Photosynthesis inhibiting activity

Sidoova E, Kralovam K, Loos D (1999) 3-(2-Alkylsulfanyl-6-benzothiazolylaminomethyl)-2-benzoxazolethiones-synthesis and photosynthesis-inhibiting activity in spinach chloropasts. Molecules 4 73-80... 

Polanski et al. carried out the synthesis of styiyl-quinolines (75) via condensation of anilines with crotonaldehyde in the presence of HCl, followed by MWI of the resulting quinaldine (74) with aldehydes (Scheme 6.29). Some of the synthesized compounds exhibited photosynthesis inhibiting activity [68]. 

Lunularic acid (100), a natural dihydrostilbene growth inhibitor found in liverworts 74) and also in algae (75), has not yet been detected in ferns. A related compound notholaenic acid (101) occurs as a frond exudate component of two gymnogrammoid ferns 76) and is reported to have photosynthesis inhibiting activity on chloroplast (77) and also antimicrobial activity 78). Ternatin (102), in which a benzene ring is linked to a monoterpene unit to form a chromene ring, has been isolated from Sceptridium ternatum 79) and S.japonicum 80). 

Growth inhibited Photosynthesis inhibited Nitrogenase activity inhibited... 

Our results show that SBPase is strongly inhibited by its product Sed-7-P. Since the stromal Sed-7-P concentration can be estimated as about 2 mM, our findings indicate that during photosynthesis the activity of SBPase is strongly controlled by the concentration of... 

Potassium is required for enzyme activity in a few special cases, the most widely studied example of which is the enzyme pymvate kinase. In plants it is required for protein and starch synthesis. Potassium is also involved in water and nutrient transport within and into the plant, and has a role in photosynthesis. Although sodium and potassium are similar in their inorganic chemical behavior, these ions are different in their physiological activities. In fact, their functions are often mutually antagonistic. For example, increases both the respiration rate in muscle tissue and the rate of protein synthesis, whereas inhibits both processes (42). 

The reported (14) mechanisms of action of allelochemlcals Include effects on root ultrastructure and subsequent Inhibition of Ion absorption and water uptake, effects on hormone-induced growth, alteration of membrane permeability, changes In lipid and organic acid metabolism, inhibition of protein synthesis and alteration of enzyme activity, and effects on stomatal opening and on photosynthesis. Reduced leaf water potential Is one result of treatment with ferulic and p-coumaric acids (15). Colton and Einhellig (16) found that aqueous extracts of velvetleaf (Abutllon theophrastl Medic.) Increased diffusive resistance In soybean fGlycine max. (L.) Merr.] leaves, probably as a result of stomatal closure. In addition, there was evidence of water stress and reduced quantities of chlorophyll In Inhibited plants. 

The action spectmm of positive and negative phototaxis of Anabaena variabilis was measured recently106). This species contains no C-phycoerythrin. Accordingly, maximum activity is found at around 615 nm (Fig. 7). In addition, in this form a second maximum occurs at around 675 nm, and a third small, but distinct, one at 440 nm, both indicating that chlorophyll a is also involved in the active light absorption (see above). The utilization via photosynthesis, however, could be excluded in this case, since the trichomes oriented themselves perfectly well to the light direction in the presence of photosynthetic inhibitors, such as DCMU and DBMIB, at concentrations in which the photosynthetic oxygen evolution was almost completely inhibited. 

Next, the studies were extended to evaluate the effect of the compounds on duckweed which is one of the best characterized models for assessing phytotoxic activity. The duckweed assay system makes it possible to study the toxic effects throughout the plant life cycle, as well as to plant specific toxic effects which target photosynthesis. Of all the isolates, only 12 and 13 showed significant phytotoxicity on duckweed at concentrations of 100 xM and 200 xM inhibiting plant growth by 80% and 100%, respectively and chlorophyll production by 40% and 84%, respectively. ... 

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