Investigating the influence of drying temperature on the flavonoid profile, quercetin content, and antioxidant activity in dayak onion

Effect of gamma irradiation treatment on the antioxidant activity, phenolic compounds and flavonoid content of common buckwheat

Dayak onion, prized for its phenolic compounds, flavonoids, and antioxidants, finds applications in medicine and as a functional food. However, improper drying techniques can lead to the degradation of these valuable compounds. This research investigates the phytochemical content, antioxidant activity, and functional groups of Dayak onion extracts processed through freeze-drying and oven-drying methods. Fresh Dayak onions underwent both drying procedures and were subsequently evaluated for phenolics, flavonoids, flavanols, and antioxidant activity. The findings revealed that freeze-dried extracts contained higher concentrations of these phytochemicals compared to their oven-dried counterparts. Fourier Transform Infrared (FTIR) spectroscopy analysis showed no notable differences in the primary functional groups (OH and CH) between the two drying techniques. The study concludes that higher drying temperatures diminish phytochemical content and antioxidant activity, although both freeze-drying and oven-drying maintain functional groups. These results have implications for sustainable agricultural practices, indicating that optimal drying methods can enhance the health benefits of this agricultural product, supporting its use as a natural antioxidant and antibacterial agent in food and medicine while promoting environmentally sustainable farming practices.

BACKGROUND: Peronema canescens (Sungkai) leaves have been popular in Indonesia which contain various bioactive compounds with empirical therapeutic efficacy in dealing with COVID-19 and various other diseases. Total phenolic and flavonoid content and antioxidant activity using the DPPH method from P. canescens leaf extract have not been studied much. AIM: This research has several objectives. The first is to compare the results of qualitative phytochemical analysis of the ethanol extract of the leaves of P. canescens (EEPL). The second is to measure the total phenol and flavonoid content. The third is to test the FTIR and antioxidant activity of the ethanol extract of P. canescens leaves in vitro using the DPPH method. METHODS: Fresh plant material and simplicia, ethanol extract extracted by maceration method using 96% ethanol as solvent from P. canescens. The Dragendorff’s and Mayer test carried out the qualitative phytochemical analysis, FeCl3 test, Salkowski method, Liebermann–Burchard method, foam test, and NaOH reagent. The total phenolic and flavonoid levels were tested using the Folin–Ciocalteu method. In vitro antioxidant activity was carried out using the DPPH (1,1-diphenyl-2-picrylhydrazyl) method. RESULTS: The results of qualitative phytochemical screening showed that alkaloids, flavonoids, saponins, tannins, and steroids were detected in the extract of P. canescens. The spectra from the FTIR test results showed various absorbance peak values indicating the bonding of specific functional groups, namely: 418.12, 599.94, 666.67, 1036.39, 1159.52, 1224.16, 1348.95, 1454.19, 1600.87, 1732.00, 2923.13, and 3353.01 cm-1. In the test results, total phenolic content was as much as 5.64% (mgEAG/g) and total flavonoid content of 142,247 mgEQ/g in a sample of 1 mg extract, which was equivalent to 1 mg quercetin. EEPL has antioxidant activity with the DPPH IC50 method of 116.7865 ppm. CONCLUSION: The data obtained at this time can contribute to the exploitation of P. canescens leaves in the future as one of the nutraceutical products, supplements, and herbal medicines by specific industries related to improving the health status of the world community. The higher the bioactive substance in preparation, the more significant the effect of the pharmacological efficacy response. P. canescens ethanol extract has good total phenolic content, total flavonoid content, and antioxidant action.

The fortification of foods with bioactive polyphenols aims to improve their functional properties and to provide health benefits. Yet, to exert their benefits, phenolic compounds must be released from the food matrix and absorbed by the small intestine after digestion, so assessing their bioaccessibility is crucial to determine their potential role. This work aims to incorporate Citrus reticulata Blanco peel extracts into wheat bread as a promising opportunity to increase their bioactive potential, along with supporting the sustainable management of citrus-industry waste. A control and a wheat bread enriched at 2% and 4% (w/v) with a phenolic extract from mandarin peels were prepared and analyzed for antioxidant activity and phenolic composition using LC-MS and UV-Vis spectrophotometry. In addition, in vitro digestion was performed, and the digested extracts were analyzed with HPLC-MS/MS. The results showed a significant increase in total flavonoid content (TFC, 2.2 ± 0.1 mg·g−1), antioxidant activity (IC50 = 37 ± 4 mg·g−1), and contents of quercetin, caffeic acid, and hesperidin in the 4% (w/v) enriched bread. Yet, most polyphenols were completely degraded after the in vitro digestion process, barring hesperidin (159 ± 36 μg·g−1), highlighting the contribution of citrus enrichment in the development of an enriched bread with antioxidant potential.

