Bioactive compounds and microbial evaluation of African walnuts (Tetracarpidium conophorum (Mull. Arg.) Hutch & Dalziel) retailed in Ilorin Metropolis

Document Type : Original research paper

Authors
1 Department of Plant Biology, Faculty of Life Sciences, University of Ilorin
2 Department of Plant Biology, Faculty of Life Sciences, University of Ilorin.
Abstract
The African walnut (Tetracarpidium conophorum) is a nutrient-dense tropical fruit that provides numerous health benefits and offers a wealth of nutritional value. This study investigated the bioactive compounds and microbes associated with African walnuts retailed in the Ilorin Metropolis. After preparing stock solutions from the obtained nuts, microbial isolations were carried out on Potatoes Dextrose Agar (fungi), Nutrient Agar, and Eosin Methylene Blue Agar (bacteria) using the pour plate method. Sixteen bioactive compounds of very significant therapeutic values were identified in the raw nuts using Gas Chromatography-Mass Spectrometry (GC-MS). Also, molecular identification of the fungal species and biochemical characterization of the bacterial species isolated from the nuts revealed the presence of four fungal species, namely Aspergillus niger, Penicillium rolfsii, Rhizopus delemar and Rhizopus arrhizus, as well as three bacterial species, namely Bacillus cereus, Staphylococcus aureus, and Escherichia coli. The GC-MS results revealed the nutritional and medicinal benefits of consuming cooked African walnuts; however, the microbial screening serves as a precaution for those consuming cooked African walnuts retailed in the Ilorin metropolis.
Keywords

