人参的分析——Ⅳ.人参皂甙的高效液相色谱测定

本文报道了人参中六种主要皂甙(Rb₁,Rb₂,Rc,Rd,Re,Rg)的HPLC测定法,用氨基键合相柱,示差折光检测,流动相为甲醇中乙腈—乙二醇—醋酸铵(0.14 mol/L)(30:70:5:10.6),同时还改进了纯化方法,此法快速、重现性好,与薄层比色法比较结果基本一致。     

Identification of gentamicin impurities by liquid chromatography tandem mass spectrometry

An HPLC/MS/MS method was developed for identification of impurities in gentamicin. The HPLC was performed on a Synergy Hydro-RP column using 50 mM trifluoroacetic acid (TFA), pH 2 adjusted with ammonium solution and methanol as mobile phase. All impurities in gentamicin were separated from main gentamicin components. Atmospheric pressure chemical ionization (APCI) was used and product mass spectra of protonated molecules were acquired. Seventeen impurities were detected in gentamicin. Reference compounds: gentamicins: C_2b, B, B₁, G-418, sisomicin, garamine and gentamines: C₁, C_1a, C₂, C_2a were used for spectra interpretation and impurities identification. All MS/MS spectra were interpreted and fragmentation transitions for gentamicins and in general for aminoglycoside antibiotics (AG) were proposed. All impurities were identified. More than one isomere were proposed for three impurities.     

Control of the composition of gentamicin sulphate by proton magnetic resonance spectrometry

The proportions of the main components present in gentamicin sulphate complex, gentamicins C₁, C_1a and C₂, can be monitored by ¹H nuclear magnetic resonance (nmr) spectrometry. The method depends on measurement of the peak heights of signals for N-methyl and C-methyl groups present in all three components and of those present in C₁ and C₂ only, followed by calculation of peak height ratios to control composition within acceptable limits. The precision and reproducibility of the method have been established through two collaborative studies each involving seven laboratories. In the second study, with an improved procedure, the mean variance between laboratories with 10 samples was 3·4 × 10^?4 for the N-methyl ratio of the peak at δ 2·75 to that at δ 2·95, and 1·25 × 10^?3 for the C-methyl ratio of the peak at δ 1·25 to that at δ 1·35. Within laboratories the mean variance for triplicate determinations was 7·4 × 10^?5 and 8·9 × 10^?5 respectively. The data presented here form the experimental basis for the test controlling the composition of gentamicin sulphate in the British Pharmacopoeia 1973: Addendum 1975, and for the introduction into the British Pharmacopoeia of nmr spectrometry as an analytical technique. The reference standards and all batches of gentamicin sulphate intended for therapeutic use in the United Kingdom examined by this procedure comply with the limits laid down.     

Molecular structural basis of ligand selectivity for 5-HT2 versus 5-HT1C cortical receptors

Summary A molecular structural criterion of ligand selectivity for the 5-HT₂ versus 5-HT_1C receptor was hypothesized on the basis of radioligand binding data. Despite the large number of compounds which have been tested at both receptors, analysis of published data led to the identification of only five agents which are greater than 10-fold selective for the 5-HT₂ versus the 5-HT_1C receptor. Comparison of the two-dimensional structures revealed that, although these five compounds represent three distinct structural classes, they share a common structural feature located in the region hypothesized to be involved in receptor binding: a carbonyl or carboxyl oxygen interposed spatially between an aromatic ring and nitrogen atom. This structural feature was used to predict the relative selectivity of compounds that had not previously been analyzed at both the 5-HT₂ and 5-HT_1C receptors.All six drugs tested which contain the identified reactive carbonyl or carboxyl group were found to be selective for the 5-HT₂ versus the 5-HT_1C receptor with selectivity ratios ranging from 26 to 380. By contrast, three agents which are structurally similar but do not contain the reactive carbonyl or carboxyl group displayed equally high affinity for both receptor binding sites. Since the physiological roles of the 5-HT₂ and 5-HT_1C receptor are markedly different, it would be of potential clinical and scientific value to utilize this molecular structural feature to further identify chemical compounds which would selectively interact with only one of the two receptors. Send offprint requests to S. J. Peroutka at the current address     

