Subscribe Now Subscribe Today
Research Article
 

Phytochemical and Antioxidant Activities of Eucheuma spinosum as Natural Functional Food from North Sulawesi Waters, Indonesia



Lena Jeane Damongilala, Defny Silvia Wewengkang, Fitje Losung and Trina Ekawati Tallei
 
Facebook Twitter Digg Reddit Linkedin StumbleUpon E-mail
ABSTRACT

Background and Objective: Research to find functional food from new natural sources has caught the attention of many researchers through the characterization of phytochemicals and biological activities. One potential source of natural ingredients is the red alga Eucheuma spinosum, which has been used as a daily source of natural food. The purpose of this study was to obtain a prospective new source of natural antioxidants from various extracts of tropical red alga (E. spinosum) through several tests, which were used as determinants of whether the alga can be used as a functional food source. Materials and Methods: Algal sample was extracted with organic solvents (methanol, n-hexane, ethyl-acetate and water) and purified by a combination of normal and reverse phase chromatography methods. Results: The algal extracts had antioxidant compounds based on free radical scavenging activities using 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) and superoxide dismutase (SOD). The ethyl acetate extract of E. spinosum scavenged DPPH and SOD free radicals, so that this extract was indicated contained powerful antioxidants. The result of the isolation of the antioxidant compound showed the presence of pure compound 3-(3-methoxyphenyl) propanal. Conclusion: This study concluded that red algae E. spinosum contained natural antioxidants which have the potential to be developed as a functional food and disease prevention and treatment. In addition, the components of these antioxidant compounds from the algae have the potential to be used as natural sources of new functional ingredients.

Services
Related Articles in ASCI
Similar Articles in this Journal
Search in Google Scholar
View Citation
Report Citation

 
  How to cite this article:

Lena Jeane Damongilala, Defny Silvia Wewengkang, Fitje Losung and Trina Ekawati Tallei, 2021. Phytochemical and Antioxidant Activities of Eucheuma spinosum as Natural Functional Food from North Sulawesi Waters, Indonesia. Pakistan Journal of Biological Sciences, 24: 132-138.

DOI: 10.3923/pjbs.2021.132.138

URL: https://scialert.net/abstract/?doi=pjbs.2021.132.138
 
Copyright: © 2021. This is an open access article distributed under the terms of the creative commons attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited.

INTRODUCTION

In the last few decades, research on functional food and its bioactive compounds has been done extensively because it provides health benefits through the content of bioactive compounds1. These compounds have benefits in the prevention and treatment of degenerative diseases and metabolic disorders. The content of bioactive ingredients in food, although in small amounts, contributes to regulating biological mechanisms. This fact shows the potential use of plant bioactive compounds, including algae, as new sources of functional food ingredients and food preservatives.

Eucheuma spinosum is the most important source of many biologically active metabolites, compared to other algae2. This alga contains bioactive compounds, for example, flavonoids, alkaloids, saponins, tannins and their derivatives which have antibacterial properties3 and antioxidants4. Antioxidants are usually added to food to slow down oxidative decline and prevent chronic diseases in the body5. This research was conducted to find a new source of natural antioxidants from tropical alga E. spinosum using 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) and superoxide dismutase (SOD). Phytochemical screening was conducted to determine the presence of secondary metabolites of the alga.

MATERIALS AND METHODS

Specimen collection and determination: Red alga E. spinosum was cultivated and collected in April, 2018 from Arakan waters, North Sulawesi, Indonesia. The specimen was identified at the Plant Taxonomy Laboratory, Department of Biology, Faculty of Mathematics and Natural Sciences, Padjadjaran University, Bandung, Indonesia. This research project was conducted from April-August, 2018.

Extraction method: The fresh alga was well washed in freshwater on the day it was collected and chopped into smaller pieces. The sample was extracted with methanol (analytical grade-Merck Millipore-Germany) and then partitioned in succession with water-n-hexane (analytical grade-Merck Millipore-Germany) and water-ethyl acetate (analytical grade-Merck Millipore-Germany). Then, the supernatant of the mixture was filtered through a Whatman filter (Whatman Clifton, NJ, USA), concentrated in a rotary vacuum evaporator (Buchi, Zurich, Switzerland) and made in a series of concentrations for phytochemical and antioxidant screening with DPPH and SOD activity tests.

