Chapter 12
Vitamin
Pei Yu
College of Pharmacy
Jinan University
1
Vitamin


Vitamins are among those
nutrients that the human
organism cannot synthesize from
other dietary components.
Many vitamins function
biochemically as precursors in
the synthesis of coenzymes
necessary in human metabolism.
2
Classification and Effect of Vitamin
Lipid soluble vitamin
Vitamin A (retinol)
Daily dose (mg)
1.5
Vitamin D2 (ergocalciferol)
Vitamin D3 (colecalciferol)
Vitamin E
(tocopherol)
Vitamin K1 (phyonadione)
Vitamin K2
Vitamin K3
(Menadione Sodium
Bisulfite)
0.025
Main effect
Used for xerophthalmia(干眼症),
vitamin A deficiency disease
vitamin D deficiency disease,
osteoporosis（骨质疏松症）
Vitamin E deficiency,
intermittent limp（间歇性跛行）
1
Antihemorrhagic(止血)vitamin,
can resist newborn hemorrhage
(出血), low plasminogen
disease(低凝血酶原症), vitamin K
deficiency
3
Water soluble
vitamin
Daily
dose (mg)
Vitamin B1
(thiamine hydrochloride)
1.5
Vitamin B2 (riboflavine)
2
Lactochrome(核黄素)deficiency disease
3
Vitamin B dependence syndrome,
deficiency, congenital dysbolism(先天
Vitamin B6
(pyridoxine hydrochloride)
Main effect
Vitamin B deficiency, peripheral neuritis
（周围神经炎）
代谢障碍)
Vitamin B12
(cyanocobalamine)
0.005
Malignant anaemia(恶性贫血),
megaloblastic anemia(巨幼红细胞性贫血),
anaemia(贫血)and spirit system disease
caused by anti-folic drugs(抗叶酸药)
Vitamin H (biotin)
0.25
Vitamin H deficiency
Vitamin C
(ascorbic acid)
60
Vitamin C deficiency, acidation urine,
idiopathic methemoglobinemia
(特发性高铁血红蛋白血症)
4
5
Structure of Some Vitamins
维生素名称
Vitamin
name
化学结构
structure
O
Vitamin K1
3
O
O
n = 1~13
Vitamin K2
nH
O
O
Vitamin K3
O
6
NH 2
Cl+
N
Vitamin B1
N
OH
S
N
OH OH OH
OH
N
Vitamin B2
N
O
NH
N
O
R
HO
OH
. HCl
Vitamin B6
N
R = -CH2OH
吡多辛
R = -CHO　吡多醛
R = -CH2NH 2 吡多胺
7
HO
O
H
O
O
P
H
Vitamin B12
H
HO N
OH
N
NH2
HN
O
O H
N
N
H2N
Co
O
H2N
H
N
H
O
NH2
N
NH2
NO
O
NH2
O
O
H
H
H
N
Vitamin H
OH
O
S
N
H
H
8
9
Section 1.
Lipid Soluble Vitamins
Vitamin A, Vitamin D3, Vitamin E
10
Vitamin A Acetate
O
6'
1'
8
6
4
2
O
2'
Chemical name:
 (All-trans)-3,7-Dimethyl-9-(2,6,6-trimethyl-1cyclohexene-1-yl)-2,4,6,8-nonatetraen-1-ol acetate.
 All-trans retinol acetate.
11
Discovery of Vitamin A




It was first recognized as a vitamin by McCollum
and Davis in 1913 and 1915.
It was synthesized in 1947 by two Dutch chemists.
Studies of the mechanism of retinol in the visual
process were not significantly productive until
1968 to 1972.
The term Vitamin A is applied to compounds
having biological activity like that of retinol (视黄醇).
12
Vitamin A
 In foods of animal origin, the major form of
vitamin A is an ester, primarily retinyl palmitate
(视黄基棕榈酸酯)which is converted to an alcohol (retinol)
in the small intestine.
 Vitamin A can also exist as an aldehyde (retinal),
or as an acid (retinoic acid).
 Precursors to the vitamin (provitamins) are
present in foods of plant origin as some of the
members of the carotenoid(类胡萝卜素 )family of
compounds.
13
Vitamin A1
Retinol (视黄醇)
Vitamin A2
3-dehydroretinol (3-脱氢视黄醇)
OH
Vitamin A1
OH
Vitamin A2
14
-Carotene(胡萝卜素)