Effect of leaf extracts of Vernonia amygdalina on glucose utilization in chang-liver,C2C12 muscle and 3T3-L1 cells

Diabetes mellitus is a chronic disease which affects millions of people worldwide. The prevalence of this disease is increasing annually and the number of diabetics is projected to rise above 300 million before 2025. The growing number of diabetics, coupled with the harsh side effects of some synthetic drugs has led to the increasing search for more natural products of plant origin. Vernonia amygdalina Del. (Asteraceae) is one of the plants commonly used for the treatment of diabetes in Africa. This study evaluated the effect of leaf extracts of this plant on glucose utilization in 3T3-L1, C₂C₁₂ muscle, and Chang-liver cells. Treatment of the cells with the acetone, methanol, water, and n-hexane/isopropanol extracts of V. amygdalina leaves significantly increased glucose utilization in the C₂C₁₂ muscle and Chang-liver cells but showed no effect on the 3T3-L1 cells. The water and n-hexane/isopropanol extracts were the most active in the C₂C₁₂ cells with a response of 78.3 and 95.6% above the control, respectively, while in the Chang-liver cells, water and acetone extracts had a response of 65.8 and 59.6% above the control, respectively. The results, especially of the water extract, strongly corroborate the ethnomedical uses of V. amygdalina as an antidiabetic plant.     

Simplified Synthesis and Stability Assessment of Aflatoxin B1-Lysine and Aflatoxin G1-Lysine

Aflatoxins B₁ (AFB₁) and G₁ (AFG₁) are carcinogenic mycotoxins that contaminate crops such as maize and groundnuts worldwide. The broadly accepted method to assess chronic human aflatoxin exposure is by quantifying the amount of aflatoxin adducted to human serum albumin. This has been reported using ELISA, HPLC, or LC-MS/MS to measure the amount of AFB₁-lysine released after proteolysis of serum albumin. LC-MS/MS is the most accurate method but requires both isotopically labelled and unlabelled AFB₁-lysine standards, which are not commercially available. In this work, we report a simplified synthetic route to produce unlabelled, deuterated and ¹³C₆ ¹⁵N₂ labelled aflatoxin B₁-lysine and for the first-time aflatoxin G₁-lysine. Additionally, we report on the stability of these compounds during storage. This simplified synthetic approach will make the production of these important standards more feasible for laboratories performing aflatoxin exposure studies.     

高效液相色谱法研究国内外制霉菌素的组成

本文用高效液相色谱法分析了国内外12批制霉菌素,其中包括中国和国际标准品。固定相为10 μm ODS,流动相为甲醇—水(68∶32),流速1.3 ml/min,紫外检测波长为304 nm。制霉菌素可分得8～10个色谱峰。分析结果表明中国制霉菌素的主要组分及其相对含量与外国制霉菌素不同。以HPLC法进行分离制备,收集后的单一组分按中国药典一九七七年版进行初步的效价测定,其中一个主要组分的效价比中国制霉菌素标准品高一倍多。     

An examination of the behavioural specificity of hypophagia induced by 5-HT1B, 5-HT1C and 5-HT2 receptor agonists using the post-prandial satiety sequence in rats

