BuddyPress.org

Go to your bp-activity-templatetags.php file and change this line from:

return apply_filters( 'bp_get_activity_feed_item_description', html_entity_decode( str_replace( '%s', '', $activities_template->activity->content ), ENT_COMPAT, 'UTF-8' ) );

to:

return apply_filters( 'bp_get_activity_feed_item_description', utf8_decode( str_replace( '%s', '', $activities_template->activity->content ) ) );

Not sure if this will work, but worth a shot!