The influence of the extraction procedure on yield of indole‐3‐acetic acid in plant extracts

Abstract

Different types of plant material, including both dry and swollen maize kernels, swollen bean seeds, bean seedlings and dry rose seeds, were extracted by different methods and the yield of IAA was determined with the indolo‐α‐pyrone method. Extraction of dry maize kernels during short time experiments, varying from 3 to 24 h, gave the highest IAA yield when methanol was the extractant and a significant lower yield when diethyl ether or dichloromethane were used. The duration of the extraction period increased the yield with all the extractants. Progressive extractions for several days or weeks had little effect on the yield when 100% acetone was used in contrast to methanol and ether as extractants, which increased the yield during prolonged extraction. Extractions of tissue treated to 100°C for 1 h contradicted the hypothesis that IAA is enzymatically liberated during ether extraction. Water in the extractant solvents increased the yields. This was most pronounced when aqueous acetone was used instead of 100% acetone. Increased extraction temperature augmented the IAA yields. The yield of IAA from other types of tissue extracted with methanol for periods of 3 or 24 h was, however, independent of the duration of the extraction time. This indicates that some tissues contain less not easily extractable IAA than dry maize kernels. The terms “free” and “bound” IAA are discussed; they should be replaced by “easily extractable” and “not easily extractable” IAA. The results also show that IPyA in vitro can partly be converted to IAA during extraction and fractionation.

Free radical-scavenging activity of indolic compounds in aqueous and ethanolic media

“…The plant hormone IAA that can be detected in plant tissues (from ng g -1 FW in leaves, fruits, roots, stems tõ 1 µg g -1 FW in seeds and seedlings) [26]. Thus, the IAA of maize kernels (~240 ng g -1 FW) [27] may contribute a 2 nmol equivalent of Trolox g -1 FW to HAA, a value 15 times higher than melatonin. In the case of apex lupin seedlings (650 ng IAA g -1 FW) [28], their contribution to the antioxidant activity will be of 5.6 nmoles equivalents Trolox g -1 FW (40 times higher).…”

Effects of arbuscular mycorrhiza (AM) on health ofLinum usitatissimum L. infected by fungal pathogens

“…Two g of fresh plant material were used for the extraction and purification of auxin, following the procedure described by Hemberg and Tillberg (1980). Auxin content was determined by the indole-c~-pyrone fluorescence method (Stoessl and Venis, 1970), with a spectrophotometer (UV/VS551, Perkin-Eelmer).…”

Production de composés indoliques rhizogènes par le ver de terre <i>Lumbricus terrestris</i>

“…Cette différence dans l'intensité de la rhizogenèse serait due à une dégradation partielle des dérivés indoliques rhizogènes lors des opérations d'extraction et de fractionnement, plutôt qu'à un partage du pouvoir rhizogène dans les trois groupes de fractions A, B et C. Cette explication semble plus plausible dans la mesure où les Les dérivés indoliques d'origine animale ou végétale sont des composés très instables. Ils s'oxydent facilement en pré-sence d'oxygène et de peroxydes (Hinman et Lang 1965;Sandberg et al 1981aSandberg et al , 1981b) et sont à la fois thermolabiles et photolabiles (Atsumi et al 1976;Sweetser et Swartzfager 1978;Hemberg et Tillberg 1980). L'emploi d'antioxydants (Lino et Carr 1982;Sandberg et al 1984Sandberg et al , 1985 n'est pas toujours couronné de succès.…”

“…D'autres auteurs utilisent l'acétone et l'éther diéthylique. Hemberg et Tillberg (1980) ont rapporté que la quantité d'AIA extraite à partir du maïs sec avec l'éther diéthylique augmente continuellement avec le temps d'extraction. Srivastava (1963) a expliqué cette augmentation, soit par la conversion d'autres indoles, soit par l'hydrolyse progressive de l'AIA présente sous forme conjuguée.…”