Preliminary phytochemical screening: Phytochemical screening was conducted to determine secondary metabolite compounds including alkaloids, terpenoids and flavonoids. The extraction was performed using methanol, n-hexane, ethyl acetate (EtOAc) and water (H2O) solvents by following methods of Harbone6.

DPPH activity assay: The percentage of antioxidant activity (%) of E. spinosum extract was assessed by DPPH free radical test. Measurement of DPPH radical binding activity was carried out according to the method described by Williams et al.7. The sample was reacted with stable DPPH radicals in an ethanol solution. The reaction mixture consisted of 0.5 mL of sample, 3 mL of absolute ethanol and 0.3 mL of DPPH radical solution (0.5 μM in ethanol). DPPH will bind the hydrogen donated by antioxidants contained in the sample. The binding reaction was characterized by a change in color from dark purple to light yellow. The change in color was observed at absorbance with a wavelength of 517 nm after 100 min of reaction using a UV-Vis Spectrophotometer (Shimadzu UV-Vis 1800-Japan). A mixture of ethanol (3.3 mL) and a sample (0.5 mL) are presented as negative controls. A positive control solution was prepared by mixing ethanol (3.5 mL) and a radical DPPH solution (0.3 mL). Quercetin and catechin were used as positive controls. The percentage of scavenging activity (%) was determined based on Mensor et al.8 as follows:

Superoxide dismutase (SOD) activity assay: The SOD activity of the sample was evaluated using the indirect method of riboflavin photoreduction. This method involves a competitive reaction between complex and reduced NBT (nitroblue tetrazolium) for O2% produced by riboflavin in lighting at room temperature (25°C). The sample mixture (240 μL) contained eleven different sample concentrations, 6 μM riboflavin, 0.8 μM N,N,N',N'-tetramethylethylenediamine (TMEDA) in 0.016 M phosphate buffer (pH 7.4 ) and 85 μM NBT. The reaction was stopped by turning off the lights after 15 min (4 fluorescence tubes, Philips TLD/20 W, a distance of 20 cm) and NBT absorbance was measured at λ 560 nm with Thermo Scientific Multiskan GO Microplate Spectrophotometer (Thermo Fisher Scientific GmbH, Germany)9.

Structure determination of active pure compound: The pure compound was isolated from EtOAc extract and its structure was characterized by spectroscopic methods. The 1H and 13C NMR spectra were measured using JEOL JNM ECA 500 MHz NMR Nuclear magnetic resonance spectroscopy (Akishima, Tokyo Japan), which operates at 500 and 125 MHz, respectively.

RESULTS AND DISCUSSION

Rendement and phytochemical composition of E. spinosum extracts: As much as 4.1 kg fresh E. spinosum was extracted with methanol for 3×24 hrs and continued with partitioning using n-hexane-water and EtOAc-H2O. The extract results for each solvent are as follows: MeOH (12.9 g), n-hexane (0.0649 g), EtOAc (0.4969 g) and H2O (8.5265 g). It was observed that the MeOH solvent produced the highest yield of 12.9 g. The extraction results using EtOAc solvent also produced a higher yield than using n-hexane solvent. This means that polar solvents attracted more compounds than non-polar solvent. The composition of secondary metabolites according to the phytochemical screening results is presented in Table 1.

Phytochemical screening results showed that tannin was found in all E. spinosum extracts. Methanol extract also contained steroids and triterpenoids, n-hexane extract contained alkaloids and EtOAc extract contained flavonoids, steroids, triterpenoids and saponins. These results provide strong evidence that alga E. spinosum is a potential source of natural bioactive compounds. This result is supported by previous research which showed that E. spinosum contained important antioxidant compounds10.

Scavenging activities of the extracts: The present study confirmed that n-hexane, EtOAc and H2O extracts had antioxidant activity using DPPH and SOD. Test results showed that algal extract scavenged DPPH free radicals with increased concentration, especially in EtOAc extract. However, water, EtOAc and n-hexane extracts were active with inhibition activity (IC50) of 2,478.1, 402.8 and 1,537.1 ppm, respectively, as shown in Table 2.

