Valorization of Aronia melanocarpa Pomace: A Sustainable Source of Bioactive Compounds for Developing Colored Healthcare Textiles, Biomedical Hydrogels, and Green Corrosion Inhibitor

Characterization of the antioxidant activity, identified free radical-relieving components by LC/QTOF/MS and acute oral toxicity studies of Tri-Tharn-Thip tea

With growing global awareness and concern for environmental protection through the use of less hazardous and environmentally-friendly extracts of plant origin, there has been a plethora of green corrosion inhibitors research with far reaching contributions to the science of corrosion prevention and control. Attention has increasingly turned towards green corrosion inhibitors, compounds of natural origin with anti-oxidant activity towards metals and their alloys. Green inhibitors have been investigated for their corrosion and adsorption properties with good results. The findings from these research works provide evidence of the adsorption behavior of green inhibitors which was confirmed by the adsorption isotherms that were proposed. Adsorption is the first step of any surface reaction and since corrosion is a surface phenomenon the effectiveness of green corrosion inhibitors is related to their ability to adsorb on metal surfaces. This review proposes the potential of plant dna as an emerging and promising novel inhibitor for mild steel. It begins with a list of plants that have been used in studies to determine corrosion inhibition properties and moves on to establish the adsorption behavior of bio macromolecules; protein, polysaccharides (chitosan) and dna. It reviews studies and investigation of dna interaction and adsorption on inorganic surfaces before focusing on the use of salmon (fish) sperm dna and calf thymus gland dna as green corrosion inhibitors for mild steel. It concludes that plant dna is a promising candidate for green corrosion inhibitor given the similarity between the plant and animal dna structure and function, and the fact that the use of plant is more environmentally sustainable than animal-based product.

Aims: The membrane associated tyrosinase is an enzymatically active monomeric glycoprotein which is purified to only a low degree. It has gained importance in the present era due to its antioxidant and immunomodulatory properties as well as applications in industry. Moreover its role in the synthesis of melanin in skin for protection from UV radiations also paved the way towards the better understanding of this enzyme.
 Study Design: Biochemical and molecular characterization of tyrosinase producing soil bacterium had been followed by the assessment of its antioxidant, cytotoxic and anti-cancer activities.
 Place and Duration of Study: Whole work had been completed at the Microbiology and Molecular biology labs of IMBB during 2018- 2019.
 Methodology: Tyrosinase producing species were identified by biochemical characterization followed by their genomic DNA sequencing and BLAST analysis while crude tyrosinase was characterized by Bradford's methods, tyrosinase activity and total protein activity, followed by their molecular characterization on SDS-PAGE. The antioxidant and free radical scavenging properties of tyrosinase were evaluated via DPPH, ABTS and FRAP assays and cell proliferation inhibition and the cytotoxicity was calculated via antitumor and MTT assays.
 Results: P. putida, B. cereus, B. mycoides, M. luteus, K. pneumonia were found to be tyrosinase producing species while their SDS-PAGE analysis showed that the molecular mass of crude tyrosinase was about 39 kDa. Protein contents, total tyrosinase and specific tyrosinase activity was found to be highest in tyrosinase from B. mycoides [0.008±0.06 mg/ml, 1500±0.06 U/ml and 346820.8±0.03 U/mg of tyrosinase respectively]. The results of biological activities of crude tyrosinase vary from bacteria to bacteria. Tyrosinase from P. putida showed higher antioxidant [66.4±0.01% in DPPH assay, 32.04±0.06%in ABTS assay and 320.6±0.06 in FRAP assay], antitumor [67.8±0.01%] and cytotoxic activity [39±1.0% cell viability], followed by B. Cereus tyrosinase [64.7±0.06% antioxidant power in DPPH assay, 53.41±0.03% in ABTS assay and 159.6±0.06% in FRAP assay, 46.46±0.01% antitumor and 43±0.75% cell viability].
 Conclusion: The study revealed that tyrosinase isolated from different bacterial strains depicted optimal percentage of anti-oxidative, anti-proliferative and cellular viability and can be used in the near future for medical and industrial purposes.