Carotenes in plants can be changed into
Vitamin A ( Provitamin A).
There are at least 10 kinds of carotenes
which can be changed into Vitamin A.
α、ß、γ-Carotene and zeaxanthin(玉米
黄素) are most important.
2/3 of Vitamin A in human body come
from ß -Carotene.
6
1
7
15
15'
Carotene
1'
7'
6'
15
Stability of Vitamin A

O
Unstable to UV， easily be oxidized in air.
OH
OH
O
H+, rearrangement
OH
O
16
OH
Lewis Acid
Vitamin A is unstable ( dehydration) in acid .
It can react with antimony trichloride( SbCl3) present
dark blue.
Retinol shows flavo-green fluorescence, can be used
for quality and quantity analysis.
Vitamin A acetate is more stable than Vitamin A.
17
Metabolism of Vitamin A Acetate
O
H 2O
O
OH
OH
[ O]
O
[ O]
O
Vitamin AËá
Retinoic Acid
ÊÓ»Æ
È©
Retinal
11
11Z11ZÐÍÊÓ
Retinal
Ȯ
È©
O
11Z -Retinal, one of Vitamin A metabolites, is a
photoactive substance of cellula visualis(视觉细胞)，it
participates the formation of vision.
18
Retinoic Acid


Retinoic Acid, active metabolite of Vitamin A, has
similar activity to Vitamin A, it mainly influences on
bone growth and epithelial(上皮组织) metabolism.
It has good effect in preventing cancer and anticancer.
Retinoic Acid and its isomer 13Z-Retinoic Acid are in
clinical use.
13
HO
O
13-顺式维生素A酸
13Z-Retinoic acid
19
Analogues of Retinoic Acid
O
O
OH
O
O
O
ÒÀÇúÌæõ¥
Etrestinate
Etrestinate
ÒÀÇúÌæËá
Acitretin
Etretin
Analogues of retinoic acid in clinic use.
20


Retinamidoester and N-(4-Hydroxycarbophenyl)retinamide can prevent precancerous change of
cervix(宫颈), oral cavity(口腔) and esoph(食管).
Vitamin A derivates synthesized by Chinese researcher.
O
O
O
O
O
N
H
ά°· õ¥
Retinamidoester
Retinamidoester
OH
N
H
ά°· Ëá
N-(4-Hydroxycarboxyphenyl)retinamide
Synthesized by Chinese researchers
21
SAR of Vitamin A
4 chain double bonds must be conjugated with cyclodouble bond,
4¸öË«¼ü
ÐëÓë»·will
ÄÚË«¼ü
éî £¬·ñÔò»î ÐÔ
Ïû ʧ£¬
otherwise
the activity
be ¹²
disappeared;
either
longthening
Ôö³¤»òËõ¶Ì Ö¬·¾Á´£¬»î ÐỐóΪ ½ µ Í
or shortening of chain will decrease activity distinctly
The
of double
Ôönumber
¼Ó
Ë«¼üÊýÄ¿
»î ÐÔ
ÏÂ ½ µ
bonds increased, the
activity decreased
OH
Ester or aldehyde will not
theõ¥»¯»ò»»³ÉÈ©
change activity,
»ù£¬»î ÐÔ
²»
but±ä£¬µ«»»³ÉôÈ
carboxy only»ùʱ£¬»î
containsÐÔ
½ö
Îactivity
ª Vitamin
1/10 A
1/10
ofAµÄ
vitamin
Double bonds are hydrogenated or partly
Ë«¼üÇâ
»¯»ò²¿·ÝÇâ
ÐÔ
ɥʧ
hydrogenated,
the
activity is»¯Ê±£¬»î
disappeared
22
Synthesis of Vitamin A
O
O
OH
紫罗兰酮 ß-ionone
OH
OH
OH
OH
23
Pharmacology Action of Vitamin A
It plays a role in a variety of functions throughout the body:
 Vision
 Gene transcription
 Immune function
 Embryonic development(胚胎发育) and reproduction
 Bone metabolism
 Haematopoiesis(造血作用)
 Skin health
 Reducing risk of heart disease
 Antioxidant Activity
24
Side effect of Vitamin A
 Excesses taken can lead to:
nausea, jaundice(黄疸), irritability, anorexia (厌食)
vomiting, blurry vision, headaches, muscle and
abdominal pain and weakness, drowsiness (嗜睡) and
altered mental status(精神状态改变).
 Acute toxicity generally occurs at doses of 25,000 IU/kg
of body weight, with chronic toxicity occurring at 4,000
IU/kg of body weight daily for 6-15 months. Children
can reach toxic levels at 1500IU/kg of body weight.
25
Vitamin D3
Names：
 (3β,5Z,7E)-9,10-secocholesta-5,7,10(19)-trien-3-ol
 Cholecalciferol(胆骨化醇)
26
Structure
of Vitamin D3
H
HO
It is structurally similar to steroids such as
testosterone(睾酮), cholesterol(胆固醇), and cortisol(氢化
可的松), though vitamin D3 itself is a secosteroid (开环
甾类化合物).
27
Forms of Vitamin D
These are known collectively as calciferol (钙化固醇).
Vitamin D1: molecular compound of ergocalciferol (麦角钙化醇)with
lumisterol(光甾醇), 1:1
Vitamin D2: ergocalciferol (made from ergosterol麦角固醇)
Vitamin D3: cholecalciferol胆骨化醇 (made from 7-dehydrocholesterol
in the skin).
Vitamin D4: 22-dihydroergocalciferol
Vitamin D5: sitocalciferol谷甾醇 (made from 7-dehydrositosterol)
28
Natural Vitamin D
5
R1
5
H
OH
OH
H
R2
7
OH
7
R1 = -H, R2 = -H
µ¨¹Ç»¯´¼ Colecalcif erol VitD3
R1 = -H, R2 = -OH ¹Ç»¯¶þ´¼ 25-Hy droxy VitD3 (Calcif ediol)
R1 = -OH, R2 = -OH ¹Ç»¯Èý´¼ 1,25-Dihy droxy VitD3 (Calcitriol)
(5Z,7Z)
5,6-trans-25-Hy droxy -colecalf erol
(5E,7Z)
29
Vitamin D2 and Vitamin D3