The EtOAc extract showed the highest DPPH radical scavenging activity with IC50 of 402.8 ppm compared to reference compounds quercetin and catechin with IC50 of 20.98 and 91.82 ppm, respectively. The activity of these reference compounds is less effective than the activity of EtOAc extract11,12. In a previous publication, it was reported that methanol extract from E. spinosum and E. cottonii scavenged DPPH free radicals with IC50 of 75.27 and 64.73 ppm, respectively13. According to the results of the phytochemical analysis, secondary metabolites such as flavonoids, steroids, terpenoids, saponins and tannins contained in EtOAc extract had linear correlations with their antioxidant activities.

Increased concentrations in E. spinosum extract scavenged SOD free radicals, especially in EtOAc extract. An increase in the antioxidant activity of algae extracts for H2O, EtOAc and n-hexane depended on each concentration. The IC50 of each algal extract was 155, 25 and 870 ppm, respectively, as shown in Table 3.

Analysis of antioxidant based on SOD free radical scavenging activity showed that EtOAc extract was also the most active compared to other extracts, with IC50 of 25 ppm, while SOD activity for quercetin and catechin reference compounds were 3.33 and 26.51 ppm, respectively.

Table 1:Phytochemical composition the E. spinosum extracts

Table 2:Antioxidant DPPH free radical scavenging activities of algal extracts

Table 3:Antioxidant SOD radical scavenging activities of algal extracts

A study reported that E. cottonni methanol extract scavenged SOD free radicals with IC50 of 42.52 ppm14. This shows that the E. spinosum EtOAc extract was more active than the methanol extract of E. cottonni. Other data showed that extracts ethyl acetate of Pinus maririma, commercial pine, Quercus robur, Cinnamomum zeylanicum and Ilex paraguariensis scavenged DPPH free radical, successively at 94.51, 92.79, 88.60, 84.43 and 71.75%. Ethyl acetate extract also scavenged SOD free radicals with a value of 60.32, 53.48, 81.20, 51.79 and 52.44%, respectively15. The data indicate that EtOAc extract was more active in scavenging free radical DPPH and SOD.

Ethyl acetate extract could extract more phenols as evidenced by the presence of tannins, flavonoids, triterpenoids and steroids. The relatively high molecular weight tannin group exhibits greater antioxidant activity than simple phenols16. The hydroxyl phenol group was reported to have a major role in antioxidant activity, especially flavonoids17-19. The combination of phenolic compounds and saponins (crude extracts) had higher antioxidant activity than saponins isolated from the same source. This shows that other molecules increased the antioxidant activity of the extract20. Steroid compounds showed the highest flushing activity in the generation of intracellular ROS21. The triterpenoid content detected in Merlot and Syrah had antioxidant activity22.

DPPH is a stable free radical that is widely used to evaluate natural antioxidants in algae and algal products, because of its stability, simplicity and reproducibility. Some antioxidants can react slowly and some even do not react with DPPH23. DPPH as free radical by the delocalization of the spare electron contributes to changing the deep purple color to pale yellow after a reduction in the substrate24. SOD catalyzes the conversion of Super Oxide (SO) to hydrogen peroxide and oxygen, an important reaction that removes SO in cells. Super Oxide is very reactive and can cause cell damage and excessive amounts trigger reactions that cause damage to biologically important macromolecules, such as DNA, lipids and proteins25,26.

Antioxidants by their mechanism of action are grouped into primary and secondary antioxidants. Primary antioxidants are the main antioxidants that give hydrogen atoms (H) quickly to radical compounds. Radical compounds formed produce lipid derivatives and antioxidant radicals (A*). It acts as a hydrogen atom donor to fat-free radicals, to reshape molecules. So, if antioxidants are given to prevent the formation of new radicals, they will inhibit the process of auto-oxidation27.

Isolation and structure determination of antioxidant compound-1 from the EtOAc extract of E. spinosum: The active antioxidant extract from the EtOAc fraction was selected for further separation of the active compound. Ethyl acetate extract (1.1 g) was chromatographed on Silica G 60 and eluted using a stepwise 5% gradient of n-hexane-EtOAc to produce two active fractions of I or compound-1 (165 mg) and II (178.8 mg).

