Butyrogenic, bifidogenic and slight anti-inflammatory effects of a green kiwifruit powder (Kiwi FFG®) in a human gastrointestinal model simulating mild constipation.

Green kiwi (Actinidia deliciosa var. Hayward) is a fruit with important nutritional attributes and traditional use as a laxative. In this work, we studied in vitro the colonic fermentation of a standardized green kiwifruit powder (Kiwi FFG®) using representative intestinal microbial content of mildly constipated women. Static (batch) and dynamic configurations of the Simulator of the Human Intestinal Microbial Ecosystem (SHIME®) were used to estimate the impact of Kiwi FFG® in the human gut. Analysis of metabolites revealed a significant butyrogenic effect of the kiwifruit powder and, consistently, butyrate-producing bacterial populations (i.e., Faecalibacterium prausnitzii, Cluster IV, Roseburia spp.) were greatly increased in the dynamic gastrointestinal model. Bifidobacterium spp. was also found boosted in the microflora of ascending and transverse colon sections, and a significant rise of Akkermansia muciniphila was identified in the transverse colon. Reporter gene assays using human intestinal cells (HT-29) showed that kiwifruit fermentation metabolites activate the aryl hydrocarbon receptor (AhR) transcriptional pathway, which is an important regulator of intestinal homeostasis and immunity. Moreover, modulation in the production of human interleukins (IL-6 and IL-10) in Caco-2 cells suggested a potential mild anti-inflammatory effect of the kiwifruit powder and its gut microbiota-derived metabolites. Our results suggested a potential health benefit of Kiwi FFG® in the gut microbiota, particularly in the context of constipated people.

Identification of regulatory sequence elements within the transcription promoter region of NpABC1, a gene encoding a plant ABC transporter induced by diterpenes.

Expression of NpABC1, a gene encoding a plasma membrane ATP binding cassette (ABC) transporter in Nicotiana plumbaginifolia, is induced by sclareol, an antifungal diterpene produced at the leaf surface, as well as by sclareolide, a close analog. A genomic fragment including the 1282-bp region upstream of the NpABC1 transcription start was fused to the reporter beta-glucuronidase (gus) gene and introduced into N. tabacum BY2 cells for stable transformation. A 25-fold increase in gus expression was observed when cells were treated with sclareolide and some other terpenes. The combined use of 5'-deletion promoter analysis, gel mobility shift assays, DNase I footprinting, and site-directed mutagenesis allowed us to identify three cis-elements (sclareol box 1 (SB1), SB2, and SB3) located, respectively, within nucleotides -827 to -802, -278 to -243, and -216 to -190 upstream of the NpABC1 transcription start. In vivo evaluation of these elements on sclareolide-induced expression showed that mutation of SB1 reduced expression by twofold, while that of SB2 had no effect. On the other hand, SB3 had a marked effect as it completely abolished sclareolide-mediated expression. NpABC1-gus expression was not induced by the stress signals, salicylic acid and ethylene, but was mediated, to some extent, by methyl jasmonate, which is known to promote diterpene synthesis.