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Abstract Croton argyrophylloides Muell. Arg., from the Euphorbiaceae family, popularly known as marmeleiro prateado or sacatinga, is a plant from the Caatinga biome commonly found in Brazil’s northeastern region. The present study aimed to evaluate the antioxidant activity of the species. The phytochemical study was performed through qualitative analysis of chemical constituents and quantitative determination of the total phenol content through the Folin-Ciocalteu test. The qualitative and quantitative antioxidant tests were performed using the DPPH method (2.2 diphenyl-1-picryl hydrazil) and ferric reducing antioxidant power (FRAP). The minimum inhibitory concentration (MIC) was determined by microdilution in 96-well plates. The ethanolic extract of the leaves of C. argyrophylloides manifested antioxidant action in the quantitative DPPH test with a significant bioactivity of 84.70 AAO% in 500 µg/mL, with an EC50 of 236.79. The content of total phenolic compounds was 946.06 mg of gallic acid equivalents/g of sample, and total flavonoids was 58.11 mg of quercetin equivalents/g of sample, the result obtained for FRAP was 15294.44 µM Trolox/g of sample and ABTS was 718 μM Trolox of sample. The prospecting of the chemical constituents of the leaves of C. argyrophylloides revealed the presence of the main compounds that manifests the antioxidant activity and it was proven by the DPPH method that there is antioxidant activity in the analyzed sample, in addition to demonstrating a significant content of phenolic compounds and total flavonoid content in the species, which corroborates the antioxidant activity of the plant sample. The leaf extracts presented growth inhibition halos of 10 and 12 mm upon Staphylococcus aureus ATCC 25923.

Since their discovery in 2004, carbon dots have attracted strong interest in the scientific community due to their characteristic properties, particularly their luminescence and their ease of synthesis and derivatization. Carbon dots can be obtained from different carbon sources, including natural products, resulting in a so-called ’green synthesis’. In this work, we obtain carbon dots from tomato juice in order to obtain nanoparticles with the antioxidant capabilities of the natural antioxidants present in that fruit. The obtained material is characterized regarding nanoparticle size distribution, morphology, surface functional groups and optic properties. Antioxidant properties are also evaluated through the DPPH method and their cytotoxicity is checked against human dermal fibroblast and A549 cell-lines. The results indicate that carbon dots obtained from tomato have a higher antioxidant power than other already-published antioxidant carbon dots. The bandgap of the synthesized materials was also estimated and coherent with the literature values. Moreover, carbon dots obtained from tomato juice are barely toxic for healthy cells up to 72 h, while they induce a certain cytotoxicity in A549 lung carcinoma cells.

Free radicals are constantly produced by either cell metabolism or from external sources. At high concentration, they induced a tissue damage called oxidative stress. Soursop leaf (Annona muricata L.) and noni leaf (Morinda citrifolia L.) are medicinal plants with potency as antioxidants. This study aimed to evaluate the capacity of Lactobacillus plantarum BP102 in elevating the antioxidant activity of soursop and noni leaves. Dried-powder and methanol extract of soursop and noni leaves were diluted with sterile distilled water 3 g/30 mL and 0.3 g/30 mL, respectively, inoculated with 1% (v/v) of L. plantarum BP102 inoculum. The antioxidant activity was carried out using the 2.2-diphenyl-1-picrylhydrazyl (DPPH) method. The antioxidant activity increased in dried-powder and methanol extract of soursop and noni leaves with different activity levels after being fermented using L. plantarum BP102 based on IC50. The increasing antioxidant activity in dried-powder of soursop leaves IC50 6.41±0.06 to 0.034±0.01 mg/mL (99.5%) was higher than of the methanol extract IC50 2.78±0.00 to 0.11±0.01 mg/mL (96%). Unfortunately, the effect of fermentation towards noni leaves could only be observed in the form of methanol extract IC50 12.8±0.01 to 0.33±0.02 mg/mL (increased by 97.4%), the dried-powder of noni leaves was suspended and produced a dark color. The probiotic L. plantarum BP102 was used as a fermented agent in increasing the bioactive compounds especially related to antioxidant activity.

