Chemistry and Bioactivity of ent -Kaurene Diterpenoids

Dearomative logic in natural product total synthesis

Covering: 2011 to 2022The natural world is a prolific source of some of the most interesting, rare, and complex molecules known, harnessing sophisticated biosynthetic machinery evolved over billions of years for their production. Many of these natural products represent high-value targets of total synthesis, either for their desirable biological activities or for their beautiful structures outright; yet, the high sp³-character often present in nature's molecules imparts significant topological complexity that pushes the limits of contemporary synthetic technology. Dearomatization is a foundational strategy for generating such intricacy from simple materials that has undergone considerable maturation in recent years. This review highlights the recent achievements in the field of dearomative methodology, with a focus on natural product total synthesis and retrosynthetic analysis. Disconnection guidelines and a three-phase dearomative logic are described, and a spotlight is given to nature's use of dearomatization in the biosynthesis of various classes of natural products. Synthetic studies from 2011 to 2021 are reviewed, and 425 references are cited.

Transformation of 15-ene steviol by Aspergillus niger, Cunninghamella bainieri, and Mortierella isabellina

Transformation of 15-ene steviol (ent-13-hydroxy-kaur-15-en-19-oic acid) by growth cultures of Aspergillus niger BCRC 32720, Cunninghamella bainieri ATCC 9244, and Mortierella isabellina ATCC 38063 was conducted to generate various derivatives for the development of bioactive compounds. Four previously undescribed compounds along with six known compounds were obtained. The newly identified isolates were characterized using 1D and 2D NMR, IR, and HRESIMS, and three compounds were further confirmed by X-ray crystallographic analyses. Subsequently, the effects of 15-ene steviol and its derivatives on lipopolysaccharide (LPS)-induced cytokine production by THP-1 cells were examined, with dexamethasone used as a positive control. Results indicated that most of the tested compounds showed lower inhibitory effects than those detected in the dexamethasone-treated group, except that 15-ene steviol showed better effects than dexamethasone on the reduction of LPS-induced monocyte chemoattractant protein (MCP)-1, -2, and -3 release. Three specialized products similarly showed better effects than dexamethasone on the inhibition of LPS-induced secretion of regulated on activation, normal T cell expressed and secreted (RANTES). Moreover, none of the tested compounds showed any cytotoxicity or triggered cell apoptosis, and none affected the protein integrity of toll-like receptor 4 (TLR4) or MyD88, suggesting that these compounds may exert the anti-inflammatory activity downstream of membrane-associated TLR4 and MyD88 molecules.

Diterpenoids of terrestrial origin

This review covers the isolation and chemistry of diterpenoids from terrestrial sources from 2017.

Preservative effect of Chinese cabbage (Brassica rapa subsp. pekinensis) extract on their molecular docking, antioxidant and antimicrobial properties

This study aimed at investigating the antimicrobial activity of different solvent extracts of Chinese cabbage Brassica rapa subsp. pekinensis (BRARP) and their antioxidant and cytotoxicity properties. Of the different solvents extracts, the chloroform extracts (CE) were significantly inhibited the bacterial pathogens at minimum inhibitory concentration (MIC) of 16.5 mg.mL^-1. Biochemical analysis revealed that total phenol (62.6 ± 0.05 mg GAE.g^-1) and flavonoids (27.6 ± 0.04 mg QE.g^-1) were higher in the extracts of BRARP, which resulted in enhanced antioxidant activity in CE. A total of eight dominant compounds were detected in the potent antimicrobial extract from BRARP based on GC-MS analysis. The molecular interactions study revealed that, among the screened compounds the 1,2-benzenedicarboxylic acid and 2,3-dicyanopropionamide interacted with the active site of pathogenicity and survival related protein with lipopolysaccharide (LpxC) with higer binding energy. This work concluded that the 1, 2-Benzenedicarboxylic acid and 2, 3-Dicyanopropionamide from BRARP was reported to be good non-cytotoxic and antioxidant antimicrobials against bacterial pathogens.