Records of Natural Products Articles

From different plant parts of Calotropis species (C. gigantea and C. procera), various classes of compounds such as oxy pregnanes, terpenoids, sterols, cardenolides and flavonoids have been isolated. Of these compounds, the cardenolides stand out as many of them have anticancer properties. Cardenolides are C 23 steroids with a five-membered unsaturated butyrolactone ring consisting of a steroid nucleus, a lactone moiety at C-17 and a sugar moiety at C-3. The roles of cardenolides in the treatment of human cancer have been established as they can induce apoptosis and inhibit the growth of cancer cells. Structure‒activity relationship analyses have yielded some interesting findings on their cytotoxicity. Compounds with six-membered ring sugar groups generally have significantly stronger inhibitory activity than those with five-membered ring sugar groups. A formyl or methyl-hydroxyl group at C-10 enhances cytotoxicity while the presence of a 4´-OH or 16-OH group decreases cytotoxicity. Chemical modification of 2”-oxovoruscharin, a novel cardenolide extracted from the root bark of C. procera, has led to the synthesis of UNBS1450. The compound is characterized by more potent anti-proliferative activity, lower toxicity, and is a strong sodium pump inhibitor and inducer of non-apoptotic cell death. UNBS1450 is currently in Phase I clinical trials.

Along with present study it is designed to examine phenolic compositions, in vitro antioxidant and cytotoxicity activities of methanol and ethyl acetate extracts of Salvia aethiopis L. and S. ceratophylla L. (Lamiaceae) from Turkey. Total phenolic contents of S. aethiopis methanol (SA-ME) and ethyl acetate (SA-EA) extracts were between 94.36±1.36-290.62±1.51 mg GAE/g extract while S. ceratophylla methanol (SC-ME) and ethyl acetate (SC-EA) extracts were between 168.35±1.97-330.14±2.28 mg GAE/g extract. The main phenolic acid of the methanol and ethyl acetate extracts was rosmarinic acid (40.25 and 140.6 µg/100 g plant for S. aethiopis; 74 and 234.5 µg/100 g plant for S. ceratophylla). Phenolic acids of S. aethiopis and S. ceratophylla extracts has much more cinnamic acid derivatives then benzoic acid derivatives. Studied Salvia extracts showed dose-dependent radical scavenging activities. HPLC results allow to make a correlation between antioxidant capacity and quantity of these phenolic acids showed as strongly antioxidant components. It is suggested that to utilize the potential antioxidant properties of these plant extracts, they can be used in safe under 266 µg mL-1, 230 µg mL-1, 150 µg mL-1 and 133.3 µg mL-1 for SC-ME, SA-ME, SA-EA and SC-EA extracts, respectively. The p roliferation of the cells was assessed by the MTT assay. Viability percentage of the extracts was determined relative to controls and measured on 15.6 - 1000 µg mL -1 extract concentrations. IC 50 value of SA-ME extract at 24 hours was 230.0 ± 17.3 and at 48 hours was 93.3 ± 5.8 while 266.7 ± 41.6 (24 h) and 180.0 ± 20.0 (48 h) for SC-ME extract. Toxicities of extracts were decreased in turn, SA-EA>SC-EA>SA-ME>SC-ME. The most toxic extract was SA-EA also with high phenolic contents while SC-ME was the lowest.

In the phytochemical investigation of Buddleja lindleyana , a new 3-acetyl substituted triterpene, 13, 28-epoxy-23-hydroxy-3β-acetoxy-olean-11-ene (1), together with four same skeleton type known compounds (2-5) were isolated. The structure of 1 was elucidated by means of extensive spectroscopic analysis. Their neuroprotective effect against 1-methyl-4 -phenylpyridinium ion-induced (MPP +-induced) neurotoxicity in SH-SY5Y cells were evaluated. The structure activity relationship of compounds 1-5 has been discussed preliminarily.

