Chee-Kok Chin

Anti-tumor activity of the crude saponins obtained from asparagus

The crude saponins from the shoots (edible part of asparagus) of asparagus (asparagus crude saponins; ACS) were found to have antitumor activity. The ACS inhibited the growth of human leukemia HL-60 cells in culture and macromolecular synthesis in a dose and time dependent manner. The ACS at 75-100 micrograms/ml range was cytostatic. ACS concentrations greater than 200 micrograms/ml were cytocidal to HL-60 cells. The ACS at 6 and 50 micrograms/ml inhibited the synthesis of DNA, RNA and protein in HL-60 cells by 41, 5, and 4, respectively, or by 84, 68 and 59%, respectively. The inhibitory effect of ACS on DNA synthesis was irreversible.

Modification of fatty acids changes the flavor volatiles in tomato leaves

Expression of the yeast Delta9 desaturase gene in tomato (Lycopersicon esculentum Mill.) resulted in changes in the profiles of fatty acids in tomato leaves. Transgenic leaves displayed a dramatic increase in cis-Delta9 16:1, which only existed in a small quantity in control leaves. Also higher, but not as dramatic, were 18:1 and 16:3 fatty acids. Several fatty acids, viz. 16:0, 18:0, and 18:3 declined in transgenic leaves. Changes in fatty acids were accompanied by changes in certain volatile compounds derived from fatty acids. On a percentage basis, most notable increases (>3-fold) were 1-hydroxy-2-butanone, 1-penten-3-ol, heptanal, 3-hexen-1-ol, 2-octanol,cis-3-hexenal, hexanal and 2-nonenal. Several flavor compounds not known to be biochemically derived from fatty acids, viz. 2-ethyl-furan, 5-ethyl-2-[5H]-furanone, eugenol, and 2-ethylthiophene also showed sharp increases in transgenic leaves.

Bioactive constituents from gum guggul (Commiphora wightii)

Bioactivity-directed fractionation and purification afforded cytotoxic components of Commiphora wightii. The exudates of C. wightii were extracted with EtOAc and the extract was subjected to repeated column chromatography. A fraction showing cytotoxic activity was characterized as a mixture of two ferulates with an unusual skeleton by spectral and chemical methods, including by NMR, GC-MS and chemical derivatization. This fraction also showed moderate scavenging effect against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals.

Two-phase culture for the enhanced production of benzophenanthridine alkaloids in cell suspensions ofEschscholtzia californica

Abstract Accumulation of the benzophenanthridine alkaloids sanguinarine, chelerythrine, chelirubine and macarpine occurred in suspension cultures of Eschscholtzia californica . An enhanced production of some of these alkaloids was found in a two-phase culture system and in a system with elicitation in conjunction with two-phase culture. A versatile and practical accumulation phase for culture of E. californica was discovered. This phase was composed of silicone fluid, which accumulated a large amount of the alkaloid and greatly increased alkaloid production compared to cultures grown in its absence. Furthermore, elicitation in combination with two-phase culture additionally increased alkaloid production 10-fold.

Respiratory Upsurge in Blueberries and Strawberries as Influenced by Ethylene and Acetaldehyde

The effects of acetaldehyde and ethylene were compared in the induction of a respiratory rise in blueberry and strawberry fruits. The increase in CO2 production in blueberries caused by acetaldehyde was more pronounced than that caused by ethylene. Acetaldehyde induced a climacteric-like respiration in straw-berries, while ethylene had no effect. The results suggest that the action of acetaldehyde and ethylene involves different mechanisms.

Taxol partitioning in two-phase plant cell cultures of Taxus brevifolia

An accumulation phase for taxanes was evaluated for its effect on growth and production kinetics in Taxus brevifolia cell cultures. The second phase, tricaprylin, is an eight-carbon triglyceride that favorably partitions taxol secreted into the medium. Cell growth was generally unaffected by the presence of tricaprylin and a moderate increase in taxol synthesis over a 4-week period was observed. Adjustments of the medium pH can be used to obtain significantly higher partitioning (at higher pH), but this adversely affects the cell productivity with a net loss in taxol production for pH values greater than 7.5. Nevertheless, in situ liquid partitioning provides a clean reservoir for taxane separation in otherwise normal cell culture that can also be easily sampled and replaced during a semi-batch or continuous culture.

Culture of asparagus protoplasts on porous polypropylene membrane

A method of using a buoyant porous polypropylene membrane floated on liquid medium to culture protoplasts of Asparagus officinalis L. is described. This method supports very good growth and eliminates the need to periodically replenish culture medium lost to evaporation.

Promotion of asparagus shoot and root growth by growth retardants

Plantlets regenerated from shoot-tip culture of Asparagus officinalis L. possessed weak shoots and roots. Various combinations of auxins and cytokinins did not improve the plantlets. Incorporation of a number of growth retardants, viz. ancymidol, B-995, phosfon, Amo 1618, cycocel and paclobutrazol, promoted growth of stronger shoots and roots. The effectiveness of the growth retardants varied, with ancymidol being most effective and cycocel least effective.The response to ancymidol was prevented by exogenous GA3 and GA4/7. GA1/3 and GA4/7-like activities were detected in asparagus shoot-tip culture and these activities were reduced by the presence of the growth retardants ancymidol, Amo-1618, and cycocel.

A hybrid bioreactor for high density cultivation of plant cell suspensions.

SummaryA hybrid bioreactor was developed for the production of secondary metabolites from high density cultivation of plant cell suspensions. Some of the advantages of both air-lift and cell-lift by agitation were combined. The addition of a decanting column also made it possble to run a perfusion system for high density culture or to run a two-stage culture efficiently. Cell growth and the production of berberine from Thalictrum rugosum in the hybrid bioreactor are reported in this paper. A cell density up to 31 g/l was obtained by perfusion without any problems in mixing or loss of cell viability and the specific berberine productivity was comparable to that in shake flasks. The maximum berberine concentration was 88 mg/l at 3 weeks operation and declined thereafter.

Differential rates of sucrose and hexose transport by asparagus cell cultures

Abstract Cell cultures of asparagus ( Asparagus officinalis L.) grew well on media containing 3% (w/v) sucrose, glucose or fructose. However, optimal growth occurred with sucrose. The objective of this work was to characterize sugar transport and to determine the presence of sugar carriers in these cells. Cell cultures preferentially transported fructose, glucose, 3- O -methyl glucose (3-OMG), sucrose and l -glucose, in that order. Both sucrose and 3-OMG uptake was inhibited by carbonylcyanide chlorophenyl hydrazone (CCCP) and p -chloromercuribenzene sulfonic acid (PCMBS). Due to high cell wall invertase activity, sucrose was efficiently hydrolyzed so that no sucrose was detected in the culture medium after 5 days and cells accumulated more hexose than sucrose. Furthermore [ 14 C]sucrose uptake was partially inhibited in the presence of unlabeled 3-OMG. Cell cultures transported 1′-fluorosucrose, a sucrose analog not subject to invertase hydrolysis, at rates similar to that of sucrose. The evidence indicated that despite the presence of high cell wall invertase activity and efficient hexose transport, a sucrose carrier is present at the plasmalemma of asparagus cell cultures. Therefore, sucrose hydrolysis by invertase is not essential for transport into these cells.