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Metabolite profiling reveals temperature effects on the VOCs and flavonoids of different plant populations

Goh HH, Khairudin K, Sukiran NA, Normah MN, Baharum SN

Plant Biol (Stuttg), 2016 Jan;18 Suppl 1:130-9.
PMID: 26417881 DOI: 10.1111/plb.12403

Temperature is one of the key factors in limiting the distribution of plants and controlling major metabolic processes. A series of simulated reciprocal transplant experiments were performed to investigate the effect of temperature on plant chemical composition. Polygonum minus of different lowland and highland origin were grown under a controlled environment with different temperature regimes to study the effects on secondary metabolites. We applied gas chromatography-mass spectrometry and liquid chromatography time-of-flight mass spectrometry to identify the chemical compounds. A total of 37 volatile organic compounds and 85 flavonoids were detected, with the largest response observed in the compositional changes of aldehydes and terpenes in highland plants under higher temperature treatment. Significantly less anthocyanidin compounds and larger amounts of flavonols were detected under higher temperature treatment. We also studied natural variation in the different plant populations growing under the same environment and identified compounds unique to each population through metabolite fingerprinting. This study shows that the origin of different plant populations influences the effects of temperature on chemical composition.

Matched MeSH terms: Flavonoids/isolation & purification; Flavonoids/metabolism*; Flavonoids/chemistry
Antimitotic and cytotoxic flavonols from Zieridium pseudobtusifolium and Acronychia porteri

Lichius JJ, Thoison O, Montagnac A, Païs M, Guéritte-Voegelein F, Sévenet T, et al.

J Nat Prod, 1994 Jul;57(7):1012-6.
PMID: 7964782

Bioassay-guided fractionation of the extracts of Zieridium pseudobtusifolium and Acronychia porteri led to the isolation of 5,3'-dihydroxy-3,6,7,8,4'-pentamethoxyflavone [1], which showed activity against (KB) human nasopharyngeal carcinoma cells (IC50 0.04 micrograms/ml) and inhibited tubulin assembly into microtubules (IC50 12 microM). Two other known flavonols, digicitrin [2] and 5-hydroxy-3,6,7,8,3',4'-hexamethoxyflavone [5], were also isolated together with three new ones, 3-O-demethyldigicitrin [3], 3,5,3'-trihydroxy-6,7,8,4'-tetramethoxyflavone [4], and 3,5-dihydroxy-6,7,8,3',4'-pentamethoxyflavone [6]. All of these flavonols showed cytotoxic activity against KB cells.

Matched MeSH terms: Flavonoids/isolation & purification*; Flavonoids/pharmacology; Flavonoids/chemistry
Meliternatin: a feeding deterrent and larvicidal polyoxygenated flavone from Melicope subunifoliolata

Hung Ho S, Wang J, Sim KY, Ee GC, Imiyabir Z, Yap KF, et al.

Phytochemistry, 2003 Apr;62(7):1121-4.
PMID: 12591266

We screened more than 60 Malaysian plants against two species of insects and found that Melicope subunifoliolata (Stapf) T.G. Hartley (Rutaceae) showed strong feeding deterrent activity against Sitophilus zeamais Motsch. (Curculionidae) and very good larvicidal activity against Aedes aegypti L. (Diptera). One anti-insect compound, meliternatin (3,5-dimethoxy-3',4',6,7-bismethylendioxyflavone) (6) and six other minor polyoxygenated flavones were isolated from M. subunifoliolata.

Matched MeSH terms: Flavonoids/isolation & purification; Flavonoids/pharmacology*; Flavonoids/chemistry*
Detection of naringenin and kaempferol in Justicia gendarussa leaf extracts by GC-FID

Zahidah Ayob, Shajarahtunnur Jamil, Siti Pauliena Mohd Bohari, Farediah Ahmad, Azman Abd Samad

Sains Malaysiana, 2017;46:457-461.

Justicia gendarussa methanolic leaves extract from four different locations in Southern region of Malaysia and distribution
of two flavonoids, naringenin and kaempferol in plant organs (young and mature leaves) were determined using gas
chromatography-flame ionization detector (GC-FID) analysis. Naringenin and kaempferol contents were detected
and quantified in leaves extract. The results indicated that mature leaves contained more naringenin and kaempferol
compared to young leaves. The highest concentration of naringenin and kaempferol were recorded in mature leaves from
Skudai and Muar regions which were 507.692 and 1226.964 mgkg-1, respectively. Data analysis showed that naringenin
content was directly proportional to the amount of kaempferol in the leaf extracts. In conclusion, this study suggested
geographical variation among plant samples and physiological stage of organ parts could contribute to variation in
flavonoids concentration in a plant species.

