Cordycepin Isolated from Cordyceps militaris: Its Newly Discovered Herbicidal Property and Potential Plant-Based Novel Alternative to Glyphosate

Abstract

There is currently much interest in finding new phytochemicals among plants and fungi as nature-based alternatives to replace problematic herbicides such as glyphosate, which are preferentially used in agricultural production n. We discovered striking herbicidal potency in Cordyceps militaris (L.) and identified cordycepin as its principal plant growth inhibitor. Cordycepin obtained as an ethyl acetate extract was subjected to column chromatography and evaluated for its bioassay-guided phytotoxic capacity against Raphanus sativus (radish), showing a maximum inhibition on germination and growth of radish (IC₅₀ = 0.052-0.078 mg/mL). Gas chromatography-mass spectrometry (GC-MS) (m/z: 251.2) and liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) ([M + Na]⁺ m/z: 274.1; [M + H]⁺ m/z: 252.1) analyses confirmed cordycepin as the major component of the tested column fraction (55.38%). At 0.04 mg/mL, cordycepin showed 3.8-5.9- and 3.3-3.7-fold greater inhibition of the germination and growth of radish than benzoic acid (BA) and glyphosate, respectively. Compared with BA, isolated cordycepin reduced plant chlorophyll and carotenoid contents (2.0-9.5 -fold), while proline, total phenolic and total flavonoid contents were increased 1.2-1.8-fold. Finally, cordycepin promoted electrolyte leakage and malondialdehyde accumulation in radish aerial parts. Thus, cordycepin successfully isolated from Cordyceps militaris is a highly potent plant growth inhibitor with pending worldwide patent and may become a potential plant-based novel alternative to the disputed glyphosate.

Keywords: Cordyceps militaris; Raphanus sativus; allelochemical; allelopathy; column chromatography; cordycepin; germination; glyphosate; growth; inhibition; plant growth inhibitor.

Figure 1

Procedure of extraction and fractionation of C. militaris fruiting-bodies (Frs: fraction, C: chloroform, M: methanol).

Figure 2

Pigment contents of radish treated with CM4 fraction, synthetic cordycepin and BA at 0.04 mg/mL. Columns with different superscript letters (^a,b,c,d) in bars showed significant differences at p < 0.05 by Fisher’s test.

Figure 3

Electrolyte leakage (%) of radish treated by CM4 fraction, synthetic cordycepin and BA at 0.04 mg/mL. Columns with similar superscript letters (^a,b,c,d) in bars were not significantly different according to Fisher’s test (p <0.05).

Figure 4

Lipid peroxidation expressed as malondialdehyde (MDA) accumulation in radish among control and treatments (CM4 fraction, synthetic cordycepin and BA) at 0.04 mg/mL. Columns with different superscript letters (^a,b,c,d) in bars indicate significant differences at p < 0.05 by Fisher’s test.

Figure 5

The changes of total phenolic accumulation in the roots and aerial parts of radish among control, CM4 fraction, synthetic cordycepin and BA at 0.04 mg/mL. Columns with similar superscript letters (^a,b,c,d) were not significantly different at p < 0.05 by Fisher’s test.

Figure 6

Total flavonoid contents (TFC) of radish among control, CM4 fraction, synthetic cordycepin and BA at 0.04 mg/mL. Columns with different superscript letters (^a,b,c,d) in the aerial parts and roots indicated significant differences at p < 0.05 by Fisher’s test.

Figure 7

Proline contents in root and aerial parts of radish treated by CM4 fraction, synthetic cordycepin and BA at 0.04 mg/mL. Columns with different superscript letters (^a,b,c,d) were significantly different at p < 0.05 by Fisher’s test.

Figure 8

(a) HPLC chromatograms of synthetic cordycepin as standard, (b) HPLC chromatograms of cordycepin in the CM4 fraction compared with the standard (0.5 mg/mL).

Figure 9

Total ion chromatogram and mass of cordycepin detected in the CM4 fraction.

Figure 9

Total ion chromatogram and mass of cordycepin detected in the CM4 fraction.