Key Laboratory of Marine Drugs, the Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao, 266003, China.
Laboratory for Marine Drugs and Bioproducts, Qingdao National Laboratory for Marine Science and Technology, Qingdao, 266071, P. R. China.
Sci Rep. 2018 Jul 12;8(1):10541. doi: 10.1038/s41598-018-28980-z.
Marine organisms especially sessile invertebrates, such as soft corals, gorgonians and sponges, can survive in the competitive environment mainly relying on their second metabolites with chemoecological effects including allelopathy and algal growth inhibition. It is well known that the microscale models are urgently needed in marine chemoecology assessment to evaluate the algal growth inhibition activity of trace quantity natural products. In this work, a microalgal growth inhibition model was established for microalgal inhibition evaluation of marine natural products with 96-well microplate by automatic fluorescence observation using microplate reader. Subsequently, this model was applied to bioassay-guided isolation and preliminary bioactivity screening of the secondary metabolites from soft corals, gorgonians, sponges and their symbiotic microbes collected from the South China Sea. As a result, fifteen compounds (1‒15) were found to exhibit microalgal growth inhibition activities against at least one of marine microalgae, Karenia mikimotoi, Isochrysis galbana, and Heterosigma akashiwo. Specifically, altersolanol C (13) demonstrated potent activity against K. mikimotoi with the 96h-EC value of 1.16 µg/mL, more than four times stronger than that of the positive control KCrO. It was suggested that the microalgal growth inhibition microscale model is suitable for bioassay-guided isolation and preliminary bioactivity screening of marine natural products.
海洋生物，尤其是固着无脊椎动物，如软珊瑚、柳珊瑚和海绵，可以依靠具有化学生态效应的次生代谢产物在竞争环境中生存，这些产物包括化感作用和抑制藻类生长。众所周知，在海洋化学生态评估中，需要微尺度模型来评估痕量天然产物对藻类生长的抑制活性。在这项工作中，通过使用微孔板读数器进行自动荧光观察，建立了一种基于 96 孔微孔板的微藻生长抑制模型，用于评估海洋天然产物对微藻的抑制活性。随后，该模型被应用于南海软珊瑚、柳珊瑚、海绵及其共生微生物次生代谢产物的生物活性导向分离和初步筛选。结果发现，有 15 种化合物（1-15）对至少一种海洋微藻，包括卡氏藻、新月菱形藻和赤潮异弯藻，表现出抑制微藻生长的活性。具体来说，变体山醇 C（13）对 K. mikimotoi 的活性最强，96h-EC 值为 1.16 µg/mL，比阳性对照 KCrO 强四倍以上。这表明微藻生长抑制微尺度模型适用于海洋天然产物的生物活性导向分离和初步筛选。
