Compound for blocking absorption of heavy metals by plants and a composition containing the same

Abstract

The invention relates to a compound capable of blocking the absorption of heavy metals by plants and a composition containing the same. The compound was extracted from Aegiceras corniculatum. The compound is extracted by enzyme extraction, filtration, concentrating and drying. The compound is derived from natural plants, and no organic solvents are used in the extraction process. The compound and the composition formed by the compound have a certain barrier effect on the absorption of heavy metals by plants. ##STR00001##

Claims

1. A method of preparing a compound having the following Formula I comprising: ##STR00004## mixing fresh or dry Aegiceras corniculatum raw material with water, conducting an enzyme extraction using a biological enzyme selected from the group consisting of a pectinase, a cellulase, a neutral protease, and a papain, filtering and concentrating an extract to a relative density of 1.05-1.1 g/mL at 80-85° C., and drying to obtain the compound of Formula I.

2. The method according to claim 1, wherein the Aegiceras corniculatum raw material consists of above ground parts or below ground parts, wherein the above ground parts are leaves, flowers, stems, or seeds; and the below ground parts are roots.

3. The method according to claim 1, wherein the method comprises the following steps: (1) drying and pulverizing the Aegiceras corniculatum raw material and sieving; (2) mixing the raw material in step (1) with water at a weight ratio of 1:10-1:15, adding 0.2 wt %-0.3 wt % of the biological enzyme based on the weight of the raw material, adjusting pH to 2-10, and stirring at a constant temperature of 35-40° C. for 2-3 h; (3) after completing extraction, boiling extracting solution from step (2) for 5-10 minutes and cooling; (4) concentrating the extracting solution from step (3) to a relative density of 1.05 to 1.1 g/mL at 80 to 85° C., and drying; (5) recrystallizing extracted product from step (4) with ethanol:petroleum ether=3:1 to obtain a light yellow flaky crystal, the compound of Formula I.

4. The method according to claim 3, wherein the drying in step (4) is vacuum drying or spray drying.

5. The method according to claim 1, further comprising: applying the compound of Formula I to block plants from absorbing heavy metals, and the plants are preferably food crops.

Description

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

(1) The present invention is further described below through examples. It should be understood that the methods described in the embodiments of the present invention are only used to illustrate the present invention, rather than limiting the present invention. Simple improvements to the preparation method of the present invention are within the scope of protection of the present invention. All raw materials and solvents used in the examples are commercially available products.

(2) The Aegiceras corniculatum extract of the present invention was obtained by the following method:

(3) (1) drying and pulverizing Aegiceras corniculatum raw materials and sieving;

(4) (2) mixing the material in step (1) with water at a weight ratio of 1:10˜1:15, adding 0.2 wt %-0.3 wt % of a biological enzyme based on the weight of the raw material, adjusting the pH to 2-10, and stirring at a constant temperature of 35-40° C. for 2-3 h;

(5) (3) after the completion of the extraction, boiling the extract in step (2) for 5-10 minutes and cooling;

(6) (4) concentrating the filtered extract of step (3) to a relative density of 1.05 to 1.1 g/mL at 80 to 85° C., and drying;

(7) (5) recrystallizing the extract of step (4) with V ethanol: V petroleum ether=3:1 to obtain a light yellow flaky crystal, i.e., the compound of formula I.

(8) Preferably, the biological enzyme used for the enzymatic hydrolysis of the organism is pectinase (enzymatic activity ≥10,000 u/g), cellulase (enzymatic activity ≥10,000 u/g), neutral protease (enzymatic activity ≥300,000 u/g), or papain (enzyme activity ≥400,000 u/g);

(9) Preferably, the drying method is vacuum drying or spray drying.

EXAMPLE 1

Pectinase (Enzyme Activity ≥10,000 u/g) (No.: A-1)

(10) Taking 2 kg of Aegiceras corniculatum roots and sieving; adding 20 kg of water and 0.2% biological enzymes, adjusting the pH to 5, stirring at 35° C. for 3 h; boiling for 10 min, cooling; the relative density of the filtrated extract when concentrated to 80° C. was about 1.05 g/mL, drying; recrystallizing with V ethanol: V petroleum ether=3: 1 to obtain 1.5 g of light yellow flaky crystal, i.e., the compound of formula I.

EXAMPLE 2

Neutral Protease (Enzyme Activity ≥300,000 u/g) (No.: A-2)

(11) Taking 5 kg of Aegiceras corniculatum roots and sieving; adding 70 kg of water and 0.3% biological enzymes, adjusting the pH to 7, stirring at 40° C. for 3 h; boiling for 10 min, cool; the relative density of the filtrated extract when concentrated to 85° C. was about 1.1 g/mL, drying; recrystallizing with V ethanol: V petroleum ether=3: 1 to obtain 3.2 g of light yellow flaky crystals, i.e., the compound of formula I.