BACKGROUND: Many vegetables and fruits have been shown to be sources of antioxidant such as lemons, apples, cabbage, mangoes, beets, and guavas AIM: This research aimed to determine antioxidant activity of Cucumis sativus L. (cucumber) pulp and leaves extracts using DPPH and CUPRAC methods, total phenolic content (TPC), total flavonoid content (TFC), correlation of TPC and TFC on antioxidant activity, correlation between the two methods, identification of marker, and total marker content. METHODS: Antioxidant activity was examined by determining IC50 and AAI of DPPH and EC50 and AAI of CUPRAC. TFC and TPC was measured using UV-visible spectrophotometer. Correlation of TPC and TFC on antioxidant activity was analysed by Pearson’s method. RESULTS: AAI of DPPH of cucumber pulp and leaves extracts in the range of 0.22 - 2.18, whereas AAI of CUPRAC 0.07 - 0.95. All extracts showed antioxidant activity. Ethyl acetate cucumber pulp extract had highest antioxidant by DPPH assay, whereas n-hexane cucumber leaves extract had highest antioxidant activity by CUPRAC assay. Ethyl acetate cucumber leaves extract had highest TFC value (21.47 g QE/100 g) and TPC value (2.34 g GAE/100 g). Flavonoids in cucumber pulp extract contributed to antioxidant activity of CUPRAC method and phenolic compounds in cucumber pulp extract gave a contribution to antioxidant activity of DPPH method. Quercetin content as marker in ethanol cucumber pulp extract was 0.00114%. AAI CUPRAC and DPPH of cucumber leaves extract showed positive correlation but not significant. CONCLUSION: Antioxidant activity between CUPRAC and DPPH methods on cucumber extracts were not linear.

Singkel (Premna serratifolia Linn.) is a medicinal plant commonly found in tropical regions, including Indonesia, which contains flavonoids, alkaloids, polyphenols, and triterpenoids. Flavonoids in singkel leaves act as antioxidants that can prevent oxidative stress, which is a causative factor of degenerative and chronic diseases such as cancer, arthritis, and cardiovascular diseases. This study aims to determine the effects of total flavonoid content and IC50 values in singkel leaves based on extraction methods, solvent concentration, and the ratio of extract to solvent. The methods used include maceration, soxhlet extraction, and Microwave-Assisted Extraction (MAE), with ethanol solvent concentrations of 60%, 70%, 80%, and 96%, and extract-to-solvent ratios of 1:10, 1:20, and 1:30. Antioxidant activity was measured using the DPPH (2,2-diphenyl-1-picrylhydrazyl) method with UV-Vis spectrophotometry. The results showed that the soxhlet extraction method yielded the highest total flavonoid content of 24.56±1.81 mgQE/g with an IC50 value of 20.31±1.58 μg/mL. The 96% solvent concentration provided the best results with a total flavonoid content of 26.12±0.06 mgQE/g and an IC50 value of 15.51±2.17 μg/mL. In the solvent ratio testing, the 1:20 ratio showed the highest total flavonoid content of 19.37±0.5 mgQE/g, while the 1:10 ratio provided the best IC50 value of 11.99±1.02 μg/mL. In conclusion, the extraction method, solvent concentration, and solvent ratio significantly affect the flavonoid content and antioxidant activity of singkel leaves.

Flos Sophorae Immaturus (FSI) contains a large number of bioactive substances with antioxidant and hypoglycaemic activity. However, a feasible drying process plays an important role in the retention of its biological activity. The present work investigated the effects of ultrasound-assisted vacuum drying (UAVD) on FSI samples in terms of drying time, colour, microstructure, and total flavonoid content (TFC). Meanwhile, the antioxidant activity and α-glucosidase inhibition activity were also evaluated. The results show that the drying time of UVAD samples was decreased by 40% compared to that of the single vacuum-dried (VD) samples (600 W for 10 min). The cellular porous structures of FSI tissue were formed by UAVD, which promoted the migration of water from the inside to the outside. Furthermore, samples treated by UAVD exhibited better antioxidant activities and α-glucosidase and α-amylase inhibition capacities, with DPPH (81.86%), ABTS (88.61%), FRAP (83.05%), α-glucosidase inhibition capacity (89%), α-amylase (85%), drying time (3 h), and total aberration (ΔE) (1.63) being the highest characteristic traits. In this condition, the highest levels of total flavonoid content (TFC), rutin, quercetin, kaempferol, isorhamnetin, and genistein were obtained with 266.94, 239.46, 35.56, 8.54, 10.37, and 5.64 mg/g DW, respectively. The results confirm that UAVD is a novel method that significantly reduced the VD time and promoted the release of the bioactive substances of FSI.

