The ethanol extract of propolis from the Vietnamese stingless bee Trigona minor possessed potent preferential cytotoxicity against PANC-1 human pancreatic cancer cells in nutrient-deprived medium, with a PC50 value of 14.0 μg/mL. Chemical investigation of this extract led to the isolation of 15 cycloartane-type triterpenoids, including five new compounds (1–5), and a lanostane-type triterpenoid. The structures of the new compounds were elucidated on the basis of NMR spectroscopic analysis. Among the isolated compounds, 23-hydroxyisomangiferolic acid B (5) and 27-hydroxyisomangiferolic acid (13) exhibited the most potent preferential cytotoxicity against PANC-1 human pancreatic cancer cells under nutrition-deprived conditions, with PC50 values of 4.3 and 3.7 μM, respectively.

From the chloroform extract of the leaves of Uvaria dac, four new highly-oxygenated cyclohexene derivatives named uvaridacols I–L (1–4) were isolated together with nine previously reported compounds (5–13). Their structures were determined based on the extensive NMR spectroscopic data and circular dichroism spectroscopic analysis. Among the new compounds, uvaridacol L (4) displayed strong preferential cytotoxicity in the nutrient deprived medium against five different tested pancreatic cancer cell lines, PANC-1 (PC50, 20.1 μM), PSN-1 (PC50, 9.7 μM), MIA PaCa-2 (PC50, 29.1 μM), Capan-1 (73.0 μM) and KLM-1 (25.9 μM).Download high-res image (104KB)Download full-size image

The chloroform extract of the Japanese cypress Chamaecyparis obtusa was found to kill PANC-1 human pancreatic cancer cells preferentially in the nutrient-deprived medium without causing toxicity in the nutrient rich condition. Phytochemical investigation on this extract led to the isolation of a new sesquiterpene (1), together with the six sesquiterpenes (2–7) and a lignan (8). The isolated compounds were tested for their preferential cytotoxicity activity against five different human pancreatic cancer cell lines [PANC-1, MIA PaCa2, CAPAN-1, PSN-1, and KLM-1] by utilizing an antiausterity strategy. Among them, α-cadinol (2) was identified as the most active constituent. α-Cadinol (2) was found to inhibit the activation of Akt/mTOR pathway, and the hyperactivation of autophagy leading to preferential PANC-1 cell death during nutrient-starvation.Download high-res image (83KB)Download full-size image

•9′-Methoxypinoresinol, calofurfuralside A, and calofurfuralside B were isolated from C. gigantea.•9′-Methoxypinoresinol showed the cytotoxicity against PANC-1 cells with an IC50 value of 3.7 μM.•9′-Methoxypinoresinol significantly inhibited the colony formation of PANC-1 cells.A new lignan, 9′-methoxypinoresinol (1), and two new glycosylated 5-hydroxymethylfurfurals, calofurfuralside A (2), and calofurfuralside B (3), together with nine known compounds (4–12) have been isolated from the active fractions, CHCl3 (IC50, 0.32 μg mL−1) and EtOAc (IC50, 0.55 μg mL−1) fractions of the leaves of Calotropis gigantea. Their structures were elucidated based on NMR and MS data. Among the isolated compounds, compounds 1 and 9 exhibited potent cytotoxicity against PANC-1 human pancreatic cancer cell line under the normoglycemic condition with IC50 values of 3.7 and 3.3 μM, respectively. 9′-Methoxypinoresinol (1) significantly inhibited the colony formation of PANC-1 cells in a concentration-dependent manner.Download high-res image (129KB)Download full-size image

A striking feature of the metabolite profile of Ancistrocladus likoko (Ancistrocladaceae) is the exclusive production of 5,8′-linked naphthylisoquinoline alkaloids varying in their OMe/OH substitution patterns and in the hydrogenation degree in their isoquinoline portions. Here we present nine new compounds of this coupling type isolated from the twigs of this remarkable Central African liana. Three of them, the ancistrolikokines E (9), E2 (10), and F (11), are the first 5,8′-linked naphthyldihydroisoquinolines found in nature with R-configuration at C-3. The fourth new metabolite, ancistrolikokine G (12), is so far the only representative of the 5,8′-coupling type that belongs to the very rare group of alkaloids with a fully dehydrogenated isoquinoline portion. Moreover, five new N-methylated naphthyltetrahydroisoquinolines, named ancistrolikokines A2 (13), A3 (14), C2 (5), H (15), and H2 (16) are presented, along with six known 5,8′-linked alkaloids, previously identified in related African Ancistrocladus species, now found for the first time in A. likoko. The structural elucidation was achieved by spectroscopic analysis (HRESIMS, 1D and 2D NMR) and by chemical (oxidative degradation) and chiroptical (electronic circular dichroism) methods. The new ancistrolikokines showed moderate to good preferential cytotoxic activities towards pancreatic PANC-1 cells in nutrient-deprived medium (NDM), without causing toxicity under normal, nutrient-rich conditions, with ancistrolikokine H2 (16) being the most potent compound.

