<Insert Table 2: Antioxidant activity (Percent
Inhibition) of essential oil in DPPH free radical scavenging
activity>
The assay result is presented as percentage inhibition of free radical
in table 2. The results reveal that the essential oil of black cardamom
extracted by MAHD and HD methods show concentration-dependent
antioxidant activity. The percentage inhibition goes from 54.43 to 74.44
and from 47.44 to 64.84 for MAHD and HD extracted essential oil
respectively as we increase concentration from 10 to 25 µg/ml. the
percentage inhibition for MAHD and HD extracted oil was significantly
lower as compared to standard ascorbic acid (AA).
< Insert Figure 7 Plot of percentage of DPPH radical
scavenging capacity against the concentration of essential oils By MAHD
and HD methods >
The IC50 values which we get from the plot of percentage of DPPH radical
scavenging capacity against the concentration of essential oils (Fig. 7)
for MAHD and HD extracted essential oils are 7.5 µg/ml and 12.71 µg/ml
respectively. The percentage inhibition and IC50 values of the essential
oil extracted by MAHD and HD techniques show that MAHD extracted oil has
better antioxidant activity than the HD extracted oil. Biological
activities such as antibacterial and antioxidant activity possibly
allied with total phenolic content. The strong antioxidant activity of
MAHD extracted essential oil is related to its higher phenolic content
i.e. 1, 8-cineol[24][33].
Conclusion
In this study, the composition and yield of essential oil of Amomum
subulatum were varied with the extraction methods. Microwave assisted
hydrodistillation requires the significantly shorter time of extraction
than conventional hydrodistillation method. The energy requirement is
lesser in case of MAHD than traditional methods. This study also
highlights that MAHD method is advantageous to recover more oxygenated
monoterpenes (1, 8-cineol, Terpinen-4-ol and α-terpineol). However, the
hydrocarbon monoterpenes such as α-pinene and β-pinene have a lower
percentage of MAHD extract. Antibacterial activity of essential oil
obtained by MAHD method is greater than HD. against both the studied
microorganisms viz. Staphylococcus aureus and E. coli. Radical
scavenging activity (DPPH) of both essential oils was good but essential
oil extracted by MAHD showing better results.
Conflict of Interest : The authors declare that they have no
conflict of interest.References
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