Structural Elucidation of Garcipaucinones A and B From Garcinia paucinervis Using Quantum Chemical Calculations.

Two tocotrienol derivatives, garcipaucinones A (1) and B (2), and a biosynthetically related known analogue (3) were isolated from the fruit of Garcinia paucinervis. Their structures including absolute configurations were unequivocally determined by spectroscopic methods complemented with electronic circular dichroism (ECD) calculations and gauge-independent atomic orbital (GIAO) NMR calculations. Compounds 1 and 2 are the first naturally occurring tocotrienol derivatives with a 3,10-dioxatricyclo-[7.3.1.02,7]tridecane skeleton incorporating an unusual γ-pyrone motif. A reasonable biosynthetic pathway for formation of the two compounds is proposed. The antiproliferative and anti-inflammatory activities of compounds 1 and 2 were also evaluated.

Acylphloroglucinol Derivatives with a Tricyclo-[4.4.1.11,4] Dodecane Skeleton from Garcinia bracteata Fruits.

Two novel polycyclic polyprenylated acylphloroglucinols (PPAPs), garcibractinones A (1) and B (2), as well as three known analogues doitunggarcinones A-B (3-4) and garcibracteatone (5) were isolated from Garcinia bracteata fruits. Their structures were elucidated by comprehensive spectroscopic methods and single crystal X-ray diffraction. Compounds 1 and 2 possess an unprecedented caged tricyclo-[4.4.1.11,4] dodecane skeleton, and their biosynthetic pathways are also proposed. Compounds 1-2 were tested for their inhibitory effects on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW 264.7 macrophages.

Prenylated xanthones and benzophenones from the fruits of Garcinia bracteata and their potential antiproliferative and anti-inflammatory activities.

Ten previously undescribed compounds, including five prenylated xanthones (1-5), two caged xanthones (16-17) and three rearranged benzophenones (27-29), together with nineteen known compounds were isolated from the fruits of Garcinia bracteata. Their structures were established on the basis of spectroscopic analysis, electronic circular dichroism calculations, and X-ray crystallographic data. Compound 17 was a caged xanthone bearing a rare 8, 8a-epoxy moiety. Compound 28 belonged to the rearranged benzophenones with rare 2, 7-dioxabicyclo-[2.2.1] heptane moiety fused at C-2 and C-3 respectively. The antiproliferative and anti-inflammatory activities of all isolated compounds were evaluated. Compounds 23 and 24 exhibited remarkable inhibitory activities against three human cancer cell lines (HepG2, T98, MCF-7) with IC50 values ranging from 3.21 ± 1.00 to 6.27 ± 1.03 µM. Moreover, compounds 20 and 24 also displayed significant inhibitory effects against NO production with IC50 values of 1.22 ± 0.01 and 1.77 ± 0.23 µM respectively. These results enrich the structural diversities of xanthones and benzophenones from Garcinia plants. Neobractatin (24) due to its anti-tumor and anti-inflammatory effects is worth further investigation in anticancer research.

Two novel cyclohexanone-monocyclic polycyclic polyprenylated acylphloroglucinols from Garcinia multiflora fruits.

Two novel cyclohexanone-monocyclic polyprenylated acylphloroglucinol (C-MPAP) derivatives, named norgarmultinones A (1) and B (2), were isolated from the fruits of Garcinia multiflora. Their structures were clarified by NMR, HRESIMS and calculated electronic circular dichroism (ECD) spectra. Compound 2 is the first example of naturally occurring C-MPAPs containing tetrahydropyran moiety by the cyclization of an enolic hydroxyl with an isogeranyl side chain. The reasonable biosynthetic routes of 1 and 2 were also put forward.

Polyprenylated Acylphloroglucinols With Different Carbon Skeletons From the Fruits of Garcinia multiflora.