The two major forms are vitamin D2 or ergocalciferol麦
角固醇, and vitamin D3 or cholecalciferol胆骨化醇.
In 1930, Askewd successfully separated Vitamin D2 and
confirmed its structure.
In 1932, Windaus separated Vitamin D3 and confirmed
its structure，its stereo-structure have been confirmed
in 1948, and its full synthesis was completed in 1960.
H
VitD2(Ergocalcif erol) R =
H
R
OH
H
H
VitD3(Colecalcif erol) R =
H
30
In vivo transformation
-2H
uv
B
HO
HO
µ¨ çÞ´¼
cholesterin胆甾醇
7-dehydrocholesterin
7-ÍÑÇ⵨ çÞ´¼
άÉúËØD3
HO
Vitamin D3
uv
B
HO
HO
Âó½Ç
çÞ´¼
ergosterin麦角甾醇
άÉúËØ
D2
Vitamin
D2
31
Function of Vitamin D
 Vitamin D is important for the absorption of calcium
from the stomach and for the functioning of calcium
in the body.
 Vitamin D affects the immune system by promoting
phagocytosis(吞噬), anti-tumor
activity, and immunomodulatory(免疫调制 ) functions.
32
Vitamin D3 metabolism pathway
OH
25-OH-VitD3
HO
liver
¸Î Ôà
HO
VitD3
OH
1,25-(OH)2-VitD3
HO
OH
OH
OH
ÉöÔà
kidney
HO
24,25-(OH)2-VitD3
33
SAR of Vitamin D3
No substitutent,
ÎÞ È¡ ´ú»ù»î ÐÔ̧ß
high activity
20
If ether or ester, activity will
Ϊ ÓÎÀëôÇ»ù£¬³ÉÃÑ»òõ¥º óÎÞ
disappear
»î ÐÔ
£¬ÛÏ»ùÈ¡ ´úÒ²ÎÞ »î ÐÔ
HO
22
24 25
24-CÒý
methyl
decrease
activity
24λ
Èë¼×»ù»î
ÐÔ
ÏÂ ½ µ
£¬Òý
ÈëÒÒ
»ù ，
ethyl
decreaseÈëôÈ
activity
more,
Ôò
»î ÐÔ̧üС£¬Òý
»ù»î ÐÔ
ɥʧ if
carbonyl, activity is disappear.
side carbonyl chain will make
²àÁ´Îª ôÇ»ùʧȥ»î ÐÔ
activity disappear
1
2
34
Synthesis of Vitamin D3
µ¨ ¹Ì ´¼
choleat
O
O
HO
O
7-dehydrogenate
7-ÍÑÇ⵨
çÞ´¼
choleat
OH
H
HO
HO
HO
VitD3
OH
Alfacalcidiol
35
Vitamin E Acetate
Chemical name :
(±)3, 4-Dihydro-2, 5, 7, 8-tetramethyl
-2-(4, 8, 12-trimethyl-tridecyl)-2H- benzopyran-6-ol
acetate.
 -Tocopherol (生育酚)Acetate

