＜正＞萜类化合物结构类型丰富,具有各类重要生物活性,作为临床药物应用的例子也很多。我们研究小组在长期研究中发现了大量的萜类化合物（包括萜类生物碱）,其结构新颖多样、并普遍具有高度复杂的稠多环体系,部分化合物显示多种重要生物活性。近五年来,通过对60余种富含萜类的药用植物进行系统的化学成分研究,获得了500多个新化合物,特别是发现了多种新骨架类型和具有重要活性的天然化合物,包括抗疟疾、抗肿瘤、免疫抑制和抗艾滋病等活性等。对新骨架化合物的生源合成进行了探讨,并对其中的一些重要活性萜类衍生物进行了生源启发的全合成研究1-6。

Cephalodiones A-D (1-4), the first example of C-19-norditerpenoid dimers, were isolated and fully characterized from a Cephalotaxus plant. These new skeletal natural products shared a unique tricyclo[6.4.1.1(2,7)]tetradeca-3,5,9,11-tetraene-13,14-dione core that was capped in both ends with rigid multicyclic ring systems either C-2-symmetrically or asymmetrically. Compounds 1-4 were proposed to be biosynthetically produced by the [6+6]-cycloaddition of two identical C-19-norditerpenoid troponoids, which was validated by the semisyntheses of dimers 2-4. Moreover, some compounds showed significant inhibition on Th17 cell differentiation.

Four new diterpenoids, casearoids A similar to D (1 similar to 4), including dolabrane, orosane, labdane, and cembrane, were isolated and characterized from Aficrodesmis casearifolia. Their structures were elucidated by extensive spectroscopic data analysis. The absolute configurations of these diterpenoids were established by analysis of the electronic circular dichroism (ECD) data.

Eighteen new limonoids, including eight methyl angolensates (1-8) and 10 cipadesins (9-18), were isolated from the leaves of Cipadessa baccifera. Their structures were characterized by means of spectroscopic data analyses, single-crystal X-ray diffraction, and quantum chemistry computational methods. The C-6 configurations in those compounds possessing a C-6 hydroxy group were all assigned as S regardless of the magnitude of J(5,6), and the C-2' configuration in those bearing a 2-methylbutyryl residue was defined by single-crystal X-ray diffraction and NMR data. Compounds 1, 5, 6, 7, 11, and 12 showed moderate antimalarial activities with IC50 values ranging from 12 to 28 mu M.

Crokonoid A (1), a highly rearranged diterpenoid featuring a dual-bridged tricyclo[4.4.1.1(1,4)]dodecane-2,11-dione ring system and its two possible ent-kaurene diterpenoid precursors (2 and 3), was isolated and structurally characterized by solid data from Croton kongensis. Compound 1 exhibited significant cytotoxicity against HL-60 and A-549 cell lines with IC50 values of 1.24 +/- 0.56 and 1.92 +/- 0.60 mu M, respectively.

.Summary of main observation and conclusion Securines A-E, three dimeric diarymethane derivatives (1-3) and two enantiomeric diarymethane derivative monomers (4 and 5), were isolated and characterized from the medicinal plant Securidaca inappendiculata. Compounds 1 and 2 are a pair of enantiomeric diarymethane derivative dimers, and compound 3 is a mesomeric diarymethane derivative dimer. Their structures were determined by a combination of spectroscopic data, X-ray crystallography, electronic circular dichroism (ECD) analysis, and computational ECD calculations. Dimeric compounds 1-3 showed moderate antiplasmodial activities with IC50 values of 0.9, 1.4, and 1.5 mu M, respectively.

An ethanol extract of the powdered twigs of Podocarpus imbricatus afforded 14 new diterpenoids (1-14), which all share an aromatized C ring. These isolates belong to five diterpenoid types that include abietanes (1-3), semperviranes (4-9), totaranes (10-12), a C-17 norabietane (13), and an icetexane (14). Their structures were assigned mainly by analysis of the spectroscopic data, and the absolute configuration of 1 was determined by X-ray crystallography. A biosynthetic pathway for five of the biogenetically related types of diterpenoids was proposed. Compound 7 showed moderate inhibitory activity against Zika virus with an IC50 value of 2.5 mu M.

Four unprecedented macrocyclic nonapeptides,orberryamides A–D(1–4),were isolated from Glycosmis pentaphylla(orangeberry)and structurally characterized by obtaining solid data from numerous analytical measurements.Co

Two highly rearranged daphniphyllum alkaloids, daphnillonins A (1) and B (2), were isolated from Daphniphyllum longeracemosum and structurally characterized by a combination of diverse methods, including the calculation of electronic circular dichroism. Compound 1 possesses an unprecedented carbon architecture with a very unique 8-methyl-6-azabicyclo[3.2.1]octane moiety, and compound 2 represents a new carbon skeleton with an uncommon 7/6/5/7/5/5-fused ring system. The biosynthetic pathways for the two alkaloids were proposed with the concurrent major alkaloids as the precursors.