Phytochemical analysis and antioxidant potential of the leaves of Garcinia travancorica Bedd.

Phytochemical analysis of the leaves of Garcinia travancorica, a hitherto uninvestigated endemic species to the Western Ghats of south India, resulted in isolation and characterisation of the polyisoprenylated benzophenones 7-epi-nemorosone (1) and garcinol (2) along with biflavonoids GB-1a (3), GB-1 (4), GB-2 (5), morelloflavone (6) and morelloflavone-7″-O-β-d-glycoside or fukugiside (7). The compounds were identified using various spectroscopic techniques, mainly through NMR and MS. The methanol extract and the biflavonoids 3, 4, 5 and 7 showed potential in vitro antioxidant activities. The IC₅₀ value of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of compound 7 was 8.34 ± 2.12 μg/mL, comparable to that of standard ascorbic acid (3.2 ± 0.50 μg/mL). In the superoxide radical scavenging assay, compound 7 gave IC₅₀ value of 6.95 ± 1.33 μg/mL close to standard ascorbic acid with IC₅₀ value of 5.8 ± 0.25 μg/mL. Validated HPTLC estimation revealed G. travancorica as a rich source of morelloflavone-7″-O-β-d-glycoside (7.12% dry wt. leaves).     

Neolignan and phenylpropanoid compounds from the fruits of Illicium simonsii Maxim

One new sesqui-neolignan compound, namely, sesqui-illisimonan A (1), one new neolignan, illisimonan A (2), and one new phenylpropanoid compound, illisimoid A (3) were isolated from the fruits of Illicium simonsii Maxim. The structures and absolute configurations of these compounds were determined by extensive spectroscopic, including NMR, circular dichroism and calculated electronic circular dichroism methods. The antioxidant activities of compounds 1–3 were also evaluated. Vitamin E was selected as the positive control (IC₅₀ = 49.73 ± 0.88 μM). Compounds 1 and 2 exhibited in vitro antioxidant activity with an IC₅₀ value of 55.76 ± 1.30 and 59.36 ± 0.50 μM, respectively. However, the compound 3 didn’t show obvious antioxidant activity.     

Structure activity relationship of bergenin,p-hydroxybenzoyl bergenin, 11-O-galloylbergenin as potent antioxidant and urease inhibitor isolated from Bergenia ligulata

Ethanol extract of the aerial parts of Bergenia ligulata was subjected to solvent–solvent separation followed by various chromatographic techniques that lead to isolation of bergenine (1), p-hydroxybenzoyl bergenin (2), 11-O-galloylbergenin (3) and methyl gallate (4) as major constituents. Ethyl acetate fraction showed a dose-dependent urease inhibitory pattern with IC₅₀ value of 54μg/mL. Structures of compounds 1 and 3 were established by XRD and 2, 4 by NMR. All these compounds were subjected to DPPH scavenging activity, reducing power assay and urease inhibitory activity. The EC₅₀ 7.45 ± 0.2 μg/mL and 5.39 ± 0.28 μg/mL values in terms of antioxidant and reducing power, respectively, were less for 3. Compounds 1–3 showed moderate to significant urease inhibitory potential with IC₅₀ 57.1 ± 0.7, IC₅₀ 48.4 ± 0.3 and 38.6 ± 1.5. Antioxidant activities and urease inhibitory potential were investigated and compound 3 was found to be the most active.     

Officinalioside,a new lignan glucoside from Borago officinalis L.

A new lignan glucoside, officinalioside (1), was isolated from n-BuOH fraction of the aerial parts of Borago officinalis L., together with four known compounds: actinidioionoside (2), roseoside (3), crotalionoside C (4) and kaempferol 3-O-β-D-galactopyranoside (5). The structure of the new compound was established by means of spectroscopic and chemical analyses. Compounds 1 and 2 showed a moderate DPPH radical scavenging activity (IC₅₀: 52.6 ± 1.70 and 41.3 ± 0.25 μM, respectively) comparable with that of the standard trolox (16.6 ± 2.2 μM) without any significant cytotoxicity towards human cell line A549 (IC₅₀ > 100 μM).     

New C20-gibberellin diterpene from the leaves of Schefflera sessiliflora De P. V.

From the leaves of Schefflera sessiliflora De P. V., one new C₂₀-gibberellin diterpene 2β,12β-dihydroxygibberellin (12β-hydroxy-GA₁₁₀ or 2β-hydroxy-GA₁₁₂) (1), together with three known compounds, trans-tiliroside (2), kaempferol 3-O-β-d-glucuronopyranoside (3), 5-p-trans-coumaroylquinic acid (4), was isolated for the first time from the genus Schefflera by various chromatography methods. Their structures were elucidated by IR, UV, HR-ESI-MS, NMR 1D and 2D experiments and comparison with previous reported data. The α-glucosidase inhibitory activity of all compounds was measured. The isolates (2, 3) showed better α-glucosidase inhibitory activity (IC₅₀ = 134.60, 147.10 μM, respectively) than the standard drug acarbose (IC₅₀ = 214.50 μM).     

