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Panthip Boonsong, Natta Laohakunjit, Orapin Kerdchoechuen and Frank B. Matta

Fourteen Thai herbal plants were extracted using methanol, ethanol, and acetone. Comparison of the various extraction methods for pigments and polyphenols (colorants) showed that methanol provided a more complete extraction than ethanol and acetone. Percentage yield ranged from 1.7 to 40.7 and was dependent on the plant extracted and solubility of pigments and polyphenols (colorants) extracted by the various solvents. The absorption spectra of pigments and polyphenols (colorants) in the plant extract were present in the visible region (351 to 665 nm) and the absorption spectra of polyphenols were present in the ultraviolet region (200 to 349 nm). Color of plant extracts varied and included violet–blue, yellow–green, red, orange–red, gray–purple, blue–green, gray–orange, gray–yellow, and black. High-performance liquid chromatography (HPLC) was used to separate and identify compounds of plant pigments and polyphenols (colorants). Ya-nang had the greatest number of peaks and chlorophyll A and chlorophyll B were found only in Ya-nang. Numerous pigments and polyphenols were detected. Such compounds have the potential to be used as coloring dyes.

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Orapin Kerdchoechuen, Natta Laohakunjit, Sasathorn Singkornard and Frank B. Matta

Essential oils from sweet basil (Ocimum basilicum L.), holy basil (O. americanum L.), hairy basil (O. tenuiflorum L.), lime (Citrus aurantifolia Swingle), kaffir lime (C. hystrix DC.), and clove (Eugenia caryophyllus L.) were isolated by simultaneous distillation extraction. Toxicity assays against the maize weevil (Sitophilus zeamais Motschulsky) using 30 to 120 μL oil extract from the six plants on 70-mm-diameter filter paper discs resulted in 100% weevil mortality within the 5-h assay period. On rice samples, sweet basil oil extract was the most effective, resulting in 96% to 100% mortality regardless of oil extract volume on the first day during the 5-day assay period. Probit analysis showed that sweet basil oil extract applied on grains had four to five times lower LD50 (lethal dose to kill 50% of the weevils) and two to three times lower LD99 values than the remaining oil extracts. Repellency assay using 1 to 8 μL oil extract showed a different trend, because hairy basil was the most effective among treatments. Based on the effective control of the maize weevil by the oil extracted from herbal plants, such oil extracts could be useful in stored agricultural products and plant protection and reduce the risk associated with synthetic insecticides.

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Napaporn Sae-Lee, Orapin Kerdchoechuen, Natta Laohakunjit, Benjawan Thumthanaruk, Dipayan Sarkar and Kalidas Shetty

Grape (Vitis vinifera cv. Pok Dum) is a rich source of health relevant phenolic antioxidants and can be targeted to mitigate chronic oxidative stress commonly associated with noncommunicable chronic diseases (NCDs), such as cancer. Furthermore, improving health relevant phenolic bioactives and associated antioxidant properties of fruits by using chemical elicitation strategy has significant merit. Based on this biochemical rationale, chitosan and other chemical elicitors potassium dihydrogen phosphate (KH2PO4), potassium nitrate (KNO3), sodium selenite (Na2SeO3), and aluminum sulphate [Al2(SO4)3] were targeted to improve phenolic bioactive profiles and associated antioxidant and anticancer properties of cultured grape cells grown for 28 days. After chemical elicitor treatments, phenolic content, resveratrol content, antioxidant activity, phenylalanine ammonia-lyase (PAL) enzyme activity, and cytotoxicity (cell inhibition) against cancer cell lines of cultured grape cells were investigated using in vitro assay models. Overall, stimulation of phenolic bioactives and improvement in associated cytotoxicity against cancer cell lines were found in cultured grape cells after chemical elicitation treatments. Chitosan and other chemical elicitors resulted in lower growth of cultured grape cells; however, they enhanced phenolic biosynthesis on a cell weight basis when compared with the control. Chemical elicitor treatments, such as Na2SeO3 (50 mg·L−1 and 100 mg·L−1) and Al2(SO4)3 (50 mg·L−1), resulted in enhanced phenolic content at the end of 14 days of culture (1.7, 1.4, and 1.0-fold increase, respectively). Higher accumulation of resveratrol and higher antioxidant activity with Al2(SO4)3 (50 mg·L−1) and Na2SeO3 (100 mg·L−1) elicitation treatments were also observed. Enhanced phenolic bioactives in cultured grape cells in response to chemical elicitation treatment, such as Na2SeO3, also resulted in higher cytotoxicity against different cancer cell lines. Therefore, this study indicates that chemical elicitors, such as Na2SeO3 and Al2(SO4)3, as well as chitosan in select doses can be targeted to improve phenolic bioactives and associated antioxidant and anticancer properties in cultured grape cells and such strategy has relevance for wider applications with other phenolic antioxidant-enriched fruits.

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Natta Laohakunjit, Orapin Kerdchoechuen, Frank B. Matta, Juan L. Silva and William E. Holmes

The volatiles of longon (Lansium domesticum Corr. var Dongon), mangosteen (Garcinia mangostana L. var Native), durian (Durio zibethinus L. var Monthong), rambutan (Nephelium lappaceum L. var Rong-rien), and sapodilla (Manilkara zapota van Royer var Kai) were identified by headspace-solid phase microextraction with the gas chromatography-mass spectrometry technique. The headspace volatiles of fresh, unheated, salted out with NaCl, and NaCl + heated samples were determined. Salting out gave the highest number of volatile components with the longon headspace. High temperature did not have much affect on the amount of volatiles in the headspace. Major volatiles of the total 43 volatiles in longon were 1,3,5 trioxane, (E)-2-hexenal, 3-carene, α-cubebene, isoledene, δ-selinene, and α-calacorene. Major volatiles of mangosteen were 2, 2-dimethyl-4-octanal, E-2-hexenal, benzaldehyde, (Z)-3-hexen-1-ol, hexyl–n-valerate, 1,4-pentadiene, and 2-methyl-1, 3-buten-2-ol. Volatile compounds in durian consisted of a large number of sulfur-containing compounds, which included diethyltrisulfide, diethyldisulfide, dithiolane, dimetyl sulfide, and 3-methyl-thiozolidine. Nonsulfur compounds 2-methyl butanoate, butanedioic acid, and propyl-2-ethylbutanoate were also abundant. Isocitonellol, 3-hydroxy-2-butanone, pentanal, and 4-tridecyl valerate were most abundant in ‘Rong-rien’ rambutan. A total of 23 components were characterized in sapodilla with ethyl acetate, acetaldehyde, benzyl alcohol, and 2-butenyl benzene being the major volatiles.