Phytochemical study, nutritional evaluation and in vitro antiobesity potential of fruits pericarp and seeds of Livistona carinensis and Thrinax parviflora

Abstract

Overweight is a significant health hazard. It increases the risk of development of various diseases. The nutritional value, phytochemical composition and in-vitro antiobesity potential of the seeds and fruits pericarp of Livistona carinensis (L. carinensis) and Thrinax parviflora (T. parviflora) were assessed. The phytochemical screening of both plants showed the presence of tannins, carbohydrates, sterols, flavonoids and anthraquinones. GLC (Gas liquid Chromatography) analysis of lipids allowed the identification of stigmasterol as the major phytosterol in seeds and pericarp of L. carinensis (9.01% and 10.81%), respectively while β-sitosterol is the major in seeds and pericarp of T. parviflora (13.79% and 9.19%), respectively. Palmitic acid was the major fatty acid methyl ester in the pericarp of L. carinensis (35.01%), followed by myristic acid in the pericarp of T. parviflora (20.68%). Concerning unsaturated fatty acids linoleic acid is the major in seeds of T. parviflora (53.93%) followed by seeds and pericarp of L. carinensis (18.49% and 11.10%), respectively, while oleic acid is the major in pericarp of T. parviflora. Quantitative estimation of constituents revealed that L. carinensis seeds showed the highest concentration of total polyphenolics (39.02±1.24 mg/g gallic acid equivalents), flavonoids (10.75±0.40 mg/g quercetin equivalent) and tannins (15.82±0.62 mg/g tannic acid equivalents). While the highest steroidal content is found in T. parviflora pericarp (11.51±0.44 mg/g β-sitosterol equivalent). Both plants pericarps possess higher content of carbohydrates than that of seeds while the protein content is higher in T. parviflora, pericarp and seeds than that of L. carinensis. Calcium and iron are found prominent in T. parviflora pericarp (6.47 and 2.07 mg/gm, respectively) while the highest concentration of potassium was found in L. carinensis pericarp (21.43 mg/gm). The free radicle scavenging activity using DPPH is found in the following order T. parviflora seeds (13.79 μg/ml) ˃ T. parviflora pericarp (9.72 μg/ml) ˃ L. carinensis pericarp (8.95 μg/ml) ˃ L. carinensis seeds (7.37 μg/ml) compared to ascorbic acid as standard (7.80 μg/ml). In addition, seeds and pericarp of L. carinensis showed the highest α-glucosidase inhibitory activity with IC50 values 0.93 and 1.17 mg/ml, respectively followed by the seeds and pericarp of T. parviflora (IC50 =1.46 and 1.76 mg/ml, respectively), compared to acarbose (IC50 = 0.72 mg/ml). Moreover, seed extracts of L. carinensis and T. parviflora showed powerful inhibitory activity against pancreatic lipase (IC50 = 10.95 and 9.33 μg/ml, respectively) compared to orlistat (6.82 μg/ml). In conclusion, seed extracts of L. carinensis and T. parviflora showed the most powerful α-glucosidase and lipase inhibitory activities, these recommend their incorporation in anti-obesity preparations. Their pericarps showed significant antioxidant activity with high calcium, iron and potassium contents in addition to their moderate α-glucosidase inhibitory activities which recommend their daily intake in weight control programs.