The pure compound-1 was isolated as a yellowish-brown solid that was soluble in methanol. The 13C-NMR spectrum showed 10 carbon signals including 1 (one) carbonyl carbon at dC 192.7 ppm and 6 (six) olefinic carbon 156.7, 133.5, 133.2, 130.3, 117.1 and 116.2 ppm. Another signal was identified for two methylene carbon at δC 30.1 and 46.3, together with 1 (one) methoxy carbon at δC 56.4 ppm. Correlated with carbon data, it was found from the 1H-NMR spectrum that showed 4 (four) aromatics and 1 (one) proton aldehyde (δH 9.69), respectively. From the J value of 8.4 ppm, two protons at δH 7.76 (H-5') and 7.70 (H-6') were determined at the ortho position, while the other two protons at δH 6.68 (H-4') and 6.90 (H-2') ppm are in the meta position (J = 9.1 ppm). From the HMBC spectrum, the methoxyl group was attached to C-3', with a peak correlation between the methoxyl proton and carbon C-3', while one of the two methylene groups H2-2 and H2-3 was constantly attached to the carbon side of the olefin C-1', the other side was attached to olefinic carbon C-1’ from the aldehyde functional group. Based on the analysis of 1D and 2D-NMR data, the structure of compound-1 was suggested as 3-(3-methoxyphenyl) propanal (synonym: 3-(3-methoxy phenyl) propionaldehyde benzene propanal, 3-methoxy benzene propanal), as seen in Fig. 1.

Fig. 1:
Structure of compound 1 [3-(3-methoxyphenyl) propanal

Confirmation of structure 1 as reported in the publication corresponds to a synthetic compound of the same compound from 3-methoxycinnamic28. Based on references from NMR data, pure-active compounds isolated from tropical alga E. spinosum is reported for the first time in this paper with the following chemical shift values: δC 192.8 (C1), 46.3 (C2), 30.1 (C3), 133.2 (C1'), 117.1 (C2'), 156.7 (C3'), 116.2 (C4'), 133.5 (C5'), 130.3 (C6'), 56.4 (OMe-3'); δH 9.69 (1H, s, H1), 2.74 (2H, t, J = 3.25 and 1.3, H2), 2.10 (2H, s, H3), 6.90 (1H, d, 9.1, H2'), 6.68 (1H, d, J = 8.45, H4'), 7.76 (1H, d, 8.4, H5'), 7.00 (1H, d, 8.4, H6'), 3.90 (2H, s, -OMe).

Antioxidant activity of 3-(3-methoxyphenyl) propanal (compound-1) was tested against DPPH. Data show that compound-1 scavenged DPPH free radicals with IC50 of 87.97 ppm. The antioxidant activity of pure compound-1 was observed at 87.97 ppm. When compared with IC50 of the reference compounds, this pure compound was active like BHT with IC50 of 84.15±3.82 μg mL–1 29, but less active than vitamin C with IC50 of 21 μg mL1 30.

Various food antioxidants have been classified into different categories based on their chemical structure and function, which are water-soluble including citrate, norbixin, betalains, mostly phenolics, flavonoids and anthocyanins and fat-soluble components such as carotenoids, tocopherols, terpenoids and vitamin E31. Foods that are rich in bioactive compounds play important roles in the prevention and treatment of chronic gastrointestinal (GI) diseases32. Functional foods have complex matrices and their composition of bioactive compounds requires careful assessment because potential risks can arise from the isolated material. It is known that plants produce and accumulate a variety of typical chemical compounds, which are usually in low concentrations33.

The alga E. spinosum which is rich in bioactive compounds can be used as a functional food. This alga contained 3- (3-methoxyphenyl) propanal which according to Alghamdi et al.34, this compound were detected in soybean and had antibacterial activity. Natural antioxidants from marine functional food products are reported to be an alternative way to prevent or treat metabolic diseases, such as diabetes, Alzheimer's and stroke35.

