Agriculture Reference
In-Depth Information
kisasagenol B, ajugol, verminoside, 6-trans-caffeoyl ajugol, 7-hydroxy viteoid II, 7-hydroxy eucom-
mic acid, 7-hydroxy-10-deoxyeucommiol, and 10-deoxyeucommiol.
707
The major iridoids found in
the root bark and stem bark of
K. africana
are specioside, verminoside, and minecoside.
708
The
major flavonoid components of the leaves and fruits are luteolin and quercetin. They also contain
the phenolic acids 4-hydroxy cinnamic acid, ferulic acid, and caffeic acid.
Pharmacological Studies —
Extracts of
Kigelia
and isolated compounds have been shown
to possess antibacterial, antifungal, antineoplastic, analgesic and anti-inflammatory, antimalarial,
antiprotozoal, antidiarrheal, and CNS stimulant activities.
709
Bioassay-guided fractionation and
separation of
K. africana
led to the isolation of norviburtinal and isopinnatal, which are partially
responsible for the antineoplastic effect of the plant. Norviburtinal showed a much greater cytotoxic
effect but showed little selectivity toward melanoma cell lines. Isopinnatal displayed slightly greater
cytotoxic activity against the melanoma cell lines, but its high cytotoxicity against the noncancer
fibroblasts indicates that it probably has a general cytotoxic effect that precludes it from being con-
sidered as a lead molecule for novel anticancer agents. It is interesting to note that the crude extract
of
Kigelia
had a lower IC
50
value than the isolated compounds alone, which suggests that several
compounds are working together synergistically to give the observed antineoplastic effect.
710,711
The short-term effects of
Kigelia africana
fruit extract (KAFE) on cisplatin-induced testicular
histomorphometric changes in SD rats have been investigated.
712
It was found that cisplatin treatment
caused over 37.5% mortality of SD rats. Qualitative histological assessment showed no deleterious
changes following treatment with KAFE alone or as a pretreatment with cisplatin. KAFE posttreat-
ment resulted in focal vacuolar changes in the seminiferous tubules (STs) of the SD rats. Cisplatin treat-
ment negatively affected the histoarchitecture of these STs, with massive loss of spermatogenic cells.
There was also a significant reduction in testicular weight/volume, ST diameter, and cross-sectional
areas (
p
< 0.001), but KAFE positively improved these parameters. KAFE alone and as prophylaxis
significantly increased body weight, serum testosterone, and follicle-stimulating hormone (
p
< 0.001).
It showed a significant elevation in CAT activity, decline in MDA, and upregulation of GSH levels (
p
< 0.001). These parameters were negatively affected by cisplatin treatment. It was suggested that the
cytoprotection against cisplatin-induced testicular damage by KAFE is likely via an antioxidant modu-
latory pathway and also the possibility that KAFE may possess an androgen-stimulating property.
712
The extracts from the fruits have been shown to possess remarkable antidiabetic properties. In
STZ-induced diabetic Wistar rats, daily oral treatment with the methanolic extract of
K. africana
flowers and standard drug for 21 days significantly reduced blood glucose, serum cholesterol, and
triglyceride levels. The HDL cholesterol level was improved (
p
< 0.01) compared to the diabetic
control group. Iridoids isolated from
Kigelia
have been evaluated for a GLUT4 translocation modu-
latory effect in skeletal muscle cells. 7-Hydroxy eucommiol and three related iridoid glycosides
showed significant stimulation of GLUT4 translocation to the cell surface in skeletal muscle cells
without any adverse effect on cell viability. The effect of these four compounds was concentration
dependent and comparable to the standard drug rosiglitazone. These findings indicate that constitu-
ents of
K. africana
may provide leads for the therapeutics for insulin resistance and diabetes.
713
The anti-inflammatory and analgesic properties of the extracts of
Kigelia africana
have been
shown to be comparable to those of synthetic anti-inflammatory agents and analgesics. Supercritical
CO
2
extracts of
Kigelia
have been shown to be more effective than indomethacin (a potent synthetic
anti-inflammatory agent) when evaluated against two anti-inflammatory assays, the inhibition of
“oxidative burst” on human neutrophils and inhibition of COX-2.
714
The methanol extract of the flow-
ers exhibited significant (
p
< 0.01) anti-inflammatory and analgesic activities with doses of 100, 200,
and 400 mg/kg in rats and mice, respectively.
715
The plant extracts and the constituent compounds
showed significant antioxidant activity and a potent effect against
Trypanosoma brucei brucei
,
T.b.
rhodensiensis,
and
Entamoeba histolytica
. In the
E. histolytica
studies, it was found that when tested
against the HK-9 strain, verminoside had twofold the antiamoebic activity of metronidazole, the stan-
dard antiamoebic drug, while specioside showed comparable activity with metronidazole.
716
