| In recent years, in order to utilize the plant resources effectively, and to avoid the blind exploitation and over exploitation of resources, study on endophytic fungi of medicinal plants have been carried out extensively at domestic and abroad. In the stage where the endophytic fungi accompany or accrete medicinal plants, they affect each other to different degrees. However, it won't be obviously harmful to medicinal plants. Due to abundant biodiversity and different growing environment of host plant, endophytic fungi can produce secondary metabolites with rich diversity and good biological activity. Plant endophytic fungi are a large class of new microbial resources that are not systematically studied, with potential applications. The present study shows that there are more active components of secondary metabolites of endophytic fungi in medicinal plants, some of which are same as or similar with the host plant, and some are totally different. In this subject, an endophytic fungus separated from leaves of Saposhnikovia divaricata is selected, the chemical composition in secondary metabolites of the strain are studied, expecting to get with better bioactive compounds.In this paper, we separated 32 active strains from Saposhnikovia divaricata, the plants were collected from qinling mountain area, strain DL02 was selected as study object, and the strain was identified by morphological characteristics and molecular biology characteristics, the results showed that the strain DL02 is Schizophyllum commune (Franch.). Fermented the strain DL02 by the rice solid medium, and then extracted the loftdried culture by ethyl acetate and methanol. The compounds were purified by silica gel column chromatography, Sephadex LH-20 column chromatography and recrystallization methods. Their structures were identified according to physicochemical property and spectrum data. Fourteen compounds were identified as nicotinic acid (1), succinic acid (2), ergosterol (3),22E-5a,8a-epidioxyergosta-6,22-dien-3?-ol (4), tryptanthrin (5), lawsaritol A (6), daucosterol (7), erythritol (8), kojic acid (9),?-sitosterol (10), uracil (11), allantoin (12), stigmasta-7,22-diene-3?,5a,6a-triol (13), adenosine (14). Compounds 6,9,11,12,13,14 are reported as metabolite from fungi for the first time.Four bacteria (Enterococcus coli, Pseudomonas aeruginosa, Streptococcus lactis, Staphylococcus aureus) and ten plant pathogenic fungi (Cytospora mandshurica, Colletotrichum gloeosporioides, Sclerotinia sclerotiorum, Setosphaeria turcica, Alter-naria brassicae, Botrytis cirerea, Phytop hthoracapsic, Peony anthracnose, Fusarium grami-nearum, Alternaria alternateta) were used for antibacterial activity test. The minimum inhibitory concentration (MIC) values that were got by double-dilution method showed antibacterial activity intensity of the 14 compounds. The results indicated that compound 5 (tryptanthrin) showed strong antibacterial activity on plant pathogenic fungi and bacteria, with a MIC value of 3.9 ?g/mL to Enterococcus coli, and 15.6 ?g/mL to Cytospora mandshurica. Compound 1 (nicotinic acid),2 (succinic acid),8 (erythritol), and 9 (kojic acid) were showed different inhibitory activity on plant pathogenic fungi and bacteria, while the inhibition intensity is weaker. The rest of compound 3 (ergosterol),4 (22E-5a,8a-epidioxyergosta-6,22-dien-3?-ol),6 (lawsaritol A),7 (daucosterol),10 (?-sitosterol),11 (uracil),13 (stigmasta-7,22-diene-3?5?,6?-triol) have no obvious inhibitory activity on plant pathogenic fungi and bacteria.The antioxidant activities of 14 compounds were tested, and compared with vitamin C. The results showed that these compounds did not found strong antioxidant activity. Compound 9 (kojic acid),11 (uracil),12(allantoin) and 14 (adenosine) have showed a weaker antioxidant activity, while other compounds didn't obviously showed any antioxidant activity.In summary, this paper focused on the study of the secondary metabolites of endophytic fungi strain DL02 from Saposhnikovia divaricata. A total of 14 compounds were separated and purified from fermentation culture. According to the results of the antibacterial activity test and antioxidant activity test, compound 5 (tryptanthrin) showed strong antibacterial activity on plant pathogenic fungi and bacteria, it has broad-spectrum antibacterial activity. Compound 1 (nicotinic acid),2 (succinic acid),8 (erythritol), and 9 (kojic acid) also showed a certain extent activity. Therefore, further research can be taken on strain DL02, as a source of antimicrobial agents. Strain DL02 can also be used as a biological antibacterial tool, protecting host plants from infection bacteria and plant pathogenic fungi. This study enriches the research of endophytic fungi from Saposhnikovia divaricata and makes a great difference on the development and utilization of Schizophyllum commune (Franch.). Besides, the study also shows endophytic fungi play an important role in developing medicine. |
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