In many parts of Indonesia, the alga E. spinosum is used as food and eaten raw or cooked. It’s application as a functional food ingredient containing natural antioxidants, among others, by adding its extract to processed food products, or as a raw material for medicine or for the prevention of certain diseases. This study is a preliminary evaluation aimed at determining the antioxidant activity of E. spinosum. Henceforth, it is necessary to study the content of other antioxidants that have the potential to act as antidotes to free radicals, as well as the process of making food products with the addition of natural antioxidants.

CONCLUSION

In this study, red alga E. spinosum was identified as a potential source of natural antioxidants that actively scavenged free radicals DPPH and SOD, so that it can be used as an alternative antioxidant as a functional food for disease prevention and treatment. The pure antioxidant compound found in E. spinosum extract was predicted as 3-(3-methoxyphenyl) propanal based on its chemical composition.

SIGNIFICANCE STATEMENT

This study discovers that the compound 3-(3-methoxyphenyl) propanal found in E. spinosum extract is a pure antioxidant compound which is thought to have a significant contribution to the high antioxidant activity of this algal extract. This study will help researcher to uncover more potential of this alga as a functional food. This study will help researchers to uncover other types of pure antioxidants contained in this alga that may have a high ability to ward off free radicals. In addition, it can also be used as a reference for formulating this alga as other food additives.

ACKNOWLEDGMENT

This research was funded by the Directorate of Research and Community Service; Directorate General of Research and Development Strengthening; Ministry of Research, Technology and Higher Education, Republic of Indonesia, Budget Year 2018, Contract Number: 087/SP2H/LT/DRPM/2018.

REFERENCES
1:  Yeung, A.W.K., A. Mocan and A.G. Atanasov, 2018. Let food be thy medicine and medicine be thy food: A bibliometric analysis of the most cited papers focusing on nutraceuticals and functional foods. Food Chem., 269: 455-465.
CrossRef  |  Direct Link  |  

2:  El Gamal, A.A., 2010. Biological importance of marine algae. Saudi Pharmaceut. J., 18: 1-25.
CrossRef  |  Direct Link  |  

3:  O'Sullivan, A.M., Y.C. O'Callaghan, M.N. O'Grady, B. Queguineur and D. Hanniffy et al., 2011. In vitro and cellular antioxidant activities of seaweed extracts prepared from five brown seaweeds harvested in spring from the west coast of Ireland. Food Chem., 126: 1064-1070.
CrossRef  |  Direct Link  |  

4:  Safitri, A., A. Srihardyastutie, A. Roosdiana and S. Sutrisno, 2018. Antibacterial activity and phytocemical analysis of edible seaweed Eucheuma spinosum against Stapilococcus aureus. J. Pure Appl. Chem. Res., 7: 308-315.
CrossRef  |  Direct Link  |  

5:  De Alencar, D.B., F.C.T. de Carvalho, R.H. Reboucas, D.R. dos Santos and K.M.D.S. Pires-Cavalcante et al., 2016. Bioactive extracts of red seaweeds Pterocladiella capillacea and Osmundaria obtusiloba (Floridophyceae: Rhodophyta) with antioxidant and bacterial agglutination potential. Asian Pac. J. Trop. Med., 9: 372-379.
CrossRef  |  Direct Link  |  

6:  Harbone, J.B., 1973. Phytochemical Methods: A Guide to Modern Technique of Plant Analysis. 2nd Edn., Chapman Hall, New York, Pages: 278.

7:  Brand-Williams, W., M.E. Cuvelier and C. Berset, 1995. Use of a free radical method to evaluate antioxidant activity. LWT-Food Sci. Technol., 28: 25-30.
CrossRef  |  Direct Link  |  

8:  Mensor, L.L., F.S. Menezes, G.G. Leitao, A.S. Reis, T.C. dos Santos, C.S. Coube and S.G. Leitao, 2001. Screening of Brazilian plant extracts for antioxidant activity by the use of DPPH free radical method. Phytother. Res., 15: 127-130.
CrossRef  |  PubMed  |  Direct Link  |  

9:  Deawati, Y., D. Onggo, I. Mulyani, I. Hastiawan and D. Kurnia et al., 2018. Synthesis, crystal structures and superoxide dismutase activity of two new multinuclear manganese (III)-Salen-4, 4'-bipyridine complexes. Inorg. Chim. Acta, 482: 353-357.
CrossRef  |  Direct Link  |  