A new rearranged abietane diterpene from Clerodendrum inerme with antioxidant and cytotoxic activities

Eight compounds were isolated from the leaves of Clerodendrum inerme, including one new rearranged abietane diterpene, crolerodendrum B (1). Their structures were determined by means of spectroscopic methods including one-dimensional and two-dimensional nuclear magnetic resonance (1-D and 2-DNMR), high-resolution electrospray ionisation mass spectrometry (HR-ESI-MS) and circular dichroism (CD). The DPPH radical scavenging and cytotoxic activities of isolated compounds against MCF7 (breast), HCT116 (colon) and B16F10 (melanoma) cancer cell lines were evaluated. Compounds 1, 3 and 4 exhibited strong DPPH radical-scavenging effects (ED₅₀ values of 17.6 ± 2.1, 10.1 ± 0.8 and 11.3 ± 0.3 μM, respectively) and 4 showed strong cytotoxicity against the HCT116 cell line (IC₅₀ = 3.46 ± 0.01 μM).     

New flavonoid and pentacyclic triterpene from Sesamum indicum leaves

Two new and one known compounds were isolated from the methanol extract of Sesamum indicum leaves. By means of spectroscopic methods, their structures were elucidated and identified to be 3-epibartogenic acid (1), kaempferol 3-O-[2-O-(trans-p-coumaroyl)-3-O-α-L-rhamnopyranosyl]-β-d-glucopyranoside (2) and epigallocatechin (3). Compound 1 and 3 strongly inhibited α-amylase with the IC₅₀ values of 146.7 and 303.9 μM, respectively, in comparison with acarbose (IC₅₀ 124.0 μM).     

Bioactive constituents from Croton sparsiflorus Morong

Whole plant extracts of Croton sparsiflorus in methanol have shown significant enzyme inhibition and antioxidant activities. Bioassay-guided isolation of chloroform fraction at pH 3 resulted in the identification of crotsparinine (1) and crotsparine (2), while sparsiflorine (3) was purified from the chloroform fraction at pH 9. The structures of the compounds were confirmed through spectral analyses (EI-MS, ¹H and ¹³C NMR). The isolated compounds 1–3 exhibited remarkable enzyme inhibition activity with IC₅₀ values 27.01 ± 1.1, 22.26 ± 1.0 and 18.02 ± 1.3 μM in xanthine oxidase and 48.42 ± 1.5, 48.05 ± 1.4 and 7.42 ± 1.0 μM in acetylcholine esterase assays, respectively. These compounds also showed potent radical scavenging and reducing properties in DPPH and FRAP assays, respectively. The present results suggest the validity of the traditional uses of C. sparsiflorus in rheumatism and gout. Furthermore, the isolated noraporphine alkaloids can be useful in the treatment of neurodegenerative diseases.     

Polyphenolic compounds from Malus hupehensis and their free radical scavenging effects

One new 4-chromanone glycoside, 5-O-β-d-glucopyranoside-4-chromanone (1), together with 21 known polyphenols, was isolated from the leaves of Malus hupehensis. Their structures were elucidated on the basis of extensive spectroscopic methods including NMR (1D and 2D), mass (ESIMS and HRESIMS), IR, and by comparison with the data reported in the literature. Some of the isolated compounds were screened for antioxidant activity. Compounds 18 and 14 exhibited significant antioxidant activities with SC₅₀ values 2.73 and 2.91 μg/mL, respectively, while 17, 19, 11, 7, 20, 22, 12 and 13 exhibited moderate activities with SC₅₀ values ranging from 5.24–11.86 μg/mL. The HPLC fingerprint profiles of the leaves and fruits extracts were also analysed, which showed that the constituents were almost the same in both the extracts except for the content of phlorizin which was present in higher amount in the leaves.     

Three new biflavonoids from the branches and leaves of Cephalotaxus oliveri and their antioxidant activity

Three new biflavonoids, named oliveriflavones A-C (1–3), together with two known flavonoids (quercetin (4) and rutin (5)), were isolated from the endangered plant Cephalotaxus oliveri. The chemical structures of these compounds were elucidated by comprehensive spectroscopic methods including NMR, HRESIMS, IR, UV, and CD spectra. Compounds 1–5 were first isolated from the genus Cephalotaxus. All the compounds were tested for their antioxidant activity. Compounds 4 and 5 showed excellent activity with IC₅₀ values of 0.03 ± 0.06 μM and 0.02 ± 0.10 μM, respectively.     

