Ozonolysis of aromatic abietane (+)-carnosic acid (4) is used to create an important intermediate in an enantiomerically pure form, resulting in a simple, concise, readily scalable, and asymmetric synthesis of (−)-antrocin (1). This strategy not only provides an efficient approach to (−)-antrocin (1) synthesis but can also be readily adopted for the syntheses of optically pure (+)-asperolide C (2) and (−)-trans-ozic acid (3) from the naturally abundant aromatic abietanes (+)-podocarpic acid (5) and (+)-dehydroabietic acid (6). The strategy presented here is an example of the use of naturally occurring aromatic abietanes as a chiral pool and offers an account of the asymmetric synthesis of terpenoids.

Androgen deprivation therapy (ADT) is a systemic therapy for advanced prostate cancer (PCa); although most patients initially respond to ADT, almost all cancers eventually develop castration-resistant PCa (CRPC). Currently, most research focuses on castration-resistant tumors, and the role of tumors in remission is almost completely ignored. Here, we report that odorant-binding protein (OBP2A) released from tumors in remission during ADT catches survival factors, such as CXCL15/IL8, to promote PCa cell androgen-independent growth and enhance the infiltration of myeloid-derived suppressor cells (MDSCs) into tumor microenvironment, leading to the emergence of castration resistance. OBP2A knockdown significantly inhibits CRPC and metastatic CRPC development and improves therapeutic efficacy of CTLA-4/PD-1 antibodies. Treatment with OBP2A-binding ligand α-pinene interrupts the function of OBP2A and suppresses CRPC development. Furthermore, α-pinene–conjugated doxorubicin/docetaxel can be specifically delivered to tumors, resulting in improved anticancer efficacy. Thus, our studies establish a novel concept for the emergence of PCa castration resistance and provide new therapeutic strategies for advanced PCa.

Chemoenzymatic strategies that combine synthetic and enzymatic transformations offer efficient approaches to yield target molecules, which have been increasingly employed in the synthesis of bioactive natural products. In the biosynthesis of macrocyclic nonribosomal peptides, polyketides, and their hybrids, thioesterase (TE) domains play a significant role in late-stage macrocyclization. These domains can accept mimics of native substrates in vitro and exhibit potential for use in total synthesis. This review summarizes the recent advances of TE domains in the chemoenzymatic synthesis for these natural products that aim to address the common issues in classical synthetic approaches and increase synthetic efficiencies, which have the potential to facilitate further pharmaceutical research.

Owing to their structural complexity, target-oriented syntheses of natural products usually require the design of individualized routes that are tailor-made for the specific targets. As such, route re-design is needed when targets of different skeletal connectivities are considered. Here, we report a versatile synthetic strategy that runs counter to this conventional wisdom and allows access to a range of terpenoids with distinct skeletal frameworks from the sesquiterpene lactone sclareolide as the starting material. By viewing a biocatalytically-installed alcohol as an exploitable motif rather than a structural endpoint, a number of abiotic skeletal rearrangements were designed, resulting in significant structural divergence from the original drimane ring system of sclareolide. Using this approach, the syntheses of four terpenoid natural products, namely merosterolic acid B, cochlioquinone B, (+)-daucene and dolasta-1(15),8-diene, were achieved.