Chemical profile and antimicrobial activity of Ocimum gratissimum L. essential oil from Dak Lak province, Vietnam

Pham My Hao(Pham My Hao ),Le Pham Tan Quoc(Le Pham Tan Quoc ) (사)한국식물생명공학회 2024 JOURNAL OF PLANT BIOTECHNOLOGY Vol.51 No.1

Effect of Different Carrier Agents on Physicochemical Properties of Spray-dried Pineapple (Ananas comosus Merr.) Powder

Le Pham Tan Quoc 대한화학회 2020 대한화학회지 Vol.64 No.5

The main purpose of this study is to examine the different physicochemical properties of spray-dried products. The carrier agents and powders after the spray-drying process were analyzed for encapsulation yield, moisture content, color parameters, total polyphenol content (TPC), antioxidant capacity (AC), bulk density, flowability, wettability, hygroscopicity, water solubility index (WSI), particle size and microstructure. The spray-drying process was carried out with different carrier agents including maltodextrin (MD) and the combination of maltodextrin and gum arabic (MD-GA) with MA/GA ratio of 70/ 30, dried at the inlet/outlet air temperature of 160 °C/70 °C, 4 bar, airflow rate of 70 m3·h-1 and feed flow rate of 750 mL·h-1. The results showed that the different carrier agents have significant influences on the physicochemical properties of the powder produced by the spray-drying method. In there, while the values of recovery efficiency and flowability of spray-dried products from MD are higher than those of spray-dried products from MD-GA combination, the opposite is true for the values of TPC, AC, bulk density and wettability, whereas hygroscopicity and WSI values are equally represented in both products.

Assessment of the antioxidant and nematicidal activities of an aqueous extract of Chromolaena odorata (L.) King and Robins against Radopholus similis infestation in Cavendish banana plants: An in vitro and in vivo study

Tran Thi Phuong Nhung(Tran Thi Phuong Nhung ),Le Pham Tan Quoc(Le Pham Tan Quoc ) (사)한국식물생명공학회 2024 JOURNAL OF PLANT BIOTECHNOLOGY Vol.51 No.1

What Influences Decision on Seasoned Equity Offerings of Listed Vietnamese Companies?

LE, Long Hau,NGUYEN, Thi Binh Nhi,PHAM, Xuan Quynh,VUONG, Quoc Duy,LE, Tan Nghiem Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.5

This paper investigates the determinants on decision to conduct seasoned equity offerings (SEOs) of listed companies on the Ho Chi Minh Stock Exchange in Vietnam. Seasoned equity offerings (SEOs) are defined as the issue of more stocks by a firm to raise more capital after a primary issue. Using panel data collected from audited financial statements of 99 listed companies on the Ho Chi Minh Stock Exchange during 2014-2018, the study employs a logit regression model by fixed effects method to examine factors that affect the decision to implement seasoned equity offerings of those companies. The findings of this study show that profit, revenue growth and company's size have a positively significant impact on the decision, while dividend pay-out ratio negatively significantly influences the equity issuing decision. Furthermore, these results are robust after controlling for the forms of equity offerings, i.e. bonus stocks, stock dividends and rights to buy shares. These findings are consistent with economic theories such as agency theory, pecking order theory, and growth opportunity theory, and also could be explained by the real situations of the Vietnamese stock exchange. This study has important implications for corporate managers, policy makers and investors.

Evaluation of physicochemical and biological properties of python fat (Python bivittatus)

Pham Thi Quyen,Le Pham Tan Quoc 한국식품저장유통학회 2023 한국식품저장유통학회지 Vol.30 No.5

The main aim of this study was to determine python fat’s several physicochemical properties, including dimensions, color, structure, acid value (AV), saponification value (SV), density, and recovery efficiency. The optimum yield obtained was approximately 80.40% at 180℃ for 60 min with an AV of 0.3366 and SV of 179.56 mg KOH/g. Fatty acids, comprising oleic acid (72.462%), palmitic acid (26.243%), linolenic acid (0.835%), and myristic acid (0.459%), were identified using gas chromatography-mass spectrometry (GC-MS). The python fat had a very weak antioxidant capacity and almost no antibacterial ability with gram-positive (Staphylococcus aureus - ATCC 25923 and Bacillus cereus - ATCC 10876) and gram- negative (Escherichia coli - ATCC 25922 and Salmonella enterica - ATCC 35664) bacteria (used the paper disc diffusion method for antibiotic susceptibility testing). Moreover, python fat is considered to be very resistant to high temperatures.