Previous studies have shown that administration of 5-HT_1B, 5-HT_1C or 5-HT₂ agonists decreases food intake in rats. However, it has not been established whether these drugs induce satiety or decrease feeding by a non-specific mechanism. In the present study the post-prandial satiety sequence was used to characterise the actions of the 5-HT₂ receptor agonist, 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), the 5-HT_1B/5-HT_1C receptor agonists, 1-(3-chorophenyl) piperazine (mCPP) and 1-[3-(trifluoromethyl)phenyl] piperazine (TFMPP), and the 5-HT_1B agonist, 5-methoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)H-indole (RU 24969), on feeding in rats. All four compounds reduced food intake in rats that had been food deprived overnight. The 5-HT_1B/5-HT_1C agonists, TFMPP (at a dose of 1.0 mg/kg) and mCPP (at a dose of 3.0 mg/kg), appeared to produce satiety as their effects on the satiety sequence were similar to those induced by a food pre-load. In contrast, the 5-HT_1B agonist RU 24969 and the 5-HT₂ agonist DOI did not produce behavioural profiles that resembled satiety. Thus, RU 24969 elevated active behaviours and did not accelerate resting whereas DOI appeared to induce hypophagia by a non-specific fragmentation of behaviour. The results suggest that simultaneous activation of 5-HT_1B and 5-HT_1C receptors may be sufficient to elicit behaviourally specific satiety in the rat. In contrast, selective activation of 5-HT₂ receptors does not induce satiety but elicits active behaviours and decreases feeding by response competition.     

Serotonin 1B and 2C receptor interactions in the modulation of feeding behaviour in the mouse

Rationale To examine the functional relationship between 5-HT_1B receptors (5-HT_1B-R) and 5-HT_2C receptors (5-HT_2C-R) in the control of food intake. Objectives To compare the hypophagic effect of the 5-HT_2C/1B-R agonist m-chlorophenylpiperazine (mCPP), with that of the selective 5-HT_1B-R agonist CP-94,253 in both wildtype (WT) and 5-HT_2C knockout (KO) mice. Methods The hypophagic effects of mCPP (1, 3 and 5.6 mg/kg) and CP-94,253 (5, 10 and 20 mg/kg) were assessed in WT and 5-HT_2C KO mice using the behavioural satiety sequence paradigm. The effects of pre-treatment with the selective 5-HT_2C-R antagonist SB 242,084 (0.5 and 1.5 mg/kg) were assessed in two groups of WT mice, with each group given only mCPP or CP-94,253. Results The 5-HT_2C/1B receptor agonist mCPP and the selective 5-HT_1B receptor agonist CP-94,253 both suppressed food intake in WT mice. 5-HT_2C KO mice were insensitive to the hypophagic effects of mCPP but were more sensitive to CP-94,253-induced hypophagia than WT controls. mCPP induced a significant increase in post-prandial activity in 5-HT_2C KO mice, but this effect was absent in 5-HT_2C KO mice who were given CP-94,253. Data from WT mice, who were pre-treated with the 5-HT_2C receptor antagonist SB 242,084 and then challenged with either mCPP or CP-94,253, were similar to those obtained from 5-HT_2C KO mice. Conclusions 5-HT_2C-R and 5-HT_1B-R activation are each sufficient to induce a hypophagic response. However, concurrent 5-HT_2C-R inactivation can potentiate the hypophagic response to 5-HT_1B-R activation, consistent with an inhibitory role for the 5-HT_2C-R in behaviour mediated by the activation of other 5-HT receptors. These results also confirm that 5-HT_1B-R activation alone cannot account for the hyperactive response of 5-HT_2C KO mice to mCPP.     

5-HT1C receptors in the serotonergic control of periaqueductal gray induced aversion in rats

The functional role of brain 5-HT and 5-HT receptor subtypes in periaqueductal gray (PAG) induced aversion has been investigated in rats. Antiaversive effects were found with the serotonin agonists TFMPP, mCPP and DOI but not with RU 24969 which was found to facilitate PAG aversion. The first three serotonin agonists share potent 5-HT_1C activity while RU 24969 differs with a high 5-HT_1A activity. Proaversive effects were found with the mixed 5-HT_1C/5-HT₂ antagonists cyproheptadine and ritanserin; this effect was already reported for the mixed 5-HT_1C/5-HT₂ antagonists metergoline and mianserin and is opposite to the effects of the selective 5-HT₂ antagonists ketanserin, pirenperone, trazodone and spiperone. The antiaversive effects of mCPP (1 mg/kg) could be prevented by pretreatment of the animals with mianserin (1 and 10 mg/kg). These results suggest that 5-HT_1C receptors play an important role in the serotonergic control of PAG aversion. 5-HT_1C receptor activation seems to mediate antiaversive effects whereas acute 5-HT_1C receptor blockade appears to facilitate PAG aversion. Functional interactions take place between several receptor types in the in vivo control of PAG aversion, where 5-HT_1C receptors appear to play a predominant function.     

