Efficacy of Neem Kernel Bioactives Extracted using Supercritical Fluid Carbon Dioxide on Selected Dermatophytes and Foodborne Pathogens.

Neem seed kernel was subjected to supercritical
fluid carbon dioxide (SCF) process and evaluated for the
inhibition of selected dermatophytes such as Candida albicans,
Candida tropicalis, Candida parapsilosis, Trichophyton rubrum,
Trichophyton mentagrophytes. The extraction was carried out by
SCF-CO2 at 300 bar 50 °C with and without entrainer (30 %
methanol and acidified methanol). Results showed that the
inhibition of the growth of all the dermatophytes is maximum in
the extract obtained at 300 bar 50 °C with methanol (SCF-Me)
followed by 300 bar 50 °C without methanol (SCF). The acidified
SCF (SCF-MeA) extract did not show any remarkable inhibition.
Of the dermatophytes, SCF-Me showed the inhibition against
Candida parapsilosis of 18.46±0.25 mm compared to Candida
albicans 16±0.26 mm, whereas the methanol control exhibited
10±0.3 mm inhibition. Out of the two fungal organisms, SCFMe inhibited the growth of Trichophyton rubrum and
Trichophyton mentagrophytes at 21.53±0.23 mm and 18.1±0.1
mm respectively. The extracts were also evaluated for its
inhibition against the foodborne pathogens (bacteria, fungi, and
yeast). The SCF-Me extract showed maximum inhibition against
Pseudomonus aeroginosa (27.26±0.25) compared to Bacillus
subtilis (24.36±0.35) at the concentration of 70mg. In fungus,
Aspergillus ochraceus (16.7±0.60) was maximum when
compared to Aspergillus niger (15.2±0.43) and yeast exhibited the
inhibition of 15.93±0.20 at the concentration of 80mg. The
dermatophytic and antimicrobial activity of the SCF-Me extract
is due to the presence of higher amount of triterpenoinds such as
Azadirachtin (50.7 %), 6-deacetyl nimbin (0.14 %), Nimbin (0.08
%), Salannin (1.83 %) and Epoxy azadiradione (1.58 %) which
were confirmed by liquid chromatography and mass spectroscopy
(LC-MS).