Tabernaecorymine a, an 18-normonoterpenoid indole alkaloid with antibacterial activity from Tabernaemontana corymbosa

Alstoscholarisine M, a 6,7-seco-vallesamine monoterpenoid indole alkaloid with antimicrobial activity from Alstonia scholaris

Alstoscholarisine M is a 6,7-seco-vallesamine monoterpenoid indole alkaloid with a rare methylcarbamate fragment, isolated from the leaves of Alstonia scholaris. Extensive spectroscopic data analyses, quantum chemical computations, and single-crystal X-ray diffraction elucidated its structure. The fascinating compound exhibited potential antifungal activity against Trichophyton rubrum, and its activity was roughly comparable to the first-line antifungal drug griseofulvin and significantly more effective than berberine, an important antimicrobial drug originating from plants.

Bioactive sorbicillinoid derivatives from an endophytic fungus Trichoderma citrinoviride

Three new sorbicillinoid derivatives, citrinsorbicillinol A-C (1-3), along with three known compounds, such as trichosorbicillin G (4), dibutyl phthalate (5), and 3-(4-methoxyphenyl) propanoic acid (6), were isolated from the endophyte Trichoderma citrinoviride of Coptis chinensis. Their structures were elucidated through extensive analyses of spectroscopic data, computer-assisted structure elucidation (ACD/Structure Elucidator), density functional theory (DFT) calculations of the nuclear magnetic resonance (NMR) spectra, and electronic circular dichroism (ECD). Biologically, compounds 1-4 exhibited potential antioxidant activity, as assessed using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay, with IC50 values ranging from 27.8 to 89.6 μM. In particular, compounds 2 and 3 demonstrated radical scavenging activity comparable to that of the positive control, ascorbic acid, with IC50 values of 27.8 and 31.2 μM, respectively. Moreover, compound 1 exhibited potential anti-inflammatory activity by inhibiting nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages, with an IC50 value of 52.7 μM. These findings underscore the therapeutic potential of the new sorbicillinoid derivatives for antioxidant and anti-inflammatory applications.

Four Alkaloids from Alstonia scholaris with Antitumor Activity via Disturbing Glutathione Homeostasis

Alstoschoquinolines A-D (1-4) representing three unprecedented scaffolds were isolated from the leaves of Alstonia scholaris through direct separation by LC/MS detection. 1 and 2 consisted of a 5/6/5-coupled quinoline architecture containing six consecutive chiral carbons, while 3 and 4 possessed a bridged ring featuring 6/6/6/6 and 6/6/8/6 skeletons, respectively. They might be derived from the corynantheine-type indole alkaloid via sequential oxidation and rearrangement. Compound 3 exhibited a significant inhibitory effect on colon carcinoma cells by disturbing glutathione circulation.

Design, Synthesis, and Antimicrobial Activity Evaluation of Novel Isocryptolepine Derivatives against Phytopathogenic Fungi and Bacteria

This research adopted the Fischer indole synthesis method to continue constructing a novel drug-like chemical entity based on the guidance of isocryptolepine and obtained four series of derivatives: Y, Da, Db, and Dc. The antimicrobial activity of these derivatives against plant pathogens was further evaluated. The results showed that Dc-2 had the best antifungal effect against Botrytis cinerea, and its EC50 value was up to 1.29 μg/mL. In addition, an in vivo activity test showed that the protective effect of Dc-2 on apples was 82.2% at 200 μg/mL, which was better than that of Pyrimethanil (45.4%). Meanwhile, it was found by scanning electron microscopy and transmission electron microscopy that the compound Dc-2 affected the morphology of mycelia. The compound Dc-2 was found to damage the cell membrane by PI and ROS staining. Through experiments such as leakage of cell contents, it was found that the compound Dc-2 changed the permeability of the cell membrane and caused the leakage of substances in the cell. According to the above studies, compound Dc-2 can be used as a candidate lead compound for further structural optimization and development.

Antimicrobial indole alkaloids from Tabernaemontana corymbosa

Four unreported monoterpene indole alkaloids, tabernaecorymines B-E (1-4), together with twenty-one known indole alkaloids (5-25) were obtained from the stem bark of Tabernaemontana corymbosa. Their structures and absolute configurations were elucidated by extensive spectroscopy, quantum chemical calculations, DP4+ probability analyses and Mo₂(OAc)₄-induced electronic circular dichroism experiment. The antibacterial and antifungal activities of these compounds were evaluated and some of them showed significant activity against Staphylococcus aureus,Bacillus subtilis, Streptococcus dysgalactiae and Candida albicans.

Monoterpene indole N-oxide alkaloids from Tabernaemontana corymbosa and their antimicrobial activity

Tabernaemontana corymbosa is a traditional folk medicine. In our research, six monoterpene indole N-oxide alkaloids and their parent alkaloids were obtained from the stem bark of T. corymbosa, including seven new alkaloids (1-7) and five known alkaloids (8-12). Their structures and absolute configurations were elucidated by extensive spectroscopy, quantum chemical calculations, and DP4+ probability analyses. The antimicrobial activity of the obtained compounds was evaluated, among which alkaloids 4, 8, 12 showed significant antimicrobial activity against Staphylococcus aureus with an MIC value of 6.25 μg/mL, while alkaloids 11, 12 showed moderate antimicrobial activity against Bacillus subtilis with an MIC value of 25 μg/mL.