Chemical profiles and biological activities of essential oil of Citrus hystrix DC. peels

Do Minh Long,Le Pham Tan Quoc,Tran Thi Phuong Nhung,Vuong Bao Thy,Nguyen Le Quynh Nhu 한국식품저장유통학회 2023 한국식품저장유통학회지 Vol.30 No.3

Essential oil (EO) was extracted from the peel of Citrus hystrix DC. originating from Tinh Bien, An Giang province (Vietnam), using steam distillation. The study aimed to determine some physicochemical properties of Citrus hystrix peel EO (ChpEO), including the acid value (AV), saponification value (SV), ester value (EV), density, specific gravity, and freezing point. The chemical composition was also analyzed by gas chromatography-mass spectrometry (GC-MS). Compounds like β-pinene (30.19%), D-limonene (22.15%), and sabinene (21.37%), with antioxidant and antibacterial properties, had a relatively high content. The EO was also capable of inhibiting the growth of both Gram-positive and Gram-negative bacteria, including Pseudomonas aeruginosa (ATCC 27853), Staphylococcus aureus (ATCC 25923), Salmonella typhimurium (ATCC 13311), and Bacillus cereus (ATCC 11778) specifically.

Evaluating the insecticidal potential of ethanol extracts from Melia azedarach Linn. against Bactrocera cucurbitae - a pest inflicting damage on Momordica charantia Linn.

Tran Thi Phuong Nhung,Le Pham Tan Quoc (사)한국식물생명공학회 2024 JOURNAL OF PLANT BIOTECHNOLOGY Vol.51 No.2

This study explores the insecticidal efficacy of ethanol extracts - obtained from the fruits and seeds of Melia azedarach (MAFS) - against Bactrocera cucurbitae. We assessed the effectiveness of the MAFS extracts at concentrations ranging from 1 to 625 ppm using both laboratory and greenhouse models. Sofri protein 10 DD (1.2 liters/ha) served as the standard insecticide, while water functioned as the negative control. Key parameters evaluated include pupation period, germination time, quantities of pupae and adult individuals, and the severity of damage to bitter melon fruits. In the laboratory model, MAFS significantly prolonged the pupation period (p < 0.05), reduced pupal numbers (p < 0.05), and affected the pupation percentage of B. cucurbitae (p < 0.05). In addition, the germination time (p < 0.05) and proportion of adult B. cucurbitae emergence (p < 0.05) were also significantly impacted. In the greenhouse experiment, MAFS significantly reduced the quantity of B. cucurbitae eggs on bitter melon plants (p < 0.05), resulting in a notable decrease in both larval (p < 0.05) and pupal quantities (p < 0.05). The inhibitory effects of MAFS on larval (p < 0.05) and pupal quantities (p < 0.05), as well as survival from the larval to adult stage, were equivalent to the sofri protein (p < 0.05). MAFS effectively mitigated the severity of damage to bitter melon fruits caused by B. cucurbitae (p < 0.05). Moreover, MAFS exhibits significant effects throughout the various developmental stages of B. cucurbitae. These findings support the potential of MAFS ethanol extracts as an efficient and eco-friendly solution for pest infestation management.

Rare Complication of Strongyloidiasis in Vietnam: A Case of Venous Thromboembolism and Duodenal Obstruction

Tien Huynh Manh,Khanh Quoc Le Tran,Phat Tan Ho,Man Minh Vo,Thong Quang Pham,Thong Duy Vo 대한소화기학회 2023 대한소화기학회지 Vol.81 No.6

Strongyloidiasis, a chronic helminth infection caused by the parasitic nematode Strongyloides stercoralis, has various clinical manifestations. Although rare, duodenal obstructions and venous thromboembolism are possible complications of strongyloidiasis. This paper presents the case of a 47-year-old Vietnamese male with a history of right lower limb edema, anorexia, nausea, vomiting, diarrhea, and abdominal discomfort lasting for four months. Venous Doppler ultrasound detected a thrombus in the right femoral vein, while an abdominal CT scan revealed a mass lesion suggestive of a lower bile duct tumor. Esophageogastroduodenoscopy showed a friable duodenal cap mucosa with multiple ulcers and edematous mucosa of the second part of the duodenum that caused a partial lumen obstruction. The final histological examination of the biopsy specimen revealed chronic duodenitis with larvae consistent with Strongyloides stercoralis. The patient was treated with Ivermectin for two weeks and anticoagulation therapy for three months. After treatment and a six-month follow-up, the patient's gastrointestinal symptoms and leg swelling resolved completely. This is the first documented case of a patient in Vietnam with strongyloidiasis who presented with venous thromboembolism and duodenal obstruction.

