A Synergistic Botanical Composition Increases Resting Energy Expenditure and Reduces Adiposity in High-Fat Diet-Fed Rats

OBJECTIVE

An imbalance between dietary energy intake and energy expenditure may result in body fat gain or obesity. Increasing resting energy expenditure (REE) is an attractive strategy for managing body fat gain. The objective of the current study was to generate proof-of-concept data on a synergistic composition (LN19183) of Citrus aurantifolia fruit rind (CA) and Theobroma cacao seed (TC) extracts to increase REE and reduce body fat gain in a high-fat diet (HFD)-fed rats.

METHOD

In in vitro cell-based experiments, CA, TC, or LN19183 were tested for fibroblast growth factor 21 (FGF-21) production from 3T3-L1 mouse adipocytes. Uncoupling protein 1 (UCP-1) and beta3-adrenergic receptor (β3-AR) protein expressions in LN19183-treated 3T3-L1 lysates were also tested. The 56-day in vivo study in male Sprague Dawley (SD) rats (age: 12-14 weeks; body weight [b.w.]: 115-197 g) contained 2 phases of 28 days each of induction and supplementation. Seven rats received a regular rodent diet (RD) over 56 days. In the induction phase, 21 rats received HFD; in the supplementation phase, the obese rats (n = 7) received either HFD alone or in concurrence with a daily oral dose of either 100 or 250 mg/kg b.w. of LN19183 for 28 days.

RESULTS

In 3T3-L1 adipocytes, LN19183 synergistically increased FGF-21 production and dose-dependently increased β3-AR and UCP-1 protein expression. In HFD-fed rats, both doses of LN19183 supplementation significantly (p < 0.05) decreased the body weight gain, total fat mass, and liver weight and increased (p < 0.05) REE. High-dose LN19183 also significantly (p < 0.05) increased fat oxidation and UCP-1 protein expression in white fat tissue and reduced liver triglyceride (TG) level. LN19183-supplemented groups substantially reduced serum TG and glucose levels compared to the HFD rats.

CONCLUSIONS

LN19183 reduces body fat mass and weight gain via increased REE and fat oxidation in HFD-fed obese rats.

A synergistic blend of Garcinia mangostana fruit rind and Cinnamomum tamala leaf extracts enhances myogenic differentiation and mitochondrial biogenesis in vitro and muscle growth and strength in mice

Background

A proprietary combination of Garcinia mangostana fruit rind and Cinnamomum tamala leaf extracts (LI80020F4, CinDura®) improved the physical performance and muscle strength of resistance-trained adult males.

Objective

This study assessed the underlying mechanisms of the ergogenic potential of LI80020F4 in in vitro and in vivo models.

Methods

The individual extracts and their combination (LI80020F4) were assessed for nitrite production in EAhy926 human endothelial cells. Subsequent experiments evaluated the effect of LI80020F4 in myotube formation in C2C12 mouse myoblasts, expression of mammalian target of rapamycin (mTOR) signaling proteins, myogenic factors, and mitochondrial functions in L6 rat myoblasts.Moreover, adult male ICR mice were randomly assigned (n = 15) into vehicle control (G1), exercise alone (G2), oxymetholone-16 mg/kg body weight (bw) (G3), and 75 (G4)-, 150 (G5)-, or 300 (G6) mg/kg bw of LI80020F4, orally gavaged for 28 days. G1 and G2 mice received 0.5% carboxymethylcellulose sodium. Following completion, muscle strength and physical performance were assessed on forelimb grip strength and forced swimming test (FST), respectively. Gastrocnemius (GA), tibialis anterior (TA) muscle weights, muscle fiber cross-sectional area (CSA), levels of muscle, and serum protein markers were also determined.

Results

LI80020F4 increased nitrite production in EAhy926 cells in a dose-dependent manner. LI80020F4 induced C2C12 myotube formation, increased mitochondrial biogenesis, upregulated the expressions of activated mTOR and other mitochondria and myogenic proteins, and mitigated H2O2-induced mitochondrial membrane depolarization in the myoblast cells. In the animal study, 75, 150, and 300 mg/kg bw LI80020F4 doses significantly (P < 0.05) increased the animals' forelimb grip strength. Mid- and high-dose groups showed increased swimming time, increased muscle weight, CSA, muscle growth-related, and mitochondrial protein expressions in the GA muscles.

