essential oils (Chowdhury et al. 2007,
Sonibare and Effiong 2008). Therefore,
antibacterial activities of L. camara leaf and
flower extracts reported here might be due to
the presence of some of these chemical
constituents particularly lantadenes and
theveside in the extracts. Bhakta and
Ganjewala (2009) have recently confirmed
the presence of phenolics, anthocyanins and
proanthocyanidins in L. camara leaves which
could also be responsible for the antibacterial
properties of the L. camara reported here.
Though, the mechanism of the action of these
chemical constituents is not yet fully known it
is clear that the effectiveness of the extracts
largely depends on the type of solvent used.
Perhaps it is one of the reasons behind
differences in the antibacterial activities of the
plants. Moreover, the effectiveness of the
extracts varies with its concentration and the
kind of bacteria used in the study. These
differences in the susceptibility of the test
organisms to the different extracts might be
due to the variation in the rate at which active
ingredients penetrate their cell wall and cell
membrane structures (Nikaido and Vaara
1985, Priya and Ganjewala 2007). Thus, S.
aureus was found to be resistant to all the
extracts, which is most probably due to its
outer membrane. Nevertheless, it is the ability
of the active principle of the extracts that
disrupt the permeability barrier of cell
membrane structures and thus inhibit the
bacterial growth (Nikaido and Vaara 1985,
Priya and Ganjewala 2007). In conclusion, the
four L. camara plants with different flower
colours studied here have displayed variable
antibacterial activities most probably due to
the differences in the biochemical and
phytochemical compositions of the concerned
plant materials (leaves and flowers) used.