The determination of flavonoid contents in mulberry and their scavenging effects on superoxide radicals

doi:10.1016/S0308-8146(98)00102-2

Food Chemistry

Volume 64, Issue 4, March 1999, Pages 555-559

https://doi.org/10.1016/S0308-8146(98)00102-2 Get rights and content

Abstract

Flavonoid content of mulberry leaves of 19 varieties of species, determined spectrophotometrically in terms of rutin equivalent, varied from 11.7 to 26.6 mg g⁻¹ in spring leaves and 9.84 to 29.6 mg g⁻¹ in autumn leaves. Fresh leaves gave more extract than air-dried or oven-dried ones. HPLC showed that mulberry leaves contain at least four flavonoids, two of which are rutin and quercetin. The percentage superoxide ion scavenged by extracts of mulberry leaves, mulberry tender leaves, mulberry branches and mulberry bark were 46.5, 55.5, 67.5 and 85·5%, respectively, at a concentration of 5 μg ml⁻¹. The scavenging effects of most mulberry extracts were greater than those of rutin (52.0%).

Introduction

For some time it has been recognized that several classes of flavonoids show antioxidant activity towards a variety of readily-oxidizable compounds. Flavonoids exist widely in the plant kingdom and are especially common in leaves, flowering tissues and pollens (Larson, 1988). Plant flavonoids are an important part of the diet because of their effects on human nutrition (Frankel, 1995). These phytochemicals can modulate lipid peroxidation involved in atherogenesis, thrombosis and carcinogenesis. Known properties of the flavonoids include: free radical scavenging, strong antioxidant activity, inhibition of hydrolytic and oxidative enzymes (phospholipase A₂, cyclooxygenase, lipoxygenase), and antiinflammatory action (Frankel, 1995). Some evidence suggests that the pharmacological effects of flavonoids are correlated with their antioxidant activities (Gryglewski, Korbut, Robak, 1987). Superoxide radicals have been observed to kill cells, inactivate enzymes and degrade DNA, cell membranes and polysaccharide (Fridovich, 1978). Moreover, it is suggested that the overall antioxidant effect of flavonoids on lipid peroxidation may be related to their ·OH and O₂^−. scavenging properties and their reaction with peroxy radicals (Husain, Cillard, Cillard, 1987). Thus, O₂^−. may play an important role during the peroxidation of unsaturated fatty acids and possibly other susceptible substances (Nice and Robinson, 1992). Therefore, the study of the scavenging effects of antioxidants on O₂^−. is one of the most important ways of making clear the mechanism of antioxidant activity and has therefore caused growing interest among researchers.

Flavonoids can be used directly to scavenge O₂^−. and ·OH by single electron transfer. The scavenging process can generally be followed by means of electron spin resonance (ESR) (Chen, Li, Zao, Zheng, Xin, 1989Dan, Li, Zhao, Zhang, Xin, 1989), but the expense of such instruments hinders their use by the average laboratory. The photochemical reduction of riboflavin was first used to determine the dismutation of O₂^−. by superoxide dismutase (SOD) (Beauchamp and Fridovich, 1971) and has been adapted for analysis of the dismutation of O₂^−. by a model compound of superoxide dismutase and other natural compounds (Luo, Sen, Gao, Peng, 1990).

Although the mulberry mainly supplies leaves to raise silkworms, mulberry leaves, mulberry bark and mulberry branches have long been used in Chinese medicine to treat fever, protect the liver, improve eyesight, strengthen the joints, facilitate discharge of urine and lower blood pressure. It is only recently that the mechanism of their action has been related to their antioxidant activity. The chemical composition of mulberry leaves includes rutin, quercetin, isoquercitrin and other flavonoids.

This article is mainly concerned with the method of extracting flavonoids from mulberry leaves and the determination of the content of flavonoids in the extracts. In parallel, the scavenging effects of mulberry extracts on the superoxide radical was analysed using the photochemical reduction of riboflavin. The confirmation of the antioxidant potential of flavonoids has made possible the exploitation of a natural antioxidant from superfluous mulberry leaves.

Section snippets

Materials

Mulberry leaves were obtained from the sample sections of Zhejiang Agricultural University. Spring mulberry leaves were picked on 5 May, 1996 and autumn mulberry leaves on 11 November, 1996. The mulberry leaves were washed with distilled water and air-dried. The dry leaves were ground in a mortar, sieved through a 40-mesh sieve and stored in a glass bottle.

Determination of percentage dry weight

Between 30 and 50 g of fresh leaves were accurately weighed and dried to constant weight in an oven at 100–105°C for 4 hours.

Extraction of flavonoids

Powdered

Effects of different pretreatments on the flavonoid content extracted from mulberry leaves

The amount of flavonoids extracted from fresh leaves, oven-dried and air-dried leaves was determined as above (Table 1).

The results indicate that fresh leaves allow the largest amount to be extracted, air-dried leaves rank second and oven-dried leaves come last. The order may be explained by the decomposition of flavonoids after a long period of storage or under high temperature. However, there is a possibility that the matrix has changed to make the flavonoids less extractable.