In this research work, a series of heterocyclic Schiff base compounds bearing arylsulfonyl ester moiety (2a-i) were designed, synthesized, characterized by spectral techniques such as 1D NMR (1H and 13C), 2D NMR (COSY and HMQC), and FT-IR; and then examined their antioxidant activity was by using four different methods as DPPH, ABTS, CUPRAC, and β-carotenelinoleic acid assays. According to the results obtained, it determined that all synthesized molecules had antioxidant activity. In the DPPH assay, it was found that compound 2e (IC50: 96.23±0.02 μM/mL) demonstrated the antioxidant activity among all synthesized molecules. In ABTS assay, compounds 2e (IC50: 41.88±0.21 μM/mL) and 2g (IC50: 50.75±0.32 μM/mL) were determined to be the molecules with the activity, respectively. Compound 2e (IC50:73.49±0.00 μM/mL) indicated the best antioxidant activity in the CUPRAC assay compared to other synthesize molecules. In the β-carotene-linoleic acid assay, compound 2e (IC50: 58.79±0.58 μM/mL) displayed antioxidant activity than all other synthesized molecules. Compounds 2d (IC50: 74.17±0.22 μM/mL) and 2g (IC50: 66.06±0.13 μM/mL) indicated higher antioxidant activity than the remaining molecules in this series, except for compound 2e. In conclusion, it is thought that this study will contribute to the ongoing studies on the design and synthesis of new antioxidant agents.

In brewing coffee, a huge amount of food waste is generated; that waste, coffee husks in particular, should be comprehensively exploited. They offer a rich source of bioactive compounds such as caffeine, chlorogenic acid, and trigonelline. The aim of this study was to investigate the effects of extraction methods on the bioactive compounds and antioxidant activity of such waste. Coffee husks in this study were fermented with S. cerevisiae based on a solid-state fermentation technique. The study method included ethanolic or water extraction with varied controllable factors, i.e., temperature (60, 100°C) and extraction technique. Bioactive contents were investigated with the Folin-Ciocalteu assay and 1H-NMR spectroscopy. The antioxidant activity was investigated with DPPH and FRAP assays. Results show that yields were the highest in the extract of fermented coffee husks at 100°C. The highest levels of bioactive contents (total trigonelline content at 3.59% and antioxidant activity at 23.35% (DPPH) and 25.9% (FRAP)) were found in the ethanolic extract of fermented coffee husks at 60°C. The bioactive content and bioactivity, including antioxidant activity, depended on different raw materials, preparation methods, and extraction conditions. This study illustrates the potential for using food waste such as coffee husks as a sustainable source of bioactive compounds or bioactive extracts.

Influence of roasting on the antioxidant activity of small black soybean ( Glycine max L. Merrill)

Phenolic compounds play a very important role in human life because of their antioxidant activity which can prevent harmful diseases caused by free radicals. In the present work, we have synthesized some Schiff bases by the reaction of different hydroxybenzaldehydes and primary aromatic diamines using Stannous Chloride ( $$\hbox {SnCl}_{2}{\cdot }2\hbox {H}_{2}\hbox {O}$$ ) as the catalyst. The products were characterized by FT-IR spectroscopy, GCMS and NMR spectroscopy. Furthermore, the antioxidant activity of the Schiff bases were determined by using DPPH assay and ABTS assay and the results were compared with a standard compound, trolox as well as with the parent aldehydes. The synthesized compounds were found to have better antioxidant activity than their corresponding parent aldehydes. Phenolic Schiff bases were synthesized by the reaction of different hydroxybenzaldehydes and primary aromatic diamines using $$\hbox {SnCl}_{2}\cdot 2\hbox {H}_{2}\hbox {O}$$ as the catalyst and dichloromethane as the solvent. Antioxidant activity of the synthesized compounds were determined by DPPH assay and ABTS assay and results were compared to the parent aldehydes as well as Trolox.

