Methods and Results: Using checkerboard assay, we investigated the anti-borreliae reciprocal cooperation of phytochemicals and micronutrients against two species of Borrelia selected as prevalent causes of Lyme disease in the US and Europe. We tested 28 combinations of phytochemicals such as polyphenols (baicalein, luteolin, rosmarinic acids), fatty acids (monolaurin, cis-2-decenoic acid), and micronutrients (ascorbic acid, cholecalciferol, and iodine). The results showed that the combinations of baicalein with luteolin as well as monolaurin with cis-2-decenoic acid expressed synergistic anti-spirochetal effects. Moreover, baicalein and luteolin, when combined with rosmarinic acid or iodine, produced additive bacteriostatic and bactericidal effects against typical corkscrew motile spirochetes and persistent knob/round-shaped forms, respectively. An additive anti-biofilm effect was noticed between baicalein with luteolin as well as monolaurin with cis-2-decenoic acid. Finally, application of the combination of baicalein with luteolin increased cytoplasmic permeability of Borrelia spp. but did not cause DNA damage. Conclusions: These results show that a specific combination of flavones might play a supporting role in combating Borrelia spp. through either synergistic or additive anti-borreliae effects. Significance and Impact of Study: Presented here in vitro results might help advancing our knowledge and improving the approach to target Borrelia spp.
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biofilm, Borrelia sp., cysts, micronutrients, phytochemicals, spirochetes