Matched MeSH terms: Flavonoids
Optimisation of microwave-assisted extraction (MAE) of anthraquinone and flavonoids from Senna alata (L.) Roxb

Yeong YL, Pang SF, Putranto A, Gimbun J

Nat Prod Res, 2021 Feb 04.
PMID: 33538194 DOI: 10.1080/14786419.2021.1881096

This paper investigates the optimum processing conditions of microwave assisted extraction (MAE) of anthraquinone (aloe emodin, AE) and flavonoids (kaempferol 3-gentiobioside, K3G and kaempferol, KA) from Senna alata (L.) Roxb. The kinetic study indicates that MAE showed a greater extraction rate, compared to ultrasonic-assisted and maceration, due to the enhanced power which altered the leaf microstructures. The optimisation was undertaken using one-factor-at-a-time, two-level factorial design and central composite design were used to maximise the yield of the target compounds. The optimum yield of K3G (4.27 mg/g DW), KA (8.54 mg/g DW) and AE (0.86 mg/g DW) was obtained at 90.5% ethanol, microwave power of 18.6 W/mL with a desirability of 0.82. In addition, the yield of K3G and KA is correlated positively with the antioxidant activity.

Matched MeSH terms: Flavonoids
Nutritional values of Baccaurea pubera and comparative evaluation of SHS treatment on its antioxidant properties

Shaharuddin S, Husen R, Othman A

J Food Sci Technol, 2021 Jun;58(6):2360-2367.
PMID: 33967332 DOI: 10.1007/s13197-020-04748-0

Baccaurea pubera is a blood red coloured fruit found exclusively in Borneo. This study was conducted to evaluate the effect of superheated steam treatment on its antioxidant properties and mineral content as well as to determine nutritional values of the fruit. The fruits were treated with superheated steam at 170 °C for 15 min prior to extraction and freeze drying. The results showed that, in comparison to the control, superheated steam treatment enhanced the total phenolic content by 147.8% (287.16 mg GAE/100 g vs. 115.87 mg GAE/100 g) and DPPH radical scavenging activity by 23.7% (66.94% vs. 54.13%). However, there were reductions, as compared to the control treatments, in total flavonoid content by 16.5% (8.29 mg QE/100 g vs. 9.93 mg QE/100 g), lycopene content by 28.6% (0.020 μg/100 g vs. 0.028 μg/100 g) and ferric reducing antioxidant power by 22.2% (844.41 mg TE/100 g vs. 1085.15 mg TE/100 g). The superheated steam treatment was also observed to reduce the mineral content of the fruit, from as little as 3.6% to as high as 52% depending upon the specific mineral.

Matched MeSH terms: Flavonoids
Fulltext Eupatorin Suppressed Tumor Progression and Enhanced Immunity in a 4T1 Murine Breast Cancer Model

Abd Razak N, Yeap SK, Alitheen NB, Ho WY, Yong CY, Tan SW, et al.

Integr Cancer Ther, 2020 8 25;19:1534735420935625.
PMID: 32830560 DOI: 10.1177/1534735420935625

Eupatorin is a polymethoxy flavone extracted from Orthosiphon stamineus and was reported to exhibit cytotoxic effects on several cancer cell lines. However, its effect as an anti-breast cancer agent in vivo has yet to be determined. This study aims to elucidate the potential of eupatorin as an anti-breast cancer agent in vivo using 4T1 challenged BALB/c mice model. In this article, BALB/c mice (20-22 g) challenged with 4T1 cells were treated with 5 mg/kg or 20 mg/kg eupatorin, while the untreated and healthy mice were fed with olive oil (vehicle) via oral gavage. After 28 days of experiment, the mice were sacrificed and blood was collected for serum cytokine assay, while tumors were harvested to extract RNA and protein for gene expression assay and hematoxylin-eosin staining. Organs such as spleen and lung were harvested for immune suppression and clonogenic assay, respectively. Eupatorin (20 mg/kg) was effective in delaying the tumor development and reducing metastasis to the lung compared with the untreated mice. Eupatorin (20 mg/kg) also enhanced the immunity as the population of NK1.1+ and CD8+ in the splenocytes and the serum interferon-γ were increased. Concurrently, eupatorin treatment also has downregulated the expression of pro-inflammatory and metastatic related genes (IL-1β. MMP9, TNF-α, and NF-κB). Thus, this study demonstrated that eupatorin at the highest dosage of 20 mg/kg body weight was effective in delaying the 4T1-induced breast tumor growth in the animal model.