36
Natural Vitamin E
substituent
group
取代基
Chemical
structure
化学结构
R1
O
4
5
O
R2
8
O 2
1
1'
5'
9'
R1
R2
CH3
CH3
-生育酚
CH3
H
-生育酚
H
CH3
-生育酚
H
H
-生育酚
CH3
CH3
-生育三烯酚
CH3
H
-生育三烯酚
H
CH3
-生育三烯酚
H
H
-生育三烯酚
13'
R1
O
O
R2
O
Chemical
name
化学名称
37
Identification of Vitamin E
Vitamin E can be easily oxidized to -Tocopherol
Quinone by Fe3+ , and getting Fe2+ , which react with
2,2’-sympyridine to produce red complex.
HO
+ Fe3+
O
O
+ Fe2+
C16H33
O
HO
C16H33
2+
Fe
Fe2+ + 3
N
N
N
N
3
Ѫºìred
É«
blood
38
Properties of Vitamin E

It can be oxidized to hydroxide compound. Heating its
alcohol solution with nitric acid, tocopherol red(生育红)
was produced and its solution shows salmon pink.
O
HO
HNO3
O
C16H33
75.C
O
O
salmon
pink
³Èºì
É«
C16H33
39

Vitamin E is stable when heating to 200℃ without
oxygen, but it is very sensitive to oxygen under light
and air, producingα-Tocopherol Quinone and α Tocopherol dimeride.
O
O
O
O
HO
O
HO
C16H33
-ÉúÓýõ«
a-Tocopherol
Quinone
C16H33
O
C16H33
O
Dimer
C16H33
40
Metabolism of Vitamin E Acetate
O
È¥õ¥»¯
O
O
major
HO
O
C16H33
C 16H 33
-ÉúÓý
·Ó£¨ Ö÷Òª£©
α-tocopherol
α-tocopherol
acetic ester
-ÉúÓý·Ó´×Ëáõ¥
O
Ñõ»¯
oxidize
C 16H 33
Ñõ»¯
oxidize
HO
O
O
HO
C16H33
HO
α-tocopherolquinone
-ÉúÓýõ«£¨ Ö÷Òª£©
O
Ñõ»¯
oxidize
Ñõ»¯ reduction
»¹ Ôoxidize
HO
C 16H 33
-ÉúÓý
·Ó¶þ¾Û
Ìå £¨
´Î Òª£©
α-tocopherol
dimer
O
OH
C16H33
HO
-ÉúÓýÇâõ«£¨ ´Î Òª£©
α--tocopherolhydroquinone
O
HO
OH
O
-ÉúÓýËᣨ ´Î Òª£©
α-tocopheronic
acid
¸Î
liver
ÓëÆÏglucose
Ì ÑÌǽáºÏ
Bonding with
¾-µ¨ Ö-ºÍ through
ÉöÅųö bile and kidney
Excrete
41
Synthesis Vitamin E Acetate
HO
+
OH
HO
HO
Zn, CH 3COONa
O
O
O
O
Vitamin E Acetate
42
Section 2.
Water Soluble Vitamins
VitaminB1, B2, B6, B12and Vitamin C
43
Vitamin B
Vitamin B1 (thiamine硫胺)
Vitamin B2 (riboflavin核黄素)
Vitamin B3 (niacin烟酸)
Vitamin B5 (pantothenic acid泛酸)
Vitamin B6 (pyridoxine, pyridoxal, and pyridoxamine)
Vitamin B7 (biotin生物素), also known as vitamin H
Vitamin B9 (folic acid叶酸), also vitamin M
Vitamin B12 (various cobalamins)
44
Use of Vitamin B
 Support and increase the rate of metabolism.
 Maintain healthy skin and muscle tone(肌张力).
 Enhance immune and nervous system function.
 Promote cell growth and division — including that
of the red blood cells that help prevent anemia(贫血).
 Reduce the risk of pancreatic cancer(胰腺癌).
45
46
Vitamin B1
NH2
Cl
+
N
N
N
S
OH
Chemical name ：
 3-[(4-Amino-2-methyl-5-pyrimidinyl) methyl]-5-(2hydroxyethyl)-4-methyl thiazolium chloride
47
48
Action of Vitamin B1

Used for Vitamin B1 deficiency symptom:
neuritis(神经炎), CNS lesion(中枢神经系统损害), digestive
dysfunction and cardiac function obstruction.

