| 释义 |
provitamin Biol.|ˈprəʊvɪtəmɪn|
Also pro-vitamin.
[a. G. provitamin (Windhaus & Hess 1926, in Nachr. von der K. Ges. d. Wissensch. zu Göttingen (1927) 175): see pro-2 and vitamin.]
A substance which is converted into a vitamin within an organism. (Freq. with following capital letter indicating relationship to a specific vitamin.)
1927Rosenheim & Webster in Lancet 5 Feb. 306/2 These observations suggest that the provitamin (we propose to use this convenient term, suggested by Prof. Windhaus, for the parent substance of vitamin D) is destroyed by bromine. 1943Endeavour Apr. 73/2 It became evident that, though the diets of the tropical natives were often deficient in the calcifying vitamin,..they really had ample supplies because of the action of sunlight on the provitamin. 1952New Biol. XIII. 40 Doubling the number of chromosomes in pure yellow corn caused a 40% increase in the carotenoid pigment content, including the active provitamin A fraction of the carotenoids. 1971Nature 22 Jan. 255/2 Vitamin D..is produced in the skin when ultraviolet radiation is absorbed by the pro-vitamin 7-dehydrocholesterol. 1976H. Campion et al. in B. E. C. Nordin Calcium, Phosphate & Mineral Metabolism xii. 445 The two principal pro⁓vitamins D, ergosterol..and..7-dehydrocholesterol..are formed in vivo by two very similar routes. |