Antifungal properties of 1,3,7-trimethylxanthine, isolated from Coffea arabica

Anti-Alzheimer's disease potential of Arabian coffee versus Date palm seed extract in male rats

Coffee is among the most commonly consumed beverage all over the world. Studies have increasingly suggested caffeine and coffee as effective therapeutic interventions against Alzheimer's disease (AD). We have therefore utilized the aluminum chloride rat model for AD to compare the influence of moderately caffeinated (Arabian) and decaffeinated (Date palm seed) coffee on cognitive impairment and pathological events in AD. AD rats given Arabian or Date palm seed coffee were protected against memory impairment and had lower serum levels of the abnormal protein (amyloid-beta; Aβ1-42), the central pathogenic contributor to AD, and transforming growth factor-beta (TGF-β). Interestingly, Date palm seed (decaffeinated) coffee seems to provide more pronounced protection against AD than Arabian (moderately caffeinated) coffee as evidenced by the greater decrease in serum Aβ levels. These results suggest a surprising therapeutic potential of moderate caffeine intake in Arabian coffee to ameliorate AD through decreasing serum Aβ levels. However, Date palm seed (decaffeinated) coffee, rich in flavonoids, appears to provide a better AD-modifying ability through a direct reduction of Aβ production. PRACTICAL APPLICATIONS: Consumption of moderately caffeinated Arabian coffee attenuated AD-induced cognitive impairment via its anti-amyloidogenic potential, decreasing Aβ levels. Moreover, intake of decaffeinated Date seed extract, rich in flavonoids, exerted a superior anti-AD potential through a direct reduction of Aβ production. Both of them were also safe and maintained hepatic and renal functions in a rat model of AlCl₃ -induced AD. Further clinical studies are warranted to confirm current results and to recommend the regular drinking of Arabian coffee or Date seed extract as a protective approach to delay AD progression in vulnerable individuals or in early disease stages.

Caffeine fostering of mycoparasitic fungi against phytopathogens

Caffeine (1,3,7-trimethixanthine) is a typical purine alkaloid produced in more than 80 plant species. Its biological role is considered to strengthen plant's defense capabilities, directly as a toxicant to biotic attackers (allelopathy) and indirectly as an activator of defense system (priming). Caffeine is actively secreted into rhizosphere through primary root, and possibly affects the structure of microbe community nearby. The fungal community in coffee plant rhizosphere is enriched with particular species, including Trichoderma family, a mycoparasite that attacks and kills phytopathogens by coiling and destroying their hyphae. In the present study, the caffeine response of 8 filamentous fungi, 4 mycoparasitic Trichoderma, and 4 prey phytopathogens, was examined. Results showed that allelopathic effect of caffeine on fungal growth and development was differential, being stronger on pathogens than on Trichoderma species. Upon confronting, the prey immediately ceased the growth, whereas the predator continued to grow, indicating active mycoparasitism to have occurred. Caffeine enhanced mycoparasitism up to 1.7-fold. Caffeine thus functions in a double-track manner against fungal pathogens: first by direct suppression of growth and development, and second by assisting their natural enemy. These observations suggest that caffeine is a powerful weapon in the arms race between plants and pathogens by fostering enemy's enemy, and we propose the idea of "caffeine fostering" as the third role of caffeine.

Influence of caffeine on the survival of leaf-cutting ants Atta sexdens rubropilosa and in vitro growth of their mutualistic fungus

BACKGROUND

Leaf-cutting ants collect plant fresh material for the cultivation of their mutualistic fungus. Atta sexdens rubropilosa Forel (Hymenoptera: Formicidae) cause great economic losses through their foraging activity, mainly in agriculture. The main control method is the application of granulated toxic baits incorporated with an active ingredient (AI). The present goal is to evaluate the effect of caffeine on in vitro growth of the mutualistic fungus and on the survival of the leaf-cutting ants, aiming to verify the potential toxicity of this secondary metabolite over these organisms.

RESULTS

Three distinct patterns of fungal growth correlated with caffeine concentration were observed: (1) no effect (0.01% caffeine); (2) intermediate growth reduction (0.05% caffeine); (3) drastic growth reduction (0.10 and 0.50% caffeine). The highest caffeine concentration causes fungus death in the first week. As for insect survival, caffeine does not seem to exert any effect. The treatments with diet containing caffeine showed similar values of M50, irrespective of caffeine concentration.

CONCLUSION

As caffeine was shown to reduce growth of the mutualistic fungus of Atta sexdens rubropilosa, but with no conclusive effect on insect survival, a hypothetical explanation for the selection of different Coffea species by this leaf-cutting ant species might be associated with caffeine toxicity to the fungus.

Structural alterations in Candida albicans by caffeine and caffeine salts

Cytological alterations of Candida albicans following exposure to subinhibitory concentrations of caffeine and caffeine salts were examined by light and transmission electron microscopy (TEM). The effect was different from that induced by ketoconazole. Caffeine and especially caffeine salts caused an increase in unusual modes of proliferation with signs of multiple budding in Candida albicans. Structurally, such yeast cells present some resemblance to Paracoccidioides brasiliensis.