Eleven new polycyclic polyprenylated acylphloroglucinols (PPAPs, 1-11) and three new monocyclic polyprenylated acylphloroglucinols (MPAPs, 12-14), together with ten known analogues were isolated from the fruits of Garcinia multiflora. These PPAPs belong to three types including the bicyclic polyprenylated acylphloroglucinols (BPAPs), the caged PPAPs, and the complicated PPAPs. Their structures and absolute configurations were determined through HRESIMS, NMR spectroscopy data, electronic circular dichroism (ECD) calculations, and gauge-independent atomic orbital (GIAO) NMR calculations with DP4+ analyses. Moreover, compounds 2 and 7 exhibited moderate cytotoxicity against three human cancer lines (MCF-7, T98, and HepG2) with IC50 values ranging from 9.81 ± 1.56 to 17.00 ± 2.75 µM.

Anti-inflammatory and antiproliferative prenylated sulphur-containing amides from the leaves of Glycosmis pentaphylla.

Glycosmis pentaphylla (Retz.) DC (Rutaceae) has been traditionally considered as anti-cancer and anti-inflammatory medicine. However, active compounds of sulphur-containing amides remain largely unknown. In the present work, eighteen previously undescribed sulphur-containing amides (1-18) and three known analogues (19-21) were isolated from the leaves of G. pentaphylla. Their structures were elucidated by NMR spectroscopy and mass spectrometry. All isolated prenylated sulphur-containing amides were evaluated for their anti-inflammatory properties together with antiproliferative activities in vivo. Prenylated sulphur-containing amides exhibited significant inhibitory effects against nitric oxide (NO) production stimulated by lipopolysaccharide in mouse macrophage RAW 264.7 cells with the IC50 values ranging from 0.16 ± 0.10 to 16.74 ± 2.81 µM. Meanwhile, sulphur-containing amides also exhibited considerable antiproliferative activities against HepG2 cell line with IC50 values ranging from 7.47 ± 0.91 to 16.23 ± 0.80 µM. These findings enrich and improve the research on the structural diversity and biological activity of sulphur-containing amides and provide phytochemical and pharmacological evidence for the further development and utilization of the leaves of G. pentaphylla in pharmaceutical industry.

Homoadamantane polycyclic polyprenylated acylphloroglucinols from the fruits of Garcinia multiflora.

Five new homoadamantane polycyclic polyprenylated acylphloroglucinols (PPAPs, 1-5) were isolated from the fruits of Garcinia multiflora. Their structures and absolute configurations were determined by extensive spectroscopic analyses including NMR, HRESIMS and electronic circular dichroism (ECD). Compounds 1-3 possessed an unique core structure consisting of tetracyclo[7.3.1.13,11.03,7]tetradecane-2,12,14- trione. In comparison with those of 1-3, compound 4 had tricyclo[4.3.1.13,8]undecane- 2,9,11-trione with the loss of prenyl unit. Garcimultinone C (5) was the first example of seco-homoadamantane-type PPAPs with 5-oxatricyclo[7.3.1.03,7]tridecane skeleton derived from C(4)/C(5) carbon-carbon bond cleavage by retro-Claisen reaction.

Adamantyl and homoadamantyl derivatives from Garcinia multiflora fruits.

Nine undescribed caged polycyclic polyprenylated acylphloroglucinols (PPAPs), including adamantane type PPAPs (1-2), and homoadamantane type PPAPs (3-9), were isolated from the fruits of Garcinia multiflora, along with three known analogues. A new epimeric pair of isohypersampsonone B (5) and epi-isohypersampsonone B (6), featuring an unusual hexahydrofuro[2,3-b]furan-diepoxy ring system fused in a homoadamantane skeleton, was not separated due to the rapid equilibration between the two isomeric forms. All new caged PPAPs (1-9), sharing a common isogeranyl group, were determined on the basis of comprehensive NMR and MS spectroscopic data. Their cytotoxicity against three human tumor cell lines (SGC-7901, HepG2, HCT-116) and the nitric oxide production inhibitory activity of lipopolysaccharides-stimulated RAW 264.7 cells were tested. Compounds 8 and 12 displayed mild cytotoxicity against three human cancer cell lines with IC50 values of 10-20 µM. Furthermore, compounds 8 and 12 also exhibited NO production inhibitory effect with an IC50 value of 18.24 and 12.50 µM respectively.