Two new resin glycosides, ipomeolides A (1) and B (2), both with an unusual nonlinear heteropentasaccharide core, along with five known compounds were isolated from the n-hexane/CHCl3 (1:1) extract of the aerial parts of Ipomoea pes-caprae. Ipomeolides A (1) and B (2) are macrolactone analogues of the rare (11R)-jalapinolic acid, and macrolactonization occurred at C-2 of the second saccharide moiety. Compounds 1 and 2 show structural variation even in the pentasaccharide core. The structures of 1 and 2 were established by a combination of spectroscopic techniques as well as chemical modifications such as acetyl and acetonide derivatives as well as hydrolysis products. The new glycosidic acid was named ipomeic acid (1c). Compounds 1, 1b, and 2b were evaluated for cytotoxicity against human tumor cell lines. Compounds 1b and 2b were not effective on epithelial cells, but affected survival of K-562, which is of hematopoietic origin. A sublethal concentration of compound 1 (4 μM) when used in combination with 1 μM doxorubicin, an anticancer agent, significantly enhanced cytotoxicity to tumor cells. Such combined synergistic potency against leukemia cells and the absence of effects on epithelial cells may be beneficial for chemotherapy with minimal side effects to treat CML (chronic myeloid leukemia) malignancies.

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The biotransformation of the front-line antimalarial drug, artemisinin (1) by the filamentous fungus Aspergillus flavus MTCC-9167 was investigated. Incubation of compound 1 with A. flavus afforded a new hydroxy derivative (2) along with three known metabolites (3-5). The new compound was characterized as 14-hydroxydeoxyartemisinin (2) by extensive spectroscopic data analysis (IR, H andC NMR, HSQC, HMBC, COSY, NOESY, and HR-ESIMS). The known metabolites were identified as deoxyartemisinin (3), artemisinin G (4), and 4α-hydroxydeoxyartemisinin (5). This is the first report of hydroxylation of a secondary methyl of artemisinin at C-14 by the fungus A. flavus, which is synthetically not accessible. In addition, these compounds were evaluated for their in vitro antiplasmodial activity. Artemisinin G (4) exhibited IC values in the submicromolar range, which was better than those of the nonperoxidic metabolites.

Excolides A-B (1-4) represent the first examples of a new class of secolabdanoids with an unprecedented framework, which were isolated from the stems of Excoecaria agallocha. Their structures were determined by spectroscopic analysis, chemical modifications, CD, and single-crystal X-ray analysis (1 and 4) as excolide A (1), 11-epi-excolide A (2), 11,13-di-epi-excolide A (3), and excolide B (4). In addition, the structure of rhizophorin A (7), a novel bicyclic secolabdanoid, was revised as excolide A (1).

Agallochaexcoerin A (1), a seco-manoyl oxide diterpenoid was metabolised by pathogenic fungus, Aspergillus flavus, in growth media to yield a new metabolite, termed agallochaexcoerin G (2). It was confirmed by using IR, UV, (1)H NMR and HR-ESI-MS techniques. This microbial bioconversion was achieved by unusual dehydration at C-4 position.

Main observation and conclusion Boswelliains A—E (1—5), five new cembrane‐type diterpenoids, were isolated from the resin of Boswellia papyifera. Their structures, determined by using spectroscopic, computational and chemical methods, demonstrate that 2—5 are novel 4,5‐seco‐, 4,5‐seco‐, 9,10‐seco‐, and 6,7‐seco‐cembrane diterpenoids, and that 1, 4 and 5 bear aldehyde moieties. An evaluation of the wound healing properties of these natural products along with a derivative of 2 shows that compounds 2 and 3 significantly stimulate proliferation, mobility and tuber formation of human umbilical vein endothelial cells (HUVECs) at the concentration of 20 μmol/L.

Two novel compounds (1‐2), cerioptins A−B, along with seven known compounds were isolated from the mangrove, Ceriops tagal. These new compounds were characterized as a rare ethyl‐[(2‐allyl‐2‐chloromethyl)‐2H‐1‐benzopyran]‐3‐carboxylate (1) and a novel tetraterpenoid congener of heterodimeric diterpenoid, pimara‐11‐enol‐(16→2′)‐dolabra‐1,4(18),15‐triene (2) by extensive modern spectroscopic 2D NMR [COSY (correlation spectroscopy), NOESY (Nuclear Overhauser Effect Spectroscopy), HSQC (heteronuclear single‐quantum correlation), HMBC (heteronuclear multiple bond correlation)], IR (infrared) and mass data analysis. The naturally occurring new heterodimeric diterpene is derived from two new diterpenes as pimara‐11‐enol and dolabra‐1,4(18),15‐triene.

Phytochemical investigation into the CHCl extract of the fruits of Barringtonia racemosa resulted in the isolation of two new metabolites along with isoracemosol A and betulinic acid as known metabolites. The new compounds were characterised as phytosphingosine-type ceramide [(2S,3S,4R)-2-[(2R)-2-hydroxyhexadecanoyl amino]-hexacos-8(E)-ene-1,3,4-triol, 1] and racemosol E [21β-acetoxy-22α-(2-methylbutyroxy)-olean-12-ene-3β,16α,28-triol, 2] on the basis of extensive spectroscopic data analysis and chemical modifications. In addition, the self-gelating property of isoracemosol A (3) was investigated for the first time, which leads to the unexpected agglomerated porous-like morphology.