Tamarillo (Solanum betaceum Cav.) is a plant that is spread in Java, Bali and North Sumatra, which is rich in nutrients and contain flavonoid as antioxidants that can prevent cell damage due to oxidative stress. Clay-based face masks have a firming and cleansing effect on the skin. Tamarillo was extracted by maceration method using 96% ethanol extract, phytochemical screening was carried out. Clay mask formulation with extract concentration of 1.5%, 2%, 2.5% and blanks. Physical quality test of clay mask preparations included homogeneity test, stability test, pH test, dry time test, irritation test, effectiveness test of clay mask preparation on volunteers using the Skin Analyzer Checkher (Aram), preference test and antioxidant test using the DPPH method. The results showed that the ethanol extract tamarillo contained alkaloids, flavonoids, saponins and could be formulated into a clay mask preparation that was homogeneous, stable, met the pH requirements, and dried time. The results of the effectiveness test using a checkher skin analyzer give the effect of reducing blemishes, reducing pores, moisturizing, not causing irritation to the skin. The antioxidant activity of the ethanol extract tamarillo were in the moderate category with an IC50 value of 201 g/mL and the clay mask preparation of the ethanol extract tamarillo with a concentration of 2.5% was in the medium category with an IC50 value of 221 g/mL.

Abstract Plants possess a renewable source of metabolites with enormous chemical structural diversity, which may have potential therapeutic relevance. Furthermore, this chemical diversity favors the possibility of finding new and different chemical constituents with antimicrobial, antioxidant and anti-tumor activities. This work analyzed preliminary phytochemical profiles and evaluated the antimicrobial, antioxidant and cytotoxic activities of hexane extracts of leaves of ten species of the family Melastomataceae. Phytochemical screening was performed using staining methods while total phenols and flavonoids were quantified by spectrophotometry. Antimicrobial activity was evaluated using the disk diffusion method. Antioxidant activity was determined by the 2,2-diphenyl-1-picrylhydrazil (DPPH) method. Toxicity was recorded using the lethality test with Artemia salina Leach (1819). Cytotoxic activity of the extracts was assessed in vitro with acute monocytic leukemia cells (THP-1). Phytochemical analysis detected the presence of tannins, terpenes, steroids, polyphenols and flavonoids and the absence of alkaloids. Clidemia capitellata (Bonpl.) D. Don had the greatest amount of polyphenols (205.95 mg/g ± 4.14) while Clidemia hirta (L.) D. Don had the highest content of total flavonoids (143.99 mg/g ± 4.18). The hexane extracts did not show antimicrobial activity nor toxicity against Artemia salina. The extract of Tibouchina francavillana Cogn. was the most active in sequestering the DPPH radical. The extracts showed cytotoxicity in THP-1 cells with the appearance of apoptotic bodies and cell death. The extracts of Miconia amoena, Clidemia sericea and Clidemia capitellata are non-toxic against Artemia salina and induce the formation of apoptotic bodies and cell death of the THP-1 lineage.

  This scientific work was aimed to evaluate the antioxidant potential of aromatic plants of Thymus spp. in the East of Ukraine. These plants are known as medicinal and food around the world. All antioxidant parameters were investigated spectrophotometrically: total content of polyphenols (TPC), the total content of phenolic acids (TPAC), the total content of flavonoids (TFC), molybdenum reducing power of extracts (MRP), and antioxidant activity by DPPH method (DPPH). Investigation of ethanolic extracts demonstrated that TPC varied from 57.89 to 123.67 mg/g gallic acid equivalent (GAE) DW for Th. pulegioides, from 61.43 to 168.18 mg GAE/g for Th. serpyllum, and from 47.36 to 115.67 mg GAE/g for Th. vulgaris. TPAC ranged from 27.36 to 50.22 mg/g caffeic acid equivalent (CAE) DW for Th. pulegioides, from 28.58 to 59.62 mg CAE/g for Th. serpyllum, and from 22.95 to 53.82 mg CAE/g for Th. vulgaris. TFC was determined in a range from 29.88 to 61.23 mg/g quercetin equivalent (QE) DW for Th. pulegioides, from 36.0 to 82.43 mg QE/g for Th. serpyllum, and from 24.59 to 55.41 mg QE/g for Th. vulgaris. MRP was detected in the range of 94.65 – 204.76 mg/g Trolox equivalent (TE) DW for Th. pulegioides, 96.06 – 219.0 mg TE/g for Th. serpyllum, and 87.56 – 215.43 mg TE/g for Th. vulgaris. The antioxidant activity of extracts by the DPPH method was 6.34 – 9.23 mg TE/g for Th. pulegioides, 8.11 – 9.21 mg TE/g for Th. serpyllum, and 4.97 – 9.53 mg TE/g for Th. vulgaris. It was established that polyphenol accumulation depended on the growth stage and species. For all species was found a strong correlation between TPC and TFC (r = 0.938, 0.908, and 0.854). Investigated Thymus spp. are a valuable source of antioxidants that can be used in pharmacological studies and the food industry.

