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Evaluation of In vitro Phytotoxic
Activity of Medicinally Important
Acer pentapomicum (Maple Plant)
Shehla Khan*, Jehan Bakht
Institute of Biotechnology and Genetic Engineering, The University of Agriculture Peshawar, Pakistan
Submission: July 07, 2020 Published: August 18, 2020
*Corresponding author: Shehla Khan, Institute of Biotechnology and Genetic Engineering, The University of Agriculture Peshawar, Pakistan
How to cite this article: Shehla K, Jehan B. Evaluation of In vitro Phytotoxic Activity of Medicinally Important Acer pentapomicum (Maple Plant). Organic
& Medicinal Chem IJ. 2020; 9(5): 555774. DOI: 10.19080/OMCIJ.2020.09.555774.
Over recent years new bioherbicides compounds from natural sources has gained much interest from the researcher’s world widely. In this study the phytotoxicity of the crude extract and its various fractions from both the stem and leaves of Acer pentapomicum (maple plant) against Lemna minor has been studied. All the fractions except aqueous extract have exhibited highly significant phytotoxicity at different concentration when compared Paraquat as a positive control. The highest herbicidal activities of 87%, was exhibited by butanol extracted samples from stem, followed by chloroform and ethyl acetate exhibiting 81% and 80% respectively. Our results confirmed that both leaves and stem extracted samples possess potent inhibitory activity against Lemna minor.
Increasing emergence of herbicidal resistant weeds requires the discovery of new herbicides as the synthetic herbicide is becoming less effective day by day. Researchers, therefore, are trying to discover the new herbicides from the natural resources such as plant products [1-3]. These bioactive agrochemicals from the plant served to be more effective, nonhazardous, and
ecofriendly . The increase in interest on medicinal plants is due to the easier screening process of phytotoxic plants and the various bioactive compounds present in plant extracts that could be used as potential phytotoxic agent . There are several ways in which these phytotoxic plants could be utilized to control weeds such as
a. Planting them as cover crops with other main plants,
b. Direct application of the crude extracts,
c. Isolating and characterizing the bioactive substances
and using them as a new natural and biodegradable source for
herbicides development [6,7].
The genus Acer (Aceraceae), generally known as Maple family.
The genus Acer (Aceraceae) is composed of 128 species, majority
of these species are indigenous to Asia while some are native to
North Africa, North America, and Europe . Acer pentapomicum
commonly known as maple is one of the species of Aceraceae
family. A. pentapomicum is a deciduous small-tree or shrub with
brownish grey, flat bark. Leaves palmately 3-lobed; lobes are
trilateral, the upper side of the leaves is grey-green while the
lower side is pale green.
Flowers: greenish, 5-merous, smaller petals. 8-stamens
present at edges of the disc. Ovary is glabrate: style connate at
the surface. A pentapomicum is locally known as Tarkana and
is native to Northern areas of Pakistan . The plant is phenolic
rich and known to possess potent medicinal properties .
In our current study, we investigated the phytotoxic activity of
various plant extracted samples from the leaves and stems of Acer
pentapomicum. To the best of our knowledge we are the first one
to report the phytotoxic activity of Acer pentapomicum.
The A. pentapomicum plant was collected from the Swat
valley Northern area of Pakistan, which is known for its rich flora
of medicinal plants. The leaves and stems were shade dried and
powdered using Anex blender grinder AG-6040.
Extraction and fractionation of plant material
For extraction of plant material, method described by  was
followed. Briefly, about 500gm of A. pentapomicum leaves powder
was soaked in methanol for 5-6 days with daily thoroughly mixing.
The crude methanolic extract obtained was then filtered and
concentrated through rotary evaporator. Few grams of the dried
crude methanolic extracts thus obtained was kept aside and the
rest was dissolved in 300ml distilled water for fractionation with
different solvents of hexane chloroform ethyl acetate, butanol,
and water. The different fraction thus obtained were filtered,
concentrated, and dried using rotary evaporator. Hence, six
different solvent extracted samples were obtained and used for
phytotoxic activities (Figure 2).
Phytotoxic activity of different plants extracted samples
Phytotoxic activity of crude methanolic extract and its
different fractions was screened against Lemna minor (weed)
plants following the method of . The Lemna minor plants
were provided by Botany Department University of Peshawar,
KPK Pakistan. Stock solutions of different solvent extracted
fractions were prepared by dissolving 30mg of each sample in
1ml methanol. The test samples in the concentration of 10, 100,
1000μg/ml from the stock solutions were inoculated into separate
sterilized flasks. The flasks were then left for 24hrs. so that the
organic solvent get evaporated. The flasks with test samples were
introduced with 20ml of enriched media and inoculated with
10 healthy Lemna minor plants each having a rosette of three
fronds. The flask only with an enriched medium, Lemna minor
plants and no tested sample served as negative control while the
flask with plants and Paraquat (standard growth inhibitor) in a
concentration of 0.015μg/ml was used as a positive control. All
the flasks were placed in a growth chamber at room temperature
and for 7 days. On the eighth day, the phytotoxic activity was
determined by recording the number of fronds in test sampled
flasks and in control. The percent growth inhibition was calculated
by the following formula described by .
Percent growth inhibition (%) = No. of fronds in test sample / No. of fronds in Control x 100
In the present study we investigated the phytotoxic potential
of A. pentapomicum plant (stem and leaves) extracted samples to
explore its efficacy and use as a natural herbicide. The phytotoxic
activity of crude methanolic extract and its different fractions from
leaves of A. pentapomicum against Lemna minor is graphically
depicted in Figure 3 which revealed that crude methanol,
butanol and ethyl acetate extracts were equally effective against
L.minor plants in inhibiting its proliferation at all concentration
(10μl, 100μl, 1000μl. Butanol and ethyl acetate fractions both
showed same 70% of phytotoxic potential at 1000μl. Hexane and
chloroform were effective at higher concentration. However, were
found ineffective at low concentration. Our data further suggested
that ethyl acetate fraction carried highest inhibitory activity
against L.minor plants at all concentration. [13,16] reported
similar results for different plants. Aqueous extract however,
did not show any detectable inhibition against the L.minor. The
order of phytotoxic efficacy for different fractions of leaves against
the tested plant was found to be ethyl acetate ˃ butanol ˃ crude
methanol ˃ hexane ˃ choloroform ˃ aqueous.
Regarding the phytotoxic activity of different solvent fractions
of Acer pentapomicum stem, our data clearly indicated that all the
fractions except aqueous extract were effective against Lemna
minor growth (Figure 4) The highest inhibitory activities of 87%,
81% and 80% were exhibited by butanol, chloroform and ethyl
acetate at 1000μl respectively. However, moderate herbicidal
activities were recorded for hexane and crude methanolic fractions.
Aqueous fraction, on the other hand, was found to be completely
ineffective at lower concentration. Phytotoxic activity of different
tested fractions was in the order of chloroform ˃ butanol ˃ ethyl
acetate ˃ hexane ˃ crude methanol ˃ aqueous fraction .
It is the first ever reported study, and our results indicated
that Acer pentapomicum plant extracts have potent phytotoxic
efficacy against the tested weed and hence it might be useful as
natural herbicide product.