It is converted to diphosphothiamine (二磷酸硫胺) after
absorption, which is a bioactive substance as a part of
decarboxylase coenzyme, participate in maintaining
normal glycometabolism and nerves , heart system
function.
49
Vitamin B2
OH
OH
OH
OH
N
N
O
NH
N
Riboflavin
(核黄素)
O
Organ meats, nuts, cheese, eggs, milk and lean meat are
great sources of riboflavin, but is also available in good
quantities in green leafy vegetables, fish, legumes, whole
grains, and yogurt.
50
Use of Vitamin B2
 It is required by the body to use oxygen and the
metabolism of amino acids, fatty acids, and
carbohydrates.
 Riboflavin is further needed to activate vitamin B6
(pyridoxine), helps to create niacin and assists the
adrenal gland.
 It may be used for red blood cell formation, antibody
production, cell respiration, and growth.
 Vitamin B2 is required for the health of the mucus
membranes in the digestive tract and helps with the
absorption of iron and vitamin B6.
51
Vitamin B6
R
HO
OH
. HCl
N
pyridipca
R = -CH2OH
R = -CHO¡¡
pyridipca
ßÁ¶àÐÁ
vitamin
B6
ßÁ¶àÈ©
R = -CH2NH2 pyridoxamine
ßÁ¶à°·
vitamin B6
pyridoxamine
52

HO
HO
OH
P
O
O
PLP
N
All three forms of vitamin B6 are precursors of an
activated compound known as pyridoxal 5'phosphate (PLP), which plays a vital role as the
cofactor of a large number of essential enzymes
in the human body.
53
54
Vitamin C
OH
H
OH
O
HO
O
OH
Chemical name：



2-oxo-L-threo-hexono-1,4- lactone-2,3-enediol.
(R)-3,4-dihydroxy-5-[(S)- 1,2-dihydroxyethyl]
furan-2(5H)-one.
Ascorbic Acid.
55
Albert Szent-Györgyi, pictured here in 1948,
was awarded the 1937 Nobel Prize in
Medicine "for his discoveries in connection
with the biological combustion processes,
with special reference to vitamin C and the
catalysis of fumaric acid反丁烯二酸".
James Lind, a British Royal Navy
surgeon who, in 1747, identified that a
quality in fruit prevented the disease
of scurvy(坏血病)in what was the first
recorded controlled experiment.
56
4 Optical Isomers of Vitamin C
OH
H
OH
O
HO
O
O
OH
L-(+)-¿¹»µÑªËá
L-(+)antiscorbic acid
HO
H
HO
OH
OH
OH
D-(-)-antiscorbic
acid
D-(-)-¿¹»µÑªËá
O
OH
O
HO
H
O
O
OH
D-(-)-Ò쿹»µÑªËá
D-(-)-isoantiscorbic
acid
HO
HO
O
OH
H
OH
L-(+)-Ò쿹»µÑªËá
L-(+)-isoantiscorbic
acid
 L-(+)antiscorbic acid has highest activity, which is 20
times of D-(-)-isoascorbic acid.
 D-(-)- antiscorbic acid and L-(+)- isoascorbic acid are
ineffective.
57
Property of Vitamin C
White or slightly yellow crystals
or powder.
 It is odorless and , exposure to
light, gradually darkens.
 1% aqueous solution has a pH2.7
and is not very stable.