Matched MeSH terms: Flavonoids
Fulltext Comparison of antioxidant properties of tamarillo (Cyphomandra betacea), cherry tomato (Solanumly copersicum var. cerasiform) and tomato (Lyopersicon esulentum)

Noor Atiqah, A.A.K., Maisarah, A.M., Asmah, R.

International Food Research Journal, 2014;21(6):2355-2362.
MyJurnal

The emerging studies suggest antioxidant may represent an important role in defence against certain diseases outlined the necessity of determining their contents in tamarillo (Cyphomandra betacea), cherry tomato (Solanum lycopersicum var. cerasiforme), and tomato (Lycopersicon esculentum). This study aims to determine the antioxidant capacity, total phenolic content and total flavonoid content in tamarillo, yellow cherry tomato, red cherry tomato, and tomato in 70% ethanol and water extracts. The ethanol extract showed the highest scavenging activity, ferric reducing activity, phenolic and flavonoid contents, whereas, the water extract showed higher value for antioxidant activity in β-Carotene bleaching assay. Tamarillo showed the highest antioxidant activity (22.92 ± 3.60%, 28.89 ± 3.85%), scavenging activity (44.25 ± 0.82 μg/ml, 47.38 ± 1.11 μg/ml), ferric reducing activity (12.17 ± 0.53 μM Fe (II)/g, 3.72 ± 0.20 μM Fe (II)/g), phenolic content (7.63 ± 0.37 mg GAE/g edible portion, 1.83 ± 0.50 mg GAE/g edible portion) and flavonoid content (6.44 ± 0.16 mg CE/g edible portion, 2.22 ± 0.31 mg CE/g edible portion) in ethanol and water extracts respectively. For ethanol extracts a positive correlations existed (0.66 ≤ r ≥ 0.97) between ferric reducing activity, antioxidant activity, phenolic content and flavonoid content. While, in water extract correlation test revealed a positive correlations between antioxidant activity, ferric reducing activity and phenolic content (0.645 ≤ r ≥ 0.706) and between antioxidant activity and flavonoid content (r = 0.820). In conclusion, tamarillo exhibits the highest antioxidant capacity, phenolic content and also flavonoid content.

Matched MeSH terms: Flavonoids
Medicinal uses, chemistry and pharmacology of Dillenia species (Dilleniaceae)

Sabandar CW, Jalil J, Ahmat N, Aladdin NA

Phytochemistry, 2017 Feb;134:6-25.
PMID: 27889244 DOI: 10.1016/j.phytochem.2016.11.010

The genus Dillenia is comprised of about 100 species of evergreen and deciduous trees or shrubs of disjunct distribution in the seasonal tropics of Madagascar through South and South East Asia, Malaysia, North Australia, and Fiji. Species from this genus have been widely used in medicinal folklore to treat cancers, wounds, jaundice, fever, cough, diabetes mellitus, and diarrhea as well as hair tonics. The plants of the genus also produce edible fruits and are cultivated as ornamental plants. Flavonoids, triterpenoids, and miscellaneous compounds have been identified in the genus. Their extracts and pure compounds have been reported for their antimicrobial, anti-inflammatory, cytotoxic, antidiabetes, antioxidant, antidiarrheal, and antiprotozoal activities. Mucilage from their fruits is used in drug formulations.

