for non-alpha characters use:
$_pagi_sql = "SELECT
config_field_3,
config_field_5,
config_field_6,
config_field_7,
mnl_items.cat_id ,
mnl_items.sub_cat_id ,
mnl_items.item ,
mnl_items.item_id
FROM mnl_items
WHERE mnl_items.item REGEXP '^[^a-zA-Z]'
ORDER BY item ASC "
and to add your other condition try this:
$_pagi_sql = "SELECT
config_field_3,
config_field_5,
config_field_6,
config_field_7,
mnl_items.cat_id ,
mnl_items.sub_cat_id ,
mnl_items.item ,
mnl_items.item_id
FROM mnl_items
WHERE mnl_items.item REGEXP '^[^a-zA-Z]' AND active='yes'
ORDER BY item ASC "