UJIAN AKHIR SEMESTER
MATA KULIAH : KIMIA BAHAN ALAM
SKS : 2
DOSEN : Dr. Syamsurizal, M.Si
WAKTU : 22-29 Desember 2012
1. Jelaskan dalam jalur biosintesis triterpenoid,
identifikasilah faktor-faktor penting yang sangat menentukan dihasilkannya
triterpenoid dalam kuantitas yang banyak.
Jawab :
Triterpenoids
consisting of frame with 3 cyclic 6 which joined cyclic 5 or 6 units in the
form of four cyclic isoprene biosynthesis and is derived from the C-30 acyclic
hydrocarbons, ie skualena, these compounds are colorless, crystalline, high
melting point and is optically active have specific functional groups on the
cyclic. While naming further simplified by giving the numbering on each carbon
atom, thus facilitating the determination of the substituents on each carbon
atom.
Triterpenoid usually
found in shark liver oil, vegetable oil (olive oil) and there is also
ditemukandalam seprimitif sphagnum plants but the most common is the seed
plants, free and glycosides. Triterpenoids have been used as medicinal herbs
for diabetes, menstrual disorders, pecks snake, skin disorders, liver damage,
and malaria.
Terpenoids is a form
of compounds with structures derived from isoprene units (C5) are coupled in
the model head to tail, whereas isoprene units derived from acetic acid
metabolism by mevalonic acid pathway
Mevalonic acid
pathway
The mechanism of the
reaction steps of terpenoid biosynthesis is activated by acetic acid as
coenzyme A did produce acid Claisen type condensation asetoasetat. Compounds
produced by the condensation of acetyl coenzyme A did produce aldol type
branched carbon chains as found in mevalinat acid, subsequent reactions are
fosforialsi, elimination of phosphoric acid and dekarboksilasimenghasilkan
isopentenyl (IPP) dimethyl allyl yangselanjutnya berisomerisasi be piropospat
(DMAPP) by enzimisomeriasi. IPP as isoprene unti actively joined the head to
ekordengan DMAPP and this merger is the first step to produce isoprene
daripolimerisasi terpenoid.Penggabungan This happens because the attack
IPPterhadap electron from the double bond carbon atoms from electron-deficient
DMAPP followed olehpenyingkiran pyrophosphate ion generating geranil.pirofosfat
(GPP) for all compounds yaitusenyawa the next monoterpenoid.Penggabungan
between the IPP and GPP unti the same result menaismeyang Farnesil
pyrophosphate (FPP) which is seskuiterpenoid senyawaantara for all compounds.
Diterpenoid compounds derived dariGeranil-geranil Pyrophosphate (GGPP) derived
from the condensation between one untiIPP and GPP by the same mechanism
Terpenoida a wide
range of structures arising as a result of subsequent secondary reactions such
as hydrolysis, isomerization, oxidation, reduction and cyclization
over-geranil, farnesil-and-geranil geranil pyrophosphate.
In general, the
biosynthesis of terpenoids occurred three basic reactions are:
1. Formation of
active isoprene derived from acetic acid via mevalonic acid.
2. Merging head and
tail of two isoprene units to form mono-, seskui-, di-. Sester-, and
poly-terpenoids.
3. The incorporation
of the tail and the tail unit C-15 or C-20 produces triterpenoids and steroids.
2. Jelaskan dalam penentuan struktur flavonoid, kekhasan
signal dan intensitas serapan dengan menggunakan spektrum IR dan NMR. Berikan
dengan contoh sekurang-kurangnya dua struktur yang berbeda.
Jawab:
Examples of flavonoid
structure breadfruit leaves and bark
The molecular
structure of compounds 1 and 2 are set based on the results of the analysis of
spectroscopic data, covering the spectrum of UV, IR, and NMR. UV spectrum
measured in solution using methanol solvent,
with sliding reagent
NaOH. IR spectra determined in the solid state KBr pellets, and the NMR
spectrum
measured in the
solvent CDCl3 and acetone-d6.
