Investigation of functional characteristics of water soluble polysaccharides and ethanolic extract from Plantago major

Introduction:In recent years,attention has been paid to medicinal plant and its extracted compounds due to desirable functional properties as the natural additives in food technology and for producing functional food. According to the mentioned cases, it is observed that in no period has the attention to medicinal plants and the effects of their use and method of use been completely stopped (Mirshekari,1394). Due to the fact that the active ingredients in herbal medicines have a state of biological equilibrium due to their association with other substances, so they do not accumulate in the body and do not cause side effects. Therefore, a significant advantage over medicines. They have chemicals (Maghsoudi et al,1397).One of the applications of medicinal plants is their use as antimicrobial agents. Studies show that extracts of many medicinal plants are able to inhibit the growth of microorganisms(Kermanshahi,1385). Increased use and use of common therapeutic antibiotics leads to the spread of antibiotic-resistant pathogenic microbial species.In other words, the emergence of these antibiotic-resistant strains prolongs the healing process. Therefore, paying attention to medicinal and native plants with antimicrobial effect can greatly reduce the problems caused by antibiotics (Nejati et al,2013). Plantago major is a perennial plant of the genus (Plantago major). Botanically,the leaf of a perennial plant is apparently hairless or slightly hairy (Alizadeh Behbahani et al, 2013). This plant is widely cultivated in Iran and the production of many seeds is one of the main characteristics of this plant (Samuelsen, 2000). Plantago genus includes species wellknown as medicinal plants and others can be used for food and animal feeding (P. coronopus, P. lanceolata, P. serraria). A large amount of data about the Plantago species usage refers to the leaves both in traditional and modern medicine (Oprica et al,2015). Traditionally, this plant has been used as a wound healer, immune booster and antioxidant (Samuelsen, 2000). In ancient medicine, fresh Plantago leaves were effective in healing wounds. This plant not only protects wounds from infection but also helps to heal quickly (Stanisavljevic et al ,2008). Plantago major contained significant amounts of phenolic compounds and has a potential antioxidant and antibacterial activities (Karima et al,2015). The medicinal plant (Plantago major) contains the glycoside compounds ocobin and plantagen and its antimicrobial properties and its growth is possible in most parts of Iran.This plant is involved in the treatment of respiratory problems, blood purification, fever, diarrhea, reduction of rheumatic pain, healing of inflammation of the kidneys and bladder (Amin,1384). The aim of this study was to extract polysaccharide and ethanolic extract from Plantago major and was to evaluate its functional properties.
Material and methods: In this study, Plantago with skin was prepared from Ahvaz city (Khuzestan province).Bacterial microbial strains were purchased from Iran Scientific-Industrial Research Organization and all chemicals used by German Merck Company. Extraction of polysaccharides was performed during several stages included defatting, water extraction and sedimentation with ethanol. Ethanol extract was prepared using 80% ethanol at room temperature. To investigate the structural properties of extracts Fourier transform infrared (FTIR) was used. The Fourier transform infrared range from 400 to 4000 cm-1 with a resolution of cm-1 was recorded using a spectrometer equipped with ATR system. Functional properties, including water holding capacity (WHC) and oil absorption capacity (LAC) of extracts extracted from plantago seeds were calculated according to the method of Carvalho et al (2009). Antioxidant activity was calculated using the DPPH method. DPPH radicals are widely recognized as a suitable method for evaluating the ability of antioxidant compounds to trap free radicals. Antimicrobial property of extracts against on Staphylococcus aureus and Escherichia coli was studied using microdilution broth. To determine the antimicrobial properties, Staphylococcus aureus index bacterium was used as gram-positive and Escherichia coli as gram-negative. All data were analyzed using SPSS software version 21 in a completely randomized design and the means were compared using one-way analysis of variance and Duncan's test at 95% level.
Results and discussion: Characteristic bands in FTIR spectra of both extract were same.In the FTIR spectrum of isolated polysaccharides, polysaccharide index bands and some effective groups were observed in their bioactive properties. The results showed that the indicator absorption bands in the infrared Fourier transform spectrum were similar for both types of extracts.The results showed that the extracted polysaccharides in compared with ethanol extract had lower (WHC) and higher (LAC)(p<0.01). In this study, the water absorption capacity of the extracted ethanolic extract and polysaccharide were observed 8.1 and 2.1, respectively.The antioxidant activity of polysaccharide extract was more than ethanolic extract. Thus, the antioxidant activity of the extracted polysaccharide at concentrations of (1,2,3,4)% was reported to be (18,31,36,44)%, respectively, which was higher compared to ethanolic extract. With increasing the concentration of polysaccharide and ethanolic extracts plantago major, a significant increase in antioxidant or free radical scavenging of DPPH was observed (P<0.05). Observation of optimal antioxidant activity in the studied concentrations showed that this extract can be used as an alternative to synthetic antioxidants and by delaying the oxidation of fat in food to maintain nutritional value and create desirable sensory properties. The effect of ethanolic extracts to inhibit the growth of Staphylococcus aureus and Escherichia coli was more than polysaccharides but bactericidal effect of both extract against of studied bacteria was same.
Conclusion: In recent years, the presence of antimicrobial compounds in extracts and essential oils of medicinal plants, long-term storage of food without additives and improving the quality of storage during storage have been considered by most researchers in this industry. Therefore, the relationship between medicinal plants and their health properties, with existing technologies in the food industry, guarantees the health of consumers and improves health properties. The result of this study indicating the application potential of the extracts isolated from Plantago major in food technology for modification of food formulation and creation of health promoting effects for producing functional food and food without chemical additive. It is hoped that based on this research, a big step will be taken to use this useful medicinal plant in the food industry.