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 al, 1998).
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 & Labuda, 2008).
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 (Jardin, 1968).
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,
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, 2000).
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).