UV spectrum of
compound 1 showed absorption maximum at λmaks 206, 232 (shoulder), 277, 314 nm,
which corresponds to the substituted benzoyl chromophore, and shows a shift
batokromik the addition of NaOH solution, which means the free phenol in the
chromophore. IR spectrum of compound 1 showed a hydroxyl functional group
(νmaks 3401 cm-1), alkyl (νmaks 2923 and 2855 cm-1), conjugated carbonyl (νmaks
1633cm-1), and aromatic (1496 cm-1). 13C NMR spectrum of compound 1 (Fig. 2)
shows 25 signals yangterpisah well to 25 carbon atoms, which consist of a
conjugated carbonyl carbon (δC 204.1 ppm), 16 and 8 carbon-carbon sp2-sp3.
Having regard to the intensity of the signal, 16-sp2 carbon dapatdirinci
consists of 4 = CO-(oksiaril), 5 = C (quaternary) -, and 7 = CH (metin aromatic
/ alkene), while 8-sp3 carbon divided into 5 C- methylene and 3 C-methyl. Based
on the knowledge of phytochemicals Artocarpus, and with regard to the types of
carbon, it can be suggested that compound 1 is a dihidrokalkon containing four
hydroxyl groups and one group geranil. Structural units contained in one
further compound identified by the signals of protons in the 1H NMR spectrum
(Table 1). 1H NMR spectrum of compound 1 showed a signal at δH 12.85 ppm for
the-OH group terkelasidengan-C = O, two triplet signals of two methylene groups
in the δH 3.11 and 2.97 ppm for two gugusmetilen-α and-β from dihidrokalkon,
and the number of signals corresponding to one unit geranil (sinyalsinyalpada
δH 5.17, 5.02, 3, 40, 2.08, 2.06, 1.79, 166,
1.57 ppm). In
addition, the analysis of signals in the aromatic region shows the unit 1,2,3,4
-
tetrasubstitusi
benzene (δH 6.71 and 6.65 ppm) and 2,4-gu-gus dihidroksibenzoil (δH 7.58, 6.37
and 6.35 ppm). Having regard to the value of shear proton chemical signals of
two aromatic units, it was concluded that compound 1 is 2-geranil 2 ', 4'
,3,4-tetrahidroksidihidrokalkon. 13C NMR data comparisons (Table 1) between the
isolated compound 1 with those reported showing compliance
high (Patil et al.,
2002). It can be concluded that 2-geranil-2 ', 4' ,3,4-tetrahidroksidihidrokalkon
designated as compound 1.
UV and IR spectrum of
compound 2 is similar to the UV and IR spectra of compounds 1, which means that
the compound 2 also has substituted benzoyl chromophore.
3. Dalam isolasi alkaloid, pada tahap awal dibutuhkan
kondisi asam atau basa. Jelaskan dasar penggunaan reagen tersebut, dan berikan
contohnya sekurang-kurangnya tiga macam alkaloid.
Jawab:
for example caffeine
in tea
Alkaloid testing
reagents used meyer and dragendroff basically using nature alkaloid-reactive
heavy metals. In this case, meyer reagents containing heavy metals Bi (bismuth)
and reagent dragendroff heavy metals Pb (lead). Evidence of the presence of
alkaloids in the sample, especially by looking at the presence of a clot or
precipitate after the reaction between the sample and reagent meyer or
dragendroff. In reagent meyer, if there are alkaloids, alakaloid will react
with bismuth so agglomerate and settle in a yellow precipitate. In dragendroff
reagent, if there are alkaloids, alkaloids react with lead so that agglomerate
and settle in sediments dark red or brownish red.
