| Gibberellins (GAs) are bioregulators that control physiological processes of plants such as, floral synchronization and fruit development. The objective of this study was to extract, isolate, and characterize the gibberellins from green seeds of photoperiodic pigeon peas (Cajanus cajan L. Huth). Seeds of approximately 0.8 cm of diameter were homogenized with ice-cold 80% aqueous methanol and extracted with ethyl acetate. The organic phase was purified through adsorption chromatography using a polyvinylpolypirrolidone column followed by charcoal-celite column chromatography. The compounds obtained were separated through four C18 cartridges in series and by reversed-phase high performance liquid chromatography (HPLC) using a Nova-Pak C18 column with a linear gradient of 30 to 100% aqueous methanol with a flow rate of 0.75 mL/min. The HPLC fractions with biological activities of gibberellins were identified using the lettuce (Lactuca sativa L.) bioassay hypocotyl test. These fractions were characterized by gas chromatography-mass spectrometry (GC-MS) using as reference a GA's library. The results demonstrated the presence of GA1, GA3, GA5, GA8, GA20, GA29, and GA44, in addition to the catabolites of GA8 and GA29. The fractions with the highest biological activity correspond to the gibberellins GA1 and GA3. Moreover, GA29 catabolite enol #3, GA 3-isolactone, abscisic acid, and the enol form of abscisic acid were also found. These results suggest that the endogenous GAs biosynthesis of pigeon peas follow the metabolic pathway of the gibberellins hydroxylated in positions 13, 2, and 3. |
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