Vilai Santisopasri

Cassava starch granule structure–function properties: influence of time and conditions at harvest on four cultivars of cassava starch

Abstract Impact of environmental conditions on cassava starch variability was examined by studying four commercially important cultivars, Rayong 1, Rayong 60, Rayong 90, and Kasetsart 50 (KU 50). Age of the root and environmental conditions at harvest influenced granule structure and hydration properties. All cultivars were grown under identical field conditions, and harvested at different times. Starches extracted from cassava roots harvested at different times were characterised by unique starch granule structure and function. Apparent amylose size of starches from all cultivars did not change significantly during the trial period. However, apparent amylose content of starches changed, decreasing in the older roots. Granule size distribution was affected by age of the root, gradually changing from normal to bimodal distribution when harvested very late during the trial. The integrity and crystalline structure of starch granules also depended on the environmental conditions, evidenced as a change in peak profile obtained by thermal analysis. This can result in the difference in water uptake of starches, and their consequent swelling power and gelatinization. Pasting temperature of all starches increased during the dry period, and was lowered during the wet period. Peak and final viscosity of starch decreased from early to mid-harvest time when environmental conditions became drier, and increased close to or greater than the original value when conditions became wet again. Breakdown and setback also followed a similar trend to viscosity. This study suggests an impact of time and conditions of harvest on the structural and functional properties of all cassava cultivars, and based on this study, it is recommended that starch should be extracted from either early or very late harvested roots.

Impact of water stress on yield and quality of cassava starch

Abstract Cassava ( Manihot esculenta Crantz) is an important source of industrial raw materials. Products obtained from cassava include chip/pellets for animal feed and starch. Important for major industrial uses are the amount and quality of starch obtained from this crop. Production efficiency, including yield and quality of starch, from cassava is markedly influenced by environmental conditions, especially water stress during early plant development and immediately before root harvest. In early plant development plants deprived of water for the first 6 months were characterized by a lower yield of starch compared to plants without water stress (starch yields of six varieties including Rayong 1, Rayong 5, Rayong 60, Rayong 90, Kasetsart 50 and CMR 33-57-81 were 0.1–0.2 and 5.0–8.7 t/ha for water-stressed and without water-stressed plants). Furthermore, starch from plants deprived of water for the first 6 months of growth, was functionally different to that laid-down under optimum growing conditions. Plants responded to subsequent rainfall and after 2 months contained significant amounts of starch, though this amount was less than was expected. Despite the fact that water-stressed plants responded to the availability of water by producing starch, most functional properties remained different. The portfolio of changes was sufficient as regards the starch of lower quality. Most effected were the hydration properties. Starch granules despite being smaller (mean size and distribution) than expected were morphologically normal. A second drought period further influenced some of the starch properties, but the sustained influence of the early drought seemed to dominate the response of the plants starch metabolism. All varieties were similarly affected.

In vitro anti-tumor promoting and anti-parasitic activities of the quassinoids from Eurycoma longifolia, a medicinal plant in Southeast Asia

Some quassinoids (1-6) isolated previously as plant growth inhibitors from the leaves of Eurycoma longifolia Jack. (Simaroubaceae) were subjected to in vitro tests on anti-tumor promoting, antischistosomal and plasmodicidal activities. The most active compound for inhibition of tumor promoter-induced Epstein-Barr virus activation (anti-tumor promotion) was 14,15beta-dihydroxyklaineanone (5, IC(50) = 5 microM). Longilactone (1) gave significant antischistosomal effect at a concentration of 200 microg/ml. 11-Dehydroklaineanone (3) and 15beta-O-acetyl-14-hydroxyklaineanone (6) showed potent plasmodicidal activity (IC(50) = 2 microg/ml). Thus it was suggested that E. longifolia possesses high medicinal values due to the occurrence of a variety of quassinoids.

Occurrence of the insecticidal 16,17-didehydro-16(E)-stemofoline in Stemona collinsae

The occurrence of two alkaloids, 16,17-didehydro-16(E)-stemofoline and its isomer at C-4, 16,17-didehydro-4(E)-16(E)-stemofoline, were found together with a known insecticidal compound, stemofoline, in Stemona collinsae. The 16,17-didehydro-16(E)-stemofoline displayed higher insecticidal and antifeedant activities against the diamondback moth larvae than stemofoline.

Quassinoids from Eurycoma longifolia as plant growth inhibitors.

Seven quassinoids including a new 12-epi-11-dehydroklaineanone were isolated from the leaves of Eurycoma longifolia (Simaroubaceae) as plant growth inhibitors or related compounds. The strongest activity was found in 14,15beta-dihydroxyklaineanone.

Environmental conditions during root development: Drought constraint on cassava starch quality

Cassava has the reputation of being a drought tolerant crop, however, when deprived of water, plant and root development are affected. This ultimately will translate to an altered starch synthesis expressed by variation of starch quality. The magnitude of which, is influenced by the severity of stress conditions and stage of plant maturity. During early plant development,water stress retards growth, which will only be resumed after the immature plant has received sufficient water. Despite of an increased starch yield, the effect of initial water stress on starch quality is still sustained. In mature plants, starch quality is affected by environmental conditions prior to root harvest, especially the onset of rain after a stress period as indicated by a reduced starch paste. This paper presents the argument for extending the scope of traditional breeding programs beyond selecting for plant growth under drought conditions, to strategies that place greater emphasis on stabilizing starch quality.

Corrigendum to “In vitro anti-tumor promoting and anti-parasitic activities of the quassinoids from Eurycoma longifolia, a medicinal plant in Southeast Asia”: [Journal of Ethnopharmacology 82 (2002) 55–58]

Corrigendum to “In vitro anti-tumor promoting and anti-parasitic activities of the quassinoids from Eurycoma longifolia, a medicinal plant in Southeast Asia” [Journal of Ethnopharmacology 82 (2002) 55–58] Suratwadee Jiwajinda a,∗, Vilai Santisopasri b, Akira Murakami c, Masanori Kawanaka d, Hiromu Kawanaka d, Monique Gasquet e, Riad Elias e, Guy Balansard e, Hajime Ohigashi f a Central Laboratory and Greenhouse Complex, Kamphaeng Saen Campus, Kasetsart University, Nakhon Pathom 73140, Thailand b Department of Biochemistry, Faculty of Science, Kasetsart University, Chatuchak, Bangkok 10900, Thailand c Department of Biotechnological Science, Faculty of Biology-Oriented Science and Technology, Kinki University, Iwade-Uchita, Wakayama 649-6493, Japan d National Institute of Infectious Diseases. Toyama 1-23-1, Shinjuku-ku, Tokyo 162, Japan e Department of Pharmacognosy and Parasitology, Faculty of Pharmacy, University of Marseille II, 27 Boulevard Jean Moulin, 13385 Marseille Cedex 5, France f Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan