2.4.5.5 Non Food or Medicinal Uses
Beyond
the uses of Moringa as a food and for human health, other possible uses
exist. It can be used as a natural plant growth enhancer; indeed leaves
are rich in zeatin (a plant hormone belongs to the cytokinin group).
Seed extracts can stimulate plant growth and increasing crop yield.
Researches performed using a spray based on seed extracts of wheat,
maize and rice support the wide range of beneficial effect on crops
(Ashfaq et al., 2012). Moringa seed powder can be used for water
purification, replacing dangerous and expensive chemicals such as
aluminum sulfate.
Interestingly, seed extracts and also seed extracts
show biopesticide activity, effective against larvae and adults of
Trigoderma granarium and can reduce the incidence of fungi on groundnut
seed (Ashfaq et al., 2012). One of the interesting applications of
Moringa seed is their utilization as biomass for biodiesel production.
Due to the increasing energy demand and environmental problems
associated with fossil fuels, the improvement of alternative fuels and
renewable sources of energy is required. Biodiesel can replace
petroleum-derived oil (petrodiesel), without any sulphur or aromatic
compound and with lower emission of monoxides, hydrocarbons and
particulates. Furthermore, biodiesel can reduce dependence on imported
fuels: a crucial problem in developing countries (Karmakar et al.,
2010).
Moringa seed have an oil content of 30%–40%, with a high-quality fatty acid composition
i.e.,
high oleic acid (>70%) (Rashid et al., 2008). In addition they
possess significant resistance to oxidative degradation. These
proprieties make Moringa oil a good candidate to produce biodiesel after
transesterificaton (Ofor and Nwufo, 2011). Biswas and John (2008), in a
study conducted in Australia; report that approximately 3030 kg of oil
are required to produce 1000 litters of biodiesel. Furthermore, an
equivalent of 3.03 tonnes/ha of oil seed can be harvested from dry land,
and 6.06 tonnes/ha can be harvested from irrigated land. Since
biodiesel production with Moringa seed oil is a second generation
production (i.e., not in direct competition with existing farmland and
with food crops) and as Moringa can grow on degraded land, studies
suggest that Moringa biodiesel is an acceptable substitute to fossil
fuels, even when compared against biodiesel derived from vegetable oil
of other species.
2.4.5.6 Flavonoids
Flavonoids are a
sub-group of polyphenolic compounds having a benzo-γ-pyrone structure
and are ubiquitous in plants, as they are synthesized in response to
microbial infections (Kumar and Pandey, 2013).
Epidemiological
studies have consistently shown that high intake of flavonoids has
protective effects against many infectious (bacterial and viral
diseases) and degenerative diseases such as cardiovascular diseases,
cancers, and other age-related diseases (Kumar and Pandey, 2013).
Moringa oleifera leaves are an interesting source of flavonoids
compounds. Total flavonoids concentration in dried leaves ranges from
5.059 to 12.16 mg/g of DW (Yang et al., 2008), namely, close to or
larger than that in many fruits and vegetable normally consumed (Coppin
et al., 2013). These values are indeed the overall sum of the amounts of
single flavonoids. However, some flavonoids were studied only by some
authors and, therefore, these amounts may be inaccurate. The total
concentration of flavonoids in freeze-dried leaves ranges from 21.0 to
61.62 mgRE/g of DW (Siddhuraju et al., 2003; Zhang et al., 2011).
Myricetin, quercetin and kaempferol are the main flavonoids found in
Moringa oleifera leaves. In dried leaves, myricetin concentration is
approximately 5.804 mg/g of DW, while quercetin and kaempferol
concentrations range from 0.207 to 7.57 mg/g of DW and not detectable
amounts (ND) to 4.59 mg/g of DW, respectively (Prakash et al., 2007).
Higher
amounts were found in freeze-dried leaves. In particular, quercitin and
kaempferol concentrations range from 5.47 to 16.64 mg/g and 1.5 to 3.5
mg/g of DW, respectively (Siddhuraju et al., 2003). Isorhamnetin
concentration in dried leaves is approximately 0.118 mg/g of DW, while,
in freeze-dried leaves, its concentration is up to 7 times larger,
ranging from 0.52 to 0.72 mg/g of DW (Yang et al., 2008; Coppin et al.,
2013). Other flavonoids, such as luteolin, apigenin, daidzein and
genistein, were found in not detectable concentrations in Moringa
oleifera leaves (Yang et al., 2008). However these compounds were
investigated only in few studies and, therefore, further investigations
are needed. In addition, in this case, the high inter-studies variations
for these compounds may be explained taking into account
