Tinctorin, a new spiroterpenoid from the lichen Parmotrema tinctorum (Despr. ex Nyl.) Hale growing in Vietnam

In vitro and in silico studies of alpha glucosidase inhibition and antifungal activity of coffea canephora husk

The coffea canephora husk, a protected agricultural crop, is abundant in Vietnam. Examining the effects of C. canephora husk compounds on α-glucosidase and antifungal drug activity was the primary objective of this research. A cholestane-type steroid, coffeacanol A (1), was extracted from the ethyl acetate extract. Three cholestane-type derivatives (2-4) and three additional known compounds (5-7) were separated, and we used a variety of chromatographic techniques to identify a total of six substances. We used NMR to determine the chemical structures of these substances. Extensive HR-MS-ESI analysis and NMR experimental data were used to confirm the structure of the novel metabolite (1). The cholestane-type steroid was initially discovered in the Coffea canephora husk, marking the first instance in the coffee plant family to reveal chemical structures (1-7). The inhibition of α-glucosidase was found to be significantly higher in all compounds tested, with the exception of compounds (2) and (5). In vitro, the positive control showed the lowest inhibition, and the range of IC50 values was calculated to be 27.4 to 96.5 μM, which is lower than the IC50 value of 214.50 μM for the acarbose control. With an IC50 value of 27.4 μM, compound (7) showed the greatest capacity to inhibit α-glucosidase among the test compounds. The 3TOP and 2VF5 enzyme crystal structures were used for in silico docking investigations and validations of compounds (1-7). In silico calculations to explain how compound (7) shows high activity in vitro via the enzyme inhibition mechanism by residual amino acids, like Gly 1102 (B chain) and Glu 1095 (B chain), and their relative interaction with compounds (7) and acarbose. Compound (7) exhibited the best antifungal activity against Candida albicans fungus among three fungi, namely Candida albicans, Trichophyton mentagrophytes, and Trichophyton rubrum, with a MIC value of 25 μM. Compound (7) and fluconazole combined to form similar interactions in the contact ligand model, including the functional group, capping group, and linker part, which interacted fully with the 2VF5 enzyme, leading to effective in vitro inhibition.

Morusacerane: A new gammacerane triterpenoid from the trunk of Morus Alba linn. with α-glucosidase inhibitory activity

This phytochemistry investigation on the trunk of Morus alba L. resulted in the isolation of three triterpenoids, including a new gammacerane triterpenoid - morusacerane (1); along with two known compounds of betulinic acid (2) and ursolic acid (3). The structure elucidation was thoroughly conducted based on 1D, 2D-NMR and HRESIMS spectra, followed by a comparison with existing literatures. The evaluation on α-glucosidase inhibitory exhibited the great potential of the application of these isolated compounds in diabetes treatments. The results show that morusacerane (1), betulinic acid (2), and ursolic acid (3) demonstrate the strong inhibitory with the IC50 values of 106.1, 11.12, and 7.20 μM, respectively. All of these compounds interacted well with the allosteric site enzyme α-glucosidase MAL32 through H-bonds and hydrophobic interaction.

Tinctoric acid A-B, two new hopan-type triterpenoids from the Vietnamese lichen, Parmotrema tinctorum (Despr. ex Nyl.) hale with α-glucosidase inhibitory activity

Two new hopan-type triterpenoids, namely tinctoric acid A-B (1-2), were isolated from the lichen Parmotrema tinctorum (Despr. ex Nyl.) Hale. Their structures were elucidated by extensive spectroscopic analyses (1D and 2D NMR). The absolute configuration at C-22 of 1 was established through DP4 probability. Compounds 1-2 were evaluated for their inhibitory activity against α-glucosidase and found to be more potent than those of positive control (acarbose, IC50 168 µM) with values IC50 74.7 and 98.2 µM, respectively. Both of these compounds interacted well with enzyme α-glucosidase MAL32 through H-bonds and hydrophobic interaction.