Qualitative analysis of flavonoids in the mulberry

Fig. 1 shows the

Acknowledgements

The authors wish to thank the Department of Sericulture for providing mulberry samples and Professor Lou Chenfu for identifying the mulberry species.

References (14)

C. Beauchamp et al.
Superoxide dismutase: Improved assays and an assay applicable to acrylamide gels
Analytical Biochemistry
(1971)
R.A. Larson
The antioxidants of higher plants
Phytochemistry
(1988)
D.J. Nice et al.
Inhibition of lipid autoxidation by bovine superoxide dismutase
Food Chemistry
(1992)
K. Tajima et al.
Reaction of biological phenoic antioxidants with superoxide generated by Cytochrome P₄₅₀ model system
Biochemical and Biophysical Research Communications
(1983)
Y.T. Chen et al.
ESR study of the scavenging effect of natural products of rutin etc superoxide and hydroxyl radical
Acta Biophysica Sinica
(1989)
N. Dan et al.
Scavenging effects of probimane on active oxygen free radicals by electron spin resonance
Acta Pharmacologica Sinica
(1989)
N.P. Das et al.
Effects of flaononids on thermal autoxidation of Plam oil: structure–activity relationship
Journal of the American Oil Chemists’ Society
(1990)

There are more references available in the full text version of this article.

Cited by (6519)

