Antioxidant, antibacterial properties and the light barrier assessment of raw and purified melanins isolated from Citrullus lanatus (watermelon) seeds

Open access


Introduction: The nutritive value and terapeuthic activity of watermelon seeds is known, but up to day no studies on isolation and characterisation of their melanin were conducted.

Objective: The aim of the study was to evaluate the antioxidant, antibacterial and light barrier properties of raw and purified melanins isolated from watermelon seeds.

Methods: Native melanin was isolated from seeds by alkaline extraction. Obtained pigment was purified by acid hydrolysis. Chemical tests and FT-IR analysis were conducted to determine the melanin nature of the isolated pigments. UV-Vis, transmittance and colour properties were evaluated spectrophotometrically. Antioxidant activity was determined using ABTS and antibacterial activity through a well diffusion method.

Results: The results of the study demonstrated that melanins isolated from watermelon seeds had antioxidant, light barrier and antibacterial properties. A purified form of melanin had higher antioxidant activity and light barrier properties than the raw form. Both melanins inhibited the growth of Enterococcus faecalis and Pseudomonas aeruginosa.

Conclusions: Watermelon seeds may be considered as a promising source of natural melanin which possess remarkable therapeutic action that can support the traditional use of this plant in the ethnomedicine.

If the inline PDF is not rendering correctly, you can download the PDF file here.

  • 1. Deshmukh CD Jain A Tambe MS. Phytochemical and pharmacological profile of Citrullus lanatus (Thunb). Biolife 2015; 3(2):483-488. doi:

  • 2. Mehra M Pasricha V Gupta R. Estimation of nutritional phytochemical and antioxidant activity of seeds of musk melon (Cucumis melo) and water melon (Citrullus lanatus) and nutritional analysis of their respective oils. J Pharmacogn Phytochem 2015; 3(6):98-102.

  • 3. Tabiri B Agbenorhevi JK Wireko-Manu FD Ompouma EI. Watermelon seeds as food: nutrient composition phytochemicals and antioxidant activity. IJNFS 2016; 5(2):139-144. doi:

  • 4. Adetutu A Olorunnisola OS Owoade OA. Nutritive values and antioxidant activity of Citrullus lanatus fruit extract. Food Nutr Sci 2015; 6:1056-1064. doi:

  • 5. Seidu KT Otutu OL. Phytochemical composition and radical scavenging activities of watermelon (Citrullus lanatus) seeds constituents. Croat J Food Sci Technol 2016; 8(2):83-89. doi:

  • 6. Edwards AJ Vinyard BT Wiley ER Brown ED Collins JK Perkins-Veazie P et al. Consumption of watermelon juice increase plasma concentrations of lycopene and β-carotene in humans. J Nutr 2003; 133:1043-1050.

  • 7. Scheiber A Stintzing FC Carle R. By-products of plant food processing as a source of functional compounds – recent developments. Trends Food Sci Technol 2001; 12(11):401-413. doi:

  • 8. Wani AA Sogi DS Singh P Wani IA Shivhare US. Characterisation and functional properties of watermelon (Citrullus lanatus) seeds proteins. J Sci Food Agric 2011; 91:113-121. doi:

  • 9. Sani UM. Phytochemical screening and antidiabetic effect of extracts of the seeds of Citrullus lanatus in alloxan-induced diabetic albino mice. J Appl Pharm Sci 2015; 5(3):51-54. doi:

  • 10. Rahman H Manjula K Anoosha T Nagaveni K Chinna Eswaraiah M Bardalai D. In-vitro and antioxidant activity of Citrullus lanatus seeds extracts. Asian J Pharm Clin Res 2013; 6(3):152-157.

  • 11. Oyeleke GO Olagunju EO Ojo A. Functional and physiochemical properties of watermelon (Citrullus lanatus) seeds and seed-oil. IOSR-JAC 2012; 2(2):29-31. doi:

  • 12. Koocheki A Razavi SMA Milani E Moghadam TM Abedini M Alamatiyan S et al. Physical properties of watermelon seed as a function of moisture content and variety. Int Agrophysics 2007; 21:349-359.

  • 13. Erhirhie EO Ekene NE. Medicinal values of Citrullus lanatus (Watermelon): Pharmacological review. IJRPBS 2013; 4(4):1305-1312.

  • 14. Mbonyiryivuze A Nuru ZY Ngom BD Mwakikunga B Dhlamini SM Park E et al. Morphological and chemical composition characterization of commercial sepia melanin. AJN 2015; 3(1):22-27. doi:

  • 15. Li H Li J Zhao Z. Characterisation of melanin isolated from apricot (Armeniaca sibirica) and its effect on hydrazine-induced rat hepatic injury. Sci Asia 2016; 42:382-391. doi:

  • 16. Wang H Pan Y Tang X Huang Z. Isolation and characterization of melanin from Osmanthus fragrans’ seeds. LWT – Food Sci Technol 2006; 39(5):496-502. doi:

  • 17. Kannan P Ganjewala D. 2009. Preliminary characterization of melanin isolated form frutis and seeds of Nyctanthes arbor-tristis. J Sci Res 1(3):655-661. doi:

  • 18. Cuevas-Juárez E Yuriar-Arredondo KY Pío-León JF Montes-Avila J López-Angulo G Díaz-Camacho SP et al. Antioxidant and α-glucosidase inhibitory properties of soluble melanins from the fruits of Vitex mollis Kunth Randia echinoc-arpa Sessé et Mociño and Crescentia alata Kunth. J Funct Foods 2014; 9:78-88. doi:

  • 19. Al-Tayib OA El Tahir KE Idriss MH Eram KE Hassib AM. Nigella sativa L. seeds melanin: A new hypoglycemic agent. Comparison with insulin in alloxan-diabetic rats. SAJP 2014; 3:332-335.