5-HT1C receptor-mediated stimulation of inositol phosphate production in pig choroid plexus

Summary 1) 5-HT (5-hydroxytryptamine, serotonin) induces inositol phosphate production in a pig choroid plexus preparation. This effect has been pharmacologically characterized and the data compared to those obtained from radioligand binding studies performed with [³H]mesulergine to 5-HT_1C sites in pig choroid plexus membranes. 2) The rank order of potency of agonists stimulating inositol phosphate production was: -methyl-5-HT > 1-methyl-5-HT > DOI > bufotenine = SKF 83566 = 5-HT > 5-MeO-DMT > 5-MeOT = RU 24969> SCH 23390> 5-CT. 8-OH-DPAT was virtually devoid of activity at 100 mol/l. 3) The increase in inositol phosphate production induced by 5-HT and other agonists was surmountably antagonised by mesulergine, ketanserin and spiperone with pK_B values of 8.7, 6.7 and 5.3, respectively. 4) The rank order of potency of antagonists was: metergoline > mesulergine > LY 53857 > ritanserin > methiothepin > mianserin > cyproheptadine > pirenperone > cinanserin > ketanserin > spiperone. The following antagonists were virtually devoid of activity at 100 mol/l; pindolol, 21-009 and yohimbine. 5) The results obtained both with agonists and antagonists strongly support the view that 5-HT_1C receptors mediate agonist induced production of inositol phosphates in pig choroid plexus. This is illustrated by the close similarity between 5-HT_1C binding and stimulation of inositol phospholipid turnover in this preparation. 6) The present data also show that compounds believed to be selective for dopamine D1 receptors (SKF 83566, SCH 23390) or 5-HT₂ receptors (DOI, -methyl-5-HT, LY 53857, ritanserin, cyproheptadine) also interact with 5-HT_1C receptors. 7) A case can be made for the 5-HT_1C receptor, with its similarities to the 5-HT₂ receptor in terms of pharmacology and second messenger coupling, being a 5-HT₂ receptor subtype.These data have been presented in part at the Spring Meeting of the German Pharmacological Society, March 1987 (Hoyer et al. 1987) Send offprint requests to D. Hoyer at the above address     

Prenylated C6–C3 compounds from the fruits of Illicium simonsii

Two new prenylated C₆–C₃ compounds, 4-epi-illicinone E-12-shikimate (1) and 3-hydroxyillifunone B (2), together with five known prenylated C₆–C₃ compounds (3–7), were isolated from the fruits of Illicium simonsii. Their structures were elucidated on the basis of extensive spectroscopic methods, including 1D and 2D NMR, CD spectra, and ESI-MS analysis.     

Determination of Urinary Biomarkers for Assessment of Short-Term Human Exposure to Aflatoxins in S?o Paulo,Brazil

In the present study, a longitudinal assessment was carried out to evaluate the short-term human exposure to aflatoxins in Pirassununga region, São Paulo, Brazil, by determination of urinary aflatoxins by a liquid chromatography coupled to mass sprectrometry (UPLC-MS/MS) method. Sixteen volunteers with ages ranging from 14 to 55 years old were instructed to collect the early morning first urine four times every three months, from June 2011 to March 2012, totaling 64 samples. Aflatoxin M₁ (AFM₁) was found in 39 samples (61%) at levels ranging from 0.19 to 12.7 pg·mg⁻¹ creatinine (mean: 1.2 ± 2.0 pg·mg⁻¹ creatinine). Residues of aflatoxins B₁, B₂, G₁, G₂ and aflatoxicol were not identified in any urine sample. No significant difference was found among the AFM₁ mean levels in urine samples collected in the four sampling periods. The levels of AFM₁ found in urine samples indicate a low short-term exposure of the population studied to aflatoxins through the diet, although further investigations are needed to assess other long-term biomarkers of exposure to AFB₁.     

