Alpha-glucosidase inhibitory activity has been commonly used for the evaluation of antidiabetic property in vitro. The aim of this study is to investigate and characterize Dalbergia tonkinensis as a potential source of antidiabetic compounds. The screening of the active parts used, such as trunk bark, heartwood, and the leaves of Dalbergia tonkinensis indicated that all these extracted parts used with methanol demonstrated potent α-glucosidase inhibitory activity. The in vitro antidiabetic property of Dalbergia tonkinensis was notably recorded for the first time and showed activity (EC₅₀ = 0.17–0.78 mg/mL) comparable to those of reported potent herbal extracts (EC₅₀ = 0.25–4.0 mg/mL) and higher activity than that of acarbose, a commercial antidiabetic drug (EC₅₀ = 1.21 mg/mL). The stability tests revealed that the heartwood of Dalbergia tonkinensis extract (HDT) possesses high pH stability with relative activity in the range of 80–98%. Further bioassay-guided purification led to the isolation of 2 active compounds identified as sativanone and formononetin from the ethyl acetate fraction and water fraction of HDT, respectively. These α-glucosidase inhibitors (aGIs) show promising inhibition against various types of α-glucosidases. Remarkably, these inhibitors were determined as new mammalian aGIs, showing good effect on rat α-glucosidase. The results suggest that Dalbergia tonkinensis is a potent source of aGIs and suggest promise in being developed as functional food with antidiabetic efficacy. The results of this study also enrich our knowledge concerning current biological activity and constituents of Dalbergia tonkinensis species.

Callicarpa candicans (Burm. f.) Hochr. (Callicarpa cana L.) is a medicinal plant that is distributed mainly in the tropics and subtropics of Asia and finds a wide range of uses in traditional medicine. In this study, we attempted and optimized the microwave-assisted hydro-distillation (MAHD) process to obtain essential oil from the leaves of C. candicans. In addition, the obtained oil was analyzed for volatile composition by gas chromatography–mass spectrometry (GC-MS) and assayed for bioactivity against several bacteria and cancer cell lines. To optimize the extraction process, response surface methodology (RSM) in combination with central composite design (CCD) was adopted. Experimental design and optimization were carried out with respect to three experimental factors including the ratio of water to raw material, extraction time, and microwave power. The optimal extraction conditions were obtained as follows: water to raw material ratio of 6/1 (v/w), extraction time 42 min, and microwave power 440 W. Composition determination of the obtained C. candicans essential oil indicated the presence of predominant components including caryophyllene (10.45%), cadinene (10.28%), gurjunene (8.95%), muurolene (8.92%), selinene (7.06%), selinene (5.59%), and copaene (5.40%). In comparison with the essential oils obtained via traditional hydro-distillation method, the essential oil extracted by MAHD exhibited superior anti-proliferative activity on all tested cancer cell lines. Current results imply that the MAHD is capable of recovering biologically-active natural products of greater quantity than that recovered by the conventional distillation.

Lignin peroxidase (LiP), which has been studied extensively in white-rot basidiomycetes and their potential to degrade dyes from textile wastewater, plays a role in the biodegradation of lignin from pulp and paper industry wastewater, as well as agricultural waste. Lignin peroxidase (LsLiP) was successfully purified from the newly isolated Lentinus squarrosulus MPN12 with a 47.1-fold purification and a 15.7% yield. After 48 h-incubation, LsLiP was able to decolorize all tested dyes up to 92% for Acid Blue 62 (NY3), followed by Porocion Brilliant blue HGR (PB, 73.5%), Acid Blue 281 (NY5, 70.5%), Acid Blue 113 (IN13, 61%), Acid red 266 (NY7, 56%), and 34.5% for Acid red 299 (NY1), compared to the negative control with the heat-denatured enzyme. The biodegradation potential of LsLiP was further suggested by the change of lignin structure based on Fourier transform infrared (FTIR) analyses. Lignin structure was noticeably changed before and after LsLiP treatment, especially in the fingerprint regions (1600 to 1000 cm-1) and 2930 cm-1 corresponding to the stretching vibrations of various groups in lignin. Thus, LsLiP has potential application in both enzyme-based decolorization of synthetic dyes and lignin biodegradation.