Matched MeSH terms: Flavonoids/isolation & purification; Flavonoids/therapeutic use; Flavonoids/chemistry
Discovery of Functional SNPs via Genome-Wide Exploration of Malaysian Pigmented Rice Varieties

Zainal-Abidin RA, Abu-Bakar N, Sew YS, Simoh S, Mohamed-Hussein ZA

Int J Genomics, 2019;2019:4168045.
PMID: 31687375 DOI: 10.1155/2019/4168045

Recently, rice breeding program has shown increased interests on the pigmented rice varieties due to their benefits to human health. However, the genetic variation of pigmented rice varieties is still scarce and remains unexplored. Hence, we performed genome-wide SNP analysis from the genome resequencing of four Malaysian pigmented rice varieties, representing two black and two red rice varieties. The genome of four pigmented varieties was mapped against Nipponbare reference genome sequences, and 1.9 million SNPs were discovered. Of these, 622 SNPs with polymorphic sites were identified in 258 protein-coding genes related to metabolism, stress response, and transporter. Comparative analysis of 622 SNPs with polymorphic sites against six rice SNP datasets from the Ensembl Plants variation database was performed, and 70 SNPs were identified as novel SNPs. Analysis of SNPs in the flavonoid biosynthetic genes revealed 40 nonsynonymous SNPs, which has potential as molecular markers for rice seed colour identification. The highlighted SNPs in this study show effort in producing valuable genomic resources for application in the rice breeding program, towards the genetic improvement of new and improved pigmented rice varieties.

Matched MeSH terms: Flavonoids
Fulltext Bioactive Compounds: Natural Defense Against Cancer?

Subramaniam S, Selvaduray KR, Radhakrishnan AK

Biomolecules, 2019 11 21;9(12).
PMID: 31766399 DOI: 10.3390/biom9120758

Cancer is a devastating disease that has claimed many lives. Natural bioactive agents from plants are gaining wide attention for their anticancer activities. Several studies have found that natural plant-based bioactive compounds can enhance the efficacy of chemotherapy, and in some cases ameliorate some of the side-effects of drugs used as chemotherapeutic agents. In this paper, we have reviewed the literature on the anticancer effects of four plant-based bioactive compounds namely, curcumin, myricetin, geraniin and tocotrienols (T3) to provide an overview on some of the key findings that are related to this effect. The molecular mechanisms through which the active compounds may exert their anticancer properties in cell and animal-based studies also discussed.

Matched MeSH terms: Flavonoids
Effects of different drying methods on the antioxidant activities of leaves and berries of cayratia trifolia

Rabeta MS, Lin S

Sains Malaysiana, 2015;44:275-280.

This study aimed to assess the effects of fresh, thermal drying method (vacuum oven drying), and nonthermal drying method (freeze drying) on the antioxidant activities of leaves and berries of Cayratia trifolia using ferric reducing antioxidant power (FRAP) and 1,1-diphenyl-1-picrylhydrazyl radical scavenging capacity (DPPH) assays. The total phenolic content (TPC) and flavonoid content (TFC) of the leaves and berries of C. trifolia were also measured. Based on the results obtained, the TPC, TFC, and antioxidant activities of the leaves and berries were arranged in the following order: freeze-dried sample with methanol extraction > vacuum-dried sample with methanol extraction > freeze-dried sample with water extraction > vacuum-dried sample with water extraction > fresh sample with methanol extraction > fresh sample with water extraction. The results showed a significant difference (p<0.05) between the fresh and dried samples. In conclusion, freeze drying was found to be a good method for maintaining TPC, TFC, and antioxidant activities by FRAP and DPPH methods in the leaves and berries of C. trifolia.

Matched MeSH terms: Flavonoids
Fulltext Recurrence Rates and Pharmacological Treatment for Hemorrhoidal Disease: A Systematic Review

Lohsiriwat V, Sheikh P, Bandolon R, Ren DL, Roslani AC, Schaible K, et al.

