previtaminn.

Brit.

/ˌpriːˈvɪtəmɪn/, U.S.

/priˈvaɪdəm(ə)n/

Origin: Formed within English, by derivation. Etymons: pre- prefix, vitamin n.

Etymology: < pre- prefix + vitamin n. Compare slightly earlier provitamin n.

Biochemistry.

An inactive precursor of a vitamin which is converted into the active form inside an organism; esp. an immediate precursor (contrast provitamin n.). Frequently with following capital letter denoting the vitamin concerned.

ΚΠ

1932 F. P. Bowden & C. P. Snow Let. in Nature 14 May 720/1 When applied to a suitable pre-vitamin, monochromatic irradiation with light of the correct wave-length produces maximum yields of the vitamin.

1964 Gettysburg (Pa.) Times 28 Nov. 6/2 Carotene or previtamin A occurs naturally in many feeds like yellow corn, hays or silage.

1987 Daily Herald (Chicago) 24 Sept. 4/3 Provitamin D occurs naturally in the skin. When exposed to ultraviolet light, provitamin D is converted to previtamin D, which spontaneously turns to vitamin D.

2004 Zoo Biol. 23 33 Zooplankton..sampled near Kaktovik, Alaska, contained no measurable vitamin D₂ or D₃, but did contain provitamin D (7-dehydrocholesterol), the cutaneous precursor for previtamin D₃ in mammals.

This is a new entry (OED Third Edition, March 2007; most recently modified version published online March 2022).

单词	previtamin
释义	previtaminn. Brit. /ˌpriːˈvɪtəmɪn/, U.S. /priˈvaɪdəm(ə)n/ Origin: Formed within English, by derivation. Etymons: pre- prefix, vitamin n. Etymology: < pre- prefix + vitamin n. Compare slightly earlier provitamin n. Biochemistry. An inactive precursor of a vitamin which is converted into the active form inside an organism; esp. an immediate precursor (contrast provitamin n.). Frequently with following capital letter denoting the vitamin concerned. ΚΠ 1932 F. P. Bowden & C. P. Snow Let. in Nature 14 May 720/1 When applied to a suitable pre-vitamin, monochromatic irradiation with light of the correct wave-length produces maximum yields of the vitamin. 1964 Gettysburg (Pa.) Times 28 Nov. 6/2 Carotene or previtamin A occurs naturally in many feeds like yellow corn, hays or silage. 1987 Daily Herald (Chicago) 24 Sept. 4/3 Provitamin D occurs naturally in the skin. When exposed to ultraviolet light, provitamin D is converted to previtamin D, which spontaneously turns to vitamin D. 2004 Zoo Biol. 23 33 Zooplankton..sampled near Kaktovik, Alaska, contained no measurable vitamin D₂ or D₃, but did contain provitamin D (7-dehydrocholesterol), the cutaneous precursor for previtamin D₃ in mammals. This is a new entry (OED Third Edition, March 2007; most recently modified version published online March 2022). < n.1932
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