Adetunji, J.B., Adetunji, C.O., and Olaniyan, O.T. (2021). African walnuts: A natural depository of nutritional and bioactive compounds essential for food and nutritional security in Africa. J. Food Secur.: 331-354.
Afolabi, O.J., Oladele, O.O., and Olususi, F.C. (2020). Assessment of bacterial loads of Clarias gariepinus (Burchell, 1822) obtained from cultured and natural habitats. J Basic Appl Zool 81: 1-7.
Alenazy, R. (2023). Antimicrobial activities and biofilm inhibition properties of Trigonella foenumgraecum methanol extracts against multidrug-resistant Staphylococcus aureus and Escherichia coli. Life 13(3): 703.
Amusa, T., Adefalu, L., and Aderinoye-Abdulwahab, S. (2016). Socio-economic potentials and threats to the African walnut in tropical lowland rainforests of southwest Nigeria. J Agric Res Dev 15(2): 88-99.
Asuzu-Samuel, H.O., and Nnamdi, J.G. (2023). Isolation and characterization of the bioactive components in Tetracarpidium conophorum as dissolvent in methanol. J. Adv. Res. Rev 20(3): 1878-1883.
Ayodeji, A.E., and Aliyu, N. (2018). Tetracarpidium conophorum (African walnut) Hutch. & Dalziel: Ethnomedicinal uses and its therapeutic activities. J. Med. Plant. Econ. Dev 2(1): 1-10.
Aziz, M., Ahmad, S., Khurshid, U., Pervaiz, I., Lodhi, A.H., Jan, N., Khurshid, S., Arshad, M.A., Ibrahim, M.M., and Mersal, G.A. (2022). Comprehensive biological potential, phytochemical profiling using GC-MS and LC-ESI-MS, and in-Silico assessment of Strobilanthes glutinosus Nees: an important medicinal plant. Molecules 27(20): 6885.
Bhat, M.P., Kumar, R.S., Chakraborty, B., Nagaraja, S.K., Babu, K.G., and Nayaka, S. (2024). Eicosane: An antifungal compound derived from Streptomyces sp. KF15 exhibits inhibitory potential against major phytopathogenic fungi of crops. Environ. Res. 251: 118666.
Corbu, V.M., Gheorghe-Barbu, I., Dumbravă, A.Ș., Vrâncianu, C.O., and Șesan, T.E. (2023). Current insights in fungal importance—a comprehensive review. Microorganisms 11(6): 1384.
Edeh, J.A., Anjorin, T.S., Asala, S.W., Onyeiwu, S.C., and Akpan, G.E. (2024). Assessment of handling practices and microbial contamination of raw and cooked African walnut (Tetracarpidium conophorum) fruit snacks in Abuja Nigeria markets. J Adv Res Rev 22(1): 888-897.
El-Shahir, A.A., El-Wakil, D.A., Abdel Latef, A.A.H., and Youssef, N.H. (2022). Bioactive compounds and antifungal activity of leaves and fruits methanolic extracts of Ziziphus spina-christi L. Plants 11(6): 746.
Eze, V., Maduka, N., Ahaotu, I., and Odu, N. (2019). Microbiological quality and shelf life of pickled African Walnut (Tetracarpidium conophorum) preserved with lactic and citric acids. Microbiol. Res. J. Int. 26(1): 1-18.
Fakile, O., Solana, O., and Okolosi, J. (2023). Antimicrobial activity of african walnut (Tetracarpidium conophorum) oil against bacterial and fungal species causing food spoilage and food poisoning diseases. J Food Agric.
Freeman Weiss, Z., Leon, A., and Koo, S. (2021). The evolving landscape of fungal diagnostics, current and emerging microbiological approaches. J. Fungus 7(2): 127.
Garuba, T., Ajala, F.A., Olahan, G.S., and Lateef, A.A. (2024). Molecular identification of dominant microbes in Kola nut (Cola nitida). Badeggi J. Agri Res Env 6(1): 13-24.
Gupta, L., Vermani, M., Kaur Ahluwalia, S., and Vijayaraghavan, P. (2021). Molecular virulence determinants of Magnaporthe oryzae: disease pathogenesis and recent interventions for disease management in rice plant. Mycology 12(3): 174-187.
Hatami, S., Mohamadi Sani, A., and Yavarmanesh, M. (2016). Chemical composition and antibacterial activity of organic extra virgin olive oil from Iran. Nutr Food Sci 46(3): 388-395.
Ikpeme, E., Ekaluo, U., Udensi, O., Ekerette, E., Ekpo, P., and Asuquo, B. (2014). Sperm quality and hormone profile of male albino rats fed with seeds of African walnut (Tetracarpidium conophorum, Mull). Annu. Res. Rev. 4(9): 1379-1386.
Javed, M.R., Salman, M., Tariq, A., Tawab, A., Zahoor, M.K., Naheed, S., Shahid, M., Ijaz, A., and Ali, H. (2022). The antibacterial and larvicidal potential of bis-(2-ethylhexyl) phthalate from Lactiplantibacillus plantarum. Molecules 27(21): 7220.
Kowalska, J., Maćkiw, E., Stasiak, M., Kucharek, K., and Postupolski, J. (2020). Biofilm-forming ability of pathogenic bacteria isolated from retail food in Poland. J. Food Prot. 83(12): 2032-2040.
Krishnamoorthy, K., and Subramaniam, P. (2014). Phytochemical profiling of leaf, stem, and tuber parts of Solena amplexicaulis (Lam.) Gandhi using GC‐MS. Int. Sch. Res. Not. 2014(1): 567409.
