Nguyen Thi Giang An

Resistance to synthetic insecticides has intensified the search for plant-derived biopesticides. Pilea plataniflora C.H.Wright (Urticaceae), a medicinal plant native to Vietnam and China, has a high essential oil yield; however, its essential oil composition and biological activities remain unreported. This study characterized the chemical composition and evaluated the pesticidal and antimicrobial activities of P. plataniflora essential oil collected across three successive years. Chemical composition was determined by GC-MS. Pesticidal activities (larvicidal, repellent, fumigant adulticidal, and molluscicidal) were evaluated following modified WHO guidelines, and antimicrobial activity was assessed by broth microdilution. Three oil samples from the same population showed considerable chemical variation. The 2018 sample (PP18) was dominated by δ-3-carene (44.1%), α-thujene (20.1%), and sabinene (7.2%). The 2019 sample (PP19) comprised δ-3-carene (15.9%), (E)-β-caryophyllene (12.2%), and β-pinene (10.6%). The 2020 sample (PP20) was dominated by δ-3-carene (26.8%), sabinene (11.6%), and terpinen-4-ol (5.5%). All samples exhibited larvicidal activity against mosquito species tested. PP19 and PP20 showed repellent effects against Aedes aegypti (Linnaeus, 1762), with protection times of 133.3±18.8 and 264.8±72.5 min at 50% concentration, respectively. PP19 showed the greatest fumigant adulticidal potency (60-min LC₅₀ = 2.98%). PP18 exhibited antimicrobial activity against Enterococcus faecalis, Staphylococcus aureus, and Candida albicans (MIC: 32-128 µg/mL). This first report on P. plataniflora essential oil demonstrates that this species is a promising source of bioactive compounds with larvicidal, repellent, fumigant, and antimicrobial properties relevant to sustainable vector management and infection control.

Camellia quephongensis and C. puhoatensis are two Vietnamese perennial plants, which has engaged the attention due to their great values in beverage and pharmacology. For the first time, the phytochemical and biological evaluations of the ethanol extracts from the flowers and leaves of two Vietnamese Camellia species C. puhoatensis and C. quephongensis were carried out. Phytochemical screenings determined the appearance of flavonoids, tannins, saponins, free-reducing sugars, and polysaccharides. These ethanol extracts are promising antioxidants since they showed strong or better than the standard trolox in lipid peroxidation inhibition activity. These alcohol extracts were also superior to the positive control streptomycin in antimicrobial assays against the growth of Gram-positive bacterium Enterococcus faecalis ATCC299212 and Gram-negative bacteria Pseudomonas aeruginosa ATCC27853 and Salmonella enterica ATCC13076. In another approach, these extracts exhibited cytotoxicity towards seven cancer cell lines A549, HT-29, SK-Mel-2, HepG2, MCF-7, Hela, and MKN-7 at different levels of results. It needs to get more studies, focusing on the explanations by mechanism of actions

Alpinia pinnanensis T.L.Wu & S.J.Chen, a species in the Zingiberaceae family, was identified and described from Phu Tho Province, Vietnam. In this study, the essential oil (EO) was extracted from A. pinnanensis rhizomes using hydrodistillation, and its phytochemical constituent was analyzed by gas chromatography-mass spectrometry (GC-MS). The main ingredients identified were β-myrcene (18.72%), farnesol (12.17%), β-linalool (11.91%), and 1,8-cineole (8.82%). The EO exhibited weak antimicrobial activity against Bacillus cereus, Pseudomonas aeruginosa, and Candida albicans with minimum inhibitory concentration (MIC) values ranging from 128 to 256 µg/mL, comparable to positive controls, streptomycin and cycloheximide. Additionally, the EO exhibited cytotoxic effects against HeLa (human cervical carcinoma) and HepG2 (human hepatocellular carcinoma) cell lines, with IC50 values of 8.50 ± 0.29 µg/mL and 7.84 ± 0.15 µg/mL, respectively. This is the first study to report on the phytochemical composition, antimicrobial, and cytotoxic effects of the EO from A. pinnanensis rhizomes.

Cytotoxic, antioxidative, and antimicrobial activities of Camellia annamensis, and its chemical compositions were first provided in the current study. Phenolic contents in the methanol extracts of its leaves and flowers were 222.73 ± 0.09 and 64.44 ± 0.08 mg GAE/g extract, whereas flavonoid contents in these parts were 108.80 ± 0.28 and 131.26 ± 0.39 mg rutin/g extract, respectively. By using HPLC-DAD analysis, gallic acid (43.72 ± 0.09 - 81.89 ± 1.83 mg/g) and (-)-epigallocatechin gallate (67.31 ± 1.26 - 70.68 ± 7.82 mg/g) were identified as the major compounds. C. annamensis leaf and flower extracts were moderately cytotoxic against A549, HT-29, SK-Mel-2, MCF-7, HepG2, HeLa, and MKN-7. Particularly, they are better than the standards trolox (IC₅₀ 7.57 ± 0.23 µg/mL) in lipid peroxidation inhibitory evaluation, and streptomycin (IC₅₀/MIC = 45.34-50.34/128-256 µg/mL) in antimicrobial assay against the Gram-positive bacteria Enterococcus faecalis ATCC299212, Staphylococcus aureus ATCC25923, and the Gram-negative bacterium Salmonella enterica ATCC13076.