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The DNSA assay has been widely employed for the in vitro detection and quantification of alpha-amylase inhibitory activity. However, the conventional method is associated with inconsistencies between protocols and requires a large volume of samples and other assay reagents that can compromise accurate quantitation. Therefore, the study aimed to develop a reliable, simple, and rapid analytical method for determining a-amylase activity. The developed method was carried out in 96-well microplates with a total volume of 250 µL and a total assay time of 1 hr, including pre-incubation. The method was validated for linearity, the limit of detection (LOD), the limit of quantitation (LOQ), and precision. A higher coefficient of determination (R²) value was observed for the developed method as compared to the conventional method (0.9983 ± 0.0003 vs 0.9667 ± 0.0383). The coefficient of variation (CV%) of each data point was less than 15%, indicating excellent data precision. The optimum assay conditions were identified at 2 U/mL of enzyme solution and 5% (w/v) starch solution at 50 °C incubation temperature with an IC50 value of 0.026 ± 0.005 mg/mL. It is concluded that the developed method is practical, precise, and accurate for estimating a-amylase inhibitory activity and would provide reproducible results. [ABSTRACT FROM AUTHOR]

Melanin is a protective pigment against cellular damage and skin cancer. Peltophorum pterocarpum has been used for centuries to treat skin diseases like eczema and psoriasis. However, whether P. pterocarpum leaf extract can affect melanin synthesis with the advantage of antioxidant defense against ultraviolet (UV) radiation remains to be investigated. We aimed to examine the melanogenesis, cytotoxicity, and antioxidant activities of P. pterocarpum leaf extracts. A two-dimensional (2D) cell culture model was employed to demonstrate the effect of P. pterocarpum extracts on melanin synthesis. The cell viability of B16-F1 melanoma cells was measured by Neutral Red Uptake (NRU) assay. Antioxidant activity was accessed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA) assays. The ethanol extract of P. pterocarpum dosedependently increased the melanin content and displayed cytotoxicity to B16-F1 melanoma cells at the highest concentration. In contrast, the equal amounts of the aqueous extract significantly inhibited melanin synthesis and did not show any cytotoxic effects on B16-F1 melanoma cells. The P. pterocarpum ethanol extract had a significantly higher total phenolic and flavonoid content than the aqueous extract and was more effective at scavenging DPPH free radicals and intracellular ROS induced by UVB, with IC50 of 519.24 ± 122.57 vs 1798.45 ± 143.09 μg/mL and 878.00 ± 23.50 vs 1379.00 ± 21.81 μg/mL, respectively. These findings suggest that the pro-melanogenic and anti-melanogenic activities of P. pterocarpum extract with antioxidant capacity against UVB-induced cellular damage are affected by the total phenolic and flavonoid contents. [ABSTRACT FROM AUTHOR]

Background: Ficus deltoidea (Ficus: Moraceae) has great potential as a functional food. Administration of F. deltoidea has been reported to reduce hyperglycemia, oxidative stress and increase insulin secretion in diabetic rats and humans. However, the poor bioavailability and intestinal absorption of F. deltoidea impede its therapeutic effectiveness at a lower dosage, thus integrating F. deltoidea into brown rice will provide additional advantages. This study aimed to examine the phyto-physicochemical profile, antioxidant properties, consumer acceptance, and safety of beverages formulated from fine powder mixtures of F. deltoidea leaves and brown rice. Methods: The new beverage formulations were prepared by mixing the fine powders of F. deltoidea leaves with brown rice at ratios of 1:6 and 1:13, respectively. Physicochemical, phytochemical, and antioxidant analyses were performed to characterize the prepared beverages. Consumer acceptance was assessed utilising a 9-point hedonic scale and an acute toxicity study was employed to determine the safety of F. deltoidea-added formulations. Results: F. deltoidea decreased the pH and increased the moisture content, ash, and viscosity of a brown rice beverage. The total phenolic, flavonoid, and tannin content as well as antioxidant activities increased significantly in both F. deltoidea-added formulations. The oral LD50 of the F. deltoidea-added formulation was higher than 2000 mg/kg body weight. Conclusions: These results suggest that adding F. deltoidea leaves to brown rice beverages is safe to consume and improves the phyto-physicochemical profile, antioxidant activities, and consumers' acceptance of the formulation. [ABSTRACT FROM AUTHOR]