Anthratectone and Naphthotectone, Two Quinones from Bioactive Extracts of Tectona grandis

Abstract

Two new quinones, (an isoprenoid quinone, and a dimeric anthraquinone) named naphthotectone and anthratectone, respectively, were isolated from bioactive leaf extracts from Tectona grandis. Their structures were determined by a combination of 1D and 2D NMR techniques. The bioactivity profile of naphthotectone was assessed using the etiolated wheat coleoptiles bioassay in aqueous solutions at concentrations ranging from 10(-3) to 10(-5)M, as well as the standard target species lettuce, cress, tomato, and onion. Naphthotectone showed high level of activities in both bioassays. This fact, along with the presence of this compound as the major component in Tectona grandis, suggests that it may be involved in the allelopathic activity previously described for this species, and probably in other defense mechanisms.

Anticancer and Antimicrobial Activities of Some Antioxidant-Rich Cameroonian Medicinal Plants

“…Particularly, the R. abyssinicus extract displays an activity comparable to that of gentamycin, and P. butyracea extract follows closely. The antibacterial activities of crude extracts from P. febrifugum, D. glomerata , V. laurentii, R. abyssinicus, F. asperifolia and T. grandis corroborate those of the literature [3], [9], [16], [20], [22]. However, the antibacterial activities of the crude extracts from H. asper and P. Butyracea are reported here for the first time.…”

“…The AOAs of crude extracts from Hibiscus asper , Tectona grandis , Ficus asperifolia and Paullinia pinnata corroborate those of the literature [2], [3], [9], [69], [70]. To the best of our knowledge, this is the first systematic screening for the quantification of total phenolics and AOA of the crude extracts/compounds from Dichrostachys glomerata , Psorospermum febrifugum , Pentadesma butyracea , Rumex abyssinicus , Rumex bequaertii and Vismia laurentii .…”

“…The Tectona grandis leaf extract was proven to be bioactive [3], due to the presence of two quinones: naphthotectone and anthratectone; it has antibacterial activity [4] and good antiradical properties [5]. A new compound: 5-hydroxylapachol [6], was isolated from the T. grandis root, and reported to be biologically active.…”

Enantioselective Total Syntheses of (R)‐ and (S)‐Naphthotectone, and Stereochemical Assignment of the Natural Product

“…The only conditions that led to product formation involved the use of Pd(OAc) 2 as Pd source, P(o-Tol) 3 , Et 3 N as base, and toluene as solvent (Table 1, entry 1). Under these conditions, the coupling product was obtained in 60 % yield.…”

“…[3] We recently described the first total synthesis of racemic naphthotectone (1) from readily available starting materials. [4] The synthetic route was efficient, and involved a late-stage onepot anodic treatment and demethylation process to form the naphthoquinone core.…”