Studies On Chemical Components And Free Radical Scavenging Active Compounds Of Cordyceps Taii

A series studies on the chemical components and free radical scavenging compounds of Cordyceps taii, collected from Jinzhai County, Anhui Province, were carried out. The studies included quantitative determination of nucleosides and ergosterol; comparative analysis of components between Cordyceps taii and Metarhizium taii; free radical scavenging active components analysis; optimization of the extraction conditions of free radical scavenging active constituent; isolation and purification of the free radical scavenging component; and studies on antibacterial activity of the free radical scavenging components.RP-HPLC analysis revealed that uridine, guanosine, adenosine and ergosterol contents in the fruiting bodies of Cordyceps taii were 0.79±0.15mg/g, 0.36±0.01mg/g, 2.73±0.32mg/g, 2.67±0.27mg/g, while there were 0.32±0.02 mg/g, 0.28±0.02 mg/g, 2.20±0.28 mg/g, 3.08±0.15 mg/g in the insect bodies of it. Content of nucleotides in fruiting bodies were significantly higher than those in insect bodies, and ergosterol content was higher in the insect bodies.HPLC-DAD-MS analysis showed that there were mannitol and a variety of fatty acids in the methanolic extracts from the fruiting bodies, insect bodies of Cordyceps taii and cultured mycelia of RCEF4124. And in the Cordyceps taii, the fatty acids existed mainly in the insect body. Apart from fatty acids, the methanolic extract from fruiting bodies of Cordyceps taii contained also C₁₅H₂₂N₂O₆, C₉H₁₁NO₂, C₃₃H₄₂N₂O₁₉, C₂₆H₂₂O₁₃ and other substances. The methanolic extract from cultured mycelia of RCEF4124 contained not only C₁₅H₂₂N₂O₆ but also C₃₃H₄₄O₈.The main components of mixed solvent of methylene chloride and ethyl acetate extract from fruiting bodies, insect bodies of Cordyceps taii and cultured mycelia of RCEF4124, were linoleic acid, palmitic acid, oleic acid, stearic acid, calendic acid, tetracosenoic acid (nerve acid) and other fatty acid substances. Apart from the fatty acids, the fruiting bodies extracts contained also C₃₀H₂₆O₁₀ and C₁₉H₄₂N₄O₁₀, meanwhile, the insect bodies extracts contained C₂₉H₃₇NO₇ and C₃₃H₄₄O₈, and the RCEF4124 exacts contained C₃₃H₄₄O₈, C₃₀H₂₆O₁₀ and C₃₀H₂₄O₁₀ .DPPH antioxidant model results showed that, at the concentration of 2.5mg/ml, the radical scavenging rates of ethyl acetate extracts from fruiting bodies and insect bodies of Cordyceps taii were 83.29±0.48% and 14.77±1.73% respectively. Comparison of radical scavenging rates and thin layer chromatograms of the extracts revealed that the free radical scavengers of the Cordyceps taii exist mainly in the fruiting body. HPLC-DAD-HRMS analysis and DPPH assay revealed that the molecular formula of the free radical scavenger was possibly C₂₆H₂₂O₁₃. Natural Products database query showed that there was no known compound matched the molecular formula. This means that the compound is possibly a novel one.By optimizing the extraction conditions, the optimum extraction conditions of free radical scavenging component from Cordyceps taii were established as follows: the optimal solvent was methanol; the optimal solid-liquid ratio was 1 : 58(W:V); the optimal ultrasonic power was 66W; the optimal ultrasonic time was 30 min; the optimal extraction time was 180 min; the optimal extraction temperature was 60℃; the optimal methanol concentration was 93.5%. The verification experiments showed that the average radical scavenging rate of the extracts was 97.3%. Compared with the theoretical prediction, the relative error was only 0.51%.The crude extract of Cordyceps taii was purified with Semi-preparative HPLC followed by further chromatographic isolation of sephadex LH-20, and a pure compound D-1 was obtained. HPLC- DAD-MS analysis revealed that D-1 was a pure compound, and its molecule formula was C₂₆H₂₂O₁₃. Result of the free radical scavenging activity assay on compound D-1 confirmed that the compound was the free radical scavenger of Cordyceps taii.Bacteriostatic test results showed that D-1 had also significant antibacterial activity against Staphylococcus aureus and E. coli, and the diameter of inhibition zones were 16.91±1.53mm and 12.22±1.32mm respectively.