Celogentin K, a new cyclic peptide from the seeds of Celosia argentea and X-ray structure of Moroidin. — (SUZUKI, H.; MORITA, H.; SHIRO, M.; KOBAYASHI*, J.; Tetrahedron 60 (2004) 11, 2489-2495; Grad. Sch. Pharm. Sci., Hokkaido Univ., Sapporo 060, Japan; Eng.)