Persistence of vaccine-induced antibodies to A/H5N1 at 30 months and 36 months after vaccination in Vietnam

Chien Vien Chinh,Viet Phu Quoc,Loc Huynh Tan,Duoc Nguyen Van,Thai Pham Quang,Be Le Van 한국역학회 2021 Epidemiology and Health Vol.43 No.-

OBJECTIVES: An A/H5N1 vaccine (IVACFLU-A/H5N1) was accepted for use in Vietnam; however, antibody persistence after vaccination has not been well characterized. We examined post-vaccination antibody persistence and related risk factors in individuals enrolled in the phase II IVACFLU-A/ H5N1 vaccine trial in Ninh Hoa, Vietnam, who received a 15-μg dose (2 injections 21 days apart). METHODS: We used a longitudinal study design to follow 86 participants, without a control group. The participants tested as anti-A/H5N1 immunoglobulin G seronegative at baseline and received both doses of the vaccine. Blood was drawn at 30 months and 36 months after the complete vaccination to assess antibody status. Antibody persistence status was compared by demographic characteristics and exposure risk factors using univariate logistic regression. RESULTS: In total, 84.9% and 52.3% of the population showed persistence of at least 1/10 of the A/H5N1 antibodies at 30 months and 36 months after IVACFLU-A/H5N1 vaccination, respectively. The odds of antibody persistence were higher in older people, but lower in people who had experienced flu-like symptoms in the past 18 months or between 2 visits. We recorded no differences between A/H5N1 antibody persistence and exposure risk factors, including having a poultry farm, coming into contact with poultry, and slaughtering and processing poultry. CONCLUSIONS: This study demonstrated noteworthy antibody persistence, indicated by the seroconversion rate and geometric mean titer at 30 months and 36 months after the IVACFLU-A/H5N1 vaccine. Further studies should investigate older people and those who experienced flu-like symptoms to determine a suitable time for a booster shot.

The responsibility of C-terminal domain in the thermolabile haemolysin activity of Vibrio parahaemolyticus and inhibition treatments by Phellinus sp. extracts

Tran Thi Huyen,Ha Phuong Trang,Nguyen Thi-Ngan,Bui Dinh-Thanh,Le Pham Tan Quoc,Trinh Ngoc Nam 한국수산과학회 2023 Fisheries and Aquatic Sciences Vol.26 No.3

The thermolabile haemolysin (tlh) of Vibrio parahaemolyticus (Vptlh) from V. parahaemolyticus is a multiple-function enzyme, initially describes as a haemolytic factor activated by lecithin and phospholipase A2 enzymatic activity (Shinoda, 1991; Vazquez-Morado, 2021; Yanagase et al., 1970). Until now, the tlh structure has hypothesized including N-terminal and C-terminal domain, but what domain of the Vptlh structure does the haemolytic activity has not been refined yet. In this study, a 450-bp VpTLH nucleotide sequence of the entire Vptlh gene encoded the C-terminal domain cloned firstly to examine its responsibility in the activity of the Vptlh. The C-terminal domain fused with a 6-His-tag named the His-tag-VpC-terminal domain was expressed successfully in soluble form in the BL21 (DE3) PlysS cell. Remarkably, both expression and purification results confirmed a high agreement in the molecular weight of the His-tag-VpC-terminal domain was 47 kDa. This work showed the His-tag-VpC-terminal domain lysed the erythrocyte membranes in the blood agar and the phosphate buffered saline (0.9%) media without adding the lecithin substrate of the phospholipase enzyme. Haemolysis occurred at all tested diluted concentrations of His-tag-VpC-terminal domain (p < 0.05), providing evidence for the independent haemolytic activity of the His-tag-VpC-terminal domain. The content of 100 μg of the His-tag-VpC-terminal domain brought the highest haemolytic activity of 80% compared to that in the three remaining contents. Significantly, the His-tag-VpC-terminal domain demonstrated not to involve the phospholipase activity in Luria-Bertani agar supplemented with 1% (vol/vol) egg yolk emulsion. All results proved the vital responsibility of the His-tag-VpC-terminal domain in causing the haemolytic activity without the required activation by the phospholipase enzyme. Raw extracts of Phellinus igniarus and Phellinus pipi at 10–1 mg/mL inhibited the haemolytic activity of the His-tag-VpC-terminal domain from 67.7% to 87.42%, respectively. Hence applying the His-tag-VpC-terminal domain as a simple biological material to evaluate quickly potential derivatives against the Vptlh in vivo conditions will accessible and more advantageous than using the whole of the Vptlh.