Adv Ther, 2023 Jan;40(1):117-132.
PMID: 36331754 DOI: 10.1007/s12325-022-02351-7

INTRODUCTION: Hemorrhoidal disease (HD) is characterized by prolapse of the inflamed and bleeding vascular tissues of the anal canal. Although HD is associated with a high recurrence rate, there is a lack of understanding around interventions that can reduce recurrence and improve outcomes for patients. As such, a systematic literature review (SLR) was conducted to summarize evidence on epidemiology, recurrence, and efficacy of interventions in HD.
METHODS: Real-world evidence (RWE) studies evaluating the incidence, prevalence, or recurrence of HD, as well as SLRs including a meta-analytic component reporting on the efficacy of systemic or topical pharmacological treatments for adults with HD, were included. Systematic searches were conducted in MEDLINE, Embase, Cumulative Index to Nursing and Allied Health Literature, and the Cochrane Database of Systematic Reviews.
RESULTS: The SLR identified 44 eligible publications. Consistent data were limited on the epidemiology of HD or HD recurrence. Specifically, incidence and prevalence reported across geographies were impacted by differences in data collection. Reported risk factors for HD were sedentary behavior, constipation, male gender, and age. Twenty-three RWE studies and one meta-analysis reported HD recurrence rates ranging from 0 to 56.5% following surgery or phlebotonics, with most (n = 19) reporting rates of 20% or less. In addition to time since treatment, risk factors for recurring disease were similar to those for HD in general. With respect to treatment, micronized purified flavonoid fractions significantly improved the main symptoms of HD compared to other pharmacological treatments.
CONCLUSION: The SLRs did not identify any RWE studies reporting recurrence in patients receiving systemic or topical treatments, highlighting the need for future research in this area. Further, more studies are needed to understand the optimum duration of medical treatment to prevent recurrence.

Matched MeSH terms: Flavonoids
Fulltext Distribution of Flavonoids and Cyclohexenyl Chalcone Derivatives in Conventional Propagated and In Vitro-Derived Field-Grown Boesenbergia rotunda (L.) Mansf

Tan BC, Tan SK, Wong SM, Ata N, Rahman NA, Khalid N

Evid Based Complement Alternat Med, 2015;2015:451870.
PMID: 25883671 DOI: 10.1155/2015/451870

The distribution patterns of flavonoids and cyclohexenyl chalcone derivatives in conventional propagated (CP) and in vitro-derived (CPA) field-grown plants of an important medicinal ginger, Boesenbergia rotunda, are described. A total of eight compounds were extracted from six organs (rootlet, rhizome, shoot base, maroon stem, stalk, and leaf) of the CP and CPA plants. Five major chromatographic peaks, namely, alpinetin, pinocembrin, pinostrobin, 4-hydroxypanduratin A, and panduratin A, were consistently observed by high performance liquid chromatography. Nonaerial organs had higher levels of flavonoids than the aerial ones for all types of samples. Among the compounds detected, pinostrobin and 4-hydroxypanduratin A were the most abundant flavonoid and cyclohexenyl chalcone derivative, respectively. The distribution and abundance of the bioactive compounds suggested that the shoot base could be more potentially useful for medicinal application than other organs of the plant and may be the site of storage or occurrence of biosynthetic enzymatic activities.

Matched MeSH terms: Flavonoids
Fulltext Hepatoprotective Activity of Elephantopus scaber on Alcohol-Induced Liver Damage in Mice

Ho WY, Yeap SK, Ho CL, Abdul Rahim R, Alitheen NB

Evid Based Complement Alternat Med, 2012;2012:417953.
PMID: 22973401 DOI: 10.1155/2012/417953

Elephantopus scaber has been traditionally used as liver tonic. However, the protective effect of E. scaber on ethanol-induced liver damage is still unclear. In this study, we have compared the in vivo hepatoprotective effect of E. scaber with Phyllanthus niruri on the ethanol-induced liver damage in mice. The total phenolic and total flavanoid content of E. scaber ethanol extract were determined in this study. Accelerating serum biochemical profiles (including AST, ALT, ALP, triglyceride, and total bilirubin) associated with fat drop and necrotic body in the liver section were observed in the mice treated with ethanol. Low concentration of E. scaber was able to reduce serum biochemical profiles and the fat accumulation in the liver. Furthermore, high concentration of E. scaber and positive control P. niruri were able to revert the liver damage, which is comparable to the normal control. Added to this, E. scaber did not possess any oral acute toxicity on mice. These results suggest the potential effect of this extract as a hepatoprotective agent towards-ethanol induced liver damage without any oral acute toxicity effect. These activities might be contributed, or at least in part, by its high total phenolic and flavonoid contents.

