The antiviral activities of plant leaves
extract of four species, were investigated. The extract were tested for
antiviral activities on the host plant (Cocumba) against Moroccan
watermelon mosaic virus. Results showed that two plants (Phyllanthus amerus and Mirabiles jalapa) presented inhibitory activities against the virus. While Ficus exaspirata and Citrus spp were unable to inhibit the virus.
Moroccan watermelon mosaic virus is still a major problem on the cucubite cultivation in Africa.
1.1 Background of study
Plant viruses are responsible for huge economic losses in many countries around the world.
A virus is an infection agent
that typically consists of nuclei and molecule in a protein coat, it is
too small to be seen by light microscopy, and is able to multiply only
within the living cells of a host. (Holmes, 1939). Viruses can be spread
by direct transfer of sap by contact of a wounded plant with a healthy
one, such contact may occur during agricultural practices, as by damage
caused by tools or hands, or naturally as by animal feeding on the
plant. Most of the viruses infecting plants rely on insects to move
from one host to another, some remain associated with the mouth parts
and can be inoculated within seconds or minutes. (Martinus, 1898).
This work those not cover insect transmission but basically mechanical
1.2 Methods employed to control plant viruses
Plant viruses and virus diseases
have been studied for more than 100 years and much attention has been
given to their control. However, this has been difficult to achieve
because of the lack of any effective means of curing virus-infected
plants. Chemotherapy, thermotherapy and Meristem-tip culture can be
successful but they cannot be used on a large scale. (Brook, 1964). The
main approach has been to prevent or delay virus infection or to
minimize its effect. Various means have been used to achieve these
objectives, including phyto-sanitation. (Involving quarantine measures,
crop hygiene use of virus-free plant materials and eradication) changes
in crop practices, use of pesticide for control of vectors, mild strain
protection and the employment of resistant or tolerant varieties.
(Sarkar, 1995). Some viruses can be eliminated from infected plant by
heat or meristem-tip therapy or by the use of chemicals (Faccioli
and Marami, 1998) these methods are used widely to develop virus-free
plants of vegetatively-propagated crops for further propagation. It
prevents plants from becoming infected, delay infection to such a life
stage of crop impaired and decrease the effects of infection. (Mink et
1.2.1 Ricinus Sp (Castor oil plant)
has being classified as a member of the sponge family, Euphobiaceae.
The seed from Ricinus sp plant contain in excess of 45% oil. The said
oil is used widely for various purposes. It is used as a lubricant, in
high speed engine and aeroplanes, in the manufacture of soap,
transparent paper, printing ink, varnishings, linolilium and
plasticizer. It is also used for medical and lighting purposes. It has
antimicrobial activities against gram positive bacteria (Nuttall &
1.2.2 Mirabilis Jalapa. (The
four 0’clock plant) has being classified as a member of the
Nyctaginaleae family the species mirabilis Jalapa is a commonly grown
ornamental plant and is available in a range of colours. The flower of
Mirabilis Jalapa is used for food colouring, and the leaves may be eaten
cooked as food. It serves as emergency food. It is used for dye
production for cakes and jellies. It is also used for cosmetics
production. It has antiviral protein (MAP) which was demonstrated to
possess abortificiant actively in pregnant mice, inhibitory effect on
call-free protein synthesis and antiproliferative effect on tumor cells.
(Wong et al, 2014).
1.2.3 Phyllanthus amerus:
is a member of the Euphorbiaceae family, it is commonly called the
stone breaker, the plant extract from Phyllanthus according to (Nicole,
1998) has being used for killing bacteria, expels stones, support
kidneys and treat malaria.
1.2.4 Adansonia Digitata:
Belongs to the family Malvaceae. This species is found in hot, dry
savannahs’ of Sub-Saharan Africa. Common names, Baobab, monkey bread
tree, dead-rat tree and cream of taster tree etc. The leaves are used
either fresh as a cooked vegetable or dried and powered as an ingredient
of soups and sauces. The shoots and roots of seedlings are eaten as
well. The roots are boiled and eaten in West Africa in times of famine.
It is used as functional food for the well being of the rural
communities, food for livestock, shelter for the living and the dead,
the bark of a digitata has been imported in the past into Europe by the
packing and paper industry and for medicinal use. Under the name cortex
Cael Cedra. It was used as a substitute for quinine to reduce fever
1.2.5 Acalypha Indica:
belong to the family Euphorbialeae. It is a common herb growing up to
75cm tall with ovate leaves. The leaves are cooked and eaten as
vegetable. This plant is held to high esteem in traditional medicine, as
it is believed to rejuvenate the body. It is useful bronchitis
pneumonia, ashma and pulmonary tuberculosis. It also has significant
antibacterial and antifungal activities, both against human and plant
pathogen. (Burkill, 1974).
1.3 Plant as reserviour Of Antiviral substance
Plants from Northern Nigeria with
a history of use in both human and veterinary traditional medicine have
been investigated for their antiviral activity and their hypotoxility
determined. Most of the extracts have activity against more than one
virus of a dose rate of between 100 and 400 microg/100 microl. (Mehesh,
Lawsonia Inermis: Popularly known as
Hemma or mehindi in the oriental world, is an evergreen medium sized
shrub belonging to the family hythraccere. This plant harbors a well
documented folklore history for treating convulsion, jaundice and
malignant ulcers. Phytochemical studies in henna plant have indicated
the presence of several bioactive molecular like isophumpagin, hipeol,
30-norlupan -3-01-20-one betuhennan, betuhennamic acid and nstigmasterol
in leaves and roots. Plant extract have been known to be depressing
antimicrobial, antioxidant, wound healing, anti-inflammatory
antipyretic, analgesis actions, (Keyvan, 2008).
1.4 Morocan water melon Mosaic virus : the moroceam water melon mosaic virus (MWMV), has been determined to be a distinct members of the polyvirus group.
(Cockerhem, 1970) the relationship of the morocean water melon mosaic virus and other polyviruses and the W strain of papaya rignspoot virus,
was examined by comparing tryptic peptide profiles using high
performance liquid chromatography. The profolus indicated that the low
protein sequence of MWMV differed substantially from those of the other
poly-viruses. (McKern, 1993).