Sikhao, Potjana

Preferred name

Sikhao, Potjana

Alternative Name

Sikhao, P.

Main Affiliation

School of Agricultural Technology

potjana.si@kmitl.ac.th

Now showing 1 - 8 of 8

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Siamese neem tree as a natural preservative: Chemical profile, antioxidant properties, and antibacterial efficacy against foodborne pathogens and spoilage bacteria
(2025-03-01)
Puttongsiri, Tongchai
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Manichart, Nutcha
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Teerarak, Montinee
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Sikhao, Potjana
;
Somala, Naphat
The objective of the present study was to investigate the effect of various ethanol in water solvent systems (0, 25, 50, 75 and 100 % v/v) on the extraction crude yield, total phenolic content, total flavonoid content, and chemical profile of Azadirachta indica (Siamese neem tree) leaf extracts. In addition, the antioxidant and antimicrobial properties were investigated using in vitro assays. Crude yield was highest for the water extract (5.78 g/100 g DW) and decreased with increased ethanol. Total phenolic and flavonoid contents were highest in the 75 % ethanol extract (26.95 mg GAE/g crude and 23.73 mg QE/g crude, respectively). GC-MS analysis of the 75 % ethanol extract revealed 33 bioactive compounds, accounting for 96.33 % of the total area. Significant components included benzene, 1,4-bis(phenylmethyl)- (15.05 %), and naphthalene, 1,6-dimethyl- (10.98 %); also present were sterols, fatty acids, hydrocarbons, aromatic, and heterocyclic compounds, indicating a complex chemical profile. In antioxidant assays, the 75 % ethanol extract revealed the highest DPPH radical scavenging activity (IC<inf>50</inf>: 143.03 mg/L), reducing power (IC<inf>50</inf>: 378.69 mg/L), and lipid peroxidation (IC<inf>50</inf>: 526.25 mg/L). However, the absolute ethanol extract exhibited both the highest metal chelating activity (IC<inf>50</inf>: 382.60 mg/L) and the strongest antimicrobial activity, inhibiting all 11 tested foodborne pathogenic and spoilage bacteria. The lowest minimum inhibitory concentration (MIC) of 25 mg/mL was observed for Staphylococcus aureus, Aeromonas hydrophila, Pseudomonas fluorescens, Latilactobacillus sakei, Streptococcus sp., and Lactococcus cremoris, with inhibition zone diameters of 27.21, 28.79, 28.19, 17.60, 15.09 and 11.20 mm, respectively. Similarly, the lowest minimum bactericidal concentration (MBC) of 25 mg/mL was obtained for S. aureus and L. sakei, indicating potent antibacterial effects against these species. Future studies should include direct comparative analyses of neem extracts and synthetic preservatives to evaluate further their relative efficacy and applicability in real-world food systems.
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High-Energy Emulsified Clove Essential Oil Nanoemulsion as a Natural Herbicidal Product: Germination Suppression and Seed Structure Alteration in Echinochloa crus-galli
(2026-03-01)
Sikhao, Potjana
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Somala, Naphat
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Manichart, Nutcha
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Dimak, Jantra
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Poonpaiboonpipat, Thanatsan
Clove (Syzygium aromaticum (L.) Merr. & L.M. Perry) essential oil (EO)-based nanoemulsions may have a promising future in eco-friendly herbicide development. Clove EO was found to have a high eugenol content of 87.27%. Organic-solvent-free nanoemulsions using clove EO as a bioactive ingredient were fabricated using ultrasonication and microfluidization emulsification methods. Fourier-transform infrared spectroscopy confirmed that both emulsification methods did not affect the EO components. The droplet size of optimized nanoemulsions was determined using dynamic light scattering. The smallest size of 66.9 nm was obtained by microfluidization at 20,000 psi and eight passes. Additionally, the smallest droplet size for a sonicated nanoemulsion was 103.9 nm, obtained by ultrasonication at 20% for 6 min. Transmission electron microscopy confirmed the droplet sizes of both optimized nanoemulsions. In a storage test, both optimized nanoemulsions were stored at 4 °C for at least four weeks. Finally, both nanoemulsions were evaluated on pre-emergence herbicidal activities against Echinochloa crus-galli. The results showed that both nanoemulsions inhibited E. crus-galli germination and seedling growth, and additionally, inhibited seed imbibition and α-amylase activity. Micro-morphological and ultrastructural analysis was observed using a scanning electron microscope and an energy dispersive X-ray spectrometer (SEM-EDS). SEM-EDS micrographs of the treated seeds showed that the seed structure was damaged, especially the endosperm, leading to the inhibition of seed germination.
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Development of a Melia azedarach L. based natural herbicide: formulation and efficacy studies
(2025-08-01)
Wichittrakarn, Pattharin
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Manichart, Nutcha
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Laosinwattana, Chamroon
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Charoenying, Patchanee
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Sikhao, Potjana
This study evaluated the phytotoxic activity of Melia azedarach L. leaf extract against Echinochloa crus-galli and Phaseolus lathyroides. Crude extracts were obtained using sequential solvent separation, of which the dichloromethane fraction exhibited the highest phytotoxicity for both weed species. However, P. lathyroides appeared more sensitive to the extracts compared to E. crus-galli. GC-MS analysis of the dichloromethane crude extract identified phytol (29.14 %), linolenic acid (21.74 %), and palmitic acid (7.20 %) as the main chemical components. Three formulations, a soluble liquid (SL), pellet, and wettable powder, were developed and evaluated for their effects on seed germination and seedling growth. The SL formulation showed the highest efficacy in inhibiting germination (p < 0.05). Further testing of its pre-emergence utility via soil application in greenhouse conditions confirmed the herbicidal efficacy, effectively suppressing P. lathyroides emergence (36.8 % over control) and reducing growth parameters. Mechanistic assays showed the SL product to affect seed imbibition, α-amylase activity, and cell division in a dose-dependent manner, suggesting these as potential mechanisms of action. This study highlights the potential of a M. azedarach-based SL product as an alternative to synthetic herbicides, potentially leading to the development of a new botanical herbicide.