  • 20. Chitturi S Gopichand V Vuppu S. Studies on protein content protease activity antioxidants potential melanin composition glucosinolate and pectin constitution with brief statistical analysis in some medicinally significant fruit peels. Der Pharmacia Lettre 2013; 5(1):13-23.

  • 21. Sava V Galkin B Hung MY Yang PC Huang GS. A novel melanin-like pigment derived from black tea leaves with immuno-stimulating activity. Food Res Int 2001; 34:337-343. doi:

  • 22. Kurian NK Nair HP Bhat SG. Melanin producing Pseudomonas stutzeri BTCZ10 from marine sediment at 96 m depth (Sagar Sampada cruise #305). Int J Curr Biotechnol 2014; 2(5):6-11.

  • 23. Laxmi M Kurian NK Smitha S Bhat SG. Melanin and bacteriocin from marine bacteria inhibit biofilms of foodborne pathogens. Indian J Biotechnol 2016; 15(3):392-399.

  • 24. Łopusiewicz Ł. Isolation characterisation and biological activity of melanin from Exidia nigri-cans. WSN 2018; 91:111-129.

  • 25. Łopusiewicz Ł. Scleroderma citrinum melanin: isolation purification spectroscopic studies with characterization of antioxidant antibacterial and light barrier properties. WSN 2018; 94:114-129.

  • 26. Solano F. Melanins: skin pigments and much more – types structural models biological functions and formation routes. New J Sci 2014. doi:

  • 27. Zhang M Xiao G Thring RW Chen W Zhou H Yang H. Production and characterization of melanin by submerged culture of culinary and medicinal fungi Auricularia auricula. Appl Biochem Biotechnol 2015; 176:253-266. doi:

  • 28. Yao Z Qi J Wang L. Isolation fractionation and characterization of melanin-like pigments from chestnut (Castanea mollissima) shells. J Food Sci 2012; 77(6):671-676. doi:

  • 29. Selvakumar P Rajasekar S Periasamy K Raaman N. Isolation and characterization of melanin pigment from Pleurotus cystidiosus (telomorph of Antromycopsis macrocarpa). World J Micro-biol Biotechnol 2008; 24:2125-2131. doi:

  • 30. Zhan F He Y Zu Y Li T Zhao Z. Characterisation of melanin isolated form a dark septate endophyte (DSE) Exophiala pisciphila. World J Microbiol Biotechnol 2011; 27:2483-2489. doi:

  • 31. Ye M Wang Y Qian M Chen X Hu X. Preparation and properties of the melanin from Lachnum singerianum. IJBAS-IJENS 2011; 11(3):51-58.

  • 32. Nerson H. Effects of seed maturity extraction practices and storage duration on germinability in watermelon. Sci Hort 2002; 93:245-256. doi:

  • 33. Mavi K. The relationship between seed coat color and seed quality in watermelon Crimson sweet. Hort Sci (Prague) 2010; 37(2):62-69.

  • 34. Zhang XK Yang GT Chen L Yin JM Tang ZL Li JN. Physiological differences between yellow-seeded and black-seeded rapeseed (Brassica napus L.) with different testa characteristics during artificial ageing. Seed Sci Technol 2006; 34:373-381. doi:

  • 35. Różanowska M Sarna T Land EJ Truscott TG. Free radical scavenging properties of melanin: interaction of eu- and pheo-melanin models with reducing and oxidizing radicals. Free Radic Biol Med 1999; 26:518-525. doi:

  • 36. Hung Y-Ch Sava V Makan S Chen Tz-HJ Hong M-Y Huang GS. Antioxidant activity of melanins derived from tea: comparision beteen different oxidative states. Food Chem 2002; 78:233-240. doi:

  • 37. Adunola AT Chidimma AL Olatunde DS Peter OA. Antibacterial activity of watermelon (Citrullus lanatus) seed against selected microorganisms. Afr J Biotechnol 2015; 14(14):1224-1229. doi:

  • 38. Thirunavukkarasu P Ramanathan T. Screening of antimicrobial effects of watermelon. J Biol Sci 2010; 10:682-685. doi:

  • 39. Sathya J Shoba FG. Assessment of antimicrobial efficacy of Citrullus lanatus methanolic seed extract. J Chem Pharm Res 2014; 6(12):640-643.

  • 40. Helan Soundra Rani M Ramesh T Subramanian J Kalaiselvam M. Production and characterization of melanin pigment from halophilic black yeast Horatea werneckii. IJPRR 2013; 2(8):9-17.

  • 41. Xu C Li J Yang L Shi F Yang L Ye M. Antibacterial activity and a membrane damage mechanism of Lachnum YM30 melanin against Vibrio parahaemolyticus and Staphylococcus aureus. Food Control 2017; 73:1445-1451. doi:

  • 42. Correa N Covarrubias C Rodas PI Hermosilla G Olate VR Valdés C et al. Differential antifungal activity of human and cryptococcal melanins with structural discrepancies. Front Microbiol 2017; 8:1-13. doi:

Journal information
All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 571 423 20
PDF Downloads 420 309 5