From the biotechnological point of view, enzymes are powerful tools that help sustain a clean environment in several ways. The enzymatic biodegradation of synthetic dyes is a promising goal since it reduces pollution caused by textile dyeing factory wastewater. Lignin peroxidase (EC 1.11.1.14, LiP) has high redox potential; thus, it is great for application in various industrial fields (e.g., paper- waste treatment and textile dyeing wastewater treatment). In the present study, a LiP from an isolated strain Pleurotus pulmonarius CPG6 (PpuLiP) was successfully purified with a specific activity of 6.59 U mg -1. The enzyme was purified by using three-step column chromatography procedures including DEAE, Sephadex G-75, and HiTrapTM Q FF columns with 17.8-fold purity. The enzyme with a molecular weight of 40 kDa exhibited enhanced pH stability in the acidic range. The activity retention was over 75% at a pH of 3.0 for more than 6 hours. Purified PpuLiP was able to oxidize a variety of substrates including veratryl alcohol, 2,4-DCP, n propanol, and guaiacol. The effect of metal ions on PpuLiP activity was analyzed. The study will provide a ground to decolorize dyes from various groups of PpuLiP. Purified PpuLiP could decolorize 35% Acid blue 25 (AB25), 50% Acid red 129 (AB129), 72% Acid blue 62 (NY3), 85% Acid blue 113 (AB113), 55% Remazol Brilliant blue R (RBBR), and 100% Reactive red 120 (RR120) for 12 hours. Most of the dyes were decolorized, but the heat-denatured enzyme used as negative control obviously did not decolorize the tested dyes. These results indicate that the PpuLiP has potential application in enzyme-based decolorization of synthetic dyes. Keywords: Decolorization; lignin peroxidase; Pleurotus pulmonarius; textile dyes.

Soybeans offer an abundant source of isoflavones, which confer useful bioactivities when existing in aglycone forms. The conversion of isoflavones into aglycones via fermentation of soybean products is often realized by β-glucosidase, an enzyme produced by fungi. In this study, a filamentous fungus, Clerodendron cyrtophyllum, was isolated from root of Clerodendron cyrtophyllum Turcz, which was able to produce the highest activity of β-glucosidase up to 33.72 U/mL at 144 h during fermentation on Potato Dextrose Broth (PDB). The obtained fungus was grown on isoflavones-rich soybean extract to produce genistein and daidzein, achieving the conversion rate of 98.7%. Genistein and daidzein were isolated and purified by column chromatography using hexane/acetone (29:1/1:1), reaching purities of over 90% of total isoflavones, as identified and determined by TLC, LC-MS/MS, and ¹H and ¹³C NMR spectroscopy. These results imply that the isolated P. citrinum is a potential fungal strain for industrial-scale production of genistein and daidzein from isoflavones-containing soybean extracts. These products may serve as potential raw materials for manufacture of functional foods that are based on aglycones.

From the biotechnological viewpoint, the enzymatic disintegration of plant lignocellulosic biomass is a promising goal since it would deliver fermentable sugars for the chemical sector. Cellobiose dehydrogenase (CDH) is a vital component of the extracellular lignocellulose-degrading enzyme system of fungi and has a great potential to improve catalyst efficiency for biomass processing. In the present study, a CDH from a newly isolated strain of the agaricomycete Coprinellus aureogranulatus (CauCDH) was successfully purified with a specific activity of 28.9 U mg⁻¹. This pure enzyme (MW = 109 kDa, pI = 5.4) displayed the high oxidative activity towards β-1–4-linked oligosaccharides. Not least, CauCDH was used for the enzymatic degradation of rice straw without chemical pretreatment. As main metabolites, glucose (up to 165.18 ± 3.19 mg g⁻¹), xylose (64.21 ± 1.22 mg g⁻¹), and gluconic acid (5.17 ± 0.13 mg g⁻¹) could be identified during the synergistic conversion of this raw material with the fungal hydrolases (e.g., esterase, cellulase, and xylanase) and further optimization by using an RSM statistical approach.