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Herbicidal Activity of the Invasive Weed Malachra capitata L.: Growth Stage Dependence, Bioassay-Guided Fractionation, and Physiological Effects on Seed Germination
(2026-03-01)
Wichittrakarn, Pattharin
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Sathuwijarn, Sirichai
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Manichart, Nutcha
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Yoneyama, Kaori
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Sikhao, Potjana
The invasive weed Malachra capitata is unsuitable for human or animal consumption but has recently attracted attention for potential alternative uses. In this study, the allelopathic potential of M. capitata for weed control was investigated, as were its allelopathic effects on selected crops. The influence of plant developmental stage on its phytotoxic activity was also assessed. In addition, the physiological effects of the extract on seed germination were investigated. Aqueous leaf extracts were obtained across a range of growth stages and evaluated using seed germination and seedling growth bioassays, followed by bioassay-guided fractionation and GC-MS analysis. Leaves extracts collected at 35 days after planting exhibited the strongest inhibitory activity. Dicot plant species (Phaseolus lathyroides, Cucumis sativus, Brassica oleracea, and B. chinensis) were more susceptible to M. capitata extracts than grassy species (Echinochloa crus-galli, Zea mays, and Oryza sativa), indicating selective phytotoxicity. In pot experiments, application of leaf residues as surface mulch at rates of 100, 200, and 400 g/m<sup>2</sup> significantly reduced P. lathyroides emergence by 11.25%, 35.00%, and 71.25%, respectively. Bioassay-guided fractionation indicated the ethyl acetate-soluble acidic fraction to contain the active allelochemicals. This inhibition was associated with reduced water uptake and suppression of α-amylase activity during seed germination. The most abundant GC-MS detectable components of the acidic fraction were octadecane (12.45%), eicosane (9.74%), and hexadecane (9.60%). Overall, these findings highlight the allelopathic potential of M. capitata, providing a foundation for further applied research and supporting its valorization for sustainable weed management.
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A study of polymer for delay germination in hybrid sweet corn seed production
(2024-05-01)
Sodakul, N.
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Sikhao, P.
The results showed that the pH values of each coating substance formulation exhibited statistically significant differences. Notably, the highest pH value was observed in the coating substance mixed with CMC. Similarly, the viscosity of the coating substances showed significant variations, with the commercial coating substance having the highest viscosity. Following this, the coating substances mixed with CMC, HPMC, NaAlg, and PVP-K30 demonstrated progressively lower viscosities. To assess the uniformity of the coating, the surface characteristics of the seeds were visually examined. The results indicated that seeds coated with the commercial coating substance exhibited the highest coating uniformity. Subsequently, the uniformity levels decreased in the following order: seeds coated with a mixture of PVP-K30, HPMC, CMC, and NaAlg. For the seed quality test after coating, the results showed that all types of polymers had no statistically significant effect on the germination percentage and germination index. If further studies are conducted on the types and concentrations of polymers, it is possible to develop seed coating formulations to delay germination.
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Determination of mechanical damage on soybean seed by clorox soak test
(2024-01-01)
Baikaden, S.
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Thepchit, K.
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Buaket, T.
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Sikhao, P.
The Clorox soak test was assessed soybean seed damage, proving to be a comfortable and effective method for detection. Among different seed lots, the third lot exhibited the lowest percentage of damaged seeds. Notably, these seeds yielded seedlings with the highest root length, shoot length, and dry weight. Regarding damage levels, both undropped seeds and those dropped two times displayed the highest shoot length and seedling dry weight. Seed vigor assessed through accelerated aging that showed Lot 2 of soybean seeds had the highest vigor across all damage levels.
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The effectiveness of seed coating with microbial fungicide on controlling seed quality and damping-off disease of tomato
(2026-01-01)
Baikaden, S.
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Sikhao, P.
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Koohakan, P.
Microbial seed coating was not significantly influenced germination percentage, germination index, or germination speed under laboratory conditions. Whereas, seeds coated with Trichoderma asperellum and Bacillus subtilis consistently demonstrated to improve seedling emergence and vigor in greenhouse conditions. With respect to disease suppression, coatings seeds with T. asperellum resulted to reduce both the incidence and severity of damping-off disease caused by Pythium torulosum. The lowest disease incidence (30.50%) and severity (17.43%) were observed in seedlings from T. asperellum-coated seeds. These findings highlighted the potential of antagonistic microbial coatings to promote seedling health and provided a sustainable strategy for managing soilborne diseases. This approach is offered a promising complement or alternative to chemical control methods in commercial tomato seedling production.
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Influence of vacuum packaging combined with storage condition on biochemical activities and quality of groundnut seed (Arachis hypogaea L.)
(2024-01-01)
Multha, N.
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Sikhao, P.
The results showed that seeds stored in 760-gauge polypropylene bags at vacuum levels of -0.04 MPa and -0.06 MPa under controlled conditions exhibited the highest dehydrogenase enzyme activity, germination percentage and index, and also displayed the lowest free fatty acid content. Additionally, it was observed that the moisture content and water activity of seeds in all packaging materials remained consistent from the beginning to the end of the storage period.

Sikhao, Potjana

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