What are thegroup or class of chemical substances which start with the letter vitamin
SELECT DISTINCT ?sbj ?sbj_label WHERE { ?sbj wdt:P31 wd:Q17339814 . ?sbj rdfs:label ?sbj_label . FILTER(CONTAINS(lcase(?sbj_label), 'vitamin')) . FILTER (lang(?sbj_label) = 'en') } LIMIT 25 
group or class of chemical substances: Q17339814