Triterpene tetraglycosides from the sea cucumber Stichopus horrens

Using various chromatographic separations, three triterpene tetraglycosides (1–3), including one new compound, namely stichorrenoside E (1) along with thelenotoside B (2) and deacetyl thelenotoside B (3), were isolated from the MeOH extract of the Vietnamese sea cucumber Stichopus horrens. Their structures were confirmed by spectroscopic experiments, such as 1D and 2D NMR and HR-ESI-MS. Deacetylated thelenotoside B (3) is firstly isolated as a natural product. Among these compounds, thelenotoside B (2) showed strong cytotoxicities against five human cancer cell lines as HepG2, KB, LNCaP, MCF7 and SK-Mel2 with the IC₅₀ values from 0.95 ± 0.08 to 1.90 ± 0.13 μM, whereas stichorrenoside E (1) and deacetyl thelenotoside B (3) exhibited significant activities with the IC₅₀ values from 6.87 ± 0.25 to 11.62 ± 1.05 μM.     

Cytotoxic triterpene saponins from the mangrove Aegiceras corniculatum

Using various chromatographic separations, sixteen compounds, including one new triterpene saponin named aegicoroside A (1), were isolated from the leaves of the Vietnamese mangrove Aegiceras corniculatum. Their structures were determined by spectroscopic methods such as 1D and 2D NMR and HR-ESI-MS. The cytotoxic activities of the isolated compounds against MCF7 (breast), HCT116 (colon), B16F10 (melanoma), and A549 (adenocarcinoma) cancer cell lines were also evaluated. Strong cytotoxicity was observed for sakurasosaponin (2) against all four cancer cell lines and for sakurasosaponin methyl ester (3) against MCF7, A549, and HCT116 cell lines with IC₅₀ values ranging from 2.89 ± 0.02 to 9.86 ± 0.21 μM.     

Hepatoprotective and neuroprotective tocopherol analogues isolated from the peels of Citrus unshiu Marcovich

Three tocopherol analogues methoxytocopherol (1), α-tocopherol (2) and γ-tocopherol (3) were isolated from the peels of Citrus unshiu Marcovich. The protective effects of the isolated compounds against tert-butyl hydroperoxide-induced hepatotoxicity in human liver-derived HepG2 cells and glutamate-induced oxidative stress in HT22-immortalised hippocampal cells were evaluated. Compounds 1–3 were significantly protective in HepG2 cells with EC₅₀ values of 21.22 ± 2.01, 25.21 ± 2.11 and 25.25 ± 1.21 μM, respectively, and in HT22 cells, compounds 1–3 had EC₅₀ values of 20.62 ± 1.36, 6.44 ± 1.65 and 9.52 ± 1.54 μM, respectively.     

Triterpenoid saponins from the buds of Lonicera similis

Four new lupane triterpenoid saponins, along with one known lupane and eight hederagenin saponins, were isolated from the EtOH extract of the buds of Lonicera similis Hemsl. The structures of the new compounds were established as 3-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl 23-hydroxybetulinic acid 28-O-β-D-glucopyranosyl ester (lonisimilioside A, 1), 3-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl 23-hydroxybetulinic acid 28-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl ester (lonisimilioside B, 2), 3-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl betulinic acid 28-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl ester (lonisimilioside C, 3) and 3-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl betulinic acid 28-O-β-D-glucopyranosyl ester (lonisimilioside D, 4), respectively. The cytotoxic activities of the isolates against human cancer cell lines HepG2, MCF-7 and A-549 were evaluated. Only the monodesmosidic saponin with a free carboxyl group at C-28 (12) exhibited significant cytotoxicities against HepG2, MCF-7 and A-549 cell lines with the IC₅₀ values of 8.98 ± 0.19, 12.48 ± 0.45 and 11.62 ± 0.54 μM, respectively. Furthermore, Hoechst fluorescence 33342 staining was used to demonstrate that 12 could induce HepG2 and A-549 cells apoptosis significantly.     

Acetylcholinesterase inhibitory active metabolites from the endophytic fungus Colletotrichum sp. YMF432

An endophytic fungus, Chaetomium sp. YMF432, was isolated from Huperzia serrata (Thunb. ex Murray) Trev. and subjected to phytochemical investigation based on its special environment. From the extracts of fermentation solid of strain YMF 432, eight compounds including 1-O-methylemodin (1), 5-methoxy-2-methyl-3-tricosyl-1,4-benzoquinone (2), 4,8-dihydroxy-1-tetralone (3), (3β,5α,6α, 22E)-3-hydroxy-5,6-epoxy-7-one-8(14),22-dien-ergosta (4), ergosta-4,6,8(14),22-tetraen-3-one (5), β-sitostenone (6), β-sitosterol (7) and (22E,24R)-ergosta-5,7,22 -trien-3β-ol (8) were obtained. Their structures were elucidated on the basis of their spectroscopic data. These compounds were evaluated for acetylcholinesterase inhibitory activities in vitro. Compounds 1, 2, and 4 showed moderate acetylcholinesterase inhibitory activities (IC₅₀ from 37.7 ± 1.5 to 370.0 ± 2.9 μM).     