10:  Muawanah, M., A. Ahmad and H. Natsir, 2016. Antioxidant activity and toxicity polysaccharide extract from red algae Eucheuma cottonii and Eucheuma spinosum. Marina Chimica Acta, 17: 15-23.
CrossRef  |  Direct Link  |  

11:  Li, X., Y. Liu, Y. Yu, W. Chen, Y. Liu and H. Yu, 2019. Nanoformulations of quercetin and cellulose nanofibers as healthcare supplements with sustained antioxidant activity. Carbohydr. Polym., 207: 160-168.
CrossRef  |  Direct Link  |  

12:  Orhan, I.E., E.K. Akkol, I. Suntar and E. Yesilada, 2019. Assessment of anticholinesterase and antioxidant properties of the extracts and (+)-catechin obtained from Arceuthobium oxycedri (D.C.) M. Bieb (dwarf mistletoe). S. Afr. J. Bot., 120: 309-312.
CrossRef  |  Direct Link  |  

13:  Damongilala, L.J., S.B. Widjanarko, E. Zubaidah and M.R.J. Runtuwene, 2013. Antioxidant activity against methanol extraction of Eucheuma cotonii and E. spinosum collected from North Sulawesi waters, Indonesia. Food Sci. Qual. Manage., 17: 7-13.
Direct Link  |  

14:  Wardani, G., N. Farida, R. Andayani, M. Kuntoro and S.A. Sudjarwo, 2017. The potency of red seaweed (Eucheuma cottonii) extracts as hepatoprotector on lead acetate-induced hepatotoxicity in mice. Pharmacogn. Res., 9: 282-286.
CrossRef  |  Direct Link  |  

15:  Dudonne, S., X. Vitrac, P. Coutiere, M. Woillez and J.M. Merillon, 2009. Comparative study of antioxidant properties and total phenolic content of 30 plant extracts of industrial interest using DPPH, ABTS, FRAP, SOD and ORAC assays. J. Agric. Food Chem., 57: 1768-1774.
CrossRef  |  

16:  Rocha-Guzmán, N.E., R.F. González-Laredo, F.J. Ibarra-Pérez, C.A. Nava-Berúmen and J.A. Gallegos-Infante, 2007. Effect of pressure cooking on the antioxidant activity of extracts from three common bean (Phaseolus vulgaris L.) cultivars. Food Chem., 100: 31-35.
CrossRef  |  Direct Link  |  

17:  Nenadis, N., L.F. Wang, M.Z. Tsimidou and H.Y. Zhang, 2005. Radical scavenging potential of phenolic compounds encountered in O. europaea products as indicated by calculation of bond dissociation enthalpy and ionization potential values. J. Agric. Food Chem., 53: 295-299.
CrossRef  |  Direct Link  |  

18:  Masaek, A., E. Chrzescijanska, M. Latos and M. Zaborski, 2017. Influence of hydroxyl substitution on flavanone antioxidants properties. Food Chem., 215: 501-507.
CrossRef  |  Direct Link  |  

19:  Zhao, F., Q. Zhang, Y. Yan, H. Jia and X. Zhao et al., 2019. Antioxidant constituents of chrysanthemum ‘jinsidaju’ cultivated in Kaifeng. Fitoterapia, 134: 39-43.
CrossRef  |  Direct Link  |  

20:  Garza, C.A., C.A.E. Leal and S.G. Lara, 2018. Steroidal saponin and flavonol content and antioxidant activity during sporophyte development of maguey (Agave salmiana). Plant Foods Hum. Nutr., 73: 287-294.
CrossRef  |  Direct Link  |  

21:  Siddiqui, M.A., Z. Ali, A.G. Chittiboyina and I.A. Khan, 2018. Hepatoprotective effect of steroidal glycosides from Dioscorea villosa on hydrogen peroxide-induced hepatotoxicity in HepG2 cells. Front. Pharmacol., Vol. 9. 10.3389/fphar.2018.00797

