TITLE:
Fluorescence of Chlorophyll a for Discovering Inhibitors of Photosynthesis in Plant Extracts
AUTHORS:
Ana C. de Carvalho, Jéssica P. Salvador, Thais de M. Pereira, Pedro Henrique A. Ferreira, João Carlos S. Lira, Thiago A. M. Veiga
KEYWORDS:
Fluorescence of ChL a, Dereplication, Photosynthesis, Natural Products
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.7 No.11,
August
17,
2016
ABSTRACT: Aims: Twelve crude extracts were prepared from different parts of Pluchea sagittalis, Cecropia palmata and Brachiaria
brizantha, and their effect
on the light reaction of photosynthesis. Study Design: Use of fluorescence of ChL a (Chlorophyll a) to detect inhibitors of photosynthesis in plant extracts. Place and
Duration of Study: Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Departamento
de Ciências Exatas e da Terra, Universidade Federal de Sao Paulo (UNIFESP), between
July 2015 and January 2016. Methodology: The samples had their effect on the light
reaction of photosynthesis studied by Chlorophyll a (Chl a) fluorescence
transient by the use of chloroplasts isolated from spinach leaves. As negative controls
we used the same amounts of DMSO that have been employed to solubilize the samples,
and as positive control we have used 10 μM of the commercial herbicide DCMU (Diuron).
Results: The extracts inhibited the photosynthesis, and their inhibition sites were
located in the range of electron flow from OEC complex and between P680 to QA of PS II, and inhibited the photosystem II (PS II) by inducing
the appearance of the transient bands K and J. Conclusion: Our results suggest an
indicative that the photochemical apparatus probably is failing at the donor and
acceptor sides of PSII, causing damage to electron transport during the photosynthesis
phenomenon.