14.10 Health Effects
14.10.1 Anti-inflammatory Effects
Borage oil has gained considerable interest owing to the presence of GLA, which has
been associated to attenuate the signs and symptoms of chronic inflammation.
Several clinical and animal studies have confirmed the anti-inflammatory effects of
GLA metabolites. GLA, di-homo γ-linolenic acid (DGLA) and arachidonic acid
(AA) are the intermediates of the metabolism of dietary linoleic acid (C18:2; Δ
9,12 )
which is an essential fatty acid. The metabolism of dietary LA and the production of
eicosanoids compounds are presented in Fig. 14.4. In the presence of Δ6-desaturase
and elongase, dietary LA is converted into GLA and DGLA, respectively. A large
number of in vivo and in vitro studies have demonstrated that human neutrophils
have elongase but not Δ5-desaturase activity (Chapkin and Coble 1991; Navarette
et al. 1992; Ziboh et al. 2000). Furthermore, it is worthy to note that the skin, murine
peritoneal and platelets also appear to have high elongase activity than Δ5desaturase activity; resulting in more synthesis of DGLA as compared to AA
(Luthria and Sprecher 1994; Pawlosky et al. 1994; Sergeant et al. 2016). In normal
situation, where Δ5-desaturase and elongase both have equal activities (e.g. in the
liver, kidney, testes, brain, intestine), DGLA is further converted into arachidonic
acid (AA) in the presence of cyclooxygenase and lipoxygenase and produces
2-series prostaglandins (PGE2) and thromboxanes (TX2) and 4-series leukotrienes
(LT), respectively. These two-series eicosanoid components are potent
pro-inflammatory and known to increase the risk of chronic inflammation, mutagenic activity, platelet aggregation, rheumatoid arthritis, atherosclerosis, obesity, etc.
(Fan and Chapkin 1998; Kapoor and Huang 2006; Sergeant et al. 2016).
Contrarily, DGLA, in the presence of the same enzymes (cyclooxygenase and
lipoxygenase), produces one-series eicosanoid compounds such as prostaglandins
(PGE1), thromoxanes and 15-hydroxydihomo-γ-linolenic acid (Wang et al. 2012;
Sergeant et al. 2016), which act as potential anti-inflammatory compounds. It is
supposed that DGLA competes with AA for the same enzymes, i.e. cyclooxygenase
and lipoxygenases, and favours lesser production of pro-inflammatory AA metabolites and more production of one-series PGE1 and PGH1 molecules (Belch and Hill
2000; Wang et al. 2012) (Fig. 14.4). It is interesting to note that DGLA itself cannot
be converted into LTs but can form 15-hydroxy-derivatives that supress the formation of LTs (LT4) from AA (Belch and Hill 2000). One-series metabolites of DGLA
have been reported to supress inflammation, promote vasodilation, lower blood
pressure, inhibit smooth muscle cell proliferation and exert antineoplastic activities
(Sergeant et al. 2016; Wang et al. 2012; Wang et al. 2015). The metabolism of GLA
and the detailed mechanism of pro- and anti-inflammatory compounds have been
explained by Sergeant et al. (2016).
360
B. Tanwar et al.
14.10.1 Anti-inflammatory Effects
Borage oil has gained considerable interest owing to the presence of GLA, which has
been associated to attenuate the signs and symptoms of chronic inflammation.
Several clinical and animal studies have confirmed the anti-inflammatory effects of
GLA metabolites. GLA, di-homo γ-linolenic acid (DGLA) and arachidonic acid
(AA) are the intermediates of the metabolism of dietary linoleic acid (C18:2; Δ
9,12 )
which is an essential fatty acid. The metabolism of dietary LA and the production of
eicosanoids compounds are presented in Fig. 14.4. In the presence of Δ6-desaturase
and elongase, dietary LA is converted into GLA and DGLA, respectively. A large
number of in vivo and in vitro studies have demonstrated that human neutrophils
have elongase but not Δ5-desaturase activity (Chapkin and Coble 1991; Navarette
et al. 1992; Ziboh et al. 2000). Furthermore, it is worthy to note that the skin, murine
peritoneal and platelets also appear to have high elongase activity than Δ5desaturase activity; resulting in more synthesis of DGLA as compared to AA
(Luthria and Sprecher 1994; Pawlosky et al. 1994; Sergeant et al. 2016). In normal
situation, where Δ5-desaturase and elongase both have equal activities (e.g. in the
liver, kidney, testes, brain, intestine), DGLA is further converted into arachidonic
acid (AA) in the presence of cyclooxygenase and lipoxygenase and produces
2-series prostaglandins (PGE2) and thromboxanes (TX2) and 4-series leukotrienes
(LT), respectively. These two-series eicosanoid components are potent
pro-inflammatory and known to increase the risk of chronic inflammation, mutagenic activity, platelet aggregation, rheumatoid arthritis, atherosclerosis, obesity, etc.
(Fan and Chapkin 1998; Kapoor and Huang 2006; Sergeant et al. 2016).
Contrarily, DGLA, in the presence of the same enzymes (cyclooxygenase and
lipoxygenase), produces one-series eicosanoid compounds such as prostaglandins
(PGE1), thromoxanes and 15-hydroxydihomo-γ-linolenic acid (Wang et al. 2012;
Sergeant et al. 2016), which act as potential anti-inflammatory compounds. It is
supposed that DGLA competes with AA for the same enzymes, i.e. cyclooxygenase
and lipoxygenases, and favours lesser production of pro-inflammatory AA metabolites and more production of one-series PGE1 and PGH1 molecules (Belch and Hill
2000; Wang et al. 2012) (Fig. 14.4). It is interesting to note that DGLA itself cannot
be converted into LTs but can form 15-hydroxy-derivatives that supress the formation of LTs (LT4) from AA (Belch and Hill 2000). One-series metabolites of DGLA
have been reported to supress inflammation, promote vasodilation, lower blood
pressure, inhibit smooth muscle cell proliferation and exert antineoplastic activities
(Sergeant et al. 2016; Wang et al. 2012; Wang et al. 2015). The metabolism of GLA
and the detailed mechanism of pro- and anti-inflammatory compounds have been
explained by Sergeant et al. (2016).
360
B. Tanwar et al.