LycopeneAn Overview

Tahirah Farrer-Bradley

Tuskegee University

Lycopene is responsible for the red pigment in…

Grapefruit Apricot

WatermelonPink GuavaRose hips

Flamingoes

Lycopene• Is the carotenoid responsible for the red pigment of

many fruits and vegetables.

• There are more than 600 naturally occurring carotenoids, of these lycopene is the largest and most abundant.

• Tomatoes and its food products are the most important source of lycopene.

• Lycopene is the major carotenoid in the diet of North Americans and Europeans. It is thus the most abundant carotenoid in the human body.

Importance of Lycopene• Research suggests a correlation

between the intake of carotenoids and reduced risks of degenerative diseases such as prostate, bladder, cervix, breast and digestive tract cancer.

• Carotenoids are non-polar, conjugated, lipophilic antioxidants.

Lycopene is assembled from 8 isoprene units

2-Methyl-buta-1,3-diene(IUPAC)

12

34

Methane

Ethane

Propane

Butane

Pentane

Hexane

Heptane

Octane

Nonane

Decane

Double bonds

1-ene

2-diene

3-triene

Isoprene

(common name)

Definition of Terms• Antioxidants- substances which slow the oxidation

rate in autoxidizable substances. Present in fruits and vegetables; protectors against degenerative diseases.

• Extraction- the removal of soluble material from a solid mixture by means of a solvent.

• Filtration- the process of separating a solid from a liquid or gas by use of a membrane of medium (e.g. filter paper, glass sinter).

• Isomer- one of two or more compounds that have the same chemical formula but different arrangements of the atoms within the molecules and that may have different physical/chemical properties.

Trans-Lycopene

Conjugated

Non polar: Will not dissolve in water

Conjugation: Alternating double bonds

Lipophilic: Will dissolve in lipids. “lipid like” or “fat loving” (defines: oils, cholesterols and waxes).

Lycopene

Trans configuration- opposite position of atoms/substituents between a double bond.

Ex.H

H

Cis configuration- atoms on the same side of a double bond

Ex.H

H

Cis (Z) and Trans (E) configurations occur in isomers

Trans is often denoted E

Cis is often denoted Z

Cis/Trans

β-Carotene

C40H56

M.W. 536.873 g/mole

Melting Pt. 180-182ºC

Trans-Lycopene

C40H56

M.W. 536.873 g/mole

Melting Pt. 172-173ºC

Isomers:

Common Forms of lycopene5Z-Lycopene

9Z-Lycopene

13Z-Lycopene

C-19

C-23

C-27

Bioavailability

• Bioavailability- the degree and rate at which a substance, such as a drug, is absorbed into a living system or is made available at the site of physiological activity.

• More than 85% of the lycopene in the body is found in its cis (Z) form while in nature (tomatoes) it is found predominately in its trans (E) form. It is therefore said that lycopene is more bioavailable in its cis form.

Possible reasons for different isomers in the body.

• Lycopene can be isomerized by:– Heat– Light– pH– Catalyst (KI)-speeds reaction w/o being

consumed (interfering).In the body the change of temperature (25°C

(RT) to 37°C (BT)) and the change in pH ~2.0 in the stomach may be the cause of isomerization in the body.

Method of Extraction• 15 g of tomato food source/carotenoid

source• In 21 mL of acetone• Stir until no longer gummy• Vacuum filtration • Place solid material in 15 mL CH2Cl2

(Methylene Chloride)• Vacuum filtration• Evaporate CH2Cl2 via heat (B.P.)/vacuum

Reading liquid volumes

• Meniscus

18 ml

What is the volume?

The curved top of a column of liquid in a small tube

Vacuum Filtration

Buchner Funnel

Flask

Rubber Cork

Spectrophotometer

• Spectronic 20 (Spec. 20)

• Spectroscopy deals with

Absorption, which occurs when

Light( UV and visible) excites

the double bonds

Of molecules such as lycopene

To different energy levels.

H

H

e-

H

H

H

H

Ground state

Excited state

Light sourceCuvette(sample)

Before excitation

spectra

UV/VisUltraviolet-Visible Spectoscopy

λmax

maximum absorption

In hexane

•Violet: 400 - 420 nm

•Indigo: 420 - 440 nm

•Blue: 440 - 490 nm

•Green: 490 - 570 nm

•Yellow: 570 - 585 nm

•Orange: 585 - 620nm

•Red: 620 - 780 nm

The ultraviolet (UV) region is normally from 200 to 400 nm, and the visible portion is from 400 to 800 nm.

The longest visible wavelength is red and the shortest is violet.

Lycopene absorbs blue light giving it a red color and its Lambda max (λmax)

The End

Eat more Tomatoes®!