22:  Herbeoui, H., I.B. Rebey, I. Ouerghemmi, A.W. Wissem and H. Zemni et al., 2018. Biochemical characterization and antioxidant activity of grape (Vitis vinifera L.) seed oils from nine Tunisian varieties. J. Food Biochem., Vol. 42. 10.1111/jfbc.12595

23:  Balboa, E.M., E. Conde, A. Moure, E. Falque and H. Dominguez, 2013. In vitro antioxidant properties of crude extracts and compounds from brown algae. Food Chem., 138: 1764-1785.
CrossRef  |  

24:  Lim, C.L., R.J. Koh, T.Y. Haw and L.A. Boudville, 2015. Antioxidant activity of the sea bird nest (Eucheuma cottonii) and its radical scavenging effect on human keratinocytes. J. Med. Bioeng., 4: 461-465.
CrossRef  |  Direct Link  |  

25:  Retroningrum, D.S., A.P. Rahayu, D. Mulyanti, A. Dita, O. Valerius and W.T. Ismaya, 2016. Unique characteristics of recombinant hybrid manganese superoxide dismutase from Staphylococcus equorum and S. saprophyticus. Protein J., 35: 136-144.
CrossRef  |  Direct Link  |  

26:  Azadmanesh, J. and G. Borgstahl, 2018. A review of the catalytic mechanism of human manganese superoxide dismutase. Antioxidants, Vol. 7. 10.3390/antiox7020025

27:  Eitenmiller, R.R., W.O. Landen Jr and L. Ye, 2008. Vitamin Analysis for the Health and Food Sciences. 2nd Edn., CRC Press, USA, Pages: 18.

28:  Zhu, L. and R. Hong, 2013. Biomimetic cationic cyclization toward ent-kaurene-type diterpenoids. Chin. J. Chem., 31: 111-118.
CrossRef  |  Direct Link  |  

29:  Lestario, L.N., S. Sugiarto and K.H. Timotius, 2010. Antioxidant activity and total phenolic content of red sea weed (Gracilaria verrucosa L.). Jurnal Teknologi Dan Industri Pangan, 19: 131-138.
Direct Link  |  

30:  Tamat, S.R., T.H. Wikanta and L.S. Maulina, 2007. Antioxidant activity and toxicity of bioactive compounds of Ulva reticulata Forsskal green seaweed extract. Jurnal Ilmu Kefarmasian Indonesia, 5 : 31-36.
Direct Link  |  

31:  Ozkan, G., P. Franco, I.D. Marco, J. Xiao and E. Capanoglu, 2019. A review of microencapsulation methods for food antioxidants: Principles, advantages, drawbacks and applications. Food Chem., 272: 494-506.
CrossRef  |  Direct Link  |  

32:  Chen, Y., H. Zhang, R. Liu, L. Mats and H. Zhu et al., 2019. Antioxidant and anti-inflammatory polyphenols and peptides of common bean (Phaseolus vulga L.) milk and yogurt in Caco-2 and HT-29 cell models. J. Funct. Foods, 53: 125-135.
CrossRef  |  Direct Link  |  

33:  Passari, L.M.Z.G., I.S. Scarminio, G.G. Marcheafave and R.E. Bruns, 2019. Seasonal changes and solvent effects on fractionated functional food component yields from Mikania laevigata leaves. Food Chem., 273: 151-158.
CrossRef  |  Direct Link  |  

34:  Alghamdi, S., H. Migdadi, M. Khan, E.H. El- Harty, M. Ammar, M. Farooq and M. Afzal, 2018. Phytochemical Profiling of Soybean (Glycine max (L.) Merr.) Genotypes Using GC-MS Analysis. In: Phytochemicals: Source of Antioxidants and Role in Disease Prevention, Asao, T. and M. Asaduzzaman (Eds.)., InTech, London, .

35:  Bashar, M.B., M. Akter, M.H. Naim, S. Eatimony and S. Kayser, 2019. Anti-diarrheal and antioxidant activity of methanolic leaf extract of Glycosmis pentaphylla Retz. World J. Pharm. Sci., 7 : 11-15.
CrossRef  |  Direct Link  |  

©  2021 Science Alert. All Rights Reserved