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Chitosan/starch nanocomposites loaded with ampicillin were prepared using the spray-drying method by mixing various ratios of chitosan and starch. The morphology of chitosan/starch nanoparticles was studied using a scanning electron microscope (SEM), and the zeta potential value and size distribution were determined by a Nanoparticle Analyzer. The results show that the chitosan/starch nanocomposites have a spherical shape, smooth surface, and stable structure. Nanoparticle size distribution ranged from 100 to 600 nm, and the average particle size ranged from 300 to 400 nm, depending on the ratio between chitosan and starch. The higher the ratio of starch in the copolymer, the smaller the particle size. Zeta potential values of the nanocomposite were very high, ranging from +54.4 mV to +80.3 mV, and decreased from 63.2 down to +37.3 when loading with ampicillin. The chitosan/starch nanocomposites were also characterized by FT-IR to determine the content of polymers and ampicillin in the nanocomposites. The release kinetics of ampicillin from the nanocomposites were determined in vitro using an HPLC profile for 24 h. The loading efficiency (LE) of ampicillin into chitosan/starch nanoparticles ranged from 75.3 to 77.3%. Ampicillin-loaded chitosan/starch nanocomposites were investigated for their antibacterial activity against antibiotic-resistant Escherichia coli in vitro. The results demonstrate that the antibacterial effectiveness of nanochitosan/starch loading with ampicillin against E.coli was 95.41%, higher than the 91.40% effectiveness of ampicillin at the same concentration of 5.0 µg/mL after 24 h of treatment. These results suggest that chitosan/starch nanocomposites are potential nanomaterials for antibiotic drug delivery in the pharmaceutical field. [ABSTRACT FROM AUTHOR]

Wild guava (Psidium guajava L.) commonly grows in tropical forests, and its leaves have long been used by Asian ethnic minorities as herbal tea and traditional medicine. This study aimed to evaluate the effects of different drying methods (sun drying, hot air drying, microwave drying, vacuum drying, and freeze drying) on the retention of bioactive compounds, antioxidant, and antidiabetic activities of wild guava leaves collected in Vietnam. The results showed that drying methods significantly affected the retention of bioactive compounds, biological activities, and color of guava leaves. The freeze-dried leaves had the highest levels of total phenolic content (173.25 ± 0.68 mg gallic acid equivalent g−1 dw), total flavonoid content (24.46 ± 0.78 mg QE g−1 dw), antioxidant capacity, and in vitro antidiabetic activity compared with others, while sun-dried leaves showed the lowest values of those parameters. The principal component analysis (PCA) showed a strong correlation among biological activities and contents of bioactive compounds, including antioxidant activity, in vitro antidiabetic activity, total phenolic content, and total flavonoid content (r2 = 0.999, p < 0.0001). Specifically, the biological activities strongly and positively correlated epicatechin, rutin, chlorogenic acid, catechin, and gallic acid. Freeze-dried guava leaves had the highest positive scores, followed by hot air-dried, microwave-dried, vacuum-dried, and sun-dried samples. FD treatment sample also exhibited better color and sensory properties than others. Consequently, freeze drying is recommended as the most suitable drying method for preserving the bioactive compounds and sensory characteristics of dried wild guava leaves. [ABSTRACT FROM AUTHOR]

Most biologically natural compounds are very sensitive and easily degradable under drying conditions. This study aimed to investigate the effect of drying temperature on the contents of phenolic compounds and in vitro antioxidant and antidiabetic activities of wild guava leaves. Wild guava leaves were dried at 40 °C, 50 °C, 60 °C, 70 °C, and 80 °C, as well as sun drying (SD). The total phenolic and flavonoid contents (TPC and TFC) were measured using the colorimetric method. Antioxidant activity was determined by the 2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH) and 2,2-azino-bis(3-ethylbenzothazoline-6-sulfonic acid (ABTS) radical scavenging activity assays. In vitro antidiabetic activity was measured by assessing α-glucosidase and α-amylase inhibitory activities. The contents of individual phenolic compounds were determined using ultra-performance liquid chromatography (UPLC). The principal component analysis (PCA) results revealed that hot air drying at different temperatures had significantly different effects on the bioactive compounds and biological properties of guava leaves. Drying at high or low temperatures resulted in a higher degradable rate of bioactive compounds leading to a weakening of the biological properties. Drying at 50 °C resulted in high TPC and TFC as well as the highest in vitro antioxidant and antidiabetic activities. Furthermore, the highest contents of gallic acid, catechin, rutin, quercetin, apigenin, quercitrin, vitexin, and apigenin-7- O -D-glucopyranoside were found in samples dried at 50 °C, whereas the highest contents of chlorogenic acid, epicatechin, and ellagic acid were observed in samples dried at 60 °C. Therefore, drying at 50 °C was the suitable temperature for retaining valuable biological compounds in wild guava leaves. [ABSTRACT FROM AUTHOR]