In the present study, 42 pure monoterpenes and volatile aromatic compounds were tested to evaluate their toxicities against adults of granary weevil, Sitophilus granarius (L.) (Coleoptera: Curculionidae) at laboratory condition. For the insecticidal activity tests, 10 and 20µL/Petri dish concentrations for liquid compounds and 10 and 20µg/Petri dish concentrations for solid compounds were used. The results show that majority of tested compounds were found to be toxic against to the adults of S. granarius and they showed various degrees of toxicity with range of 6–100% mortality. Among the compounds tested, oxygenated monoterpenes, linalool, carvacrol, terpinen-4-ol, limonene oxide, carvone, dihydrocarvone, fenchone, menthone and aromatic volatiles, p-anis aldehyde, benzyl acetate, cinnamyl aldehyde in the current study displayed complete mortality on the pest adults after 24h of exposure. In general, oxygenated monoterpenes and aromatic compounds exhibited high toxicity as compared with monoterpene hydrocarbons. Among the monoterpenes hydrocarbons, the highest toxic effects were shown by γ-terpinene, limonene and β-pinene. Our results showed that linalool, carvacrol, terpinen-4-ol, limonene oxide, carvone, dihydrocarvone, fenchone, menthone, p-anisaldehyde, benzyl acetate and cinnamyl aldehyde were the most toxic compounds against the adults of the pest. Therefore, these compounds can be used as natural insecticides against the S. garanarius adults.

Essential oils and some of their oxygenated constituents are known to possess antimicrobial activity. In the last 30 years, there is a dramatic increase in the number of resistant microorganisms against available antimicrobials and a tendency towards natural products; consequently, scientists have been forced to discover new bioactive agents preferably from nature. As a result of this, so many antimicrobial screening works have been published on plant essential oils including miscellaneous screening methods and several microorganism strains. The aim of this study was to determine the MIC values of 65 monoterpenoids and 3 phenyl propanoids commonly found in essential oils, against 24 pathogenic bacteria and Candida strains, by using standard reference broth dilution methods (CLSI M7-A7 and M27-A2). According to broth microdilution test results, when compared with standard agents, monoterpene hydrocarbons generally showed weak antibacterial effects (>16 to 4 mg/mL) where the oxygenated monoterpenes inhibited the microbial growth between the concentrations of 16 to 0,03 mg/mL. Generally, tested compounds demonstrated better inhibitory effects on Candida strains then the bacteria panel. The most effective microbial growth inhibitor constituents were determined as carvacrol, thymol, cumin alcohol, terpinen-4-ol, α-terpineol, lavandulol, estragol and thymoquinone.

Chemical composition and antimicrobial activity of the hydrodistilled essential oils from aerial parts and roots of Aster subulatus Michx. (Asteraceae) from Turkey were investigated. The essential oils of A. subulatus were analyzed by combination of GC-FID and GC-MS. Twenty-nine components comprising 79.0% of the essential oil of the roots and forty-nine components comprising 89.3% of the essential oil of the aerial parts were identified. The major constituents of the essential oil from the aerial parts were found to be elemol (21.5%), β-eudesmol (6.3%) and caryophyllene oxide (5.2%), while the main components of the root oil were hexadecanoic (33.0%), tetradecanoic (5.3%) and octanoic (4.6%) acids. The antimicrobial activities of the oils were tested against Escherichia coli, Staphylococcus aureus and Candida albicans using a TLC-bioautography method. Both of the oils showed inhibitory activity against S. aureus and C. albicans, while the oils were found to be inactive against tested E. coli strain at 1 mg/mL concentration. This is the first report on the chemical composition and preliminary antimicrobial activity of the essential oils of A. subulatus from Turkey.