Competitive antagonism by recognised 5-HT2 receptor antagonists at 5-HT1C receptors in pig choroid plexus

Summary The effects of several antagonists, known to interact with 5-HT₂ receptors (ritanserin, LY 53857, ICI 169,369, methysergide, mesulergine and ketanserin), were tested against 5-HT-stimulated production of inositol phosphate in pig choroid plexus, a 5-HT_1C receptor model. These antagonists produced dextral shifts of the concentration response curve to 5-HT in a parallel manner, without depressing significantly the maximal response. The following pA₂ values (in parentheses) were obtained: mesulergine (8.88), methysergide (8.85), LY 53857 (8.69), ritanserin (8.69), ICI 169,369 (7.86), and ketanserin (6.57). These pA₂ values were in good agreement with the pK_D values determined in radioligand binding studies performed in pig choroid plexus with [³H]mesulergine. The present data demonstrate that several drugs described as 5-HT₂ receptor selective antagonists (e.g. ritanserin, LY 53857 and ICI 169,369) are also potent, competitive and surmountable antagonists at 5-HT_1C receptors. Thus, the results provide further evidence for the pharmacological similarity of 5-HT_1C and 5-HT₂ receptors. However, in contrast to the situation described with methysergide, ritanserin and LY 53857 in several 5-HT₂ receptor models, none of these antagonists acted in a non-competitive or unsurmountable fashion at 5-HT_1C receptors. These results suggest, but do not firmly rule out, that at least in the presence of the drugs tested in the present study, 5-HT_1C receptors in the choroid plexus do not undergo an allosteric modulation; these findings are apparently in contrast to a model proposed previously for 5-HT₂ receptors (Kaumann and Frenken 1985, Naunyn-Schmiedeberg's Arch Pharmacol 328: 295–300) Send offprint requests to P. Schoeffter at the above address     

Interaction of arylpiperazines with 5-HT1A, 5-HT1B, 5-HT1C and 5-HT1D receptors: do discriminatory 5-HT1B receptor ligands exist?

Summary The effects of several putative 5-HT₁ receptorsubtype selective ligands were investigated in biochemical models for 5-HT_1A, 5-HT_1B, and 5-HT_1D receptors (inhibition of forskolin-stimulated adenylate cyclase activity in calf hippocampus, rat and calf substantia nigra, respectively) and 5-HT_1C receptors (stimulation of inositol phosphates production in pig choroid plexus). Following compounds were studied: 5-HT (5-hydroxytryptamine), TFMPP (1-(mtrifluoromethylphenyl)piperazine), mCPP (1-m-chlorophe-nyl)piperazine, 1 CGS 12066 (7-trifluoromethyl-4-(4-methyl1-piperazinyl)-pyrrolo[1,2-a]quinoxaline 1), isamoltane (CGP 361A, 1-(2-(1-pyrrolyl)-phenoxy)-3-isopropylamino-2-propranol), quipazine, 1-NP (1-(1-naphthyl)piperazine), and PAPP (LY165163, 1-[2-(4-aminophenyl)ethyl]-4-(3-trifluoromethylphenyl)-piperazine). Among reported 5-HT_1B receptor selective drugs, TFMPP had similar potency at 5HT_1A, 5-HT_1B and 5-HT_1C receptors, mCPP did not separate between 5-HT_1B and 5-HT_1C receptors, CGS 12066 was equipotent at 5-HT_1B and 5-HT_1D receptors, and isamoltane was only slightly 5-HTIB versus 5-HT_1A selective. Quipazine showed equal potency at 5-HTIB and 5-HT_1C receptors and 1-NP did not discriminate between the four receptor subtypes. PAPP described as 5-HT_1A receptor selective, was equally potent at 5-HT_1A and 5-HT_1D receptors. The potencies determined in second messenger studies were in good agreement with the affinity values determined in radioligand binding studies. Thus 5-HT_1A, 5-HT_1B, 5-HT_1C and 5-HT_1D receptors have different pharmacological profiles as predicted from radioligand binding studies. Despite claims to the contrary, none of the tested compounds had actual selectivity for a given 5-HT₁ receptor subtype. Of interest were the properties of several of these drugs, which behaved as agonists at some receptors and as antagonists at others (e. g. quipazine, 1-NP, PAPP and isamoltane). Send offprint requests to D. Hoyer at the above address     

