Abstract
Callus cultures from stems, leaves and roots of colocynth were initiated on MS media supplemented with various combinations of 2,4 dichlorophenoxyacetic acid (2,4-D) with kinetin (KIN) and benzyladenine (BA) with α-naphthaleneacetic acid (NAA). The highest percentage of callus formation frequency (98.9%) was obtained from stem explants grown on MS media supplemented with (1.0 mg/L) 2,4-D + (1.0 mg/L) KIN. The total phenolics and flavonoid content of the colocynth callus cultures were measured. The results showed that the MS medium supplemented with 6.0 mg/L 2,4-D + 2.0 mg/L KIN (MD3) gave the highest content of total phenolics (19.2 mg/100g d.w.) in leaf-derived calli. The highest content of flavonoids (47.3 mg/100g d.w.) was obtained in stem derived calli grown on the same medium (MD3). Antioxidant activities of extracts were determined using different assays, including DPPH radical scavenging activity, hydrogen peroxide (H2O2) scavenging activity and ferric reducing power. Leaf-derived calli cultured on MS medium + 2.0 mg/L 2,4-D + 1.0 mg/L KIN (MD1) showed the highest DPPH radical scavenging activity (85.3%). The highest percentage of H2O2 scavenging activity (61.4%) was detected in leaf explant-derived calli growing on MD1. The leaf-derived calli growing on (MD3) gave the highest ferric reducing power (22.3 μg/g d.w.), compared to the activities of stems, leaves and roots of in vitro grown seedlings (3.28, 12.9 and 2.85 μg/g d.w.), which were used as controls. On the basis of the current findings, we conclude that MS media supplemented with different combinations of 2,4-D and KIN yields higher phenolics, flavonoids contents and antioxidant activities than MS media supplemented with BA and NAA.
Highlights
Plant cell cultures are an attractive alternative source to whole plant for the production of high value secondary metabolites (ALFERMANN and PETERSEN, 1995; DORNENBURG and KNORR, 1997)
After that callus samples were collected for determination of callusing frequency as well as determination of total phenolics, total flavonoid and antioxidant activity by different methods
Calli of colocynth began to appear on stems, leaves and roots grown on MS media supplemented with different concentrations and combinations of growth regulators (2,4-D/KIN and BA/naphthaleneacetic acid (NAA)) within one weak
Summary
Plant cell cultures are an attractive alternative source to whole plant for the production of high value secondary metabolites (ALFERMANN and PETERSEN, 1995; DORNENBURG and KNORR, 1997). A considerable progress has been made to stimulate production and accumulation of secondary metabolites using plant cell cultures (KALIDASS et al, 2010; ABOUZID et al, 2010). Several strategies have been adopted for the enhancement of bioactive metabolite production in in vitro cultures; one of them is using growth regulators which are often a crucial factor in secondary product accumulation (DUANGPORN and SIRIPONG, 2009). The type and concentration of auxin or cytokinin or the auxin/cytokinin ratio may alter dramatically both the growth and the product formation in cultured plant cells (MANTELL and SMITH, 1984). For example kinetin stimulated the production of anthocyanins in Haplopappus gracilus but inhibited the formation of anthocyanins in Populus cell cultures (SEITZ and HINDERER, 1988)
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