Laux, C., Peschel, A., and Krismer, B. (2019). Staphylococcus aureus colonization of the human nose and interaction with other microbiome members. Microbiol. Spectr. 7(2): 10.1128/microbiolspec. gpp1123-0029-2018.
Liu, Y.-G., and Chen, Y. (2007). High-efficiency thermal asymmetric interlaced PCR for amplification of unknown flanking sequences. Biotechniques 43(5): 649-656.
Matotoka, M.M., Mashabela, G.T., and Masoko, P. (2023). Phytochemical content, antibacterial activity, and antioxidant, anti‐inflammatory, and cytotoxic effects of traditional medicinal plants against respiratory tract bacterial pathogens. J Evid Based Complementary Altern Med 2023(1): 1243438.
Mukarram, S.A., Wandhekar, S.S., Ahmed, A.E.M., Várallyay, S., Pandey, V.K., József, P., and Bela, K. (2024). Global perspectives on the medicinal implications of green walnut and its benefits: A comprehensive review. Horticulturae 10(5): 433.
Musangi, C.R., Juma, B.S., Mukhebi, D.W., Isoe, E.M., Kibiti, C.M., and Mbinda, W.M. (2024). Aspergillus population diversity and its role in aflatoxin contamination of cashew nuts from coastal Kenya. PLoS One 19(1): e0292519.
Muzahid, A.A., Sharmin, S., Hossain, M.S., Ahamed, K.U., Ahmed, N., Yeasmin, M.S., Ahmed, N.U., Saha, B.K., Rana, G.M., and Maitra, B. (2023). Analysis of bioactive compounds present in different crude extracts of Benincasa hispida and Cucurbita moschata seeds by gas chromatography-mass spectrometry. Heliyon 9(1).
Nakaziba, R., Amanya, S.B., Sesaazi, C.D., Byarugaba, F., Ogwal-Okeng, J., and Alele, P.E. (2022). Antimicrobial bioactivity and GC‐MS analysis of different extracts of Corchorus olitorius L leaves. Sci. World J. 2022(1): 3382302.
Nooralden, Z.N. (2022). Isolation and identification of fungi associated with walnuts, almonds, hazelnuts, cashews, pistachios and peanuts using molecular diagnostics technique (PCR) in the local markets of Kirkuk Governorate/Iraq. J Pharm Negat Results: 156-160.
Oladimeji, B.M., and Adebo, O.A. (2023). Dataset of metabolites extracted from African walnut (Tetracarpidium conophorum) using two different solvents. Data in Brief 47: 108930.
Olivia, N.U., Goodness, U.C., and Obinna, O.M. (2021). Phytochemical profiling and GC-MS analysis of aqueous methanol fraction of Hibiscus asper leaves. Futur. J. Pharm. Sci. 7: 1-5.
Paulussen, C., Hallsworth, J.E., Álvarez‐Pérez, S., Nierman, W.C., Hamill, P.G., Blain, D., Rediers, H., and Lievens, B. (2017). Ecology of aspergillosis: insights into the pathogenic potency of Aspergillus fumigatus and some other Aspergillus species. Microb. Biotechnol. 10(2): 296-322.
Raja, H.A., Miller, A.N., Pearce, C.J., and Oberlies, N.H. (2017). Fungal identification using molecular tools: a primer for the natural products research community. J. Nat. Prod. 80(3): 756-770.
Ryu, S., Shin, M., Yun, B., Lee, W., Choi, H., Kang, M., Oh, S., and Kim, Y. (2021). Bacterial quality, prevalence of pathogens, and molecular characterization of biofilm-producing Staphylococcus aureus from Korean dairy farm environments. Animals 11(5): 1306.
Salem, S.H., El-Maraghy, S.S., Abdel-Mallek, A.Y., Abdel-Rahman, M.A., Hassanein, E.H., Al-Bedak, O.A., and El-Aziz, F.E.-Z.A.A. (2022). The antimicrobial, antibiofilm, and wound healing properties of ethyl acetate crude extract of an endophytic fungus Paecilomyces sp.(AUMC 15510) in earthworm model. Sci. Rep. 12(1): 19239.
Semwal, P., Painuli, S., Badoni, H., and Bacheti, R.K. (2018). Screening of phytoconstituents and antibacterial activity of leaves and bark of Quercus leucotrichophora A. Camus from Uttarakhand Himalaya. Sci. Rep. 4: 1-6.
Shaaban, M.T., Ghaly, M.F., and Fahmi, S.M. (2021). Antibacterial activities of hexadecanoic acid methyl ester and green‐synthesized silver nanoparticles against multidrug‐resistant bacteria. J. Basic Microbiol. 61(6): 557-568.
Shigaeva, J., and Darr, D. (2020). On the socio-economic importance of natural and planted walnut (Juglans regia L.) forests in the Silk Road countries: A systematic review. For. Policy Econ. 118: 102233.
Stucky, B.J. (2012). SeqTrace: a graphical tool for rapidly processing DNA sequencing chromatograms. J. Biomol. Tech. 23(3): 90.
Zahara, K., Bibi, Y., Arshad, M., Kaukab, G., Al Ayoubi, S., and Qayyum, A. (2022). In-vitro examination and isolation of antidiarrheal compounds using five bacterial strains from invasive species Bidens bipinnata L. Saudi J. Biol. Sci. 29(1): 472-479.
 
Volume 12, Issue 1
June 2024
Pages 49-59

  • Receive Date 06 September 2024
  • Revise Date 28 October 2024
  • Accept Date 29 October 2024
  • First Publish Date 29 October 2024