Evidence that hypophagia induced bymCPP and TFMPP requires 5-HT1C and 5-HT1B receptors; hypophagia induced by RU 24969 only requires 5-HT1B receptors

Male Sprague-Dawley rats deprived of food for 18 h were injected with the 5-HT agonists RU 24969, 1-(3-chlorophenyl)piperazine (mCPP) or 1-[3-(trifluoromethyl)phenyl)]piperazine (TFMPP) and 20 min later presented with their normal diet. Food intake was determined 1, 2 and 4 h later. All three drugs reduced intake over 1 and 2 h. Three out of four drugs with high affinity for 5-HT_1C receptors (metergoline, mianserin, and mesulergine but not cyproheptadine) opposed hypophagia caused bymCPP. Another drug reported to have high affinity for the 5-HT_1C site, 1-naphthyl-piperazine (1-NP), also blocked the hypophagic response tomCPP at doses which attenuatedmCPP-induced hypolocomotion. Only one of the above drugs (metergoline) which also has high affinity for other 5-HT sites opposed hypophagia caused by RU 24969. Two out of three 5-HT_1B receptor antagonists [(±) cyanopindolol, (−) propranolol, but not (−) pindolol)] which oppose hypophagia caused by RU 24969 (Kennett et al. 1987) also opposed hypophagia caused bymCPP. The 5-HT₂ antagonists ketanserin and ritanserin, the 5-HT₃ antagonist ICS 205-930 and the α₂ adrenoceptor antagonist idazoxan did not oppose the hypophagic effect ofmCPP. In agreement with results formCPP, hypophagia caused by TFMPP was opposed by both, mianserin and (±) cyanopindolol. Given alone, mianserin 1-NP and cyproheptadine but not ICS 205-930 increased food consumption of normally fed rats. The results suggest that RU 24969-induced hypophagia depends on 5-HT_1B receptors but not on 5-HT_1C receptors, whilemCPP (and TFMPP)-induced hypophagia may depend on both receptors. Thus, 5-HT_1C and 5-HT_1B receptors may evoke hypophagia via a common pathway but the effect of antagonists implies that at the doses usedmCPP and TFMPP act predominantly at 5-HT_1C receptors. Since only the hypophagic response tomCPP is blocked by cyanopindolol and (−) propranolol (Kennett and Curzon 1988) it is unlikely to be secondary to hypoactivity induced by the drug.     

Calcineurin inhibits desensitization of cloned rat 5-HT1C receptors

Summary Functional responses to stimulation of rat 5-HT_1C receptors expressed in A9 cells were studied using whole cell voltage clamp recording technique. Stimulation of 5-HT_1C receptors with serotonin (5-HT) evoked calcium-dependent outward currents of 109 pA in cells clamped at — 50 mV. Pretreatment with the protein kinase C (PKC) activator phorbol myristic acetate (PMA) reduced the 5-HT-induced current amplitude by 46% of the control value. Inclusion of inositol triphosphate (IP₃) in the pipette solution induced an outward current of 84 pA. The IP₃-induced response was not affected by 60 min pretreatment with PMA. In the presence of the PKC antagonist calphostin C, 60 min treatment with PMA (10^–6 mol/1) reduced the 5-HT response only by 8%. In cells preincubated with PMA, injection of the calcium/calmodulin dependent serine proteinphosphatase calcineurin gradually increased the 5-HT-induced responses by 34%. In A9 cells which were incubated 24 h with the 5-HT_1C receptor agonist meta chlorophenylpiperazine hydrochloride (mCPP), 5-HT-induced responses were reduced by 23% of the vehicle pretreated control value. Injection of calcineurin in mCPP treated cells enhanced the 5-HT-induced response by 24%.The results suggest that in A9 cells rat 5-HT_1C receptors are desensitized after phosphorylation by PKC. This desensitization can be counteracted by calcineurin-induced: dephosphorylation. Correspondence to H. W. G. M. Boddeke at the above address     