Soursop leaves (Annona muricata L.) have anticancer and antioxidant activities; soursop leaves contain substances with the potential as antioxidants, such as flavonoids. Antioxidant assays and total flavonoid content from the three largest producing regions in South Sulawesi Province, namely Gowa, Takalar, and Pinrang, were carried out to obtain data on the antioxidant activity and flavonoid content of soursop leaves (Annona muricata L.) three areas. Total Flavonoid content was determined by UV-Vis spectrophotometry, and antioxidant activity was measured by the DPPH (1,1-Diphenyl-2-picryl Hydrazyl) method. According to the study, soursop leaves (Annona muricata L.) from the Gowa, Takalar, and Pinrang regions have total flavonoid levels of 7,6484 mg QE/g, 3,74429 mg QE/g, and 3,3105 mg QE/g, respectively, and IC50 values of 70.509 g/mL, 102.159 g/mL, and 99.246 g/mL, respectively. The results showed that soursop leaves (Annona muricata L.) from the Gowa area had the highest flavonoid content and antioxidant activity. Gowa region could be the best source of soursop leaves for developing soursop as an herbal remedy.

This study aims to observe the addition of seaweed and Dayak onions to rice crackers on the nutritional content and antioxidant activity. This study has been carried out at the Nutrition Laboratory, University of Borneo Tarakan. The seaweed used is Eucheuma cottoni. Making crackers consists of several steps, namely material preparation, dough making, molding, and drying. The results given information that the addition of seaweed and Dayak onions had an effect on the nutritional content and antioxidant activity. Puli crackers fortified with seaweed and Dayak onions contain 8.04% protein, 1.07% fat, 1.77% water, 5.96% ash, and 83.16% carbohydrates. The antibiotic activity of seaweed and Dayak onion fortified Puli crackers using the DPPH method was greater than that of commercial Puli crackers, which was 4.07%.

Co-influence of fermentation time and temperature on physicochemical properties, bioactive components and microstructure of ting (a Southern African food) from whole grain sorghum

Dayak onion (Eleutherine bulbosa (Mill.) Urb.) has the potential to be an immunostimulant to benefit fish health. This study aimed to evaluate the effectiveness of dietary supplementation with the powder and crude ethanol extracts of Dayak onion on the hematology and immune response parameters of Nile tilapia challenged with Aeromonas hydrophila. The research used a completely randomized design with six treatments and three replications. Nile tilapias were fed with Dayak onion (w/v) consisting of powders of 5% (P5), 10% (P10), and 15% (P15), while crude extract was 0.5% (E05) and given during rearing for 30 days. Positive control (C+) and negative control (C-) were used without Dayak onion. Nile tilapia in treatment C+, P5, P10, and P15 were injected with A. hydrophila 10⁶ CFU mL⁻1, while that in treatment C- was injected with phosphate buffered saline (PBS) intramuscularly. The results showed that the dietary with 15% powder and 0.5% crude extract significantly improved the hematology and immune response parameters compared to the control after the challenge against A. hydrophila (P<0.05). Dayak onion supplementation effectively increased the health status based on hematology and immune response parameters of Nile tilapia against A. hydrophila infection. Highlight Research Dayak onion has significant potential to improve nonspecific immunity in fish. Dayak onion improves hematology and immune response of Nile tilapia. Dayak onion can significantly regulate the immune system against A. hydrophila infection. Dayak onion significantly increases the production of the gene expression of IL-1β and TNF-α.

: Introduction: to obtain the optimum extraction conditions of total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity (AA) and angiotensin converting enzyme (ACE) inhibitory activity from Peperomia pellucida (L.) Kunth. Method: TPC, TFC, AA and ACE inhibitory activity was measured by Folin-Ciocalteu method, AlCl3 method, DPPH and FRAP methods, and ACE kit- WST. MAE efficiency parameters used were ethanol concentration, a sample to solvent ratio, extraction time, and microwave power. Results: The optimum conditions of MAE for TPC (49.78 mg GAE/g extract) and TFC (37.18 mg QE/g extract) were 80% ethanol, sample-solvent ratio of 1:12, extraction time of 2 min, MAE power of 30% and 80% ethanol, ratio of 1:12, time of 2 min, and 70% power respectively. The optimum AA was obtained at 65% ethanol, ratio of 1:10, time of 3 min, 50% power (DPPH method), and 65% ethanol, the ratio of 1:12, time of 1 min, and 70% power (FRAP method) respectively. The optimum ACE inhibitory activity (54.73% at a concentration of 100 μg/mL) were obtained at 80% ethanol, ratio of 1:12, time of 2 min, and 70% power. Conclusion: The analysis of Pearson correlation indicated that there was no correlation between TPC with FRAP method; TPC with ACE inhibitory activity and TFC with DPPH method.Key words: ACE, Antioxidant Activity, Flavonoid Compounds, Microwave-Assisted Extraction, Peperomia pellucida (L.) Kunth, Phenolic Compounds.