Human pancreatic cancer cell lines have a remarkable tolerance to nutrition starvation, which enables them to survive under a tumor microenvironment. The search for agents that preferentially inhibit the survival of cancer cells under low nutrient conditions represents a novel antiausterity strategy in anticancer drug discovery. In this investigation, a methanol extract of the rhizomes of Boesenbergia pandurata showed potent preferential cytotoxicity against PANC-1 human pancreatic cancer cells under nutrient-deprived conditions, with a PC50 value of 6.6 μg/mL. Phytochemical investigation of this extract led to the isolation of 15 compounds, including eight new cyclohexene chalcones (1–8). The structures of the new compounds were elucidated by NMR spectroscopic data analysis. Among the isolated compounds obtained, isopanduratin A1 (14) and nicolaioidesin C (15) exhibited potent preferential cytotoxicity against PANC-1 human pancreatic cancer cells under nutrition-deprived conditions, with PC50 values of 1.0 and 0.84 μM, respectively.

Human pancreatic cancer cell lines such as PANC-1 have an altered metabolism, enabiling them to tolerate and survive under extreme conditions of nutrient starvation. The search for candidates that inhibit their viability during nutrition starvation represents a novel antiausterity strategy in anticancer drug discovery. A methanol extract of the bark of Mangifera indica was found to inhibit the survival of PANC-1 human pancreatic cancer cells preferentially under nutrient-deprived conditions with a PC50 value of 15.5 μg/mL, without apparent toxicity, in normal nutrient-rich conditions. Chemical investigation on this bioactive extract led to the isolation of 19 compounds (1–19), including two new cycloartane-type triterpenes, mangiferolate A (1) and mangiferolate B (2). The structures of 1 and 2 were determined by NMR spectroscopic analysis. Among the isolated compounds, mangiferolate B (2) and isoambolic acid (12) exhibited potent preferential cytotoxicity against PANC-1 human pancreatic cancer cells under the nutrition-deprived condition with PC50 values of 11.0 and 4.8 μM, respectively.

•Chemical constituents of the seed kernel of Caesalpinia sappan were investigated.•Eight cassane diterpenes named tomocins A–H were isolated and structurally characterized.•Tomocins showed anti-austerity activity against PANC-1 human pancreatic cancer cells.•Potential use of tomocins as lead structures for anti-austerity drug development.Eight structurally diverse cassane diterpenes named tomocins A–H were isolated from the seed kernels of Vietnamese Caesalpinia sappan Linn. Their structures were determined by extensive NMR and CD spectroscopic analysis. Among the isolated compounds, tomocin A, phanginin A, F, and H exhibited mild preferential cytotoxicity against PANC-1 human pancreatic cancer cells under nutrition-deprived condition without causing toxicity in normal nutrient-rich conditions.

Series of 2-pyridineformamide thiosemicarbazones were synthesized. Their preferential cytotoxicity in nutrient deprived medium (NDM) was evaluated using PANC-1 human pancreatic cancer cells by employing an antiausterity strategy. 2-Pyridineformamide thiosemicarbazones induced apoptosis and exhibited preferential cytotoxic activity toward PANC-1 cells in NDM, with potencies in the submicromolar range. These compounds are potential candidates for the development of therapeutics against pancreatic cancer.

Human pancreatic cancer cell lines are known for their inherent tolerance to nutrition starvation, which enables them to survive under a hypovascular (austerity) tumor microenvironment. The search for agents that preferentially retard the survival of cancer cells under low nutrition conditions (antiausterity agent) is a novel approach to anticancer drug discovery. In this study, it was found that a dichloromethane extract of the stem of Uvaria dac preferentially inhibited PANC-1 human pancreatic cancer cells survival under nutrition-deprived conditions at a concentration of 10 μg/mL. Workup of this bioactive extract led to the discovery of (+)-grandifloracin (8) as a potent antiausterity agent as evaluated in a panel of four human pancreatic cancer cell lines, PANC-1 (PC50, 14.5 μM), PSN-1 (PC50, 32.6 μM), MIA PaCa-2 (PC50, 17.5 μM), and KLM-1 (32.7 μM). (+)-Grandifloracin (8) has been isolated from a natural source for the first time. Its absolute stereochemistry was established by single-crystal X-ray crystallography and circular dichroism spectroscopic analysis. In addition to this, seven other new highly oxygenated cyclohexene derivatives, named uvaridacanes A (1) and B (2), uvaridacols A–D (3, 4, 6, 7), and uvaridapoxide A (5), were also isolated and structurally characterized.

Chemical investigation of the stems of Uvaria dac yielded four new highly oxygenated cyclohexene derivatives named uvaridacols E–H (1–4). Their structures were established through NMR and circular dichroism spectroscopic analysis. Uvaridacols E (1), F (2), and H (4) displayed weak preferential cytotoxicity against PANC-1 human pancreatic cancer cells under nutrition-deprived conditions in a concentration-dependent manner, without causing toxicity in normal nutrient-rich conditions.