三七总皂甙及三七皂甙C1对实验动物血糖的影响

General saponin is the major effective substance in the fibrous root of Panax notoginseng (Burk) F. H. Chen, and sanchinoside C₁ is the main constitueet of this general saponin. Their effects on blood sugar were Studied on experimental animals. It was found that oral administration of sanehinoside C₁ in mice, was followed, by a slight rise in fasting blood sugar and a fall to normal level in hyperglycemia. But sanchinoside C₁ showed no influence on hyperglycemia induced by adrenalin.General saponin of Panax notoginseng can also raise the fasting blood sugar level in mice and decreases the hyperglycemia in mice and rabbits, but it did not influence on the ability of insulin in reducing blood sugarln rabbits. The effect of this general saporiin differs from sanchinoside C₁ in that the latter increases hyperglycemia induced by adrenalin in mice and rabbits.     

Four new C20-diterpenoid alkaloids from Aconitum rotundifolium

Four new C₂₀-diterpenoid alkaloids, rotundifosines D-G (1–4), along with eight known ones (5–12) were isolated from the whole plant of Aconitum rotundifolium Kar. & Kir. The structures of the compounds were elucidated on the basis of spectroscopic analyses, including HR-ESI-MS and 1D, 2D NMR. Rotundifosine F (3) is a rare C₂₀-diterpenoid alkaloid with quaternary ammonium salt. Alkaloids 1–4, 5, 6, 9, and 12 were evaluated for cytotoxicity against MCF-7, HCT-116 and HepG2 human cancer cell lines.     

Fullerene derivatives induce premature senescence: A new toxicity paradigm or novel biomedical applications

Engineered fullerenes (C₆₀) are extensively used for commercial and clinical applications based on their unique physicochemical properties. Such materials have also been recognized as byproducts of many industrial activities. Functionalization of C₆₀ may significantly influence the nature of its interactions with biological systems, impacting its applications and raising uncertainties about its health effects. In the present study, we compared the bioimpact of two chemically modified fullerene derivatives, hexa carboxyl fullerene adduct (Hexa-C₆₀) and tris carboxyl fullerene adduct (tris-C₆₀) to pristine fullerene C₆₀ encapsulated with gamma (γ)-cyclodextrin C₆₀ (CD-C₆₀), using human cutaneous epithelial cells (HEK) to simulate possible applications and occupational dermal exposure route. We report, for the first time, the discovery of premature senescence as a potential endpoint of nanomaterial elicited biological effects, providing a new paradigm for nanoparticle-induced toxicity in human cells. Moreover, this response appeared to be functionalization specific, in that, only tris-C₆₀ induced senescence. We investigated key biological responses, such as cellular viability, intracellular ROS generation, cell proliferation and cell cycle responses. Our results indicate that the often observed ‘anti-apoptotic’ function of fullerene derivatives may be independent of their ‘ROS scavenging’ role as previously reported. We discovered that the tris-C₆₀-induced responses were associated with G₀/G₁ cell cycle arrest and cellular senescence. On further evaluation of the molecular mechanisms underlying the senescent response, a significant decrease in the expression levels of HERC5 was noted. HERC5 is a ubiquitin ligase of the HERC family and is implicated to be involved in innate immune responses to viral and bacterial infections.