This study aimed to reuse groundnut oil processing by-product, groundnut cake (GNC) for the low-cost production of prodigiosin (PG) via microbial technology and to assess its novel potential application for the management of black pepper nematodes. Serratia marcescens TUN02 was found as the most active PG-producing strain. Various small-scale experiments conducted in flasks indicated that GNC at 1% may be used as the sole carbon/nitrogen source for cost-effective PG production by fermentation. Notably, no further commercial ingredients and salts are required to supplement into the culture medium of this fermentation. PG was further investigated for scale-up production in a 14-L bioreactor system and PG was produced at high yield (6886 mg/L) with large-scale volume (4 L) in a short cultivation time (10 h). PG was then purified and its nematicidal activity was evaluated and showed effective inhibition of juveniles and egg hatching of Meloidogyne incognita species, harmful on black pepper, with low IC50 values of 0.2 and 0.32 mg/mL, respectively. The simple medium containing 1% GNC is the first report of cost-effective biosynthesis of PG, as well as potential in vitro anti-egg hatching activity of PG. These results indicated the potential application of GNC for low-cost bioproduction of PG for promising and novel use in the management of black pepper nematodes. [ABSTRACT FROM AUTHOR]

Majonoside R2 (MR2), the principal saponin of Vietnamese ginseng ( Panax vietnamensis Ha & Grushv.), has the unique structure of ocotillol-type dammarane and showed remarkable biological activities. This paper deals with the new findings in the chemical analysis MR2 by the tandem LC-MS/MS and, especially, its inhibitory activities on α -glucosidase for diabetic management. The developed LC-MS/MS method revealed advantages of high selectivity with specific mass transition from precursor [M + H] + ion ( m/z 784.4) into product ion ( m/z 475.1), high sensitivity (calibration range: 5-250 ppb; LOD: 1.5 ppb; LOQ: 5.0 ppb), and high accuracy to support further pharmaceutical analysis of MR2. MR2 and its aglycone ocotillol relatively showed certain inhibitory effects on α -glucosidase in vitro with the IC 50 values of 353.05 and 219.64 µg/mL and supported by molecular docking analysis, in which MR2 and ocotillol could play as allosteric inhibitors with high binding affinity (-7.8 and -8.1 kcal/mol) evidenced by bonding interactions.

The C. luuana Orel & Curry (TD3), C. furfuracea (Merr.) Cohen-Stuard (TD4), C. bidoupensis Truong, Luong & Tran (TD6), C. sinensis (L.) Kuntze (TD7), and C. kissii var. spp (TD8), have been traditionally used as a health-promoting beverage by local people in Ta Dung, Dak Nong. Despite their potential health benefits, further scientific data on biological and phytochemical properties of these plants is needed. To address this issue, this study was conducted to investigate phytochemical and biological properties of five Camellia species extracts, using DPPH, ABTS radical scavenging, copper chelating (Cu-chelator), and tyrosinase inhibition (TI), α-amylase (Al-AI), and α-glucosidase (Al-GI) analyses. As results, ten compounds were identified using UPLC method, in which catechins (mainly EGCG and catechin (Cat)), were the most prevalent, and followed by chlorogenic acid (ChlA), quercitrin (Querci), rutin, and quercetin (Querce). Additionally, multiple factor analysis (MFA) also revealed that TD7, TD3, and TD4 containing high TPC, TFC, high concentrations of EGCG, ChlA, and caffeine were responsible for their high DPPH, ABTS radical scavenging activities, as well asTI, Al-AI and Al-GI. Furthemore, TD6 and TD8, possessing elevated levels of Apig, Querci, Rutin, Querce, Cat, and EA, exhibited a high Cu-chelator property, but a weak enzyme inhibition. From all above-mentioned results, the antioxidative and enzyme inhibitory potentials of Camellia species extracts collected in Dak Nong province in Vietnam were scientifically demonstrated paving a pathway to develop health supplement in further studies., (© 2024 Wiley-VHCA AG, Zurich, Switzerland.)