Matched MeSH terms: Flavonoids
Fulltext Variation of the Phytochemical Constituents and Antioxidant Activities of Zingiber officinale var. rubrum Theilade Associated with Different Drying Methods and Polyphenol Oxidase Activity

Ghasemzadeh A, Jaafar HZ, Rahmat A

Molecules, 2016 Jun 17;21(6).
PMID: 27322227 DOI: 10.3390/molecules21060780

The effects of different drying methods (freeze drying, vacuum oven drying, and shade drying) on the phytochemical constituents associated with the antioxidant activities of Z. officinale var. rubrum Theilade were evaluated to determine the optimal drying process for these rhizomes. Total flavonoid content (TFC), total phenolic content (TPC), and polyphenol oxidase (PPO) activity were measured using the spectrophotometric method. Individual phenolic acids and flavonoids, 6- and 8-gingerol and shogaol were identified by ultra-high performance liquid chromatography method. Ferric reducing antioxidant potential (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays were used for the evaluation of antioxidant activities. The highest reduction in moisture content was observed after freeze drying (82.97%), followed by vacuum oven drying (80.43%) and shade drying (72.65%). The highest TPC, TFC, and 6- and 8-shogaol contents were observed in samples dried by the vacuum oven drying method compared to other drying methods. The highest content of 6- and 8-gingerol was observed after freeze drying, followed by vacuum oven drying and shade drying methods. Fresh samples had the highest PPO activity and lowest content of flavonoid and phenolic acid compounds compared to dried samples. Rhizomes dried by the vacuum oven drying method represent the highest DPPH (52.9%) and FRAP activities (566.5 μM of Fe (II)/g DM), followed by freeze drying (48.3% and 527.1 μM of Fe (II)/g DM, respectively) and shade drying methods (37.64% and 471.8 μM of Fe (II)/g DM, respectively) with IC50 values of 27.2, 29.1, and 34.8 μg/mL, respectively. Negative and significant correlations were observed between PPO and antioxidant activity of rhizomes. Vacuum oven dried rhizomes can be utilized as an ingredient for the development of value-added food products as they contain high contents of phytochemicals with valuable antioxidant potential.

Matched MeSH terms: Flavonoids/pharmacology; Flavonoids/chemistry
Fulltext Identification of phenolic acids and flavonoids in monofloral honey from Bangladesh by high performance liquid chromatography: determination of antioxidant capacity

Moniruzzaman M, Yung An C, Rao PV, Hawlader MN, Azlan SA, Sulaiman SA, et al.

Biomed Res Int, 2014;2014:737490.
PMID: 25045696 DOI: 10.1155/2014/737490

The aim of the present study was to characterize the phenolic acids, flavonoids, and antioxidant properties of monofloral honey collected from five different districts in Bangladesh. A new high performance liquid chromatography (HPLC) equipped with a UV detector method was developed for the identification of the phenolic acids and flavonoids. A total of five different phenolic acids were identified, with the most abundant being caffeic acid, benzoic acid, gallic acid, followed by chlorogenic acid and trans-cinnamic acid. The flavonoids, kaempferol, and catechin were most abundant, followed by myricetin and naringenin. The mean moisture content, total sugar content, and color characteristics of the honey samples were 18.36 ± 0.95%, 67.40 ± 5.63 g/100 g, and 129.27 ± 34.66 mm Pfund, respectively. The mean total phenolic acids, total flavonoid content, and proline content were 199.20 ± 135.23, 46.73 ± 34.16, and 556.40 ± 376.86 mg/kg, respectively, while the mean FRAP values and DPPH radical scavenging activity were 327.30 ± 231.87 μM Fe (II)/100 g and 36.95 ± 20.53%, respectively. Among the different types of honey, kalijira exhibited the highest phenolics and antioxidant properties. Overall, our study confirms that all the investigated honey samples are good sources of phenolic acids and flavonoids with good antioxidant properties.

Matched MeSH terms: Flavonoids/isolation & purification*; Flavonoids/chemistry
Fulltext Fabrication of an electrochemical sensor based on gold nanoparticles/carbon nanotubes as nanocomposite materials: determination of myricetin in some drinks

