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.

Annona glabra L. Seeds: An Agricultural Waste Biosorbent for the Eco-Friendly Removal of Methylene Blue

The seeds of Annona glabra L., an invasive plant in Vietnam, were first employed as a new biosorbent for the adsorption of methylene blue (MB) from aqueous media. The characterizations of the material using FT-IR, SEM, nitrogen adsorption-desorption analysis, and point of zero charge reveals that it possesses a rough and irregular surface, various polar functional groups, and pHpzc of 5.5. Certain adsorption conditions including adsorbent dose, solution pH, contact time, and initial concentration of MB were found to affect adsorption efficiency. The kinetic data are well fitted with pseudo-second-order model with the adsorption rate of 0.002 g mg-1 min-1 and initial rate of 4.46 mg g-1 min-1. For the adsorption isotherm, three nonlinear models were used to analyze the experiment data, including Langmuir, Freundlich, and Temkin. The results indicate that the Langmuir model best describes the adsorption of Annona glabra L. seeds powder (AGSP) with a maximum adsorption capacity of 98.0 mg g-1. The investigation underpins the adsorption mechanism, whereby the electrostatic attraction between positively charged MB and negatively charged surface of AGSP is expected to be the predominant mechanism, together with hydrogen bonding and pi-pi interaction. These results make AGSP an interesting biosorbent concerning its environmental friendliness, cost-effectiveness, and relatively high dye adsorption capacity.

A Comparison of a Conventional Chemical Coagulant and a Natural Coagulant Derived from Cassia fistula Seeds for the Removal of Heavy Metal Ions

Cassia fistula seed-derived coagulant has been reported to exhibit high coagulating-flocculating activity, environmental friendliness, and cost-effectiveness for the wastewater treatment, especially of textile wastewater. For heavy metal removal, however, research focusing on evaluating the feasibility of this material is still limited. Therefore, this study reports jar-test experiments in which the Zn2+ and Ni2+ removal efficiency of C. fistula coagulant was assessed. Moreover, a comparison of coagulation performance using a conventional chemical coagulant and the natural coagulant was performed. Characterization of the C. fistula seed-derived coagulant revealed the presence of important functional groups and fibrous networks with rough surfaces. A bench-scale study indicated that the coagulation performance of the two coagulants depends strongly on the initial concentration of metal ions, pH level, and coagulant dosage. The C. fistula seed-derived coagulant was found to possess higher removal efficiency than polyaluminum chloride. This natural coagulant removed over 80% of metal ions at the optimal conditions of pH 5.0, a metal ion concentration of 25 ppm, and a dosage of 0.8 and 1.6 g/L for Zn2+ and Ni2+, respectively. This study shows that C. fistula seed-derived coagulant is a potential alternative to chemical coagulants and could be developed to provide an environmentally friendly, economical, and efficient wastewater treatment.

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

A new spiroterpenoid, namely tinctorin (1), along with one known compound, norreticulatin (2), were isolated from the lichen Parmotrema tinctorum (Despr. ex Nyl.) Hale. Their structures were elucidated by extensive spectroscopic analyses and electronic circular dichroism (ECD) calculations. The absolute configuration of 2 was established for the first time. Compound 1 was evaluated for its inhibitory activity against α-glucosidase and found to be inactive.

Eumitrins I-K: three new xanthone dimers from the lichen Usnea baileyi

In the continuing discovery and structure elucidation of natural xanthone dimers, which are still rarely reported in absolute configuration, three new xanthone dimers, eumitrins I-K (1-3) were isolated from the lichen Usnea baileyi, a rich source of natural xanthone dimers. Their structures were elucidated unambiguously by spectroscopic analyses, including high-resolution electrospray ionization mass spectrometry (HRESIMS), 1D and 2D nuclear magnetic resonance spectroscopy (1D and 2D NMR). The absolute configuration of all three compounds was established through DP4 probability and ECD calculation. All compounds revealed weak activity for their enzymatic inhibition against α-glucosidase and tyrosinase, as well as antibacterial activity.

Design, modification of phyllanthone derivatives as anti-diabetic and cytotoxic agents

Twelve benzylidene derivatives, one Baeyer-Villiger oxidative, six imine derivatives were successfully designed and synthesised from phyllanthone. In the search for potential new anti-diabetic agents, phyllanthone along with its benzylidene and oxidation analogues were evaluated for enzyme inhibition against α-glucosidase. In the benzylidene series, most analogues displayed stronger activity than the mother compound. Compound 1c revealed the strongest activity, outperforming the acarbose positive control with an IC₅₀ value of 19.59 µM. Phyllanthone and its derivatives were then tested for cytotoxic activity against the K562 cell line. The imine analogues displayed the most powerful cytotoxic activity with 3cand 3d having IC₅₀ values of 57.55 and 68.02 µM, respectively.

Synthesis, α-glucosidase inhibition, and molecular docking studies of novel N-substituted hydrazide derivatives of atranorin as antidiabetic agents

A series of novel N-substituted hydrazide derivatives were synthesized by reacting atranorin, a compound with a natural depside structure (1), with a range of hydrazines. The natural product and 12 new analogues (2-13) were investigated for inhibition of α-glucosidase. The N-substituted hydrazide derivatives showed more potent inhibition than the original. The experimental results were confirmed by docking analysis. This study suggests that these compounds are promising molecules for diabetes therapy. Molecular dynamics simulations were carried out with compound 2 demonstrating the best docking model using Gromac during simulation up to 20 ns to explore the stability of the complex ligand-protein. Furthermore, the activity of all synthetic compounds 2-13 against a normal cell line HEK293, used for assessing their cytotoxicity, was evaluated.