Ailanthus Altissima
There is an urgent need to explore and utilize naturally occurring products for combating harmful agricultural and public health pests. Secondary metabolites in the leaves of the Tree of Heaven, Ailanthus altissima L. have been reported to be herbicidal and insecticidal. The mode of action, however, of the active compounds in A. altissima are not understood. In this paper, we report the chemical characteristics of the herbicidal and insecticidal components in this tree, and will discuss the effect of light on the bioactivity of the active components.
ailanthus altissima
Extracts from the fresh leaves of A. altissima showed a strong plant germination/growth inhibitory effect in laboratory bioassays against alfalfa (Medicago sativa). The effect was dose-dependent. The growth inhibitory components were in the methylene chloride soluble fraction of the extract. The effect was greater in the light than in the dark. Other fractions had plant growth enhancing effect at lower concentrations. The extract was slightly insecticidal against yellow fever mosquito larvae (Aedes aegypti).
The extract or its semi-purified fractions of A. altissima were strong plant growth inhibitors, therefore good candidates as potential environmentally safe and effective agricultural pest management agents. The finding that light affects the activity will be useful in the application of such natural products.
There are no reports on the growth regulatory effect of the A. altissima related compounds or extracts, and the role of light on the effect has not been studied. The primary goal of this project is to reconfirm the observation of the growth inhibitory effect of A. altissima under controlled laboratory conditions, and to study the characteristics and the effect of light on the herbicidal and insecticidal activities of the extract.
Although in some reports plant leaves and other parts have been dried and ground before solvent extraction, we chose fresh leaves of A. altissima and a polar solvent methanol in the extraction because most of the bioactive components have been reported to be hydrophilic [15, 20]. The plant leaves were cut into small pieces, then soaked or blended in the solvent. No significant difference was found between the two extraction methods in total extractables (Table 1). Data in the right column of Table 1 were used in serial dilutions for the bioassays.
Since methylene chloride extracted the most active ingredients from the methanol/water extract of A. altissima, our focus was shifted to Fraction C. Fraction C was further fractionated into C1, C2, C3 and C4 using preparative TLC. Fraction C4, which had the lowest Rf value showed significantly stronger growth and germination inhibition than the other three fractions of higher Rf values (Table 3). The growth inhibitory effect of C4 was found under both light and dark conditions. The IC50's of C4 against the radicles of M. sativa in the light and dark were 3.2 and 4.2 ppm, respectively (Table 3). Germination of alfalfa seeds was completely stunted by C4 at 200 ppm. IC50's of C1, the least hydrophilic fraction, were 71.8 ppm and 98.5 ppm in the light and dark. However, it was interesting to notice that radicles of seeds treated with lower concentrations of fraction C1 grew significantly longer than those in the control, especially when incubated in the dark (Fig. 1). C2 had the least phytotoxicity. The IC50's of C2 were >200 ppm both in the light and dark. However, C2 had the strongest radicle elongation effect among the 4 fractions. Radicle lengths of alfalfa treated in the dark with C2 at 1.6 and 8 ppm were 13% and 17% longer than those in the control (Fig. 2). Fraction C3 also had slight growth stimulating effects at lower concentrations, and some inhibitory effect at higher concentrations. The IC50's of Fraction C3 were 76.0 ppm in the light and 95.2 ppm in the dark (Table 3).
Our results clearly indicated the involvement of chemical factors in the growth inhibitory and stimulating effects of A. altissima against other plants such as alfalfa. Other researchers have isolated ailanthone from of A. altissima and found it herbicidal toward various weeds [24]. Although we did not isolate the individual chemicals responsible for the growth regulatory effect found with our extract and sub-fractions, it was evident that multiple chemicals were involved. Ailanthone may be one of the principal growth inhibitory components in A. altissima, however it may not be the only one. In addition, some chemicals in the extracts of A. altissima showed growth enhancement effect. These two totally different effects indicated possible plant growth regulatory effects, namely, enhance the growth at lower concentrations and inhibit the growth at higher concentrations. Our results also agreed to the finding of Lin et al. [24] that light played an important role in the herbicidal activity of ailanthone. We found that, in most cases, the growth inhibitory effect was stronger in the presence of light. The growth regulatory effect of C1 and C2 was similar to α-terthienyl, a well known naturally occurring photosensitizer (Table 3, Fig. 1,2,3). α-terthienyl showed typical photoactivated inhibition of the growth of M. sativa radicles at high concentration and plant growth stimulation effect at low concentration (Fig. 3).
Although the extracts of A. altissima were practically non-toxic to the mosquito, the extracts had strong effects on plant growth in the alfalfa assay. The inhibitory effect on plant growth by the crude extract and some sub-fractions was enhanced by the presence of light. Some fractions showed plant growth regulatory effect against the alfalfa by inhibiting the growth of radicle at higher concentrations and enhancing the growth at lower concentrations. These effects of the extracts of A. altissima could lead to a new natural herbicide and plant growth regulators, since these natural products would likely be very biodegradable, thus posing less risk to the environment. Further investigations are needed to isolate the individual chemical(s), and to study their growth inhibitory and enhancing effects.