58

Vitamin C is stable as dry form, but it will change into
yellow color gradually under light and humidity.
Polymerized
OH
H
O
OH
O
O
O

O
O
O
O

OH
HO
O
O
O
O
O
Vitamin C are tautomer in water, majority is enol.
In keto-form isomers, 2-oxo is more stable, which can be
separated. 3-Oxo is very unstable, changing into enol easily.
OH
H
OH
O
HO
OH
OH
H
O
O
2-Ñõ´ú Îï
HO
H
OH
O
OH
O
O
OH
Ï©´¼Ê½
O
O
OH
3-Ñõ´ú Îï
59
Vitamin C present acidity
 The acidic character is due to the two enolic hydroxyls.
 The C-3 hydroxyl has a pKa value of 4.1, and the C-2
hydroxyl has a pKa of 11.6 due to C-2 hydroxyl forms
intramolecular hydrogen bond with C-1 carbonyl.
OH
OH
H
OH
O
3
HO
H
O
2O H
NaHCO3
NaO
OH
O
O
OH
60
It will be hydrolyzed in strong base such as NaOH,
producing sodium salt as follow:
OH
H
HO
OH
O
OH
O
NaOH
OH
H
HO
OH
ONa
O
OH
O
Reacting with sodium nitroprusside(亚硝基铁氰化钠)and NaOH,
the water solution of Vitamin C presents blue color.
C6H8O6 + NaOH
C6H7O6Na + Na2[Fe(CN)5NO]
C6H7O6Na + H2O
Na4[Fe(CN)5NO(C6H7O6)2]
61
Reducibility of Vitamin C


Vitamin C have two forms-oxidized and reduced form.
It is easily oxidized to become dehydroascorbic acid.
They have same bioactivity.
OH
H
HO
OH
O
OH
[H]
O
OH
H
OH
O
O
[O]
O
O
È¥Ç⿹»µÑªËá acid
Dehydroascorbic
62
Assay by iodometry(碘量法)


Vitamin C can be oxidized by iodine in acid condition.
It is the principle to assay its content by using starch
as indicator.
OH
H
HO
OH
O
OH
O
OH
+ I2
CH3COOH
H
OH
O
O
O
+ HI
O
63
 Vitamin C is also oxidized by AgNO3 to generate
black Ag precipitate.
The red aquous solution will change to
colorless when it was added 2, 6-dichlorine
indophenol.
OH
H
OH
OH
O
HO
AgNO3
O
H
OH
OH
O
O
OH
H
OH
O
+ Ag
O
(ºÚÉ«)
OH
Cl
N
H
OH
O
O +
OH
H
N
Cl
O +
OH
O
HO
O
Cl
OH
HO
O
O
Cl
64
Oxidation of Vitamin C
OH
H
OH
O
O
O
OH
H
HO
O
O
OH
H
OH- , H2O
O
O
OH
2,3-¶þͪ ¹ÅÁúÌÇËá
[O]
O
OH
H
HO
OH
H
O
OH
+
HO
O
OH
Arabic
acid
ËÕ
°¢ÌÇËá
65
Metabolism of Vitamin C
OH
H
OH
O
HO
O
OH
H
HO
O
O
OH
H
OH
H
OH
O
O
OH
O
O
O
OH
O
H
H
HO
OH
OH
OH
H
OH
ËÕÌÇËá
L-Lyxonic Acid
O
OH
HO
H
HO
H
OH
H
OH
ľÖÊËá
L-Xylonic Acid
O
HO
H
HO
H
H
OH
H
O
H
HO
OH
O
OH
+
H
HO
OH
O
OH
OH
L-ľÌÇ
L-Xylose
L-ËÕ°¢ÌÇËá
L-Threonic Acid
²ÝËá
Oxalic Acid
66
Synthesis of Vitamin C
OH
HO
HO
H
HO
OH
H
H
OH
H
HO
HO
H
HO
H 2. Ni
O
OH
O
HO
OH
H
H
OH
H
[O]
ºÚ´×Ëá¾ú
O
H
OH
H
HO
H
HO
OH
D-ÆÏÌ ÑÌÇ
D-glucose
HO
OH
OH
D-ɽ
Àǽ¼
D-glucitol
O
CO(CH 3)2, H2SO4
OH
O
L-ɽ
Àæ
ÌÇ
L-sorbin
O
O
O
O
O
NaOCl, NaOH
OH
O
2,3,4,6-Ë«
Ëõ±ûͪ ɽ
Àæ
ÌÇ
2,3,4,6diacetone
sorbose
O
O
O
OH
˫ͪ ¹ÅÁúËá acid
diketo-gulonic
OH
OH
O
HO
HCl
hydrolyze
Ë®½â
HO
OH
O
ÄÚõ¥»¯£¬Ï©´¼»¯
H
OH
2-keto-gulonic
acid
2-ͪ -L-¹ÅÁúËá
HO
OH
O
O
OH
67
68
69