Rhamnus formosana is a creeping evergreen shrub endemic to Taiwan. In traditional medicine, Rhamnaceae plants are used as herbal remedies for conditions such as itching, difficulty urinating, and constipation. This study explores the inhibitory effects of various solvent extracts and bioactive components of R. formosana on α-glucosidase, tyrosinase, acetylcholinesterase (AChE), and antioxidant activity. The 100 °C water extract exhibited strong antioxidant activity in DPPH, ABTS, superoxide, and FRAP assays. The methanol extract demonstrated the highest α-glucosidase inhibitory effect, while the ethanol extract displayed potent AChE inhibition and the acetone extract showed the most potential tyrosinase inhibitory activity among the extracts. Five main biocomponents were isolated and evaluated for their bioactivities. Among them, kaempferol (1) and quercetin (2) exhibited notable antioxidant activity in DPPH and ABTS assays. Particularly, kaempferol (1) performed the best α-glucosidase inhibitory effect, physcion (5) showed the strongest AChE inhibition, and quercetin (2) demonstrated the most potential for tyrosinase inhibitory activity. Further molecular docking studies revealed that there may be stronger binding mechanisms between bioactive components and target enzymes (including α-glucosidase, acetylcholinesterase, and tyrosinase) than the positive control. These findings suggest that bioactive extracts and compounds from the stems of R. formosana may have potential as natural antioxidant, anti-α-glucosidase, anti-AChE, and anti-tyrosinase drug candidates or dietary supplements for the management of oxidative stress-related conditions, including hyperglycemia, pigmentation disorders, and neurodegenerative diseases.

Antioxidants play a crucial role in preventing and treating non-communicable diseases (NCDs) by scavenging free radicals. Medicinal herbs, used for centuries in traditional healthcare systems, have been gaining attention recently due to the negative effects of synthetic medicines. This study assessed the total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity of aqueous extracts from eleven commonly used Sri Lankan Ayurvedic plants and determined the relationship between their phenolic and flavonoid content with antioxidant activities. TPC and TFC were measured using the Folin-Ciocalteu and Aluminum chloride methods, respectively. Antioxidant activity was evaluated using ABTS, FRAP, and DPPH assays. Pearson correlation analysis assessed the relationship between TPC and TFC with antioxidant activity. Phyllanthus emblica (PE) showed the highest TPC, TFC, and antioxidant activity (p≤0.05) significantly. TPC and TFC exhibited significantly positive correlations with FRAP and ABTS assays while the DPPH assay showed a negative correlation. Phenols and flavonoids in the selected extracts may significantly contribute to the antioxidant activity measured by ABTS and FRAP assays, while other secondary metabolites and their synergism effect may influence the DPPH assay. The significant antioxidant properties of PE, highlight its potential to treat various NCDs. Further studies are essential to determine their bioactivities, effective doses, and toxicity levels.

Alzheimer’s disease (AD) is a neurodegenerative disorder, which is the most common cause of dementia. This disease commonly occurs in elderly people. The increase in life expectancy means that that the number of people suffering from AD is expected to rise each year if there is no effective treatment found. The relation of cholinesterase and oxidative stress to Alzheimer’s disease has been reported. In our previous study, we have investigated the potency of the ethanolic extract of Cassia moschata leaves as an anticholinesterase. The current study aimed to investigate the antioxidant and anticholinesterase properties of the ethanolic and aqueous extracts of C. moschata as well as to determine the total phenolic content (TPC). Two different methods were used to evaluate the antioxidant activity by 2,2-diphenyl-1-picryl hydrazyl (DPPH) and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays. The anticholinesterase assay was carried out against acetylcholinesterase (AChE) according to the modified Ellman’s method. The TPC was determined by a colorimetric method using Folin-Ciocalteu’s phenol reagent, and employing gallic acid as a reference. The ethanolic and aqueous extracts of C. moschata demonstrated antioxidant activity in both DPPH and ABTS assays. There were statistically significant differences in the IC50 values of the ethanolic and aqueous extracts in both DPPH and ABTS assays. The aqueous extract exhibited a lower IC50 value compared to the ethanolic extract. The IC50 value for the aqueous extract was 36.46 µg/mL in the DPPH assay, and 10.61 µg/mL in the ABTS method compared to IC50 38.74 µg/mL and 17.17 µg/mL for the ethanolic extract, respectively. Meanwhile, the ethanolic extract showed higher potency as anticholinesterase with the IC50 value of 44.43 µg/mL compared to the aqueous extract with an IC50 value of 114.60 µg/mL. The TPC measurement revealed that the aqueous extract has a higher amount of phenolic than the ethanolic extract. These data suggest that the aqueous extract from the leaves of C. moschata has a higher ability to scavenge free radicals compared to the ethanolic extract, which also contains a higher amount of phenolic compounds. However, the high content of phenolic compounds in the aqueous extract did not correspond to the anticholinesterase activity. The presence of non-phenolic compounds may also contribute to the anticholinesterase activity in the ethanolic extract.

