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The recent widespread interest in the antidepressant activity of Hypericum perforatum has encouraged the investigation of secondary metabolites from other Hypericum species. The genus Hypericum occurs widely in temperate regions of the world and has been used as traditional medicinal plants in various parts of the world. As a part of program to discover new bioactive natural products form plants, we have examined the constituents of H. scabrum, and H. chinense. H. scabrum is one of the most popular medicinal herbs in Uzbekistan and is used in the treatment of bladder, intestinal, heart diseases, rheumatism, and cystitis. The MeOH extracts of the aerial part of H. scabrum were partitioned between EtOAc and H_2O. Repeated column chromatography of EtOAc soluble fraction yielded eleven new prenylated benzophenones (1-9, 11, 12), one prenylated phloroglucinol (10), and six new xanthone derivatives (14-19). Some of these new compounds (10-14, 16-18) showed mild cytotoxicity. H. chinense is used as a folk medicine for treatment of female disorders in Japan. n-Hexane soluble fraction from the MeOH extracts of the leaves, and EtOAc soluble fraction from the MeOH extracts of the stems were subjected to column chromatography repeatedly to give four new spiro compounds (35, 36, 45, 46), two new polyketide derivatives (37, 38) six new xanthone derivatives (39-44), one sesquiterpenoid (47). Biyouyanagin A (35) was isolated from the n-hexane soluble fraction from the MeOH extract of the leaves of H. chinense. 35 has a novel skeleton containing sesquiterpene, cyclobutane, and spirolactone moieties, and seems to be biosynthesized through [2+2] cycloaddition between zingiberene and hyperolactone C. In an anti-HIV test, 35 inhibited HIV replication in H9 lymphocytes with an EC_<50> value of 0.798μg/mL and it inhibited uninfected H9 cell growth with an IC_<50> value of >25μg/mL, calculated therapeutic index (TI) value of >31.3 (in general, TI>5.0 is considered to be significant activity). Furthermore, the effect of 35 in LPS-induced cytokine production was examined. In this study, 35 inhibited the LPS-induced production of IL-10, IL-12, and TNF-α. Thus, 35 can be regarded as a promising new bioactive agent with a unique structure.