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Figure 1. Pigmented callus initiation from stem explants on MS medium
supplemented with 1.0 mgL -1 (2,4-D) and 2.0 mgL -1 (TDZ) after 8 weeks
of culture.
Table 1. Effect of 2,4-D and TDZ on pigmented callus formation from stem explants of Z. decandra on MS medium.
Radfar et al. 2445
Growth regulator (mg/L)
2,4-D TDZ
Nature of callus Intensity of pigmented callus formation
0.5 0.5 Pink, creamy, compact +
1.0 1.0 Pink, creamy, compact +
0.5 1.5 Red, fragile +
1.0 2.0 Dark red, soft +++
Intensity of pigmented callus: + (low), ++ (moderate), +++ (high).
noted that some authors have attributed the high
antioxidant activity of crude betalain-containing extract to
their high concentration of flavonoids (Lee et al., 2002).
Betalains reportedly have diverse, desirable activities
(Lila, 2004), including anti-inflammatory (Lee et al., 2006)
hepatoprotective (Galati et al., 2005) and cancer chemopreventative
activities (Kapadia et al., 1996).
Recently it has been reported (Sreekanth et al., 2007)
that betanin induces apoptosis in human chronic mylloid
leucemia cells. Hence, betalains are likely to be highly
suitable in natural colorants for preparing healthy foods
and their consumption is likely to increase. Plant cell and
tissue cultures are attractive alternative sources of
bioactive plant substances, including betalain pigments
(Ramachandra and Ravishankar, 2002). The
biotechnological production of food colorants using plant
in vitro cultures offers several advantages over the
conventional cultivation of whole plants, notably the
ability to maintain aseptic, controlled conditions (Vanisree
et al., 2004).
Various factors affecting plant cell culture, such as
concentration of essential nutrients, stress factors, light,
incubation period and concentration of growth regulators,
were found to be important determinants of secondary
metabolite production. The results obtained from the
growth of Z. decandra callus culture, biosynthesis of
betalains and the uptake of the main nutrients showed
that it was distinguished by certain physiological
peculiarities, which is related to the biosynthesis of
betalains. Betalains exhibit anti cancer activity and
antioxidant properties (Gentile et al., 2004).
Conclusion
In vitro propagation of medicinal plants with enriched
bioactive principles and cell culture methodologies for
selective metabolite production is found to be highly
useful for commercial production of medicinally important
compounds. The increased use of plant cell culture
systems in recent years is perhaps due to an improved
understanding of the secondary metabolite pathway in