No abstract

No abstract

An improved method to obtain naringin, a bitter flavored flavanone glicoside with proven biological activities, from grapefruit (Citrus x paradisi L.) peel waste is described. The proposed modification of the known process, which involves extraction with methanol and crystallization in water with the addition of dichloromethane, requires shorter processing time and reduced solvent volume. Due to the direct method employed, which did not require the 3-day air-drying stage, the hot extraction of fresh grapefruit albedo using methanol led to higher yields of naringin extract in half the time required. To evaluate the obtained naringin which possessed a wide range of pharmacological properties, it was subjected to chemical transformation into the flavone apigenin, an expensive and naturally-occurring flavonoid obtained in low yields.

The first asymmetric total synthesis of Aspinolide B (1), a new 10-membered lactone discovered by chemical screening methods in the cultures of Aspergillus ochraceus, has been accomplished. The key steps included a selective Felkin-type addition of TMS-acetylene to aldehyde 3a and a Nozaki-Hiyama-Kishi coupling reaction to build the required 10-membered ring. This synthesis confirmed the absolute stereochemistry of aspinolide B, established through Helmchen's method and corrected its previously reported specific optical rotation.

No abstract