Senggani fruit (Melastoma Malabathricum L.) contains anthocyanin that functioning as an antioxidant. Anthocyanin are tremendously sensitive to thermal processes which trigger phytochemical or photo-oxidation reactions that can open anthocyanin rings. The objective of this study is to identify the effect of the simplicia drying method on the antioxidant activity of Senggani fruit extract. Senggani fruit extract was prepared by obtaining samples of ripe fruit, dry sorting, washing, wet sorting, and drying using two methods; sunlight and oven at 70oC. After the simplicia was dry, it was blended and sifted until smooth. The fine simplicia was macerated with 96% ethanol and evaporated to gain a crude extract. The crude extract was assessed with reagents for phytochemical screening. Furthermore, the crude extract was examined for antioxidant activity by the DPPH method. This study implies that the simplicia and crude extract of Senggani fruit from drying in sunlight and oven possess different organoleptic properties such as color, smell, and taste. In phytochemical testing with reagents, it was discovered that anthocyanin compounds were unveiled in drying utilizing sunlight while employing an oven at 70oC; no anthocyanins were found. The antioxidant testing of Senggani fruit extract revealed that the drying method employing sunlight had an IC50 value of 18.8 g/mL while the oven temperature of 70oC owned an IC50 value of 28.3 g/mL. Based on the study results, it can be identified that the simplicia drying method affects the antioxidant activity of the Senggani fruit extract. The drying method in the sun produces extracts with greater antioxidant activity while drying in an oven at 70oC results in a degradation process of anthocyanin compounds, thereby decreasing the antioxidant activity of the Senggani fruit extract.  

Isolation and characterization of quercetin flavonoid compound from Dutungan Island, South Sulawesi Province, Indonesia has been successfully done from ethyl acetate extract. Extraction method used maceration, isolation used chromatography, anticancer activity with MTT method and antioxidant test used DPPH radical. Structure was discussed with the FT-IR, NMR spectrophotometer and compared with the literature. Total flavonoids from ethyl acetate extract were 4.8 mgEQ/g, IC50 value of antioxidant activity was 4.23 μg/ml using the DPPH method (2,2-diphenyl-1-picrylhydrazyl), and anticancer activity of H460 cells IC50 value was 10.95 μg/ml. The quercetin compound is potential as an anticancer and was first report in the T. decurrens Bory species.

Dayak onions (Eleutherine palmifolia L. Merr) is one plant that has been proven to have benefits as an antioxidant. The Dayak extract is formulated in the self nano emulsifying drug delivery system (SNEDDS) because the extract has low water solubility. The aims this study to develop the SNEDDS formulation system by testing its antioxidant activity. We determined whether there was an increase in antioxidant activity when formulated in the form of SNEDDS or not. The results were then compared with a solution of Dayak onions extract without using SNEDDS. The obtained formula was the optimal result that has been done before using the D-optimal mixture design method. The results of the components consisted of 50 mg of Dayak extract, 10 % caprylic triglyceride as oil, 1% tween 80, and 6,60 % transcutol as a combination surfactant and 12,40 % propylene glycol as co-surfactant. Antioxidant activity testing was carried out using the DPPH (1,1-Diphenyl-2-picrylhydrazyl) method. The antioxidant test using the DPPH method was done with two samples, namely the extract solution and Dayak onion extract SNEDDS. We elaborated the research by using UV-VIS spectrophotometer. Each sample was made into five concentrations, namely 30 ppm, 60 ppm, 90 ppm, 120 ppm, and 150 ppm, and carried out three times replications. The results showed that the IC50 value in the Dayak onion extract solution was 227,19 ppm (very low), while for the SNEDDS solution for the Dayak onion extract the IC50 value obtained was 38,97 ppm (very strong). The analysis was carried out next using an independent T-Test to obtain the results. There was no significant difference between the extract solution and the SNEDDS solution of Dayak onion extract.