(12) ##STR00003##

(13) Anal. Calcd. For: C.sub.28H.sub.43NO.sub.6, Found: C 68.70; H 8.84; N 2.86; O 19.59.

(14) .sup.1HMR (300 MHz, DMSO), δ: 6.17 (s, 1H, H); 6.13 (m, 1H, H); 6.03 (s, 1H, H); 5.85 (m, 1H, H); 5.67 (m, 1H, H); 5.64 (m, 1H, H); 5.63 (m, 1H, H); 5.61 (m, 1H, H); 5.37 (s, 1H, OH); 4.77 (s, 1H, OH); 4.49 (s, 1H, OH); 3.88 (q, 1H, CH); 3.70 (s, 1H, NH); 3.53 (q, 1H, CH); 3.45 (q, 1H, CH); 3.30 (s, 3H, CH.sub.3); 3.17 (m, 2H, CH.sub.2); 3.15 (m, 1H, CH); 3.14 (m, 2H, CH.sub.2); 2.81 (q, 2H, CH.sub.2); 2.58 (m, 2H, CH.sub.2); 2.52 (m, 1H, CH); 2.21 (m, 2H, CH.sub.2); 1.63 (d, 3H, CH.sub.3); 1.62 (m, 2H, CH.sub.2); 1.61 (m, 2H, CH.sub.2); 1.53 (m, 2H, CH.sub.2); 1.52 (m, 2H, CH.sub.2); 1.38 (m, 2H, CH2).

EXAMPLE 3

Effect of Compound of Formula I on Reducing Heavy Metal Content in Vegetables

(15) Potted experiments were carried out. The test soil was collected from the topsoil (0-20 cm) of farmland in the outskirts of Chengdu, Sichuan Province. The soil type was purple soil, with a total lead content of 1209.21 mg kg.sup.−1 and a total cadmium content of 8.06 mg kg.sup.−1. After the soil samples were collected, the plant residues were removed, air-dried, and passed through a 5 mm siever for later use. Test plants were bok choy and pepper. The sieved soil was filled into a tray, and 80 g of soil was filled in each tray. Before the planting, watering was carried out for 3 days to maintain the field water holding capacity of about 60%. Seeds of uniform size were selected. The surface of the seed was sterilized with ethanol: 30% H.sub.2O.sub.2 (V:V=1:1) for 3 minutes, and rinsed with sterile deionized water. The sterilized plant seeds were divided into two groups. One group was soaked in a deionized aqueous solution (5 g/L) of the compound of formula I for 4 hours, and was set as the experimental group. The other group was soaked in deionized water for the same time as the control group. The process was repeated 4 times. The seeds after soaking were sowed in a pot. After 1 week after emergence, 3 plants were left in each pot. The above soaking treatment was performed again, and the roots of the experimental group and the control group were soaked with 5 mL of an aqueous solution containing a compound of formula I and deionized water per pot, respectively. Watering the plant daily was necessary to ensure the necessary water for plant growth. Plants were harvested after 40 days of growth. The plants were removed from the pot and washed with deionized water. After harvesting, the plants were cut into roots and above ground parts along the junction of the rhizomes. The plants were put in an oven at 105° C. for 15 minutes, dried at 70° C., and weighed the dry weight of roots and above ground parts. The plant samples were grounded and digested by the nitric acid-perchloric acid method. The contents of heavy metals Pb and Cd in the plants were determined by atomic absorption spectrophotometer. The results are shown in the following table.

(16) TABLE-US-00001 Above Ground Parts Below Ground Parts Samples Bok Choy Pepper Bok Choy Pepper Cd Concentration in Vegetables (mg/L) Control 2.71 ± 0.21 3.96 ± 0.26 5.17 ± 0.18 6.25 ± 0.18 Group Experimental 2.08 ± 0.19 2.89 ± 0.39 2.01 ± 0.33 4.58 ± 0.11 Group Pb Concentration in Vegetables (mg/L) Control 3.44 ± 0.13 4.17 ± 0.05 11.26 ± 1.21  9.76 ± 0.21 Group Experimental 1.51 ± 0.06 1.32 ± 0.08 6.71 ± 1.08 5.11 ± 0.63 Group

(17) As can be seen from the table above, compared with the control group, the experimental group can reduce the absorption of heavy metals Cd and Pb by the vegetable above ground parts and the below ground parks. The experimental group was able to significantly reduce the Cd and Pb concentrations in the above ground parts and below ground parts of bok Choy and peppers.