The Inhibitory Activity of Anthraquinones against Pathogenic Protozoa, Bacteria, and Fungi and the Relationship to Structure

Abstract

<jats:p>Plant-derived anthraquinones were evaluated in cell assays for their inhibitory activities against the parasitic protozoa Trichomonas vaginalis human strain G3 that causes the sexually transmitted disease trichomoniasis in women, Tritrichomonas foetus bovine strain D1 that causes sexually transmitted diseases in farm animals (bulls, cows, and pigs), Tritrichomonas foetus-like strain C1 that causes diarrhea in domestic animals (cats and dogs), and bacteria and fungi. The anthraquinones assessed for their inhibitory activity were anthraquinone, aloe-emodin (1,8-dihydroxy-3-hydroxymethylanthraquinone), anthrarufin (1,5-dihydroxyanthraquinone), chrysazin (1,8-dihydroxyanthraquinone), emodin (1,3,8-trihydroxy-6-methylanthraquinone), purpurin (1,2,4-trihydroxyanthraquinone), and rhein (1,8-dihydroxy-3-carboxyanthraquinone). Their activities were determined in terms of IC50 values, defined as the concentration that inhibits 50% of the cells under the test conditions and calculated from linear dose response plots for the parasitic protozoa, and zone of inhibition for bacteria and fungi, respectively. The results show that the different substituents on the anthraquinone ring seem to influence the relative potency. Analysis of the structure–activity relationships in protozoa indicates that the aloe-emodin and chrysazin with the highest biological activities merit further study for their potential to help treat the diseases in women and domestic and farm animals. Emodin also exhibited antifungal activity against Candida albicans. The suggested mechanism of action and the additional reported beneficial biological properties of anthraquinones suggest that they have the potential to ameliorate a broad spectrum of human diseases.</jats:p>

Anti-trichomonad activities of different compounds from foods, marine products, and medicinal plants: a review

“…We evaluated the anti-trichomonad activities of six anthraquinones, the structures of which are shown in Fig. 3, against the three pathogenic protozoal strains G3 (human), C1 (bovine), and D1 (feline) mentioned earlier [103] These results show that aloe-emodin was the most active compound against the three strains and that structurally different anthraquinones are a major source of new trichomonacidal compounds. In related studies, we have shown that some of the mentioned anthraquinones exhibited antioxidative and anti-inflammatory properties in chemical assays and macrophage cells [104], and that purpurin added to a high-fat diet significantly reduced weight gain in mice [105].…”

Activity of Anthracenediones and Flavoring Phenols in Hydromethanolic Extracts of Rubia tinctorum against Grapevine Phytopathogenic Fungi

“…It is known that increasing the activity of a parent molecule can be pursued either by testing multiple substituent changes on the base core (the impact of the number, nature, and location of substituents on the anthraquinone moiety on its inhibitory potency against pathogenic fungi has been studied in [ 42 ]), or by testing the effect of coexistence with other molecules with which synergistic behavior may occur. In general, anthraquinone per se is a relatively inert compound, but in the presence of glucose, anthrahydroquinone units (formed by reduction of anthraquinone) reduce the quinone–methide units (issued by dehydration of phenolic β - O -4 lignin) mainly by electron transfer leading to guaiacol [ 43 ].…”

In vitro antidermatophytic activity of bioactive compounds from selected medicinal plants

“…According to Brilhante, (2020), the antifungal mechanism of anthraquinones may be related to the inhibition of (1,3)-β-D-glucan synthase activity, leading to disruption of (1,3)-β-D-glucans in the fungal cell wall. High antifungal activity of anthraquinone aglycones was reported against clinical strains of dermatophytes in Senna alata leaves, and C. fistula pod pulp (Wuthi-udomlert et al 2010 ; Chewchinda et al 2013 ; Friedman et al 2020 ) reported the inhibitory potency of plant derived anthraquinones against pathogenic fungi.…”