Impairment of Photosystem II Donor Side by the Natural Product Odoratol

Abstract

The effect of odoratol, a natural protolimonoid, isolated from Cedrela odorata (Meliaceae) and two of its derivatives on different photosynthetic reactions of isolated spinach chloroplasts was investigated. This natural product is an inhibitor (150 µM) of oxygen evolution. Polarographic analyses of the photosynthetic partial redox reactions indicate that (a) photosystem I (PSI) activity is unaffected by odoratol, (b) there is a substantial inhibition of the electron flow of uncoupled photosystem II (PSII) as measured from water to silicomolybdate or diaminodurene, and (c) the electron flow from diphenyl carbazide to dichlorophenolindophenol of Tris-washed chloroplasts was insensitive. Collectively, these data suggest that the site of action of odoratol is located at the donor side of PSII. Comparison of chlorophyll a fluorescence induction curves of chloroplasts with authenticated donor side damage and those obtained from odoratol-treated samples further supports this interpretation. Comparative analyses using odoratol derivatives indicate that the diol moiety at positions 23 and 24 of the side chain is an important structural requirement for the inhibitory activity displayed by odoratol.

Impacts of glyphosate on photosynthetic behaviors in Kappaphycus alvarezii and Neosiphonia savatieri detected by JIP-test

“…All oxygenic photosynthetic materials investigated so far show a polyphasic rise consisting of the basic steps from the "origin" (O) through two "inflections" (I 1 , designated as J, and I 2 , termed I) to a "peak" fluorescence (Strasser et al 2004). The O-J-I-P polyphasic transient was found to change its shape according to changes in the environment conditions (Lazar 1999;Srivastava and Strasser 1997;Clark et al 2000;King-Díaz et al 1998;Achnine et al 1998). The analysis of the fast fluorescence rise according to the JIP-test allows the derivation of several expressions leading to the actual description of a photosynthetic sample in a current physiological state (Appenroth et al 2001).…”

Triterpenes from <i>Cabralea canjerana</i> as <i>in Vitro</i> Inhibitors to Light Reactions of Photosynthesis

“…Continuing with our studies [10] [13] [14] to find natural products with biological activity, we isolated a series of triterpenes from Cabralea canjerana (Figure 1). The chemical profile of Meliaceae family has found several types of compounds, like: coumarins, terpenoids and also many limonoids which were found frequently.…”

“…The difference in structures between 1 and 2 is the presence of the carbonyl group at C3 of 2, which may be is necessary for activity, while at the compound 1 have a hydroxyl group. On the other hand, odoratol had its mechanism of action site located at the donor side of PS II [14] and the (I 50 ) value on ATP synthesis for odoratol was 67 µM. This compound has a similar structure to odoratone (3), which had a calculated I 50 value of 35 µM.…”

The enhancement of hydrogen photoproduction in Chlorella protothecoides exposed to nitrogen limitation and sulfur deprivation

“…Different from the F v /F m ratio, the difference between the FPSII in N-deprived and S-deprived cultures (7 mM NH 4 Cl) was not obvious. V J is an indicator of the closure level of PSII reaction centers [32]. Changes of V J under different treatments are presented in Fig.…”

“…We hypothesize that nitrogen limitation might have altered the ratio of photosynthesis/respiration to a level that favored establishment of anaerobiosis and H 2 production. V J represents the subsequent kinetic bottlenecks of the electron transport chain, resulting in the momentary maximum accumulations of Q A À [32]. Increase in the V J indicates a loss in Q A -re-oxidation capacity [42].…”