Conclusion

LI80020F4 increases nitric oxide production in the endothelial cells, mitochondrial biogenesis and function, upregulates skeletal muscle growth-related protein expressions and reduces oxidative stress; together, it explains the basis of the ergogenic potential of LI80020F4.

Safety assessment of a novel water-soluble extract of Boswellia serrata gum resin: acute toxicity, 90-day sub-chronic toxicity, Ames' bacterial reverse mutation, and in vivo micronucleus assays

Boswellia serrata gum resin extracts have demonstrated potential benefits in alleviating joint pain and discomfort of osteoarthritis. The major objective of the present study was to assess the safety of a water-soluble B. serrata gum resin extract (LI51202F1) in diverse models of acute oral, acute dermal, primary dermal irritation, eye irritation, and 90-day sub-chronic repeated dose toxicity studies, as well as Ames' bacterial reverse mutation assay and in vivo micronucleus assay. The acute oral and dermal toxicity studies in Sprague Dawley (SD) rats demonstrated that the median lethal dose (LD₅₀) of LI51202F1 is >2000 mg/kg body weight (BW). The acute dermal and eye irritation tests in New Zealand white rabbits exhibited that LI51202F1 is non-irritating to the skin and mildly irritating to the eyes, respectively. The 90-days sub-chronic repeated oral dose study demonstrated that the LI51202F1-treated male and female SD rats did not show signs of toxicity on their BW, food intake, organ weights, thyroid hormones, and on the clinical pathology, gross pathology, and histopathological assessments. In male and female rats, the no-observed-adverse-effect level (NOAEL) of LI51202F1 was 500 mg/kg/day, the highest tested dose in the study. The results of the bacterial reverse mutation assay in Salmonella typhimurium TA98, TA100, TA1535, TA1537, and Escherichia coli WP2uvrA (pKM101) strains in the presence or absence of S9 metabolic activation system and a micro-nucleus assay in mouse bone marrow erythrocytes demonstrated that LI51202F1 is neither mutagenic nor clastogenic. In conclusion, under the conditions of these studies, LI51202F1 demonstrated broad-spectrum safety.

Combined extracts of Moringa oleifera, Murraya koeingii leaves, and Curcuma longa rhizome increases energy expenditure and controls obesity in high-fat diet-fed rats

Background

LI85008F is a proprietary combination of leaf extracts of Moringa oleifera, Murraya koeingii, and extract of Curcuma longa rhizome. This herbal extract combination is an effective weight loss supplement for overweight and obese subjects. The present study aimed to investigate the thermogenic potential of the LI85008F in high-fat diet (HFD)-induced obese Sprague Dawley rats.

Methods

Seven rats received a regular diet (RD), and twenty-one rats received a high-fat diet (HFD) for 56 days. On day 28, the HFD-fed rats were randomized into three groups (n = 7). Starting from day 29 through day 56, one HFD-fed group received daily oral gavage of 0.5% Carboxymethylcellulose Sodium (CMC) alone (HFD), and the remaining two groups received 100 and 250 mg/kg LI85008F (LI85008F-100 and LI85008F-250, respectively).

Body weight, fat mass, fat cell size, liver weight, liver triglyceride were measured. The energy metabolism parameters were measured using indirect calorimetry. In serum, the metabolic and endocrine markers were analyzed. The adipogenic and thermoregulatory proteins expression in the white adipose tissue (WAT) were analyzed using an immunoblot assay.

Results

Supplementation with both doses of LI85008F significantly increased resting energy expenditure (REE) in the obese rats. The LI85008F-250 rats showed significant up-regulation of uncoupling protein-1 (UCP-1) expression, as compared with the HFD rats. LI85008F significantly reduced body weight gain, fat mass, fat cell size, liver weight, and hepatic triglycerides. Serum triglyceride, total cholesterol, glucose, leptin, and fat cell markers were significantly reduced in LI85008F-supplemented rats compared to the HFD rats.

Conclusion

The present data suggest that LI85008F reduces body fat mass and controls body weight gain via increasing energy metabolism in combination with reduced lipogenesis in diet-fed obese rats.

