing out mainly the fruits mangaba (Hancornia speciosa) and murici (Byrsonima crassifolia). Phenolics content showed positive correlations with the investigated antioxidant capacity. However, this correlation was not observed when examining vitamin C and anthocyanins contents. Additionally, the macro- and micro-minerals of the eleven tropical fruits studied were detennined. The minerals Ca, Mg, Mn, Zn, Fe, Co, Se and Ni were analyzed by atomic absorption spectrophotometry, Na and K by flame photometry and P by the colorimetric method. The results indicated that tamarind is a rich source of all minerals available, being excellent source of Mg, Cu and K, in addition to good source of Ca, P, Fe and Se. Among the minerals evaluated in the studied fruits, K presented the highest content, followed by Ca and Mg. Sweetsop, soursop, sapodilla and murici are good sources of two or more of these minerals. Therefore, the consumption of the studied tropical fruits is suggested as an assistant on the reposition of mineral nutrients.