359
antioxidant potential to its reducing capacity. Also at high doses of 1.25–2.5 mM
aloin prevented DNA breakage due to OH radicles by 5–30% over the control value
but increases DNA damage at lower concentrations of 300–8 μM. Both aloe emodin
and EGCG at high concentrations show prooxidant effects. The experiments established that the different effects of both aloin and aloe emodin on DNA may be
attributed to the difference in their structures and concentration dependencies (Tian
and Hua 2005). Studies have established that several antioxidant agents can become
prooxidants at different concentrations and therefore their right doses should be
established before their clinical use (Lee and Park 2003).
18.5.7 Anti-inflammatory Activity
During inflammatory process, highly active pro-inflammatory mediators (prostaglandins) are produced from arachidonic acid in the presence of cyclooxygenase
(COX) enzymes (prostaglandin-H 2 -synthases) which act as catalysts (Steinmeyer
2000). Inhibiting COX enzymes, particularly the COX-2 enzyme inhibit production
of prostaglandin to resolve inflammation. Fifty-one different Aloe species were
reported to show different activity levels against COX-1 enzymes (Amoo et al.
2014). Administration of Aloe has been resulted in proliferative and phagocytic
activity by reducing prostaglandin E2 production and inhibiting COX pathways
(Park et al. 2009). Methanol extract of A. ferox inhibit the COX-1 effects as reported
by Lindsey et al. (2002). In the early phase of acute inflammatory response tumor
necrosis factor (TNF)-α genes and albumin transcription levels are involved.
Elimination of albumin gene transcription was observed in rats treated with aloeemodin. After administration of aloe- emodin, decreased level of TNF-α was
detected in livers. Rats treated with aloe-emodin showed a reduced inflammatory
infiltration of the Kupffer cells and lymphocytes (Arosio et al. 2000). The presence
of chromones and anthraquinones in the inner Aloe gel acquire strong antiinflammatory effects in murine macrophages (Park et al. 2009).
Studies report that A. vera gel had strong NLRP3 (NACHT, LRR, and PYD
domains-containing protein 3) inflammasome expression, immunomodulatory
activity and downregulating lipopolysaccharide-induced inflammatory cytokine
production in human macrophage (Budai et al. 2013). In severe traumatic–hemorrhagic rats pre-treatment of Aloe polysaccharide can attenuate reperfusion injury
and cerebral ischemia by inhibiting lipid peroxidation, systemic inflammatory
response and leukocyte aggregation (Liu et al. 2012).
Bradykinin is an inflammatory substance that is associated to cause pain during
inflammation. Bradykinase is an enzyme that causes the breakdown of bradykinin
has been discovered and isolated from aloe that cause breakdown of bradykinin thus
attributing to the plant’s anti-inflammatory properties. Furthermore, sterols present
in the plants are natural analgesics and help suppress pain (Sahu et al. 2013).
18 Aloe Species as Valuable Sources of Functional Bioactives
antioxidant potential to its reducing capacity. Also at high doses of 1.25–2.5 mM
aloin prevented DNA breakage due to OH radicles by 5–30% over the control value
but increases DNA damage at lower concentrations of 300–8 μM. Both aloe emodin
and EGCG at high concentrations show prooxidant effects. The experiments established that the different effects of both aloin and aloe emodin on DNA may be
attributed to the difference in their structures and concentration dependencies (Tian
and Hua 2005). Studies have established that several antioxidant agents can become
prooxidants at different concentrations and therefore their right doses should be
established before their clinical use (Lee and Park 2003).
18.5.7 Anti-inflammatory Activity
During inflammatory process, highly active pro-inflammatory mediators (prostaglandins) are produced from arachidonic acid in the presence of cyclooxygenase
(COX) enzymes (prostaglandin-H 2 -synthases) which act as catalysts (Steinmeyer
2000). Inhibiting COX enzymes, particularly the COX-2 enzyme inhibit production
of prostaglandin to resolve inflammation. Fifty-one different Aloe species were
reported to show different activity levels against COX-1 enzymes (Amoo et al.
2014). Administration of Aloe has been resulted in proliferative and phagocytic
activity by reducing prostaglandin E2 production and inhibiting COX pathways
(Park et al. 2009). Methanol extract of A. ferox inhibit the COX-1 effects as reported
by Lindsey et al. (2002). In the early phase of acute inflammatory response tumor
necrosis factor (TNF)-α genes and albumin transcription levels are involved.
Elimination of albumin gene transcription was observed in rats treated with aloeemodin. After administration of aloe- emodin, decreased level of TNF-α was
detected in livers. Rats treated with aloe-emodin showed a reduced inflammatory
infiltration of the Kupffer cells and lymphocytes (Arosio et al. 2000). The presence
of chromones and anthraquinones in the inner Aloe gel acquire strong antiinflammatory effects in murine macrophages (Park et al. 2009).
Studies report that A. vera gel had strong NLRP3 (NACHT, LRR, and PYD
domains-containing protein 3) inflammasome expression, immunomodulatory
activity and downregulating lipopolysaccharide-induced inflammatory cytokine
production in human macrophage (Budai et al. 2013). In severe traumatic–hemorrhagic rats pre-treatment of Aloe polysaccharide can attenuate reperfusion injury
and cerebral ischemia by inhibiting lipid peroxidation, systemic inflammatory
response and leukocyte aggregation (Liu et al. 2012).
Bradykinin is an inflammatory substance that is associated to cause pain during
inflammation. Bradykinase is an enzyme that causes the breakdown of bradykinin
has been discovered and isolated from aloe that cause breakdown of bradykinin thus
attributing to the plant’s anti-inflammatory properties. Furthermore, sterols present
in the plants are natural analgesics and help suppress pain (Sahu et al. 2013).
18 Aloe Species as Valuable Sources of Functional Bioactives