The observation of
mixing extracts C. sinensis sinensisdengan both reagents showed high levels of
alkaloids contained in the extract .. In reaction to the reagent meyer, mix
seemed murky and there endapat yellow. Also, look at his reaction to the
reagent dragendroff indicating deposition reaction, the presence of alkaloids
in the extracts properties are also increasingly likely. Based alakloid
properties can be determined that it is true is an alkaloid extracted caffeine
type.
examples of white
oyster mushroom
regarding the content
of alkaloid compounds found in oyster mushrooms
white. A total of 160
grams of powder white oyster mushroom basified with a solution
weak base, ammonia
10%, until the powder submerged (volume ± 300 ml),
then macerated using
chloroform as much as 100 ml
for 1-2 days. Then
separated with a separating funnel and retrieved phase
kloroformnya. Phase
lag of base added with chloroform,
given the same
treatment and again. Chloroform phase was obtained
put together,
analyzed by TLC using eluent methanol: ammonia
(100:1,5), were
tested for the presence of alkaloids with Dragendorff reagent.
Further purified by
column chromatography using an eluent
same. Fractions
obtained, on TLC again with the reagents and eluent
same. Positive
fractions containing alkaloids put together, evaporated
until it forms a
residue. Then the residue obtained was measured melting point
and analyzed by GC,
IR, UV-vis, and 1H NMR.
examples of white
pepper seeds
Basic
character of the various alkaloids are used to isolate it. Alkaloids taken into
dilute aqueous acid (usually hydrochloric acid, citric, or tartaric) and a
neutral or acidic components of mixed origin are separated by solvent
extraction.
4. Jelaskan
keterkaitan diantara biosintesis, metode isolasi dan penentuan struktur senyawa
bahan alam . Berikan contohnya.
Jawab:
Di dalam melakukan
sebuah penenlitian keterkaitan biosintesis , isolasi sangat berpengaruh terhadap
penentuan struktur senyawanya, dan penentuan struktur tersebut di dapatkan dari
analisis melalui biosintesis dan metode isolasi senyawa tersebut . misalnya
saja pada tanaman daun sukun Serbuk kering daun sukun (1 kg) dimaserasi dengan
metanol (3x24 jam). Ekstrak metanol dikeringkan pada tekanan rendah dan seluruh
ekstrak tersebut difraksinasi dalam etil asetat dan air, dan diperoleh fraksi
etil asetat sebanyak 20 g setelah pelarutnya diuapkan. Fraksi etil asetat yang
difraksinasi lebih lanjut dengan teknik kromatografi vakum cair (KVC) menggunakan
silika gel sebagai fasa diam dan n-heksana:etil asetat (15:5, 7:3, 6:4,
dan 1:1) sebagai fasa gerak (eluen) menghasilkan lima fraksi utama
(fraksi A-E), dengan berat
masing-masing 0,23, 1,46, 3,64, 0,8, dan 0,74 g. Fraksi B (1,46 g) difraksinasi
lebih lanjut dengan teknik yang sama (silika gel, eluen n-heksana:etil
asetat = 17:3, 4:1, dan 15:5) menghasilkan tiga fraksi B1-B3. Fraksi B2 (525
mg) yang dimurnikan secara berulang-ulang menggunakan teknik kromatografi
radial (silika gel, eluen nheksana: CHCl3:metanol=19:19:2) menghasilkan senyawa
1 (100 mg) dan senyawa 2 (55 mg). Dengan menggunakan teknik yang
sama, pemurnian fraksi B3 (420 mg) menghasilkan senyawa 1 (200 mg).2.3
Penentuan struktur Struktur molekul senyawa 1 dan 2 ditetapkan berdasarkan
hasil analisis data spektroskopi, yang meliputi spektrum UV, IR, dan NMR.
Spektrum UV diukur dalam larutan menggunakan pelarut metanol,dengan pereaksi
geser NaOH. Spektrum IR ditentukan dalam bentuk padatan pelet KBr, dan spektrum
NMR diukur dalam pelarut CDCl3 dan aseton-d6.
