z-axis component generated with the resulting information can be used to
give a spin coupling spectrum. Through this approach, correlated peaks can
be used to distinguish spin-spin coupling states for hydrogen atoms and
between hydrogen and carbon (Fig. 10.14) (Keeler 2011).
2. Heteronuclear Multiple Quantum Correlation (HMQC)
The HMQC method can be used to obtain information about carbon peaks
and the hydrogen atoms bound directly to those carbon atoms.
3. Heteronuclear Multiple Bond Correlation (HMBC)
C–H spin coupling is known as long-distance spin coupling when it passes
through two or more bonds. Long-distance spin coupling can be used to
obtain important structural analysis information not only for aromatic
compounds with few hydrogen atoms and a high degree of nonsaturation,
but also for compounds with quaternary carbon, including CO groups
(Downard 2007).
D. Mass Spectrometry (MS)
In simple terms, the principle of mass spectrometry involves the ionization of
molecules to isolate and measure them in terms of the ratio of mass to charge (m/z)
to determine molecular weight. MS can be used to precisely determine molecular
mass and composition formulas, while the fragmentation of molecules that occurs
incidentally during ionization can be used to identify linked functional groups and
part of the structure.
The horizontal axis in the mass spectrum represents the ratio of mass to ion
charge (m/z), while the vertical axis is the relative ion strength percentage. The
most important of the peaks produced is the molecular ion (also known as the
mother ion, M
+
). In many cases, the molecular ion peak represents the largest mass
in the spectrum, although the molecular ion peak may be small or may not be
observed at all, depending on the ionization method or molecular ion. Molecular
ions of M
+
-Na, M
+ -H, and M
+
-NH 4 have also been observed. Mass peaks smaller
than the molecular weight that are observed as a result of molecular cleavage are
referred to as fragment ions (daughter ions); the strongest of these peaks is called
the base peak. Peaks are typically represented in terms of their relative size, where
the base peak represents 100%.
10.3 Bioactive Substances from Marine Organisms
A bioactive substance is a substance that promotes or inhibits bodily functions over
the course of an organism’s life. They may be defined as those substances whose
job is to correct any pathological states resulted from a deficiency or excess
secretion of substances involved in coordinating functions within the body. As
such, they are very important in allowing an organism to live a better, healthier life.
New bioactive substances can be obtained from plants, animals, and other natural
368
10 Marine Natural Substances
give a spin coupling spectrum. Through this approach, correlated peaks can
be used to distinguish spin-spin coupling states for hydrogen atoms and
between hydrogen and carbon (Fig. 10.14) (Keeler 2011).
2. Heteronuclear Multiple Quantum Correlation (HMQC)
The HMQC method can be used to obtain information about carbon peaks
and the hydrogen atoms bound directly to those carbon atoms.
3. Heteronuclear Multiple Bond Correlation (HMBC)
C–H spin coupling is known as long-distance spin coupling when it passes
through two or more bonds. Long-distance spin coupling can be used to
obtain important structural analysis information not only for aromatic
compounds with few hydrogen atoms and a high degree of nonsaturation,
but also for compounds with quaternary carbon, including CO groups
(Downard 2007).
D. Mass Spectrometry (MS)
In simple terms, the principle of mass spectrometry involves the ionization of
molecules to isolate and measure them in terms of the ratio of mass to charge (m/z)
to determine molecular weight. MS can be used to precisely determine molecular
mass and composition formulas, while the fragmentation of molecules that occurs
incidentally during ionization can be used to identify linked functional groups and
part of the structure.
The horizontal axis in the mass spectrum represents the ratio of mass to ion
charge (m/z), while the vertical axis is the relative ion strength percentage. The
most important of the peaks produced is the molecular ion (also known as the
mother ion, M
+
). In many cases, the molecular ion peak represents the largest mass
in the spectrum, although the molecular ion peak may be small or may not be
observed at all, depending on the ionization method or molecular ion. Molecular
ions of M
+
-Na, M
+ -H, and M
+
-NH 4 have also been observed. Mass peaks smaller
than the molecular weight that are observed as a result of molecular cleavage are
referred to as fragment ions (daughter ions); the strongest of these peaks is called
the base peak. Peaks are typically represented in terms of their relative size, where
the base peak represents 100%.
10.3 Bioactive Substances from Marine Organisms
A bioactive substance is a substance that promotes or inhibits bodily functions over
the course of an organism’s life. They may be defined as those substances whose
job is to correct any pathological states resulted from a deficiency or excess
secretion of substances involved in coordinating functions within the body. As
such, they are very important in allowing an organism to live a better, healthier life.
New bioactive substances can be obtained from plants, animals, and other natural
368
10 Marine Natural Substances