Semenovia suffruticosa (Freyn et Bornm.) Manden. is one of the species of genus Semenovia (Apiaceae family). The essential oil of S. suffruticosa was obtained by hydrodistillation and analysed by gas chromatography coupled to mass spectrometry (GC/MS). The main components were cis-β-ocimene (12.9%), linalool (9.5%), γ-terpinene (9.0%) and α-terpinolene (7.4%), representing the 38.8% of the oil. Antibacterial activity of S. suffruticosa ethanol, chloroform, ethyl acetate and aqueous leaf extracts was evaluated for the first time. The various extracts were tested by the disc-diffusion assay for antimicrobial activity against common animal and human infectious bacteria. Pseudomonas aeruginosa exhibited the highest sensitivity against the extracts, with a 13-15 mm zone of inhibition. Antiradical activity of S. suffruticosa ethanol, chloroform, ethyl acetate and aqueous leaf extracts was determined by DPPH (2,2-diphenyl-1-picrylhydrazyl) radical, FRAP (ferric reducing antioxidant power) and β-carotene/linoleic acid assays. Ethanol extract was the most powerful free radical scavenger in all these methods. These results, though preliminary, suggest that leaf extracts of S. suffruticosa exert promising antioxidant and antibacterial activities.

n-H exane extracts of the roots, stems and flowers of Tanacetum zahlbruckneri (Náb.) Grierson (Asteraceae) were analysed for their fatty acid contents by Gas Chromatography–Mass Spectroscopy (GC-MS) method and their antimicrobial and insecticidal activities were evaluated as well. Total FAMEs percentages of the n-hexane extracts were detected as 69.94, 73.72 and 87.29 in the roots, in the stems and in the flowers, respectively. While palmitic acid was found as a major component for roots (26.12 %) and stems (21.28 %), flowers contain 33.78 % of linoleic acid as a major component. Roots and stems also contain considerable amount of α-linoleic acid as 15.30 % and 18.09 %, respectively. Additionally, α-linolenic acid percentage was found as 17.17 in the stems. Single dose screening insecticidal activity tests with Sitophilus granarius (L.) showed that n-hexane root extract has a considerably high bioactivity (83 % mortality at 100 g/L dose after 48 h). While antibacterial activity results ranged between 0.625-1.25 mg/mL for all three extracts, the antifungal activity was observed of the flowers as 0.156 mg/mL, against C. parapsilosis and C. albicans.

Bioassay-guided isolation was used to investigate the antioxidants and α-glucosidase inhibitors from extract of root of Cassia sieberiana. The ethyl acetate fraction demonstrated strong free radical scavenging (DPPH and ABTS +) and potent α-glucosidase inhibition. The subsequent fractionation and purification of the ethyl acetate fraction using silica gel chromatography and Sephadex LH-20, yielded; islandicin (1), chrysophanol (2), physcion (3), emodin (4), quercetin (5), kaempferol (6), dihydrokaempferol (7), and piceatannol (8). Quercetin (5) showed the most active antioxidant activity with IC 50 values of 1.58 mM and 1.30 mM against DPPH and ABTS + radicals, followed by piceatannol (8) with IC 50 values of 3.96 mM and 3.28 mM, which is better than the standard BHT (with IC 50 value 8.93 mM) and trolox (with IC 50 value 8.25 mM), for DPPH and ABTS + radicals scavenging activities, respectively. For the α-glucosidase inhibitory assay, quercetin (5) and piceatannol (8) showed higher potency against α-glucosidase with IC 50 values of 5.73 µM and 7.37 µM respectively, than standard quercetin with IC 50 value of 9.20 µM and acarbose with IC 50 value of 14.12 µM. This study presents the first report on the α-glucosidase inhibitors from root of C. sieberiana and all the compounds are isolated from this source for the first time.

Chemical composition and in vitro antioxidant and anticholinesterase activities of essential oils obtained from leaves and flowers of Pistacia atlantica were studied . GC/GC-MS analyses of the essential oils afforded twenty-two compounds from flower oil and thirty from leaf oil. The antioxidant activity of the essential oils was determined using b -carotene-linoleic acid, DPPH • and ABTS • + -scavenging effects . The essential oils exhibited a good antioxidant activity and inhibited the activity of acetyl- and butyrylcholinesterase.

A new diterpenoid named ganxin casta n ic acid A (1), together with four known diterpenoids (2 − 5 ) and five known phenolic acids (6 − 10 ) were isolated from the roots and rhizomes of S alvia przewalskii Maxim ., and their structure s w ere established on the basis of MS and NMR s pectral analyses.