Synthesis and antiproliferative activities of thioxoflavonoids on three human cancer cells

Two series of fifteen novel thioxoflavonoids 2a-2h and 4a-4g were synthesized from corresponding flavonoids 1a-1h and 3a-3g by reacting with Lawesson’s reagent, respectively. Their in vitro antiproliferative activities were evaluated on a panel of three human cancer cell lines (Hela, HCC1954 and SK-OV-3) using cell counting kit-8 (CCK-8) assay. The results showed that most of the target compounds exhibited moderate to good antiproliferative activities against the three human cancer cell lines. In particular, thioxoflavonoids 2f and 2g showed the strongest antiproliferative activity on all three human cancer cell lines with IC₅₀ values ranging from 3.34 to 4.67 μM, 4f showed the best antiproliferative activity on Hela cells (IC₅₀ 2.30 μM), 2e showed the best antiproliferative activity on HCC1954 cells (IC₅₀ 2.13 μM) and SK-OV-3 cells (IC₅₀ 2.33 μM). The antiproliferative activities may be involved in their antioxidant activity, which can be speculated by their ability to scavenge free radicals and by their capacity of affecting key redox enzymes.     

New cytotoxic isoprenoid derivatives from the Red Sea soft coral Sarcophyton glaucum

Chemical investigation of the soft coral Sarcophyton glaucum collected from the Red Sea led to isolation of 11 isoprenoidal metabolites (1–11). A new sesquiterpenoid, 6-oxo-germacra-4(15),8,11-triene (1), a new natural cembranoid, sarcophinediol, along with two known sesquiterpenoids (2 and 3) and seven known cembranoids (5–11) was obtained. The structures of the compounds were established based on their NMR, MS, IR and UV spectral data. All compounds were evaluated for their cytotoxicity employing three cancer cell lines (HepG2, MCF-7 and HCT116). Compounds 4 and 6 showed significant cytotoxicity towards HepG2 with IC₅₀ values of 18.8 ± 0.07 and 19.9 ± 0.02 μM; respectively. Compounds 5–7 exhibited potent cytotoxicity against MCF-7 cells with IC₅₀ values of 9.9 ± 0.03, 2.4 ± 0.04 and 3.2 ± 0.02 μM, respectively. Compounds 1, 4 and 5 showed significant activities towards HCT116 cells with IC₅₀ values of 29.4 ± 0.03, 19.4 ± 0.02 and 25.8 ± 0.03 μM, respectively.     

A new triterpenoid saponin from Gleditsia sinensis and its antiproliferative activity

Chemical investigation of the anomalous fruits of Gleditsia sinensis led to the isolation and identification of a new triterpenoid saponin, 3-O-β-D-xylopyranosyl-(1 → 2)-α-L-arabinopyranosyl-(1 → 6)-β-D-glucopyranosyl oleanolic acid 28-O-β-D-xylopyranosyl-(1 → 4)-α-L-rhamnopyrano--syl-(1 → 4)-β-D-xylopyranosyl-(1 → 4)-α-L-rhamnopyranosyl-(1 → 3)-β-D-glucopyranosyl ester (1), along with other nine known compounds (2–10). All the isolates from this species were reported for the first time. The structure of Compound 1 was determined by a detailed analysis using various analytical techniques, including 1D and 2D NMR. In vitro antiproliferative activities of Compound 1 on MCF-7 and Hep-G2 tumor cell lines were evaluated. IC₅₀ values against the two cell lines were 9.5 and 11.6 μM, respectively.     

Antileishmanial diterpenoid alkaloids from Aconitum spicatum (Bruhl) Stapf

The crude extracts of tubers of Aconitum spicatum (Bruhl) Stapf were investigated for in vitro antileishmanial activity against Leishmania major. The dichloromethane extract at pH 2.5 showed antileishmanial activity with IC₅₀ value of 27.10 ± 0.0 μg/mL. Chromatographic purification of the dichloromethane extract led to isolation of three C-19 norditerpenoid alkaloids indaconitine (1), chasmaconitine (2) and ludaconitine (3). Compounds 3 and 2 showed antileishmanial activity with IC₅₀ = 36.10 ± 3.4 and 56.30 ± 2.1 μg/mL, respectively. Compound 1 was less effective (IC₅₀ > 100 μg/mL). The cytotoxicity of compounds 1, 2 and 3 studied against MCF7, HeLa and PC3 cancer cell lines and 3T3 normal fibroblast cell line did not show cytotoxicity at 30 μM.