Total Bacterial Load within Echinacea purpurea, Determined Using a New PCR-based Quantification Method, is Correlated with LPS Levels and In Vitro Macrophage Activity

Abstract

Our previous studies indicate that the majority of in vitro monocyte/macrophage activation exhibited by extracts of Echinacea depends on bacterial components. In the present study total bacterial load was determined within E. purpurea samples and ranged from 6.4×106 to 3.3×108 bacteria/g of dry plant material. To estimate total bacterial load we developed a PCR-based quantification method that circumvents the problems associated with non-viable/non-culturable cells (which precludes using plate counts) or the coamplification of mitochondrial or chloroplast DNA with the use of universal bacterial primers (which precludes the use of qPCR). Differences in total bacterial load within Echinacea samples were strongly correlated with the activity (NF-κB activation in THP-1 cells) and content of bacterial lipopolysaccharides within extracts of this plant material. These results add to the growing body of evidence that bacteria within Echinacea are the main source of components responsible for enhancing innate immune function.

Uncovering potential ‘herbal probiotics’ in Juzen-taiho-to through the study of associated bacterial populations

“…10–12 In this theory, the herbs do not necessarily produce immunostimulants; instead they enrich beneficial bacteria with immune-boosting activity, which we call “herbal probiotics.” Humans may have been benefiting from herbal probiotics, albeit unknowingly, throughout the history of herbal medicine. Although some immune-boosting herbs are known to produce immunostimulants, such as QS21 by Quillaja saponaria , 28,29 the active factors of many herbs are poorly characterized.…”

“…Pasco and co-workers observed that bacterial loads in Echinacea correlated with immunostimulatory activities. 10 In addition, the activity of Echinacea was depleted by a polymyxin-B affinity-resin, which removes lipopolysaccharides (LPSs) of gram-negative bacteria. 11,12 These data argued for the bacterial contribution in some immune-boosting herbs.…”

Bacterial components are the major contributors to the macrophage stimulating activity exhibited by extracts of common edible mushrooms

“…2 We have found that E. purpurea samples contain bacterial loads ranging from 10 6 to 10 8 bacterial cells g −1 of dry material and that both bacterial loads and LPS content are strongly correlated with in vitro macrophage activity. 3 Other groups have reported similar findings. Endophytic bacteria contributed to the in vitro pro-inflammatory effects of E. purpurea crude extracts 4 and to the immunostimulatory activity of Angelica sinensis , one of the most potent herbs in the traditional East Asian formula Juzen-taiho-to.…”

“…These results are consistent with our previous research on immune enhancing plant botanicals showing that immune enhancing activity is strongly correlated with LPS content and bacterial load within E. purpurea . 3 …”

“…The bacterial 16S rRNA gene from each sample was then amplified using primers 799f and 1492r as described previously. 3 Bacterial loads were estimated by comparing the intensity of the 735 bp 16S bacterial band from mushroom extracts to a standard curve of DNA extracted and amplified from known quantities of bacteria. 3 …”