Toxicological Assessment of a Standardized Boswellia serrata Gum Resin Extract

The acidic and non-acidic fractions of Boswellia serrata gum resin extracts were combined to prepare a unique product, LI13019F1 (Serratrin). The present series of studies evaluated LI13019F1 for acute and subchronic (28-day) toxicity in Wistar rats and acute dermal and eye irritation in New Zealand white rabbits. The mutagenicity and clastogenicity of LI13019F1 were evaluated in bacteria and mouse bone marrow erythrocytes, respectively. All studies were performed following the Organization for Economic Co-operation and Development guidelines. Acute oral and acute dermal toxicity studies did not show mortality or signs of toxicity in Wistar rats at a limit dose of 2,000 mg/kg LI13019F1. LI13019F1 did not cause irritation to the skin or the eyes of New Zealand white rabbits. In a repeated dose 28-day oral toxicity study, LI13019F1-treated Wistar rats did not show dose-related signs of toxicity on their body weights, organ weights, and on the hematology and clinical chemistry parameters. The estimated no observed adverse effect level for LI13019F1 was 1,000 mg/kg/day in both male and female rats. The bacterial reverse mutation test and a micronucleus assay in mouse bone marrow erythrocytes revealed that LI13019F1 was neither mutagenic nor clastogenic. Together, the present observations demonstrate a broad-spectrum safety of LI13019F1.

Plasma Concentrations of Boswellic Acids in Fasting Healthy Humans Supplemented with a Water-Soluble Boswellia Extract (78% AKBA) vs. Reference Boswellia Extract (30% AKBA) (P06-005-19)

Objectives

A randomized, open label, balanced, two-way crossover study compared the oral bioavailability and pharmacokinetic profiles of two Boswellia products standardized to 3-O-acetyl-11-Keto-β-boswellic acid (AKBA).

Methods

Twenty-two fasted male participants completed the study. They received a single oral-dose of water-soluble Boswellia extract 78% (LI51202F1) or the standard Boswellia extract 30% (5-Loxin) at 30 mg AKBA equivalent with 240 mL water on 2 separate occasions 12 days apart. Plasma AKBA and KBA were analyzed using a LC-MS/MS in pre- (0 hr) and post-dose (00.50, 01.00, 01.50, 02.00, 02.50, 03.00, 04.00, 08.00, 12.00 and 24.00 hrs) blood samples. Pharmacokinetic analysis was performed using WinNonlin® version 7.0 (Pharsight corporation, USA).

Results

Comparative analysis of the pharmacokinetic parameters showed LI51202F1 had higher (111.11%) Cmax for AKBA vs. 5-Loxin. The bioavailability indicated by Geometric means of AUC0-t and AUC0-∞ were 25.49% and 16.13% higher in LI51202F1 than 5-Loxin.

Conclusions

The present study demonstrates that oral ingestion of water soluble and standard Boswellia extracts resulted in similar bioavailability. Interestingly, the water-soluble version exhibited higher Cmax and AUC values, which could be attributed to the improved solubility of LI51202F1.

Funding Sources

Laila Nutraceuticals.

Four new Sesquiterpenoids from Sphaeranthus indicus

Isolation and characterisation of two new eudesmanolides, 5α-hydroperoxy-7α-hydroxy-isosphaerantholide (1) and (11α,13-dihydro-7α-hydroxyfrullanolide-13-yl)-adenine (2) from the flower heads of Sphaeranthus indicus are described. In addition, 5α-hydroxy-isosphaerantholide (3) and 11α,13-dihydro-eudesman-3,5,7-triene-6α-12-olide (4) are reported first time as a metabolite of S. indicus and as a natural product, respectively. The structures of these compounds were established from rigorous analysis of their high-resolution mass, IR, UV, ¹H NMR, ¹³C NMR and 2D NMR spectral data.

A New Flavanone from the Leaves of Chromolaena odorata

Chromolaena odorata (Syn: Eupatorium odoratum) is a perennial plant belonging to the Asteraceae family. Extracts of C. odorata have shown strong anti-oxidant and moderate anti-adipogenenesis activities. Detailed phytochemical investigation of C. odorata led to the isolation of 21 secondary metabolites, which include a new flavanone (3), and a chalcone, 3,2'-dihydroxy-4,4',5',6'-tetramethoxychalcone (2), reported for the first time from a natural source, besides three known compounds 1, 4 and 5, all of which are reported for the first time from C. odorata. Some of these compounds exhibited potent anti-oxidant and anti-adipogenesis activities and these may be partly responsible for the activity of the extract.

