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.

Lichen-Derived Diffractaic Acid Inhibited Dengue Virus Replication in a Cell-Based System.

Dengue is a mosquito-borne flavivirus that causes 21,000 deaths annually. Depsides and depsidones of lichens have previously been reported to be antimicrobials. In this study, our objective was to identify lichen-derived depsides and depsidones as dengue virus inhibitors. The 18 depsides and depsidones of Usnea baileyi, Usnea aciculifera, Parmotrema dilatatum, and Parmotrema tsavoense were tested against dengue virus serotype 2. Two depsides and one depsidone inhibited dengue virus serotype 2 without any apparent cytotoxicity. Diffractaic acid, barbatic acid, and Parmosidone C were three active compounds further characterized for their efficacies (EC50), cytotoxicities (CC50), and selectivity index (SI; CC50/EC50). Their EC50 (SI) values were 2.43 ± 0.19 (20.59), 0.91 ± 0.15 (13.33), and 17.42 ± 3.21 (8.95) µM, respectively. Diffractaic acid showed the highest selectivity index, and similar efficacies were also found in dengue serotypes 1-4, Zika, and chikungunya viruses. Cell-based studies revealed that the target was mainly in the late stage with replication and the formation of infectious particles. This report highlights that a lichen-derived diffractaic acid could become a mosquito-borne antiviral lead as its selectivity indices ranged from 8.07 to 20.59 with a proposed target at viral replication.

α-Glucosidase Inhibition by Usnic Acid Derivatives.

This study investigated a set of new potential antidiabetes agents. Derivatives of usnic acid were designed and synthesized. These analogs and nineteen benzylidene analogs from a previous study were evaluated for enzyme inhibition of α-glucosidase. Analogs synthesized using the Dakin oxidative method displayed stronger activity than the pristine usnic acid (IC50 >200 µM). Methyl (2E,3R)-7-acetyl-4,6-dihydroxy-2-(2-methoxy-2-oxoethylidene)-3,5-dimethyl-2,3-dihydro-1-benzofuran-3-carboxylate (6b) and 1,1'-(2,4,6-trihydroxy-5-methyl-1,3-phenylene)di(ethan-1-one) (6e) were more potent than an acarbose positive control (IC50 93.6±0.49 µM), with IC50 values of 42.6±1.30 and 90.8±0.32 µM, respectively. Most of the compounds synthesized from the benzylidene series displayed promising activity. (9bR)-2,6-Bis[(2E)-3-(2-chlorophenyl)prop-2-enoyl]-3,7,9-trihydroxy-8,9b-dimethyldibenzo[b,d]furan-1(9bH)-one (1c), (9bR)-3,7,9-trihydroxy-8,9b-dimethyl-2,6-bis[(2E)-3-phenylprop-2-enoyl]dibenzo[b,d]furan-1(9bH)-one (1g), (9bR)-2-acetyl-6-[(2E)-3-(2-chlorophenyl)prop-2-enoyl]-3,7,9-trihydroxy-8,9b-dimethyldibenzo[b,d]furan-1(9bH)-one (2d), (9bR)-2-acetyl-6-[(2E)-3-(3-chlorophenyl)prop-2-enoyl]-3,7,9-trihydroxy-8,9b-dimethyldibenzo[b,d]furan-1(9bH)-one (2e), (6bR)-8-acetyl-3-(4-chlorophenyl)-6,9-dihydroxy-5,6b-dimethyl-2,3-dihydro-1H-[1]benzofuro[2,3-f][1]benzopyran-1,7(6bH)-dione (3e), (6bR)-8-acetyl-6,9-dihydroxy-5,6b-dimethyl-3-phenyl-2,3-dihydro-1H-[1]benzofuro[2,3-f][1]benzopyran-1,7(6bH)-dione (3h), (6bR)-3-(2-chlorophenyl)-8-[(2E)-3-(2-chlorophenyl)prop-2-enoyl]-6,9-dihydroxy-5,6b-dimethyl-2,3-dihydro-1H-[1]benzofuro[2,3-f][1]benzopyran-1,7(6bH)-dione (4b), and (9bR)-6-acetyl-3,7,9-trihydroxy-8,9b-dimethyl-2-[(2E)-3-phenylprop-2-enoyl]dibenzo[b,d]furan-1(9bH)-one (5c) were the most potent α-glucosidase enzyme inhibitors, with IC50 values of 7.0±0.24, 15.5±0.49, 7.5±0.92, 10.9±0.56, 1.5±0.62, 15.3±0.54, 19.0±1.00, and 12.3±0.53 µM, respectively.

Manilkzapotane, a novel dimeric alkylresorcinol derivative from the stem bark of Manilkara zapota.

