of the Tenth Amendment” and statutes were valid exercise of Congress’s Commerce Clause power); see also United States v. Brown, 72 F.3d 96, 97 (8th Cir.1995) (per curiam) (noting interstate drug trade affects interstate commerce and § 841(a)(1) is a valid exercise of congressional power), cert. denied, 518 U.S. 1033, 116 S.Ct. 2581, 135 L.Ed.2d 1095 (1996). Finally, in a supplemental brief, Deering argues that the government violated 18 U.S.C. § 201(c)(2) when it promised defense witness Cynthia Henderson a sentence reduction in exchange for her testimony at trial against him. Deering did not raise this issue in the district court, and the court did not commit plain error by failing to suppress Henderson’s testimony. See United States v. Johnson, 169 F.3d 1092, 1098 (8th Cir.1999) (<HOLDING>); United States v. Herron, 97 F.3d 234, 238
holding prosecutions failure to disclose promise of leniency to witness provided in exchange for that witnesss testimony violated due process holding that the fact that a prosecutor afforded favorable treatment to a government witness standing alone does not establish the existence of an underlying promise of leniency in exchange for testimony holding that  201c which penalizes an individual for giving anything of value in exchange for testimony does not apply to the united states government holding that  201 does not sweep so broadly as to prevent prosecutors from offering leniency to an individual in exchange for truthful testimony holding that agreements which afford cooperating accomplices leniency in exchange for testimony do not violate  201c2