448
21.2 Garlic-as Major Source of OSC
Blackwood (2000) described that normal clove of garlic weighs between 3–6 g and
has an average of 1 g of carbohydrates, 0.2 g of protein, 0.05 g of fibre, 0.01 g of fat
and vitamins A, B1, B2, B3 and C. The Vitamin B1 is merged with the allicin and
known as allithiamine which is effortlessly taken up by the intestine. Allicin does
not subsist in garlic till it is mashed or cut (Blackwood and Fulder 1987). Damage
to the bulb of the garlic stimulates the allinase enzyme (Stoll and Seebeck 1951)
which metabolizes alliin to allicin (Block 1985). These Organosulfur compounds
found in garlic have a number of properties that produce beneficial effects to life
including antioxidant, anti-cancer, anti-inflammatory, anti-bacterial, anti-hypertensive, anti-hyperlipidemic, and anti- diabetic properties amongst others.
OSCs extracted and isolated from garlic are commonly studied in terms of their
in vivo antioxidant activity (Yin and Cheng 2003). These are diallyl sulfide (DAS),
diallyl disulfide (DADS), S-ethylcysteine (SEC), and N-acetyl cysteine (NAC).
These compounds were evaluated in terms of its non-enzymatic antioxidant activity
in a liposome system (Yin et al. 2002). It was found out that antioxidant protection
can be best derived when these compounds are combined with α-tocopherol than
α-tocopherol alone. Moreover, the antioxidant activity of these compounds was
found to diminish with increasing temperature and pH except for diallyl sulfide and
diallyl disulfide. This is of importance since the data on enzymatic antioxidant
activity supports human and animal application for health consideration but not in
application for food systems (Yin et al. 2002). Moreover, determining non- enzymatic
antioxidant activity at low pH will be useful in a variety of application in food
systems.
Other OSCs from different classes derived from garlic, like allyl cysteine, allicin,
alliin, and allyl disulfide, were also examined in terms of their antioxidant properties. Alliin was found to scavenge super oxides while both allyl cysteine and allyl
disulfide did not exhibit scavenging activity against superoxide (Chung 2006).
Furthermore, allicin was also found to prevent the production of superoxide by xanthine oxidase system through thiol exchange mechanism. Allicin did not exhibit
scavenging activity against hydroxyl radicals while alliin, allyl disulfide, and allyl
cysteine did (Chung 2006). This finding is contrary to another study where allicin
was found to be the main reason for the hydroxyl scavenging activity of garlic
extract (Kourounakis and Rekka 1991). Antioxidant properties were also noted in
the organo-sulfur-rich essential oils extracted from Drypetes gossweileri barks,
Pentadiplandra brazzeana roots, and A. cepa and A. sativum bulbs (Ndoye
et al. 2016).
Exogenous antioxidant activity of garlic-derived organosulfur, DAS, DADS,
SEC, and NAC were also determined in ground beef meat and were found to significantly delay both oxymyoglobin and lipid oxidations in membrane phospholipids
(Yin and Cheng 2003). These compounds possess potent protective effect towards
biological membranes against lipid peroxidation both in vitro and in vivo (Borek
2001; Awazu and Horie 2008). The effect of cooking garlic and its antioxidant
A. M. P. Walag et al.
21.2 Garlic-as Major Source of OSC
Blackwood (2000) described that normal clove of garlic weighs between 3–6 g and
has an average of 1 g of carbohydrates, 0.2 g of protein, 0.05 g of fibre, 0.01 g of fat
and vitamins A, B1, B2, B3 and C. The Vitamin B1 is merged with the allicin and
known as allithiamine which is effortlessly taken up by the intestine. Allicin does
not subsist in garlic till it is mashed or cut (Blackwood and Fulder 1987). Damage
to the bulb of the garlic stimulates the allinase enzyme (Stoll and Seebeck 1951)
which metabolizes alliin to allicin (Block 1985). These Organosulfur compounds
found in garlic have a number of properties that produce beneficial effects to life
including antioxidant, anti-cancer, anti-inflammatory, anti-bacterial, anti-hypertensive, anti-hyperlipidemic, and anti- diabetic properties amongst others.
OSCs extracted and isolated from garlic are commonly studied in terms of their
in vivo antioxidant activity (Yin and Cheng 2003). These are diallyl sulfide (DAS),
diallyl disulfide (DADS), S-ethylcysteine (SEC), and N-acetyl cysteine (NAC).
These compounds were evaluated in terms of its non-enzymatic antioxidant activity
in a liposome system (Yin et al. 2002). It was found out that antioxidant protection
can be best derived when these compounds are combined with α-tocopherol than
α-tocopherol alone. Moreover, the antioxidant activity of these compounds was
found to diminish with increasing temperature and pH except for diallyl sulfide and
diallyl disulfide. This is of importance since the data on enzymatic antioxidant
activity supports human and animal application for health consideration but not in
application for food systems (Yin et al. 2002). Moreover, determining non- enzymatic
antioxidant activity at low pH will be useful in a variety of application in food
systems.
Other OSCs from different classes derived from garlic, like allyl cysteine, allicin,
alliin, and allyl disulfide, were also examined in terms of their antioxidant properties. Alliin was found to scavenge super oxides while both allyl cysteine and allyl
disulfide did not exhibit scavenging activity against superoxide (Chung 2006).
Furthermore, allicin was also found to prevent the production of superoxide by xanthine oxidase system through thiol exchange mechanism. Allicin did not exhibit
scavenging activity against hydroxyl radicals while alliin, allyl disulfide, and allyl
cysteine did (Chung 2006). This finding is contrary to another study where allicin
was found to be the main reason for the hydroxyl scavenging activity of garlic
extract (Kourounakis and Rekka 1991). Antioxidant properties were also noted in
the organo-sulfur-rich essential oils extracted from Drypetes gossweileri barks,
Pentadiplandra brazzeana roots, and A. cepa and A. sativum bulbs (Ndoye
et al. 2016).
Exogenous antioxidant activity of garlic-derived organosulfur, DAS, DADS,
SEC, and NAC were also determined in ground beef meat and were found to significantly delay both oxymyoglobin and lipid oxidations in membrane phospholipids
(Yin and Cheng 2003). These compounds possess potent protective effect towards
biological membranes against lipid peroxidation both in vitro and in vivo (Borek
2001; Awazu and Horie 2008). The effect of cooking garlic and its antioxidant
A. M. P. Walag et al.