A New Flavanone from the Leaves ofChromolaena odorata

Chromolaena odorata (Syn: Eupatorium odoratum) is a perennial plant belonging to the Asteraceae family. Extracts of C. odorata have shown strong anti-oxidant and moderate anti-adipogenenesis activities. Detailed phytochemical investigation of C. odorata led to the isolation of 21 secondary metabolites, which include a new flavanone (3), and a chalcone, 3,2′-dihydroxy-4,4′,5′,6′-tetramethoxychalcone (2), reported for the first time from a natural source, besides three known compounds 1, 4 and 5, all of which are reported for the first time from C. odorata. Some of these compounds exhibited potent anti-oxidant and anti-adipogenesis activities and these may be partly responsible for the activity of the extract.

Synthesis and biological evaluation of nonaprenylsulfates

A naturally occurring nonaprenylsulfate (1) and its synthetic analogue (2) were synthesized from substituted phenolic precursors in three steps with an overall yield of 40-45%. Both compounds exhibited potent anti-inflammatory activity against 5-lipoxygenase, and potent brine shrimp lethality. They also showed moderate anti-oxidant activity in the super oxide radical scavenging model. Nonaprenylsulfate (1) showed moderate inhibition of paw edema in Freund's Complete Adjuvant (FCA) induced model of arthritis, thus confirming its anti-inflammatory activity.

Synthesis and Biological Evaluation of Nonaprenylsulfates

A naturally occurring nonaprenylsulfate (1) and its synthetic analogue (2) were synthesized from substituted phenolic precursors in three steps with an overall yield of 40–45%. Both compounds exhibited potent anti-inflammatory activity against 5-lipoxygenase, and potent brine shrimp lethality. They also showed moderate anti-oxidant activity in the super oxide radical scavenging model. Nonaprenylsulfate (1) showed moderate inhibition of paw edema in Freund's Complete Adjuvant (FCA) induced model of arthritis, thus confirming its anti-inflammatory activity.

Digalloylresveratrol, a novel resveratrol analog inhibits the growth of human pancreatic cancer cells

Digalloylresveratrol (DIG) is a recently synthesized substance aimed to combine the effects of the natural polyphenolic compounds gallic acid and resveratrol, which both are excellent free radical scavengers with anticancer activity. In this study, we investigated the effects of DIG in the human AsPC-1 and BxPC-3 pancreatic adenocarcinoma cell lines. Treatment with DIG dose-dependently attenuated cells in the S phase of the cell cycle and led to a significant depletion of the dATP pool in AsPC-1 cells. The incorporation of (14)C-cytidine into nascent DNA of tumor cells was significantly inhibited at all DIG concentrations due to inhibition of ribonucleotide reductase, a key enzyme of DNA synthesis in tumor cells. Furthermore, Erk1/2 became inactivated and moderated p38 phosphorylation reflecting increased replication stress. DIG also activated ATM and Chk2, and induced the phosphorylation and proteasomal degradation of the proto-oncogene Cdc25A, which contributed to cell cycle attenuation. Taken together, DIG is an excellent free radical scavenger, strongly inhibits RR in situ activity, cell cycle progression, and colony formation in AsPC-1 and BxPC-3 cells thus warranting further investigations.

Combination effects of digalloylresveratrol with arabinofuranosylcytosine and difluorodeoxycytidine in human leukemia and pancreatic cancer cells

Digalloylresveratrol (DIG) is a newly synthesized agent aimed to combine the biological effects of the natural compounds, gallic acid and resveratrol, which both are free radical scavengers exhibiting anticancer activity. In this study, we investigated the effects of DIG on the growth of human HL-60 leukemia cells and on the colony formation of human BxPC-3 and PANC-1 pancreatic cancer cells. DIG was applied alone and in combination with arabinofuranosylcytosine (Ara-C) or difluorodeoxycytidine (dFdC), depending on the cell line employed. All IC(50) values observed were in the low micromolar range rendering DIG a promising antitumor compound in vitro. Considering the combination experiments, DIG yielded additive effects with Ara-C in HL-60 cells and-to a lesser extent-with dFdC in BxPC-3 and PANC-1 cells. Owing to our results, DIG may be further investigated in vitro and in animals.

Multifactorial anticancer effects of digalloyl-resveratrol encompass apoptosis, cell-cycle arrest, and inhibition of lymphendothelial gap formation in vitro

Background:

Digalloyl-resveratrol (di-GA) is a synthetic compound aimed to combine the biological effects of the plant polyhydroxy phenols gallic acid and resveratrol, which are both radical scavengers and cyclooxygenase inhibitors exhibiting anticancer activity. Their broad spectrum of activities may probably be due to adjacent free hydroxyl groups.

