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Bioprospecting of cyanobacteria from Thai karstic caves as potential producers of phenolic compounds with antioxidant capacity
(2026-04-01)
Suphan, Sutthawan
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Kula, Kasinee
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Lomthong, Thanasak
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Sujarit, Kanaporn
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Maneeruttanarungroj, Cherdsak
Cyanobacteria are highly adaptable microorganisms that can survive in extreme environments. Survival of cyanobacteria in assorted habitats has positively impelled them to produce a range of bioactive compounds, which show a variety of beneficial biological activities. The karstic caves are harsh environments with low light and nutrient input and serve as a unique habitat for exploring cyanobacterial biodiversity as producers of natural products of economic and ecological importance. A total of 86 cyanobacterial strains isolated from 23 karstic caves in four regions of Thailand showed photosynthetic pigments correlated with growth performance and exhibited potential for producing phenolic compounds with significant antioxidant capacity. Based on DPPH scavenging efficiency per unit concentration of crude extract, Leptolyngbya sp. LKK14, Nostoc sp. SW02, and Leptolyngbya sp. LP01 exhibited the superior antioxidant potency. The highest contents of total phenolics (42.10 mgGAE/gCE) and flavonoids (395.90 mgQE/gCE) were found in Leptolyngbya sp. LP01 extract. The presence of phenolic compounds correlated with antioxidant activity; Leptolyngbya sp. LP01 showed the highest antioxidant activity, as measured by DPPH, ABTS, and FRAP assays, with respective values of 15.79, 20.87, and 42.69 mgAAE/gCE. Nine phenolic compounds were tentatively identified based on MS/MS fragmentation patterns compared with library data by LC-ESI-QTOF-MS/MS approach, suggesting that the extract of Leptolyngbya sp. LP01 contains valuable biological antioxidants. This study contributes to our current understanding of cyanobacterial biodiversity in poorly studied habitats, particularly in terms of their biotechnological potential as producers of secondary metabolites suitable for application in the food, pharmaceutical, and cosmetic industries.
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Impact of chilling stress on quality and bioactive compounds in young and mature leaves of kratom [Mitragyna speciosa (Korth.) Havil.]
(2024-09-01)
Supapvanich, Suriyan
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Raruang, Yenjit
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Promyou, Surassawadee
Importance of the work: There has been much attention paid to kratom (Mitragyna speciosa [Korth.] Havil.) since it was declared a legal plant in Thailand. Recently, the demand for fresh leaves has increased; nevertheless, only a few studies have investigated the postharvest quality management of the leaves. Objectives: To examine the impact of chilling stress on the quality and alteration of bioactive compounds in young and mature leaves of two cultivars of commercial kratom leaves: ‘kan khiao’ and ‘hang kang’. Materials and Methods: Fresh kratom leaves of both the kan khiao and hang kang types were sampled from the young and mature leaf stages and stored for 12 d with 85% relative humidity at: 1) 10°C or 2) at room temperature (RT;30°C) . Every 3 d throughout storage, monitoring occurred of the fresh weight loss, superficial leaf color, browning score, electrolyte leakage (EL), malondialdehyde (MDA) content and bioactive compounds (ascorbic acid, antioxidant activity, total phenolic compounds and mitragynine contents). Results: Chilling injury (CI; based on brown stain on the leaf) was discovered in both types of kratom leaves refrigerated at 10°C. In both types, RT storage resulted in less weight loss and browning. Yong leaves lost less weight loss and CI than mature leaves. CI was positively associated with increased EL and MDA levels in leaves kept at 10°C. In both types, the mitragynine content in the mature leaves was higher than in the young leaves. Both types lost mitragynine, ascorbic acid, antioxidant activity and phenolic compounds due to the cold storage condition. Main finding: Cold storage induced chilling stress that resulted in leaf browning due to membrane dysfunction, as well as the loss of bioactive compounds and medicinal components, including mitragynine.
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Physicochemical properties and bioactive compounds of purple rice (Oryza sativa L.) seedlings grown under light-emitting diodes
(2022-03-01)
Techavuthiporn, Chairat
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Potaros, Treesin
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Jarerat, Amnat
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Nimitkeatkai, Hataitip
Importance of the work: There has been increasing interest in using light-emitting diodes (LEDs) to aid in the development of bioactive compounds in a variety of plants to enhance crop nutritional quality. Objectives: To investigate the effects of LEDs on the physicochemical properties and bioactive compounds of rice seedlings. Materials & Methods: Purple rice seeds of Oryza sativa L. were grown under LEDs at different wavelengths (white, red, blue, and red+blue LEDs) for 12 hr/d, while the other 12 hr were in darkness. The physical properties, chemical properties and free-radical scavenging activity of the purple rice seedlings were investigated. Results: Applying exposure to LEDs during the seedling stage significantly (p < 0.05) affected the growth and physicochemical quality of the rice seedlings. Seedlings grown under the red LEDs developed an increased plant height and reducing sugar accumulation. The leaf width, total soluble solids content, chlorophyll content (22.70 mg/g), total phenolic content (5.73 mg gallic acid equivalents/g), and free-radical scavenging activity (79.41%) were significantly higher in rice seedlings grown under the blue LEDs than those under the other LED conditions. The red, blue and red+blue LEDs had no significant effects on the hue angle, ascorbic acid content, titratable acidity or pH. Main finding: Blue LEDs can be considered as an abiotic elicitor for growing purple rice seedlings, with the advantage of an increase in the secondary metabolites.
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Effects of maltodextrin on physicochemical properties of freeze-dried avocado powder
(2021-12-01)
Chuacharoen, T.
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Moolwong, J.
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Chysirichote, T.
The effect of maltodextrin on the moisture sorption isotherm, glass transition temperature (T<inf>g</inf>), and degree of caking of freeze-dried avocado samples at room temperature (25°C) was investigated. The incorporation of maltodextrin reduced the water sorption capacity of the powder due to its less hygroscopic nature. Parameters derived from the Guggenheim, Anderson, and de Boer (GAB) model describing the properties of absorbed water are discussed. The water absorption isotherm possessed the characteristic sigmoid-shaped type II isotherm curves and the model gave the best fit over the whole range of a<inf>w</inf> tested. The differential scanning calorimetric method was used to measure the T<inf>g</inf> of freeze-dried avocado samples. Increasing the water content decreased the T<inf>g</inf>, and T<inf>g</inf> was increased with increasing maltodextrin content. Increased maltodextrin content to solid material in the freeze-dried sample was associated with less sensitivity to caking as evidenced by T<inf>g</inf> values. In addition, increased maltodextrin content in the powders caused brighter, less yellowish, and more greenish coloration and protected color change including browning index. The antioxidant capacity was significantly decreased with increasing maltodextrin content. Thus, the effect of maltodextrin concentration on physicochemical properties was a promising way to preserve the physical property and chemical compounds in freeze-dried avocado powder.

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