Marine Natural Products from Tunicates and Their Associated Microbes

Abstract

Marine tunicates are identified as a potential source of marine natural products (MNPs), demonstrating a wide range of biological properties, like antimicrobial and anticancer activities. The symbiotic relationship between tunicates and specific microbial groups has revealed the acquisition of microbial compounds by tunicates for defensive purpose. For instance, yellow pigmented compounds, "tambjamines", produced by the tunicate, Sigillina signifera (Sluiter, 1909), primarily originated from their bacterial symbionts, which are involved in their chemical defense function, indicating the ecological role of symbiotic microbial association with tunicates. This review has garnered comprehensive literature on MNPs produced by tunicates and their symbiotic microbionts. Various sections covered in this review include tunicates' ecological functions, biological activities, such as antimicrobial, antitumor, and anticancer activities, metabolic origins, utilization of invasive tunicates, and research gaps. Apart from the literature content, 20 different chemical databases were explored to identify tunicates-derived MNPs. In addition, the management and exploitation of tunicate resources in the global oceans are detailed for their ecological and biotechnological implications.

Keywords: alkaloids & bioactive compounds; peptides; pigments; symbiotic microbes; tunicates.

Figure 1

Important anticancer drugs of tunicates and their associated microbes in clinical trials.

Figure 2

Tunicate-associated epibiotic and endobiotic symbionts. (the small inserted empty box provides more details in Figure 3).

Figure 3

Illustration depicting various MNPs released from endobiotic and epibiotic microbes associated with tunicate’s endostyle and tunic.