Methods:

Protein activation and expression were analysed by western blotting, deoxyribonucleoside triphosphate levels by HPLC, ribonucleotide reductase activity by ¹⁴C-cytidine incorporation into nascent DNA and cell-cycle distribution by FACS. Apoptosis was measured by Hoechst 33258/propidium iodide double staining of nuclear chromatin and the formation of gaps into the lymphendothelial barrier in a three-dimensional co-culture model consisting of MCF-7 tumour cell spheroids and human lymphendothelial monolayers.

Results:

In HL-60 leukaemia cells, di-GA activated caspase 3 and dose-dependently induced apoptosis. It further inhibited cell-cycle progression in the G1 phase by four different mechanisms: rapid downregulation of cyclin D1, induction of Chk2 with simultaneous downregulation of Cdc25A, induction of the Cdk-inhibitor p21^Cip/Waf and inhibition of ribonucleotide reductase activity resulting in reduced dCTP and dTTP levels. Furthermore, di-GA inhibited the generation of lymphendothelial gaps by cancer cell spheroid-secreted lipoxygenase metabolites. Lymphendothelial gaps, adjacent to tumour bulks, can be considered as gates facilitating metastatic spread.

Conclusion:

These data show that di-GA exhibits three distinct anticancer activities: induction of apoptosis, cell-cycle arrest and disruption of cancer cell-induced lymphendothelial disintegration.

Neuroprotective and antiinflammatory properties of a novel demethylated curcuminoid

A demethylated derivative of curcumin (DC; 67.8% bisdemethylcurcumin, 20.7% demethylmonodemethoxycurcumin, 5.86% bisdemethoxycurcumin, 2.58% demethylcurcumin) was prepared by using a 95% extract of curcumin (C(95); 72.2% curcumin, 18.8% monodemethoxycurcumin, 4.5% bisdemethoxycurcumin). DC increased glutathione and reduced reactive oxygen species (ROS) in HT4 neuronal cells. In a model of glutamate-induced death of HT4, DC was more effective than C(95) in neuroprotection. The protective effects of DC were retained even when DC was withdrawn from culture media after pretreatment. DC treatment, unlike an equal dose of C(95), completely spared glutamate-induced loss of cellular GSH. Both DC and C(95) prevented glutamate-induced elevation of cellular ROS but failed to attenuate glutamate-induced elevation of intracellular calcium. In human microvascular endothelial cells (HMECs) challenged with TNF-alpha, GeneChip analysis revealed that only a subcluster of 23 TNF-alpha-inducible genes were uniquely sensitive to C(95). In sharp contrast, 1,065 TNF-alpha-inducible genes were sensitive to DC but not to C(95), suggesting that DC was more effective in antagonizing the effects of TNF-alpha on HMECs. Functional analysis identified that the genes uniquely sensitive to DC belonged in four functional categories: cytokine-receptor interaction, focal adhesion, cell adhesion, and apoptosis. Real-time PCR as well as ELISA studies demonstrated that TNF-alpha-inducible CXCL10 and CXCL11 expression was sensitive to DC but not to C(95). Flow-cytometry studies recognized ICAM-1 and VCAM-1 as TNF-alpha-inducible adhesion molecules that were uniquely sensitive to DC. Taken together, DC exhibited promising neuroprotective and antiinflammatory properties that must be characterized in vivo.

A double blind, randomized, placebo controlled study of the efficacy and safety of 5-Loxin for treatment of osteoarthritis of the knee

Introduction

5-Loxin^® is a novel Boswellia serrata extract enriched with 30% 3-O-acetyl-11-keto-beta-boswellic acid (AKBA), which exhibits potential anti-inflammatory properties by inhibiting the 5-lipoxygenase enzyme. A 90-day, double-blind, randomized, placebo-controlled study was conducted to evaluate the efficacy and safety of 5-Loxin^® in the treatment of osteoarthritis (OA) of the knee.

Methods

Seventy-five OA patients were included in the study. The patients received either 100 mg (n = 25) or 250 mg (n = 25) of 5-Loxin^® daily or a placebo (n = 25) for 90 days. Each patient was evaluated for pain and physical functions by using the standard tools (visual analog scale, Lequesne's Functional Index, and Western Ontario and McMaster Universities Osteoarthritis Index) at the baseline (day 0), and at days 7, 30, 60 and 90. Additionally, the cartilage degrading enzyme matrix metalloproteinase-3 was also evaluated in synovial fluid from OA patients. Measurement of a battery of biochemical parameters in serum and haematological parameters, and urine analysis were performed to evaluate the safety of 5-Loxin^® in OA patients.