A novel dimeric alkylresorcinol derivative, manilkzapotane (1), along with seven known compounds, lupeol acetate (2), lupeol (3), arjunolic acid (4), ergosterol peroxide (5), taraxerol (6), hederagonic acid (7), and glochidiol (8) were isolated from the stem bark of Manilkara zapota. Their structures were determined on the basis of spectroscopic data. DFT-NMR chemical shift calculations and a modified probability (DP4+) method were applied to define the relative configuration of 1. To the best of our knowledge, this represents the first isolation of a dimeric alkylresorcinol derivative from the Sapotaceae family.

Salazinic Acid-Derived Depsidones and Diphenylethers with α-Glucosidase Inhibitory Activity from the Lichen Parmotrema dilatatum.

Three new depsidones, parmosidones F - G (1 - 2), and 8'-O-methylsalazinic acid (3), and 3 new diphenylethers, parmetherines A - C (4 - 6), together with 2 known congeners were isolated from the whole thalli of Parmotrema dilatatum, a foliose chlorolichen. Their structures were unambiguously determined by extensive spectroscopic analyses and comparison with literature data. The isolated polyphenolics were assayed for their α-glucosidase inhibitory activities. Newly reported benzylated depsidones 1: and 2: in particular inhibited α-glucosidase with IC50 values of 2.2 and 4.3 µM, respectively, and are thus more potent than the positive control, acarbose.

Atypical Lindenane-Type Sesquiterpenes from Lindera myrrha.

Two new lindenane sesquiterpenes were obtained from the roots of Lindera myrrha. These compounds were structurally elucidated by HRMS data, extensive NMR analyses, and comparison between experimental and theoretical 13C-NMR data. Myrrhalindenane A is the first monomeric seco-d lindenane displaying a non-rearranged, cyclohexanic C-ring. Myrrhalindenane B is the second occurrence of an angular lindenane-sesquiterpene related to a C6-C7 lactonization.

Nervisides I-J: Unconventional Side-Chain-Bearing Cycloartane Glycosides from Nervilia concolor.

Two new cycloartane glycosides, nervisides I-J, were isolated from Nervilia concolor whole plants. Their structures were unambiguously established by interpretation of their HRESIMS and 1D and 2D NMR data. These cycloartanes comprised a stereogenic center at C-24, the R configuration of which was assigned based on DFT-NMR calculations and the subsequent DP4 probability score. These compounds were tested for cytotoxicity against K562 and MCF-7 tumor cell lines, revealing mild cytotoxic activity.

Sulfonic Acid-Containing Flavonoids from the Roots of Phyllanthus acidus.

Six new sulfonic acid-containing flavonoids, acidoflavanone (1), acidoauronol (2), 5- O-methylacidoauronol (3), acidoaurone (4), acidoisoflavone (5), and acidoflavonol (6), were isolated from the EtOH extract of the roots of Phyllanthus acidus. Their structures were unambiguously established by interpretation of their HRESIMS and 1D and 2D NMR data, single-crystal X-ray diffraction analysis, and comparison to the literature data. These new structures represent the first examples of sulfonic acid-containing flavanones, auronols, aurones, and isoflavones.

Cycloartane-type triterpenoids from the leaves of Sandoricum koetjape and their efficacy on α-glucosidase inhibition activity.

The preliminary α-glucosidase inhibitory activity of the methanol extract of the leaves of Sandoricum koetjape Merr. exhibited promising results. The leaves was extracted with methanol to obtain the methanol extract that was continuedly partitioned with hexane and ethyl acetate. Those fractions were further purified by various chromatographic techniques. The isolation of the potent fractions furnished two new cycloartane-type triterpenoids (1 and 2) along with ten known compounds (3-12). Their chemical structures were unambiguously established by interpretation of NMR (1 D & 2 D) and high-resolution electrospray ionization mass spectrometry (HRESIMS) data. Furthermore, the configurations of two new compounds were determined by using NOESY spectrum as well as comparing their NMR data to the reference. These compounds were evaluated against α-glucosidase. All tested compounds revealed potent activity with IC50 value in the range of 2.17-49.2 µM compared to that of acarbose (IC50 100.6 µM). Compound 10 showed the lowest IC50 value. This compound was reported as a mixed-type inhibitor. Compound 3 possessed the second strong activity with an IC50 value of 14.0 µM and was further investigated on kinetic analysis which revealed as a mixed-type inhibitor with Ki and Ki' values of 59.1 and 155.2 µM, respectively.

Charge Transfer-Promoted Excited State of a Heavy-Atom-Free Photosensitizer for Efficient Application of Mitochondria-Targeted Fluorescence Imaging and Hypoxia Photodynamic Therapy.