Background: Free radicals are chemical species a molecule, atom with unpaired electrons and reactive as oxidizing agent which cause oxidize stress in tissue. Antioxidants are substances that can protect cells from free radicals by releasing electrons to neutralize free radicals. Tamarillo peel contains phenolic and flavonoid compounds which have antioxidant activity. The aim of this study was to determine the antioxidant activity, total phenolic and flavonoid content of the ethanol extract of tamarillo peel. Methods: In this research, the maceration method was used to extract phenolic and flavonoid components from tamarillo peel with ethanol 70% solvent. Total phenolic and flavonoid content was determined with UV-vis spectrophotometer. Total phenolic content determined using the Folin-Ciocalteu reagent and expressed in GAE (Garlic acid equivalent) and the total flavonoid content used the AlCl-3 reagent and expressed in QE (Quersetin equivalent). Then, tamarillo peel ethanol extract was tested the antioxidant activity using the DPPH method. Result: The results showed that the total polyphenol content was 66.6242 mg GAE/g extract or 6.66% w/v extract, total flavonoid content was 0.74246 % w/v or 7.4246 mg QE/g extract. Antioxidant activity in IC50 value was 47.9460 ppm. Conclusions: From the results of the research conducted, it can be seen that the ethanol extract of tamarillo can provide an antioxidant effect in the very strong category.

Background: Antioxidants play a key role in the prevention and treatment of various diseases. Flavonoids, a class of secondary metabolites, are known for their strong antioxidant properties. Cayratia trifolia (L.) Domin is an Indonesian endemic plant with medicinal potential, particularly as a natural antioxidant source. The extraction process is a critical step in isolating bioactive compounds and must be optimized to maximize flavonoid content and antioxidant activity. Objective: This study aims to evaluate the effect of different extraction methods— maceration, sonication, and Soxhlet extraction—on the total flavonoid content and antioxidant activity of ethanolic extracts of C. trifolia (L.) Domin leaves. Methods: This experimental study used three extraction techniques: maceration, sonication, and Soxhlet extraction. Total flavonoid content was determined using UV-Vis spectrophotometry and expressed as mg quercetin equivalent per gram of extract (mg QE/g extract). Antioxidant activity was measured using the DPPH free radical scavenging assay and expressed as IC₅₀ (ppm). Statistical analysis was conducted using one-way ANOVA with a 95% confidence level. Results: The sonication method yielded the highest total flavonoid content (41.82 ± 0.011 mg QE/g extract) and the strongest antioxidant activity (IC₅₀ = 66.523 ± 0.449 ppm), followed by Soxhlet extraction (35.78 ± 0.01 mg QE/g; IC₅₀ = 84.217 ± 0.565 ppm), and maceration (18.48 ± 0.01 mg QE/g; IC₅₀ = 94.579 ± 1.12 ppm). Statistical analysis showed that the extraction method significantly affected both total flavonoid content and antioxidant activity (P < 0.05). Conclusion: The extraction method significantly influences the yield of total flavonoids and antioxidant activity in C. trifolia ethanolic leaf extracts. Sonication was found to be the most effective method, suggesting its potential use in optimizing the recovery of antioxidant compounds from plant materials. Keywords: Antioxidant Activity; Cayratia trifolia (L.) Domin; DPPH; Extraction methods; Total Flavonoid Contents.

Enhalus acoroides is a seagrass species known for its antioxidant potential due to its flavonoid content, including quercetin. This study aimed to optimize the extraction time using the ultrasound-assisted extraction (UAE) method based on physicochemical parameters and antioxidant activity. The simplicia was extracted for 20, 30, and 40 minutes, each in triplicate, using 96% ethanol acidified with 1% HCl. The results demonstrated that extraction time significantly influenced the physicochemical properties, including yield (highest at 30 minutes: 40.2%), total phenolic content (1.153 mg GAE/g), total flavonoid content (0.318 mg QE/g), quercetin content (0.316 mg/g), and antioxidant activity (IC₅₀ = 58.44 ppm), whereas no significant effect was observed on total ash content. Qualitative phytochemical screening revealed the presence of alkaloids, flavonoids, tannins, saponins, and triterpenoids. Based on these findings, a 30-minute extraction time is recommended as the optimal condition for obtaining E. acoroides extract with the highest antioxidant activity.