Liu, Rui; Li, Hui; Yang, Junxia published the artcile< A 2,5-Diketopiperazines from Aspergillus sp., the Endophytic Fungus of Astragalus membranaceus and their Anticancer Assay>, Safety of (3S,8aS)-3-Isobutylhexahydropyrrolo[1,2-a]pyrazine-1,4-dione, the main research area is diketopiperazine anticancer Aspergillus endophytic fungus Astragalus cancer.
2,5-Diketopiperazines are cyclodipeptides obtained by the condensation of two α-amino acids. In our ongoing screening for biol. active secondary metabolites from endophytic fungi, we investigated metabolites produced by the endophytic fungus Aspergillus sp. isolated from roots of Astragalus membranaceus, a Chinese medicinal plant of the loess plateau of China. We have continued investigating endophytes from this biotope, since previous investigations have shown that a particularly high proportion of endophytes from plants from the Hengshan Mountains, China, were biol. active. This prompted us to carry out a secondary metabolites studies on this fungus, which resulted in the isolation of eight 2,5-diketopiperazines. We herein report on the isolation, structure, and anticancer properties of these compounds The fungal strain AR-17-2 was isolated from the roots of A. membranaceus collected in the Hengshan Mountains, China, on August, 2017. Subfraction B2 was further separated by HPLC with H2O-MeOH (2:5) to give compounds 1 (24.1 mg) and 2 (12.6 mg). Subfraction B3 was chromatographed on a Sephadex LH-20 column eluting with methanol to afford compound 3 (38 mg). Subfraction B4 was chromatographed over a silica gel column eluting with petroleum ether-Et acetate (50:1) and then subjected to PTLC to yield compound 4 (15.5 mg). The bioactive Fr. C was separated by column chromatog. on silica gel with a gradient of Et acetate in petroleum ether to give five subfractions (Subfrs. C1-5). Subfraction C2 that eluted with methanol was separated by semipreparative reversed-phase HPLC (H2O-MeOH, 1:4, 2.5 mL/min) to yield compounds 5 (9 mg), 6 (10.7 mg) and 7 (8.3 mg). Compound 8 (12 mg) were obtained from Subfr. C3 after separation with Sephadex LH-20 by MeOH-CHCl3 (1:1). These eight compounds were elucidated resp. as cyclo-(Pro-Gly) (1), cyclo-(Pro-Leu) (2), cyclo-(Pro-Ile) (3), cyclo-(Pro-Vla) (4), cyclo-(Phe-Gly) (5), cyclo-(Phe-Ala) (6), cyclo-(Phe-Tyr) (7), and cyclo-(Phe-Pro) (8) by comparison of their spectral data with the reported data in the literature.
Chemistry of Natural Compounds published new progress about Antitumor agents. 2873-36-1 belongs to class pyrazines, and the molecular formula is C11H18N2O2, Safety of (3S,8aS)-3-Isobutylhexahydropyrrolo[1,2-a]pyrazine-1,4-dione.