α‑Glucosidase Inhibitors from <i>Preussia minimoides</i>

Extensive fractionation of an extract from the grain-based culture of the endophytic fungus <i>Preussia minimoides</i> led to the isolation of two new polyketides with novel skeletons, minimoidiones A (<b>1</b>) and B (<b>2</b>), along with the known compounds preussochromone C (<b>3</b>), corymbiferone (<b>4</b>), and 5-hydroxy-2,7-dimethoxy-8-methylnaphthoquinone (<b>5</b>). The structures of <b>1</b> and <b>2</b> were elucidated using 1D and 2D NMR data analysis, along with DFT calculations of ¹H NMR chemical shifts. The absolute configuration of <b>1</b> was established by a single-crystal X-ray diffraction analysis and TDDFT-ECD calculations. Compounds <b>1</b>–<b>4</b> significantly inhibited yeast α-glucosidase

Chemical Analysis and Antidiabetic Potential of a Decoction from <i>Stevia serrata</i> Roots

A decoction of the roots (31.6–316 mg/kg) from Stevia serrata Cav. (Asteraceae) as well as the main component (5–150 mg/kg) showed hypoglycemic and antihyperglycemic effects in mice. The fractionation of the active extract led to the isolation of dammaradiene acetate (1), stevisalioside A (2), and three new chemical entities characterized by spectroscopic methods and named stevisaliosides B–D (3–5). Glycoside 2 (5 and 50 mg/kg) decreased blood glucose levels and the postprandial peak during oral glucose and insulin tolerance tests in STZ-hyperglycemic mice. Compounds 1–5 were tested also against PTP1B1–400 and showed IC50 values of 1180.9 ± 0.33, 526.8 ± 0.02, 532.1 ± 0.03, 928.2 ± 0.39, and 31.8 ± 1.09 μM, respectively. Compound 5 showed an IC50 value comparable to that of ursolic acid (IC50 = 30.7 ± 0.00 μM). Docking studies revealed that 2–5 and their aglycones bind to PTP1B1–400 in a pocket formed by the C-terminal region. The volatilome of S. serrata was characterized by a high content of (E)-longipinene, spathulenol, guaiadiene, seychellene, and aromandendrene. Finally, a UHPLC-UV method was developed and validated to quantify the content of 2 in the decoction of the plant

Chemical Analysis and Antidiabetic Potential of a Decoction from <i>Stevia serrata</i> Roots

A decoction of the roots (31.6–316 mg/kg) from Stevia serrata Cav. (Asteraceae) as well as the main component (5–150 mg/kg) showed hypoglycemic and antihyperglycemic effects in mice. The fractionation of the active extract led to the isolation of dammaradiene acetate (1), stevisalioside A (2), and three new chemical entities characterized by spectroscopic methods and named stevisaliosides B–D (3–5). Glycoside 2 (5 and 50 mg/kg) decreased blood glucose levels and the postprandial peak during oral glucose and insulin tolerance tests in STZ-hyperglycemic mice. Compounds 1–5 were tested also against PTP1B1–400 and showed IC50 values of 1180.9 ± 0.33, 526.8 ± 0.02, 532.1 ± 0.03, 928.2 ± 0.39, and 31.8 ± 1.09 μM, respectively. Compound 5 showed an IC50 value comparable to that of ursolic acid (IC50 = 30.7 ± 0.00 μM). Docking studies revealed that 2–5 and their aglycones bind to PTP1B1–400 in a pocket formed by the C-terminal region. The volatilome of S. serrata was characterized by a high content of (E)-longipinene, spathulenol, guaiadiene, seychellene, and aromandendrene. Finally, a UHPLC-UV method was developed and validated to quantify the content of 2 in the decoction of the plant

Dioxomorpholines and Derivatives from a Marine-Facultative <i>Aspergillus</i> Species

Two new dioxomorpholines, <b>1</b> and <b>2</b>, three new derivatives, <b>3</b>–<b>5</b>, and the known compound PF1233 B (<b>6</b>) were isolated from a marine-facultative <i>Aspergillus</i> sp. MEXU 27854. Their structures were established by 1D and 2D NMR and HRESIMS data analysis. The absolute configuration of <b>1</b> and <b>2</b> was elucidated by comparison of experimental and DFT-calculated vibrational circular dichroism spectra. Compounds <b>3</b>, <b>5</b>, and <b>6</b> were noncytotoxic to a panel of human cancer cell lines with different functional status for the tumor-suppressor protein p53, but were inhibitors of P-glycoprotein-reversing multidrug resistance in a doxorubicin-resistant cell line