A Nigerian researcher has identified no fewer
than 520 local plants that could be used to treat fungal skin infections,
control water hyacinth, biodegrade crude oil spill, prevent dental decay, and
control uterine contraction and bleeding during child birth.
A PROFESSOR of
Botany at the University of Lagos, Adedotun Adeyinka Adekunle, has documented
520 plant species with proven antifungal properties.
Adekunle in his Inaugural lecture, titled
“Fungi: Friends or Foes to Mankind,” delivered last week at the University’s
main auditorium, said: “Several studies were carried out on the purification of
the antifungal principle from Nigerian plants. The active antifungal ingredient
was tested on human fungal pathogens (dermatophytes) as well as on plant
pathogens. It is always necessary to develop new natural drugs because of
resistance to existing drugs by microorganisms like fungi.
“A survey of
medicinal plants used in the treatment of skin rashes, eczema, athlete foot and
ring worm in the south western, Nigeria was carried out. A
medicinal plant list of 520 plant species with antifungal properties was
documented.”
Adekunle who
specializes in mycology (the study of fungi) said phytochemical properties of
some of the plant extracts were investigated and were found to contain
flavonoid, saponins, terpenes and tannins with fungicidal properties on
dermatophytes such as Epidermophyton
floccosom, Mucor mucedo
(opportunistic), Microsporium audonii,
and Trichophyton verrucosum.
Adekunle and his
team of researchers also investigated the antifungal activity of four Nigerian
chewing sticks from the stem or root of Angeissus
schimperi (ayin in Yoruba), Distemonathus
benthmianus (ayan in Yoruba), Vernonia
amagdalina (orin ewuro in Yoruba, bitter leaf) and Zanthoxylum xanthoxyloides (orin ata in Yoruba).
“This study was set up to further
scientifically support the use of chewing sticks in dental care by the Nigerian
natives. It was found that the extracts of these chewing sticks were potent
against fungi used,” he said.
The mycologist
and his team also carried out another study on the time of leaf harvest (in a
24 hour rhythm) and antifungal activity of Acalypha
wilkesiana (lara pupa in Yoruba) leaf extracts. Acalypha
wilkesiana is used to treat skin rashes in babies (ela in Yoruba).
He explained:
“The Nigerian traditional medicine practitioner believe that plants sleep at
night between 7pm to 5am for their medicinal purpose. However,
our study discovered that the best period of harvest of the Acalypha wilkesiana leaf was 3am. The
leaves harvested at 3am had the highest concentration of corilagin and geranin,
which are the antifungal active ingredients hence had the highest zone of
inhibition on the fungi.
“There was a definite change in the
antifungal activity of extracts of Acalypha
wilkesiana leaves harvested at different times of the day (3am, 6am, 9am,
12noon, 3pm, 6pm, 9pm and 12 midnight). The least activity was recorded from
leaves harvested at 12noon. Our report did not agree with the claims of the Nigerian
natives to harvest plants for medicinal purpose only during the day light in
the case of Acalypha wilkesiana
leaf.”
Adekunle and his
team also studied the efficacy of preserving plant seeds against fungi using
wood ash of some tropical trees in Nigeria. The wood ash of nine
Nigerian trees: Khaya grandifolia; Nauclea diderrichi; Piptadeniastrum
africanum; Mangifera indica; Mansonia altissima; Triplochiton scleroxylon; Ceiba pentandra; Terminalia
superba; and Terminalia ivoriensis
were used to preserve beans, maize and melon seeds.
“The seeds stored with ashes of Nauclea diderrichi and Piptadeniastrum
africanum were the most effective
stopping fungal growth and eliminating weevils. The wood ashes used compared
favourably with the orthodox fungicides benlate. The wood ash of these plants
contained flavonoids and tannins which stop fungal infection and preserve the
seeds.”
Adekunle with
his colleagues from the department of biochemistry have isolated a pathogenic
fungus called Myrothecium roridum
that is able to destroy the water hyacinth, ‘eat up’ the whole plant, within
five days post inoculation on the leaves. “The fungus can thus control
the water hyacinth. The fungal action is systemic and host specific. On further
investigation we isolated and purified a phytotopxin and mycoherbicide from Myrothecium roridum. With this discovery
in 2006, we won the Faculty Best Researchers Award at the University of Lagos
research fair. We have sent our findings and proposal to the Ministry of
environment, Lagos state for further discussions on the biocontrol of water
hyacinth in Lagos waters using this fungus,” he explained.
Adekunle and his
team have also investigated the potential of alkaloids from Panicum maximum
floret infected with the fungus Tilletia
ayresii in the control of uterine
contraction using bioassay guided fractionation technique.
They wrote: “Our aim of conducting this
research was to discover cheaper and easily accessible drugs of Nigerian origin
for controlling uterine contraction, which led to expulsion of placenta and
subsequent control of bleeding after childbirth. The only source of the uterine
contraction drug, ergometrine or ergot alkaloids before our study was from
ergot or rye, a temperate plant that cannot grow in the tropics, Nigeria inclusive.
Hence, it is imported with scarce foreign exchange.
“Ergot of rye is an infected rye floret by
the fungus Claviceps purpurea. Claviceps purpurea infects the ovary of
its host, rye, just as Tilletia ayresii
infects the ovary of its own host, Panicum
maximum (Guinea grass), a tropical plant found in Nigeria.
“We discovered an alkaloid as the active
ingredient responsible for the uterine contraction in rats, from infected Panicum maximum floret purified extract.
This discovery has been registered as a patent with the National Office of
Technology Acquisition Promotion Agency (NOTAP).”
The botanist said his team has conducted a
research to source fungi capable of biodegrading the petroleum oil from some
Nigerian oilseeds such as soybean, maize, melon, Detarium senegalense, Treculia
africana, and Irvingia gabonensis
(Ogbonno in Yoruba). “We discovered that the pathogenic fungi isolated from the
oil within 40 days. The oilseeds contain triacylglyceride, which is the
vegetable oil hydrocarbon and it is biodegradable by the pathogenic fungi. This
group of fungi was also able to biodegrade the hydrocarbon in the petroleum
oil,” Adekunle said.
Adekunle in his inaugural lecture made
several recommendations on how to improve scientific research in Nigeria. The
professor of botany called for the establishment of a fungal collection centre
to help in the confirmation of fungal identification. “Cultures are usually
sent to America or United Kingdom. It used to be free, but now fungal
confirmation attracts heavy fees in foreign currency.”
Adekunle want the government to introduce
encouragement of research through financial reward for their work as practiced
in South Africa. He said there is urgent need to establish a functional central
laboratory for research in the University; promote and establish functional
scholarship awards for post-graduate studies in all disciplines; and build
accommodation for both members of staff and students; devise newer ways of
providing sustainable electricity supply to the University.
Adekunle
concluded: “These are my contributions in mycology, making fungi friends of man
voluntarily or compulsorily scientifically. Fungi are indeed friends to
humans.”
Data: 10.11.2012
Texto: Chukwuma
Muanya
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