118
VOLUME 11 NUMBER 3 • SEPTEMBER 2014
REVIEW
SA JOURNAL OF DIABETES & VASCULAR DISEASE
diabetes mellitus, suggesting that this plant may be beneficial.
17
We undertook a systematic survey of medicinal plants used by
rural communities in South Africa and have identified several species
with beneficial effects in the prevention of renal complications in
diabetes mellitus. These effects were observed with both crude
extracts and bioactive compounds isolated from antidiabetic
plants. In particular, we showed that plants such as
Sclerocarya
birrea
[(A Rich) Hochst] [Anachardiaceae],
Persea americana
(Miller)
[Lauraceae],
Ficus thonningii
(Blume) [Moraceae] and
Helichrysium
ceres
had reno-protective effects (Fig. 2).
17,32,38
Initial studies have
shown that extracts from these plants ameliorated renal dysfunction
in experimental diabetes.
Subsequently, we isolated oleanolic acid as the bioactive
compound and have shown that it possesses reno-protective effects
in experimental diabetes mellitus. Therefore S cordatumderived
oleanolic acid caused increased renal Na+ excretion in STZ-induced
diabetic rats, which was mediated by an improvement in glomerular
filtration rate (Fig. 3).
63
Other active agents identified in these plants
include polysaccharides, flavonoids, xanthones and peptides.
There are various mechanisms by which reno-protection may be
achieved, including modulation of AGEs, of the polyol pathway, and
of the PKC pathway, and anti-oxidative properties. For example,
morroniside isolated from Corni fructus has shown reno-protection
in experimental diabetes through a reduction in the production of
AGEs.
64
Additionally, some plants have been shown to cause an
improvement in renal function in experimental diabetes mellitus
through inhibition of ET-1 and TGF-
β
1 and the endothelin-1
receptor A (ETRA).
65
Table 1.
Partial survey of medicinal plants/plant extracts which affected the cardiovascular and kidney function in diabetes mellitus
Botanical species
Bioactive compounds Antidiabetic advantages Renal function advantages Cardiovascular advantages References
Allium sativum
L (garlic)
phenols
↑
insulin secretion
↑
GFR
vasorelaxant,
67, 68
(Alliaceae)
flavonoids
↑
hepatic glycogen
↓
hypolipidaemic
Gongronema latifolium
flavonoids
↑
hepatic glycogen
anti-oxidant
↓
hypolipidaemic
69
saponins
polyphenols
Foeniculum vulgare
L
phytoestrogens
↓
glucose absorption
diuretic
vasorelaxant
70
(Apiaceae)
natriuretic
Opuntia megacantha
phenols, flavonoids
↓
glucose absorption
↑
GFR
vasorelaxant
71, 72, 73
(quercetin) taxifolin
Syzygium
spp
phenylpropanoids
↑
hepatic glycogen
↑
GFR
vasorelaxant
63, 66, 74
flavonoids sesquiterpenes
↑
insulin secretion
oleanolic acid rhamnetin
Sclerocarya birrea
flavonoids,
↑
hepatic glucose
↑
GFR
vasorelaxant
32, 75
[(A Rich) Hochst]
alkaloids, triterpenoids,
utilisation
[Anacardiaceae]
coumarins,
↑
insulin secretion
ascorbic acid
Persea americana
Mill
tannins, saponins
↑
hepatic glycogen
↑
GFR
vasorelaxant
32, 76, 77, 78
(Lauraceae) [Avocado]
flavonoids, alkaloids
↑
insulin secretion
bradycardia
glycosides
↓
hypolipidaemic
Hypoxis hemerocallidea
glycoside hypoxoside
↑
insulin secretion
reno-toxic
cardiodepressant
79, 80
β
-sitosterol sterolins,
↓
GFR
bradycardia
cytokinins
Ficus thonningii
(Blume)
alkaloids anthraquinones
↑
hepatic glycogen
↑
GFR
cardiodepressant
17, 81
[Morarceae]
flavonoids saponins
vasorelaxant
tannins
bradycardia
Olea europaea
L,
triterpenes, flavonoids,
↑
insulin secretion
↑
GFR
cardiodepressant
36, 82, 83, 84
(Oleaceae)
glycosides
↑
glucose utilisation
antioxidant
vasorelaxant
bradycardia
Helichrysum ceres
S
polyphenols, tannins,
unclear
diuretic
cardiodepressant
38, 39
Moore
triterpenes
natriuretic
vasorelaxant
[Asteraceae]
saponins
bradycardia
Ekebergia capensis
saponins
unclear
unclear
cardiodepressant
85
Sparrm
alkaloids
vasorelaxant
(Meliaceae)
flavonoids
bradycardia
tannins
Fig. 3.
Sub-chronic treatment with oleanolic acid (OA, 60 mg/kg bid every third
day) increased glomerular filtration rate in STZ-diabetic rats.66
