**Preface to "Selected Papers from the 3rd International Symposium on Life Science"**

Studies on marine natural compounds are becoming increasingly interdisciplinary. In obtaining and discussing new valuable scientific data, a wide range of different specialists have become involved, from environmental chemists to hydrobiologists and pharmacologists. Long-term studies at our G.B. Elyakov Pacific Institute of Bioorganic Chemistry (PIBOC), belonging to the Russian Academy of Science, have led to the isolation and structural elucidations of many hundreds of marine natural compounds including low molecular weight bioregulators and biopolymers. A series of marine drugs, food supplements, and functional food products were created on this basis. Some of them have been approved for industrial production and medicinal or other applications in Russia. These studies were conducted in collaboration with scientists from many countries around the world. Fruitful discussions on domestic and international scientific conferences were useful for the development of such studies. The Third International Symposium on Life Science, held 4–8 September, 2019 in Vladivostok, was organized by this Institute. Scientists from several geographic areas of the Russian Federation, from Moscow to Vladivostok, as well as chemists and biologists from Germany, the Republic of Korea, the Peoples Republic of China, and Taiwan, participated in this Symposium and delivered 81 lectures and poster presentations. The regular sub-symposium of the series Korus (Korean–Russian symposiums) was held within the framework of this scientific meeting. This was the third conference of this series, which started with the Symposium in 2012. The aim of the Symposium is to share advanced ideas not only in the field of marine natural products but also in organic and inorganic syntheses, molecular immunology, biotechnology, pharmacology, and molecular genetics to promote the obtaining of new important scientific results in life science. In accordance with invitation and sponsor support of the international scientific journal Marine Drugs, this Special Issue of this journal was published. This Issue focuses its attention on bioactive compounds from sea urchins, particularly quinoid pigments, like echinochrome A and spinochromes. Their diverse biomedicinal properties, stability, and possibility to be obtained using organic synthesis methods have attracted attention to these biologically active compounds. Studies on many other important groups of natural products, including enzymes and lectins, sterol sulfates, and alkaloids, were also discussed as well as the promise of this type investigation with the participation of several neighboring countries.

> **Valentin A. Stonik** *Special Issue Editor*