Hajian R, Yusof NA, Faragi T, Shams N

PLoS One, 2014;9(5):e96686.
PMID: 24809346 DOI: 10.1371/journal.pone.0096686

In this paper, the electrochemical behavior of myricetin on a gold nanoparticle/ethylenediamine/multi-walled carbon-nanotube modified glassy carbon electrode (AuNPs/en/MWCNTs/GCE) has been investigated. Myricetin effectively accumulated on the AuNPs/en/MWCNTs/GCE and caused a pair of irreversible redox peaks at around 0.408 V and 0.191 V (vs. Ag/AgCl) in 0.1 mol L-1 phosphate buffer solution (pH 3.5) for oxidation and reduction reactions respectively. The heights of the redox peaks were significantly higher on AuNPs/en/MWNTs/GCE compare with MWCNTs/GC and there was no peak on bare GC. The electron-transfer reaction for myricetin on the surface of electrochemical sensor was controlled by adsorption. Some parameters including pH, accumulation potential, accumulation time and scan rate have been optimized. Under the optimum conditions, anodic peak current was proportional to myricetin concentration in the dynamic range of 5.0×10-8 to 4.0×10-5 mol L-1 with the detection limit of 1.2×10-8 mol L-1. The proposed method was successfully used for the determination of myricetin content in tea and fruit juices.

Matched MeSH terms: Flavonoids/analysis*; Flavonoids/chemistry
Phenolic acid composition and antioxidant properties of Malaysian honeys

Khalil MI, Alam N, Moniruzzaman M, Sulaiman SA, Gan SH

J Food Sci, 2011 Aug;76(6):C921-8.
PMID: 22417491 DOI: 10.1111/j.1750-3841.2011.02282.x

The phenolic acid and flavonoid contents of Malaysian Tualang, Gelam, and Borneo tropical honeys were compared to those of Manuka honey. Ferric reducing/antioxidant power assay (FRAP) and the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical-scavenging activities were also quantified. All honey extracts exhibited high phenolic contents (15.21 ± 0.51- 42.23 ± 0.64 mg/kg), flavonoid contents (11.52 ± 0.27- 25.31 ± 0.37 mg/kg), FRAP values (892.15 ± 4.97- 363.38 ± 10.57 μM Fe[II]/kg), and high IC₅₀ of DPPH radical-scavenging activities (5.24 ± 0.40- 17.51 ± 0.51 mg/mL). Total of 6 phenolic acids (gallic, syringic, benzoic, trans-cinnamic, p-coumaric, and caffeic acids) and 5 flavonoids (catechin, kaempferol, naringenin, luteolin, and apigenin) were identified. Among the Malaysian honey samples, Tualang honey had the highest contents of phenolics, and flavonoids, and DPPH radical-scavenging activities. We conclude that among Malaysian honey samples, Tualang honey is the richest in phenolic acids, and flavonoid compounds, which have strong free radical-scavenging activities.

Matched MeSH terms: Flavonoids/analysis; Flavonoids/chemistry
Fulltext Reduced photoinhibition under low irradiance enhanced Kacip Fatimah (Labisia pumila Benth) secondary metabolites, phenyl alanine lyase and antioxidant activity

Ibrahim MH, Jaafar HZ

Int J Mol Sci, 2012;13(5):5290-306.
PMID: 22754297 DOI: 10.3390/ijms13055290

A randomized complete block design experiment was designed to characterize the relationship between production of total flavonoids and phenolics, anthocyanin, photosynthesis, maximum efficiency of photosystem II (Fv/Fm), electron transfer rate (Fm/Fo), phenyl alanine lyase activity (PAL) and antioxidant (DPPH) in Labisia pumila var. alata, under four levels of irradiance (225, 500, 625 and 900 μmol/m(2)/s) for 16 weeks. As irradiance levels increased from 225 to 900 μmol/m(2)/s, the production of plant secondary metabolites (total flavonoids, phenolics and antocyanin) was found to decrease steadily. Production of total flavonoids and phenolics reached their peaks under 225 followed by 500, 625 and 900 μmol/m(2)/s irradiances. Significant positive correlation of production of total phenolics, flavonoids and antocyanin content with Fv/Fm, Fm/Fo and photosynthesis indicated up-regulation of carbon-based secondary metabolites (CBSM) under reduced photoinhibition on the under low light levels condition. At the lowest irradiance levels, Labisia pumila extracts also exhibited a significantly higher antioxidant activity (DPPH) than under high irradiance. The improved antioxidative activity under low light levels might be due to high availability of total flavonoids, phenolics and anthocyanin content in the plant extract. It was also found that an increase in the production of CBSM was due to high PAL activity under low light, probably signifying more availability of phenylalanine (Phe) under this condition.

Matched MeSH terms: Flavonoids/metabolism*; Flavonoids/chemistry

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