Conventional photosensitizers (PSs) used in photodynamic therapy (PDT) have shown preliminary success; however, they are often associated with several limitations including potential dark toxicity in healthy tissues, limited efficacy under acidic and hypoxic conditions, suboptimal fluorescence imaging capabilities, and nonspecific targeting during treatment. In response to these challenges, we developed a heavy-atom-free PS, denoted as Cz-SB, by incorporating ethyl carbazole into a thiophene-fused BODIPY core. A comprehensive investigation into the photophysical properties of Cz-SB was conducted through a synergistic approach involving experimental and computational investigations. The enhancement of intersystem crossing (kISC) and fluorescence emission (kfl) rate constants was achieved through a donor-acceptor pair-mediated charge transfer mechanism. Consequently, Cz-SB demonstrated remarkable efficiency in generating reactive oxygen species (ROS) under acidic and low-oxygen conditions, making it particularly effective for hypoxic cancer PDT. Furthermore, Cz-SB exhibited good biocompatibility, fluorescence imaging capabilities, and a high degree of localization within the mitochondria of living cells. We posit that Cz-SB holds substantial prospects as a versatile PS with innovative molecular design, representing a potential "one-for-all" solution in the realm of cancer phototheranostics.

Identification and α-glucosidase inhibitory activity evaluation of two new coumarins derived from Mansonia gagei J. R. Drumm.

Five coumarins were isolated from the heartwood of Mansonia gagei, which included two newly discovered compounds, namely 11-hydroxypopulene E (1) and mansorin D (2), along with three previously identified compounds. The structures were determined through the utilisation of comprehensive spectroscopic data, ECD calculations, and a thorough comparison with existing literature data. The α-glucosidase inhibitory activities of all isolated compounds were assessed in yeast. Out of the compounds tested, compound 2 exhibited the most significant activity, displaying a percentage inhibition of 34.33% at a concentration of 200 µM.

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.

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.

Eumitrins F-H: three new xanthone dimers from the lichen Usnea baileyi and their biological activities.

The lichen Usnea baileyi is a fruticose lichen belonging to the Usnea genus. It is well known as a rich source of natural xanthone dimers and possesses various bioactivities. Nevertheless, the chemical investigation on this type of lichen is still rare as most of researches reported its components without structural elucidation. Herein, in the continuous study on this type of lichen, we further isolate xanthone dimers from the dichloromethane extract and explore three new xanthone dimers, eumitrins F - H (1 - 3). Their structures were elucidated unambiguously by spectroscopic analyses, including high resolution electrospray ionisation mass spectrometry (HRESIMS), 1 D and 2 D nuclear magnetic resonance spectroscopy (1 D and 2 D NMR), and DP4 probability. All compounds were evaluated for their enzyme inhibition against α-glucosidase, tyrosinase, and antibacterial activity. They revealed moderate antimicrobial and weak tyrosinase inhibition. For α-glucosidase inhibition, compound 3 displayed the most significant inhibitory against α-glucosidase possessing an IC50 value of 64.2 µM.

Gagones A-F: Six prenylated chalcones from the heartwood of Mansonia gagei.

Six undescribed prenylated chalcones gagones A-F were isolated from the acetone fraction of Mansonia gagei heartwood. Their structures were unambiguously established based on spectroscopic analysis (HRESIMS, 1D and 2D NMR), as well as comparison to literature data. Their absolute configurations were elucidated using DP4 and electronic circular dichroism calculations. Isolated compounds were evaluated for their inhibitory activity against α-glucosidase and DPPH assay. All of the tested compounds exhibited better activity than that of acarbose (IC50 93.6 ± 0.5 µM). Among them, gagone D exhibited the highest α-glucosidase inhibitory with the IC50 value of 3.6 ± 0.4 µM. For antioxidant activity, gagones A-C, and E showed more active than that of ascorbic acid (IC50 30.2 ± 0.5 µM) with the IC50 values of 13.2 ± 0.7, 20.1 ± 0.4, 19.3 ± 0.5 and 12.8 ± 0.2 µM, respectively.

α-Glucosidase inhibition of sesquiterpenoids from the heartwood of Mansonia gagei.

Nine undescribed sesquiterpenoids, along with ten known compounds, were isolated from the ethyl acetate extract of Mansonia gagei heartwood. Their structures were determined by spectroscopic data analysis (FTIR, 1D, 2D NMR, and HRESIMS), and their absolute configurations were established by ECD calculation. The isolated compounds were evaluated for their inhibitory effect against α-glucosidase from yeast. The results showed that mansonone U, mansonialactam, heliclactone and mansonone S exhibited exceptionally potent activities when compared to the positive control, acarbose, with IC50 values of 12.38 ± 0.71, 0.20 ± 0.05, 13.12 ± 2.85, and 12.05 ± 1.91 µM, respectively. Among them, mansonialactam possessed the most potent inhibitory activity against yeast α-glucosidase, and it showed an uncompetitive inhibition mode.

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.

Mechanism of Friedel-Crafts Acylation Using Metal Triflate in Deep Eutectic Solvents: An Experimental and Computational Study.

In this paper, we develop a method for Friedel-Crafts acylation using metal triflate in deep eutectic solvents. Various metal triflates were tested and provided good to excellent yields of corresponding ketone products. The density functional theory calculation revealed the metal effects on the formation of active intermediate acylium triflate as well as the acidic condition. The metal triflate in the deep eutectic solvent can be recovered and reused with a little loss in the catalytic activity.

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.