noteworthy for further investigations. Research by Yerbanga et al. (2014) proved
that the ethanol extract of neem leaves with gedunin as a major component
exhibited in vitro anti-malarial effect through transmission blocking activity in
P. falciparum. Yet, no further study has been done to investigate the underlying
mechanisms of action (Yerbanga et al. 2014).
16.2.5 Antimicrobial Effects of Gedunin and Derivatives
The occurrence of bacterial resistance has increased over the years in several
countries where by common antibiotics such as aminoglycosides, cephalosporins
and penicillins are no longer effective against pathogens (Chaves et al. 2015; Davies
and Davies 2010). Such resistance causes negative impacts on public health with
increasing mortality and morbidity and increase in economic burden with rising
cost for antimicrobial treatment. Therefore, myriads of natural products derived
from animal, plant and microorganism have been deemed as an alternative to
antibiotics.
Okhale et al. (2012) revealed that gedunin was inactive against Bacillus subtilis,
Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae whereas the
semisynthetic derivative 7-deacetoxy-7a-hydroxygedunin potassium salt possessed
greater antimicrobial activity against all tested bacterial species except B. subtilis. The
subsequent study by the group showed that another derivative,
7-deacetoxy-7a-hydroxygedunin exhibited antimicrobial activity against B. subtilis,
K. pneumonia and Escherichia coli but not S. aureus (Okhale et al. 2012, 2013).
Although various studies have been carried out to investigate the bioactivities of
gedunin, the antimicrobial property of gedunin is overlooked by the research
community.
16.2.6 Insect Growth Inhibition Effects of Gedunin
and Derivatives
Due to insect resistance and ecological impacts caused by commercialized insecticides, more efforts have been devoted to investigate the potential of natural
products on the insect’s growth inhibitory effect. One of the functions of the
plant-based phytochemicals as the defense system is to dissuades herbivores and
insecticides from consuming them. Over the years, studies have been carried out to
investigate the inhibitory effect of gedunin and its derivatives against insect growth
(Cespedes et al. 2016). Gedunin and photogedunin from Cedrela dugessi and
Cedrela salvadorensis were tested against the growth larvae of fall armyworm. The
results showed that these compounds were able to inhibit the growth of larvae in a
concentration dependent manner (Céspedes et al. 2000). Another study has reported
580
Y. S. Ong et al.
that the ethanol extract of neem leaves with gedunin as a major component
exhibited in vitro anti-malarial effect through transmission blocking activity in
P. falciparum. Yet, no further study has been done to investigate the underlying
mechanisms of action (Yerbanga et al. 2014).
16.2.5 Antimicrobial Effects of Gedunin and Derivatives
The occurrence of bacterial resistance has increased over the years in several
countries where by common antibiotics such as aminoglycosides, cephalosporins
and penicillins are no longer effective against pathogens (Chaves et al. 2015; Davies
and Davies 2010). Such resistance causes negative impacts on public health with
increasing mortality and morbidity and increase in economic burden with rising
cost for antimicrobial treatment. Therefore, myriads of natural products derived
from animal, plant and microorganism have been deemed as an alternative to
antibiotics.
Okhale et al. (2012) revealed that gedunin was inactive against Bacillus subtilis,
Staphylococcus aureus, Escherichia coli and Klebsiella pneumoniae whereas the
semisynthetic derivative 7-deacetoxy-7a-hydroxygedunin potassium salt possessed
greater antimicrobial activity against all tested bacterial species except B. subtilis. The
subsequent study by the group showed that another derivative,
7-deacetoxy-7a-hydroxygedunin exhibited antimicrobial activity against B. subtilis,
K. pneumonia and Escherichia coli but not S. aureus (Okhale et al. 2012, 2013).
Although various studies have been carried out to investigate the bioactivities of
gedunin, the antimicrobial property of gedunin is overlooked by the research
community.
16.2.6 Insect Growth Inhibition Effects of Gedunin
and Derivatives
Due to insect resistance and ecological impacts caused by commercialized insecticides, more efforts have been devoted to investigate the potential of natural
products on the insect’s growth inhibitory effect. One of the functions of the
plant-based phytochemicals as the defense system is to dissuades herbivores and
insecticides from consuming them. Over the years, studies have been carried out to
investigate the inhibitory effect of gedunin and its derivatives against insect growth
(Cespedes et al. 2016). Gedunin and photogedunin from Cedrela dugessi and
Cedrela salvadorensis were tested against the growth larvae of fall armyworm. The
results showed that these compounds were able to inhibit the growth of larvae in a
concentration dependent manner (Céspedes et al. 2000). Another study has reported
580
Y. S. Ong et al.