Browsing by Author "Hiroshi Araya"

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Annonaceous Acetogenins from the Seeds of Annona squamosa. Adjacent Bis-tetrahydrofuranic Acetogenins
(1994) Mahendra Sahai; Sanjewon Singh; Manorama Singh; Yogesh Kumar Gupta; Satoko Akashi; Reiko Yuji; Kazuo Hirayama; Hitomi Asaki; Hiroshi Araya; Noriyuki Hara; Tadashi Eguchi; Katsumi Kakinuma; Yoshinori Fujimoto
The petroleum ether extract of the seeds of Annona squamosa L. yielded thirteen adjacent and four non-adjacent bis-tetrahydrofuranic acetogenins, in addition to squamocin (1) and squamostatin-A. The structures of the thirteen acetogenins, named as squamocins-B (2), -C (3), -D (4), -E (5), -F (6), -G (7), -H (8), -I (9), -J (10), -K (11), -L (12), -M (13) and -N (14), have been established on the basis of spectral evidence. Squamocins-B, -D, -E, -F, -I, -K and -N are new acetogenins. The structures of these acetogenins vary in the carbon number (C37 or C35), the number and position of hydroxyl groups (substituted at C-4, C-12, C-28 or C-29) and the stereochemistry at the bis-tetrahydrofuran moiety. Squamocin-N (14) has an unprecedented threo-cis-threo-cis-threo stereochemistry in its bis-tetrahydrofuran portion. Co-occurrence of a diastereoisomeric pair, 9 and 10, is noteworthy. © 1994, The Pharmaceutical Society of Japan. All rights reserved.
Squamocin-O1 and squamocin-O2, new adjacent bis-tetrahydrofuran acetogenins from the seeds of Annona squamosa
(2002) Hiroshi Araya; Mahendra Sahai; Shubhra Singh; Ajit Kumar Singh; Mitsuzi Yoshida; Noriyuki Hara; Yoshinori Fujimoto
Two bis-tetrahydrofuran acetogenins, squamocin-O1 (1) and squamocin-O2 (2), were isolated from a MeOH extract of seeds of Annona squamosa L. Their structures were determined by spectral means including precursor-ion scanning mass spectral analysis for their aminal derivatives. The configurations at the oxymethine chiral centers were assigned as 12R, 15R, 16R, 19R, 20R, 23R, 24S, 28S, 36S for 1 and 12S, 15R, 16R, 19R, 20R, 23R, 24S, 28S, 36S for 2, based on 1H NMR analysis of their Mosher's ester derivatives and CD data, © 2002 Elsevier Science Ltd. All rights reserved.
Squamostanal-A, Apparently Derived from Tetrahydrofuranic Acetogenin, from Annona squamosa
(1994) Hiroshi Araya; Noriyuki Hara; Yoshinori Fujimoto; Mahendra Sahai
The seeds of Annona squamosa (Annonaceae) furnished squamostanal-A (1), a novel annonaceous acetogenin. The structure of squamostanal-A was established by spectral methods to be (5S)-3-(12-formyldodecyl)-5-methyl-2, 5-dihydrofuran-2-one. Copyright © 1994, Japan Society for Bioscience, Biotechnology, and Agrochemistry. All rights reserved.
Squamosten-A, a Novel Mono-tetrahydrofuranic Acetogenin with a Double Bond in the Hydrocarbon Chain, from Annona squamosa L.
(1994) Hiroshi Araya; Noriyuki Hara; Yoshinori Fujimoto; Anjani Srivastava; Mahendra Sahai
Squamosten-A, a new mono-tetrahydrofuranic acetogenin possessing a double bond in the hydrocarbon chain, has been isolated from the seeds of Annona squamosa L. (Annonaceae). The structure has been elucidated on the basis of spectral evidence, including precursor-ion scanning spectra. Chemical degradation was successfully employed to determine the position of the double bond. © 1994, The Pharmaceutical Society of Japan. All rights reserved.