Agriculture Reference
In-Depth Information
Constituents —
G
.
kola
and other members of the genus are known to elaborate a complex
mixture of phenolic compounds, including biflavonoids, xanthones, and benzophenones.
569-571
The
most important constituents of the plant include the antimicrobial benzophenone, kolanone,
572
and
biflavonoids based on eridictoyl/taxifolin moiety GB1, GB2, GB3, kolaflavanone, and garciniflava-
none.
573,574
The seeds also contain the chromanols garcinoic acid and garcinal and their derivatives,
as well as tocotrienol.
575
Pharmacological Studies —
G
.
kola
has been shown to possess remarkable antihepatotoxic
activity against a variety of experimental hepatotoxins, including carbon tetrachloride, 2-acetyl-
aminofluorene, paracetamol, and galactosamine,
576 -581
and protection against the accumulation of
heavy metals in the liver.
582
Chronic ingestion of
G
.
kola
seeds caused inhibition of gastrointestinal
motility and weight reduction and prevented castor oil-induced diarrhea in rats.
583
Other activities
of the biflavonoid mixture include those involving anti-inflammatory, antimicrobial, antidiabetic,
and antiviral properties.
584-586
The antiviral activity is quite broad and showed remarkable inhibi-
tory effects against a variety of viruses, including Punta Toro and Pichinde viruses, sandfly fever,
influenza A, Venezuelan equine encephalomyelitis, and ebola. The IC
50
values are in the range of
7.2-32/µg/ml with an MTC of more than 320 µg/ml.
587
The seed extract and the dried powder have been formulated into various dosage forms, includ-
ing tablets, lozenges, creams, vials, and toothpaste.
588
The biflavonoids also possess antidiabetic
activity and inhibited the activity of rat lens aldose reductase.
589
Examination of the liver, kidney,
and duodenum of rats fed a diet containing 10% (w/w) dry powdered seeds of
G
.
kola
for 6 weeks
has been reported as revealing some histological alterations in these organs.
465
Studies indicated a
possible role in the treatment of dermatological disorders associated with melanin hyperpigmenta-
tion. The methanol extract and a
Garcinia
biflavonoid displayed inhibitory activity (>60%) against
tyrosinase (E:C:1.14.18.1), the rate-limiting enzyme in melanin synthesis.
590
Kolaviron, the mixture of biflavonoids, benzophenones, and chromanols, as well as other
phenolic compounds in
G. kola,
possesses strong antioxidant activities. Several reports on the
experimental validation of the antioxidant properties of
Garcinia
are due essentially to kolavi-
ron. An evaluation of the antioxidant properties of garcinoic acid (structurally similar to vitamin
E) and its congeners, including investigation of the structure-antioxidative activity relationships,
identified a semisynthetic derivative with antioxidant activity that was 18.7 times stronger than
dl-a-tocopherol.
591
The aqueous extract showed antidiabetic activity in hyperglycemic rats.
592
At
a concentration of 200 mg/kg body weight, over a period of 21 days, the extract significantly (
p
<
0.05) decreased the blood glucose level and increased the activity of SOD (
p
< 0.05) and that of
malondialdehyde (MDA) (
p
< 0.05). The extract, however, had no significant effect (
p
> 0.05) on
the activity of CAT.
The clinical outcome observations on the phytomedicines prepared from the standardized whole
seeds or extracts of
G. kola
seem to support the laboratory findings reported and the use of the plant
as an adaptogen. Its bronchodilatory effect has been evaluated with a clinical study of 19 male
adults. The only respiratory parameter changed by 15 g of
G. kola
was a peak expiratory flow rate,
indicating a mild bronchodilatory effect.
593
Observational studies at the International Centre for
Ethnomedicine and Drug Development (InterCEDD) Nsukka (Nigeria) indicated potential applica-
tion as a remedy for colic in dysentery, liver disorders, upper respiratory infections, asthma, cough,
sore throat, laryngitis, arthritis, menstrual and intestinal cramps, and headache. Topical uses await-
ing clinical validation include its use as a wound dressing, as an antiparasitic lotion, and in oral
hygiene (as a chewing stick). The possible clinical uses for
Garcinia
based on the analysis of the
studies include its use as an antiviral, antihepatotoxic, and immune booster in cases of flu and liver
and respiratory diseases, as antioxidant, and in the management of diabetes.
Toxicity —
No serious adverse effects have been reported following the consumption of
Garcinia
. In response to the public health concern in West Africa about the long-term use of