Erythrina crista-galli is a plant species among the genus Erythrina known for their wide range if phytochemicals, particularly alkaloids and flavonoids. These phytochemicals may play potential role as antioxidant and anti-cholinesterase agents for Alzheimer’s Disease (AD) treatments. This study aimed to study the metabolite profile, antioxidant and anticholinesterase activity of E. crista-galli flower through in vitro and in silico studies. Metabolite profiling was conducted using UPLC-MS/MS analysis, the antioxidant activity was evaluated using DPPH, ABTS, and FRAP assay, while anticholinesterase activity was evaluated using acetylcholinesterase (AChE) activity colorimetric assay, and in silico studies were conducted using both molecular docking and molecular dynamics simulation. The methanol extract from E. crista-galli flowers was evaluated for antioxidant activity using the DPPH, ABTS and FRAP assay, showing moderate free radical scavenging activity with IC 50 of 153.6 ± 2.4 μg/ml in DPPH and 255.7 ± 14.9 μg/ml in ABTS assay, while 25.4 ± 1.8 mgQE/g extract in FRAP assay. The methanol extract inhibited 17.65 ± 1.28% of the AChE activity in the concentration of 50 μg/ml. Metabolite profiling via LC-MS/MS analysis revealed the presence of 16 erythrina alkaloids and 5 flavonoids in the methanol extract of E. crista-galli flower. Molecular docking and molecular dynamics simulations demonstrated the potency of these secondary metabolites, particularly vicenin-2 and vitexin as AChE inhibitors. This study highlights the role of E. crista-galli flowers as natural source of phytochemicals particularly alkaloids and flavonoids with potential antioxidant and anti-cholinesterase activity.

Numerous assays were developed to measure the antioxidant activity, but each has limitations and the results obtained by different methods are not always comparable. Popular examples are the DPPH and ABTS assay. Our aim was to study similarities and differences of these two assay regarding the measured antioxidant potentials of 24 phenolic compounds using the same measurement and evaluation methods. This should allow conclusions to be drawn as to whether one of the assays is more suitable for measuring specific subgroups like phenolic acids, flavonols, flavanones, dihydrochalcones or flavanols. The assays showed common trends for the mean values of most of the subgroups. Some dihydrochalcones and flavanones did not react with the DPPH radical in contrast to the ABTS radical, leading to significant differences. Therefore, to determine the antioxidant potential of dihydrochalcone or flavanone-rich extracts, the ABTS assay should be preferred. We found that the results of the flavonoids in the DPPH assay were dependent on the Bors criteria, whereas the structure–activity relationship in the ABTS assay was not clear. For the phenolic acids, the results in the ABTS assay were only high for pyrogallol structures, while the DPPH assay was mainly determined by the number of OH groups.

Phytochemical analysis and antioxidant activity of Alstonia scholaris

Different solvent extracts of leaves and bark of Mitragyna rotundifolia (Roxb.) Kuntze were evaluated by DPPH, ABTS, and FRAP assays, respectively, for antioxidant properties. Total phenolic and flavonoid content was determined as pyrocatechol and rutin equivalents, respectively, and correlated with antioxidant activities. More polar solvent extracts (n-butanol and ethyl acetate) had relatively higher antioxidant activity than nonpolar solvent extracts (petroleum ether). The n-butanol extract also exhibited a higher phenolic and flavonoid content than the other solvent extracts did. The DPPH assay was highly correlated with the ABTS assay (R2 = 0.9628, P < 0.0001). Two phenolic and four flavonoid compounds were isolated from the ethyl acetate leaf extracts. Compounds 3–6 were isolated for the first time from the genus of Mitragyna and compound 5 showed the highest antioxidant activity.

Antioxidant activities of mangrove Rhizophora apiculata bark extracts