In vitro activity of a partially purified and characterized bark extract of Castanea sativa Mill. (ENC®) against Chlamydia spp.

Castanea sativa Mill (ENC®), containing tannins against 33 Chlamydia strains, was compared to SMAP-29 with inhibitory effect against C. trachomatis and C. pneumoniae. The ENC® activity against Chlamydia spp. was evaluated determining the lowest concentration to achieve more than half reduction of intact chlamydial inclusions versus controls. ENC® reduced all Chlamydia strains tested at 1 µg/mL, while SMAP-29 induced reductions of C. trachomatis and C. pneumoniae infectivity at 10 µg/mL. A great reduction of C. trachomatis, C. pneumoniae, and C. abortus infectivity was achieved with a 10 µg/mL ENC® concentration, whereas their infectivity was almost inhibited at 100 µg/mL ENC® concentration.