Evaluation of the phytochemical content, antimicrobial and antioxidant activity of Cocos nucifera liquid smoke, Garcinia mangostana pericarp, Syzygium aromaticum leaf, and Phyllanthus niruri L. extracts

Background and Aim: Many plants contain bioactive substances with antibacterial and antifungal properties. The aim of this study was to evaluate the antibacterial and antifungal activity of Cocos nucifera shell liquid smoke (CSL), clove leaf extract (CLE), and mangosteen pericarp extract (MPE) alone and in combination against Escherichia coli and Candida utilis. The antioxidant activity, phenol, saponin, and tannin of CSL, CLE, MPE, and Phyllanthus niruri L. extract were also measured. Materials and Methods: The agar well-diffusion method was used to determine the antimicrobial and antifungal activities of CSL, methanolic MPE, and CLE and their combination CSL+MPE+CLE (COMBI) on bacteria E. coli and fungus (C. utilis). Antioxidant activity was measured by the diphenylpicrylhydrazyl method. Total phenol and total tannin were measured by the Folin–Ciocalteu method and total saponin was measured by the vanillin-sulphate method. Results: The results indicated that phenolic and tannin levels were greater in MPE than in CLE, whereas the saponin content was higher in CLE compared with MPE. Undiluted (100%) MPE exhibited lower antibacterial activity (p<0.05) than chloramphenicol against E. coli, however, undiluted CLE and COMBI showed similar activity compared with chloramphenicol against E. coli. COMBI caused significantly (p<0.05) higher inhibition compared with virginiamycin against E. coli. CSL, MPE, and COMBI exhibited significantly lower antifungal activity (p<0.05) than that of ketoconazole against C. utilis. In contrast, CLE showed improved antifungal activity (p<0.05) compared with ketoconazole. Conclusion: Cocos nucifera liquid smoke, Garcinia mangostana pericarp extract, and Syzygium aromaticum leaf extract, either alone or in combination, have the potential to be used as antibacterial and antifungal agents.