Leaves and stems of A. altissima were collected from trees less than one year old (July, 1995, Iowa State University Campus, Ames). The leaves were cut to ca. 2.5 cm in length and soaked in certified methanol in a glass container (500 g of fresh leaves in 2750 ml of methanol). This was allowed to sit at room temperature (25C) for 72 h.
A possible new source of an allergy-relevant pollen for Central Europe may be tree of heaven (Ailanthus altissima, Simaroubaceae). This tree is native to Asia, especially parts of China. Individual ornamental specimens were introduced to Germany several decades ago. Since then, this tree species has been spreading invasively, so far predominantly in larger cities such as Berlin (Fig. 1).
To date, one allergen (Ail a) is known as a major allergen [5, 6]. Positive skin prick test results with A. altissima have generally been found in polysensitized patients [7], probably due to cross-reactivity with other pollen taxa [7, 8] since A. altissima pollen contains cross-reactive calcium-binding proteins [9] and cross-reactive carbohydrate determinants (CCDs) [8] which have also been identified in pollen of unrelated species. Since the tree of heaven is now spreading in Europe, there is an opportunity to determine the current frequency of sensitization in order to follow the further development of sensitization in the coming years.
An eco-friendly green route for synthesis copper oxide nanoparticles (CuONPs) by Ailanthus altissima leaf aqueous extract was reported. The synthesized copper oxide nanoparticles were characterized in terms morphology, crystalline nature, structural and antibacterial activity with UV-vis, SEM, TEM, FT-IR analysis tools. The synthesized copper oxide nanoparticles were well crystalline in nature with particle shape spherical and average particle size 20 nm. The antimicrobial activity of CuONPs was determined by disk diffusion method against some selected species of bacteria, demonstrated a significant inhibitory activity against S. aureus followed by E. coli. In view of promising activity, the CuONPs could possibly be employed as antibacterial agent.
Free cytosolic calcium has a vital role in regulation of smooth muscle contraction and the entry of this calcium into the cell is through voltage operated calcium channels (L-Type) [38]. Free calcium into the cytoplasm activates ryanodine receptors on sarcoplasmic reticulum and results in the opening of calcium channels present on the membrane of sarcoplasmic reticulum. Calcium rushes into the cytoplasm from these sarcoplasmic stores. This calcium binds with calmodulin and calcium calmodulin complex results. This complex activates an enzyme myosin light chain kinase (MLCK). MLCK activates myosin heads and results in the formation of cross bridges and contraction of the smooth muscles occurs. Contraction of vascular smooth muscles increases peripheral vascular resistance which leads to increase in blood pressure whereas contraction of bronchial smooth muscles results in bronchoconstriction and asthma. Similarly contraction of gastrointestinal smooth muscles leads to diarrhea [25, 39]. Blockage of calcium channels inhibits the influx of calcium into the cytoplasm which results in the relaxation of smooth muscles and this blockage of voltage operated calcium channels is beneficial for the treatment of smooth muscle disorders like asthma, diarrhea, and hypertension [40, 41]. Application of high concentration of potassium (high-K+) to smooth muscle tissues results in the opening of voltage operated calcium channels which leads to smooth muscle contraction [42]. Calcium channel blockers have inhibitory role against both spontaneously contracting smooth muscles and smooth muscles preexposed to high-K+ but prominent effect against high potassium induced contractions as compared to inhibition of spontaneous contractions [43, 44]. Similarly when Aa.Cr was tested against spontaneous contractions and the contractions induced by the application of high-K+ in isolated rabbit jejunum, inhibition of both contractions was observed but inhibitory response was prominent against the contractions induced by high-K+ as observed by the verapamil. Similar response was observed by the application of Aa.DCM to the isolated jejunum of rabbit but at lower concentration than Aa.Cr. Blockage of calcium channels was further confirmed when preincubated jejunum was treated with calcium; inhibition of calcium contractile effect was a result with the shifting of concentration response curves of calcium towards right. These in vitro results were confirmed by protection against castor oil induced diarrhea. Calcium channel blockers routinely used for the treatment of gastrointestinal disorders like diarrhea and dysentery and the presence of calcium channel blocking activity in A. altissima provide a mechanistic proof for its use in the treatment of diarrhea. Aa.Aq showed spasmogenic effect when applied to isolated jejunum which was blocked with pretreatment of tissue with atropine. These findings showed that spasmolytic and spasmogenic potential is present in A. altissima but spasmolytic effect is dominant. This type of behavior (having both agonistic and antagonistic effects) is present in most herbal drugs which is beneficial to overcome the adverse effect of the herbal drugs [45]. 041b061a72