Melatonin postharvest spray influence on white mulberry browning, storage life, and biochemical changes
2024, Postharvest Biology and Technology
White mulberry (Morus alba L.) fruit is a rich source of bioactive compounds, but it is highly perishable and vulnerable to browning. In the current study, melatonin at concentrations of 0, 125, 250, 500, and 1000 µM was sprayed on mulberry fruit and stored at 1 °C for 12 d. Melatonin treatment yielded the lowest browning index during storage time. This reduction was accompanied by a significant decrease in malondialdehyde, H₂O₂ and polyphenol oxidase enzyme activity. The results showed that melatonin reduced weight loss and maintained pH, as well as total soluble solids. Furthermore, the total phenol, total flavonoids and ascorbic acid contents in treated fruit were significantly higher than in an untreated fruit, which was accompanied by an increase in antioxidant capacity. With assuming 40 % browning would render the fruit unmarketable, melatonin treatments could extend mulberry storage life beyond 8 days. The 500 and 1000 μM melatonin treatments showed the most effective results. In conclusion, exogenous melatonin application can be considered a safe and promising procedure to maintain the quality of mulberry fruit during low-temperature storage.
Selenium nanoparticle alleviates penthiopyrad-induced oxidative stress and restores the development and flavor quality of tomato fruit
2024, Journal of Food Composition and Analysis
Selenium nanoparticle (Se-NP) is promising for improving the growth, resistance and quality of crops, but there are still knowledge gaps in its molecular mechanism. Here we showed that 1 mg/L Se-NP had positive effects on tomato fruit development and flavor quality. The co-application of Se-NP with penthiopyrad promoted the ascorbic acid-glutathione cycle and the main precursors of antioxidant compounds to resist Pen-induced oxidative stress, while also increasing the content of phytohormones, promoting the maturation of the fruit. Furthermore, Se-NP restored penthiopyrad stress-induced flavor loss of the fruit by regulating genes such as SUS1, TOMLOXC and AADC2, to increase levels of glucose, fructose, and volatile organic compounds at the transcriptional level. These findings revealed that Se-NP alleviated Pen-induced oxidative stress and restored tomato fruit development and flavor quality and highlighted the great potential of Se-NP-enabled agricultural practices as an eco-friendly and sustainable crop strategy.
Effect of active layer-by-layer edible coating on quality, biochemicals, and the antioxidant system in ready-to-eat ‘Williams’ pear fruit during cold storage
2024, Postharvest Biology and Technology
This study tested an active edible coating on the quality and storage capacity of fresh-cut pear stored at 2 ± 0.5 °C for 10 days by incorporating oxalic (OA) and citric acid (CA) into carboxymethyl cellulose (CMC) and sodium alginate (SA). The physicochemical parameters, secondary metabolite and amino acid contents, and antioxidant activities were determined. Furthermore, enzymes related to oxidative stress and browning, and relative markers were also analysed. The results showed that ready-to-eat pear coated with CMC+SA+OA+CA had a significant inhibitory effect on physiological decay, minimizing the TSS and pH increase and TA decrease. In addition, coating application improved the production of secondary metabolites. The activity of all enzymes involved in ROS detoxification was shown to be promoted by the application of the coating. The degree of browning and oxidative damage that increase progressively with increasing storage time in physiological condition, resulting inhibited by coating. Furthermore, this treatment significantly reduced the protein degradation. Therefore, using the CMC+SA+OA+CA edible coating has the potential to hinder decay and greatly extend the storage period of 'Williams' pear fruit in cold storage.
Phenol 2,4 di-tert butyl, Phenol 3,5 di-tert butyl and isoaromadendrane epoxide: Termiticidal compounds isolated from Lantana camara L.
2024, Journal of Natural Pesticide Research
Termite, a havoc for infrastructure and agriculture, is still progressing its realm and continue its devastating activity to human habitat. Conventional chemicals are not sufficient to prevent infestation and are hazardous too for environment. Lantana camara, an imported wild weed, was analysed to assess the termiticidal potential. Present study was carried out after survey of termite infestation in plants which indicated that L. camara was least affected by termites in studied area thus selected to check anti-termite property against one of the pests Odontotermes obesus (Rambur). An invasive O. obesus brought from crop fields and reared in laboratory by maintaining termite mould like environment in specialized termite box in which temperature was sustained at 27 ± 5 ºC and humidity at 70 ± 5%. No choice test assay proved L. camara methanolic leaf extract was most lethal as responsible to induce 100% mortality and phytochemically most diverse among others. Among isolated phytoconstituents, terpenoids showed 100% mortality at 250 µg concentration. Terpenoids further resolved to find active constituents in which mortality obtained between 5% and 51%. LC4 content was most lethal and induced 51.66% mortality while two other contents LC5 and LC6 showed 30% mortality. GC-HRMS analysis showed that the LC-4 contained Phenol 2,4 di-tert butyl while LC5 contained Phenol 3,5 di-tert butyl and LC6 contained isoaromadendrene epoxide as active phytoconstituents. The results indicated that the detected compounds can be useful termiticidal phytochemicals and might be applicable as bioinsecticide.
An easy-to-clean nanofiber coating containing zanthoxylum bungeanum essential oil/β-cyclodextrin inclusion complex for the preservation of mangoes
2024, Food Control
This work aimed to investigat the properties of an antioxidant nanofiber coating incorporating zanthoxylum bungeanum essential oil and its function in the preservation of mangoes. Results showed that with the increase of zanthoxylum bungeanum essential oil-β-cyclodextrin inclusion complex (ZBEO-β-CD-IC) content in the nanofiber coating, the porosity, water vapor permeability, and oxygen permeability of the coating decreased, but the antioxidant activities increased. During storage, the increase of ZBEO-β-CD-IC content in the coating decreased weight loss and the respiration rate, and delayed the softening of tissue and yellowing of peel color. On the twelfth day, as the ZBEO-β-CD-IC content in the coating increased, the contents of flavonoids, total phenols, and ascorbic acid in mangoes increased from 2.36 × 10⁻² to 2.87 × 10⁻² g kg⁻¹, 23.76 × 10⁻² to 28.06 × 10⁻² g kg⁻¹, and 24.20 × 10⁻² to 39.38 × 10⁻² g kg⁻¹, respectively. Hydrogen peroxide content, superoxide anion rate, and malondialdehyde content decreased from 4.62 to 2.98 mmol kg⁻¹, 0.53 to 0.36 μmol min⁻¹ kg⁻¹, and 8.22 to 6.24 μmol kg⁻¹, respectively. The activities of peroxidase, superoxide dismutase, catalase, ascorbate peroxidase were also inhibited after mangoes were coated in nanofibers containing ZBEO-β-CD-IC.
Hot water infusion technique to prepare antioxidant-rich beverage with pomegranate peel: Formulation, nutritional study and cost analysis
2024, Food Chemistry Advances
This study aimed to utilize the pomegranate by-product for the formulation of antioxidant-rich beverage by the hot water infusion technique. The beverage was prepared with twelve variations of pomegranate peel powder at three different levels i.e. 2, 3 and 4 g along with combinations of three different spices (cardamom, ginger and cinnamon). Organoleptic properties of all the infusion formulations were examined, and it was noticed that the acceptable rate with no significant difference were there amongst the three levels of the pomegranate peel powder. Whereas, significant (p ≤ 0.05) difference in the acceptability of infusions with different spice powders was observed. However, cardamom spiced infusion was most liked by the panellist followed by ginger and cinnamon. Additionally, the antioxidant activity of the beverage was compared with four commercial brands of green teas. Peel infusion's DPPH^● and FRAP values were found to be greater than those of the green tea brands by 18 % and 11 %, respectively. Cost estimation for the most accepted flavour, was also done.

View all citing articles on Scopus

View full text

Analytical, Nutritional and Clinical Methods SectionThe determination of flavonoid contents in mulberry and their scavenging effects on superoxide radicals

Abstract

Introduction

Section snippets

Materials

Determination of percentage dry weight

Extraction of flavonoids

Effects of different pretreatments on the flavonoid content extracted from mulberry leaves

Qualitative analysis of flavonoids in the mulberry

Acknowledgements

Analytical Biochemistry

Phytochemistry

Food Chemistry

Biochemical and Biophysical Research Communications

ESR study of the scavenging effect of natural products of rutin etc superoxide and hydroxyl radical

Acta Biophysica Sinica

Scavenging effects of probimane on active oxygen free radicals by electron spin resonance

Acta Pharmacologica Sinica

Effects of flaononids on thermal autoxidation of Plam oil: structure–activity relationship

Journal of the American Oil Chemists’ Society

Analytical, Nutritional and Clinical Methods Section
The determination of flavonoid contents in mulberry and their scavenging effects on superoxide radicals