Inhibition of bacterial quorum sensing and biofilm formation by extracts of neotropical rainforest plants.

Bacterial biofilms are responsible for many persistent infections by many clinically relevant pathogens such as Staphylococcus aureus and Pseudomonas aeruginosa. Biofilms are much more resistant to conventional antibiotics than their planktonic counterparts. Quorum sensing, an intercellular communication system, controls pathogenesis and biofilm formation in most bacterial species. Quorum sensing provides an important pharmacological target since its inhibition does not provide a selective pressure for resistance. In this study, we investigated the quorum sensing and biofilm inhibitory activities of 126 plant extracts from 71 species collected from neotropical rainforests in Costa Rica. Quorum sensing and biofilm interference were assessed using a modified disc diffusion bioassay with Chromobacterium violaceum ATCC 12,472 and a spectrophotometric bioassay with Pseudomonas aeruginosa PA14, respectively. Species with significant anti-quorum sensing and/or anti-biofilm activities belonged to the Meliaceae, Melastomataceae, Lepidobotryaceae, Sapindaceae, and Simaroubaceae families. IC50 values ranged from 45 to 266 µg/mL. Extracts of these active species could lead to future development of botanical treatments for biofilm-associated infections.

Dietary docosahexaenoic acid contributes to increased bone mineral accretion and strength in young female Sprague-Dawley rats.

Growing evidence suggests that docosahexaenoic acid (DHA: 22:6n-3) enhances bone mineral content (BMC) and bone mineral density (BMD) in adulthood and during aging, however the effects during and after sexual maturation are unclear. The aim of this study was to examine the dose-response of BMC, BMD and microarchitectural properties of bone to dietary DHA in healthy growing female rats during acquisition of peak bone mass (PBM). Female Sprague-Dawley rats (n = 12/diet) were randomized to receive a control diet (AIN-93 M, 60 g soybean oil/kg diet) or an experimental diet containing 0.1, 0.4, 0.8 and 1.2% DHA (w/w of total diet) for 10 weeks. Dietary DHA increased the whole body, lumbar spine and long bone BMC compared to the control, in addition to higher aBMD and also BMD. Additionally, an increase in cortical bone microarchitecture parameters of lumbar spine as well as peak force were observed in dietary DHA diet groups. Dietary DHA contributes to PBM when consumed during and after sexual maturation, however higher doses of DHA do not provide further benefits.