Tang Zizhong, Wang Yinsheng, Yang Jingyu, Xiao Yirong, Cai Yi, Wan Yujun, Chen Hui, Yao Huipeng, Shan Zhi, Li Chenglei, Wang Gang
College of Life Sciences, Sichuan Agricultural University, Ya'an, China.
Sichuan Agricultural University Hospital, Ya'an, China.
PeerJ. 2020 Apr 15;8:e8978. doi: 10.7717/peerj.8978. eCollection 2020.
H. Lév is a medicinal plant that has a variety of pharmacological activities, but its study is at a standstill due to the shortage of resources.
This study utilized the surface sterilization method to isolate endophytic fungi, and they were preliminarily identified by morphology. Flavonoid-producing strains were screened by NaNO-Al(NO) colorimetry and further identified by the ITS sequence. Additionally, we used five antioxidant assays (DPPH, Hydroxyl radical, ABTS, FRAP and T-AOC assays) to systematically evaluate the antioxidant capacity of total flavonoids , and we also determined their antibacterial activity.
In this study, 21 endophytic fungi were isolated from wild H. Lév for the first time. There were six flavonoid-producing strains, especially CBL11, whose total flavonoid content reached 50.78 ± 2.4 mg/L. CBL12, CBL12-2 and CBL1-1 all exhibited excellent antioxidant activity. The effect of CBL12 was similar to that of ascorbic acid at low concentrations, and its radical scavenging rates for DPPH and ABTS were 94.56 ± 0.29 % and 99.88 ± 0.27%, respectively, while its IC values were only 0.11 ± 0.01 mg/mL and 0.2 ± 0.01 mg/mL. Through LC-MS, we found that CBL12 could produce many high-value flavonoids, such as 3-methoxyflavone, nobiletin, formononetin, scopoletin, and daidzein. Additionally, CBL9 had good antibacterial activity against both gram-positive and gram-negative bacteria. Notably, we obtained the high-yield strains CBL12 and CBL9, which not only had high yields (10.64 ± 1.01 mg/L and 10.17 ± 0.11 mg/L, respectively) but also had excellent biological activity. Hence, the results of this study provide new ideas for endophytic fungi that can be exploited as a source of flavonoids and other medicinal components from H. Lév. Moreover, this study can serve as a reference for the development of rare medicinal materials.
地锦草是一种具有多种药理活性的药用植物，但由于资源短缺，其研究处于停滞状态。
本研究采用表面消毒法分离内生真菌，并通过形态学进行初步鉴定。采用亚硝酸钠-硝酸铝比色法筛选产黄酮菌株，并通过ITS序列进一步鉴定。此外，我们使用了五种抗氧化测定方法（DPPH、羟基自由基、ABTS、FRAP和总抗氧化能力测定）系统评价总黄酮的抗氧化能力，并测定其抗菌活性。
本研究首次从野生地锦草中分离出21株内生真菌。有6株产黄酮菌株，尤其是CBL11，其总黄酮含量达到50.78±2.4mg/L。CBL12、CBL12-2和CBL1-1均表现出优异的抗氧化活性。CBL12在低浓度下的效果与抗坏血酸相似，其对DPPH和ABTS的自由基清除率分别为94.56±0.29%和99.88±0.27%，而其IC值仅为0.11±0.01mg/mL和0.2±0.01mg/mL。通过液相色谱-质谱联用，我们发现CBL12可以产生许多高价值的黄酮类化合物，如3-甲氧基黄酮、川陈皮素、刺芒柄花素、东莨菪素和大豆苷元。此外，CBL9对革兰氏阳性菌和革兰氏阴性菌均具有良好的抗菌活性。值得注意的是，我们获得了高产菌株CBL12和CBL9，它们不仅产量高（分别为10.64±1.01mg/L和10.17±0.11mg/L），而且具有优异的生物活性。因此，本研究结果为将内生真菌开发为地锦草黄酮类化合物和其他药用成分的来源提供了新思路。此外，本研究可为珍稀药材的开发提供参考。