Results

Seventy patients completed the study. At the end of the study, both doses of 5-Loxin^® conferred clinically and statistically significant improvements in pain scores and physical function scores in OA patients. Interestingly, significant improvements in pain score and functional ability were recorded in the treatment group supplemented with 250 mg 5-Loxin^® as early as 7 days after the start of treatment. Corroborating the improvements in pain scores in treatment groups, we also noted significant reduction in synovial fluid matrix metalloproteinase-3. In comparison with placebo, the safety parameters were almost unchanged in the treatment groups.

Conclusion

5-Loxin^® reduces pain and improves physical functioning significantly in OA patients; and it is safe for human consumption. 5-Loxin^® may exert its beneficial effects by controlling inflammatory responses through reducing proinflammatory modulators, and it may improve joint health by reducing the enzymatic degradation of cartilage in OA patients.

Trail Registration

(Clinical trial registration number: ISRCTN05212803.)

Biosynthetic characterization and chemoenzymatic assembly of the cryptophycins. Potent anticancer agents from cyanobionts

The lichen cyanobacterial symbiont Nostoc sp. ATCC 53789 and its close relative Nostoc sp. GSV 224 are prolific producers of natural products, generating >25 derivatives of the cryptophycin class of secondary metabolites. Cryptophycin 1, the prototypic member of the class, is a potent tubulin-depolymerizing agent, and several semisynthetic derivatives are being developed as anticancer therapeutics. Here we provide a detailed characterization of the cryptophycin metabolic pathway by stable-isotope labeling experiments and through cloning, sequencing, and annotating the cryptophycin biosynthetic gene cluster. A comparative secondary metabolomic analysis based on polyketide (PK)/non-ribosomal peptide gene clusters from the phylogenetically related, non-cryptophycin producing cycad symbiont, Nostoc punctiforme ATCC 29133, was used to identify the cryptophycin biosynthetic genes that encompass approximately 40 kb within the lichen symbiont Nostoc sp. ATCC 53789 genome. The pathway encodes a collinear set of enzymes, including three modular PK synthases, two non-ribosomal peptide synthetase modules, and an integrated adenylation/ketoreductase didomain for elaboration of the leucic acid subunit. In addition, genes encoding key tailoring steps, including a FAD-dependent halogenase and CYP450 epoxidase, were identified. The inherent flexibility of the cryptophycin biosynthetic enzymes was harnessed to generate a suite of new analogues by altering the pool of PK starter units and selected amino acid extender groups. Characterization of the cryptophycin CYP450 enabled development of the first stereospecific synthesis of cryptophycin 2, through a tandem chemoenzymatic synthesis from the natural seco-cryptophycin 4 chain elongation intermediate.

Isolation and structure determination of cryptophycins 38, 326, and 327 from the terrestrial cyanobacterium Nostoc sp. GSV 224

Cryptophycin-38 (2), -326 (3), and -327 (4) are three new trace constituents of the terrestrial cyanobacterium Nostoc sp. GSV 224. Cryptophycin-38 is a stereoisomer of cryptophycin-1 (1) and to date is the only naturally occurring analogue that possesses a S,S epoxide group in unit A. Cryptophycin-327 is a geometric isomer that differs from 1 in having a cis Delta(2)-double bond in unit A. Cryptophycin-326 is related to cryptophycin-21, but has two chlorines ortho to the methoxy group in unit B. The relative and absolute stereochemistries of 2 have been related to known cryptophycins by semisynthesis and/or spectral analysis.

A convergent approach to cryptophycin 52 analogues: synthesis and biological evaluation of a novel series of fragment a epoxides and chlorohydrins

Cryptophycin 52 is a synthetic derivative of Cryptophycin 1, a potent antimicrotubule agent isolated from cyanobacteria. In an effort to increase the potency and water solubility of the molecule, a structure-activity relationship study (SAR) was initiated around the phenyl ring of fragment A. These Cryptophycin 52 analogues were accessed using a Wittig olefination reaction between various triphenylphosphonium salts and a key intermediate aldehyde prepared from Cryptophycin 53. Substitution on the phenyl ring of fragment A was well tolerated, and several of these analogues were equally or more potent than Cryptophycin 52 when evaluated in vitro in the CCRF-CEM leukemia cell line and in vivo against a murine pancreatic adenocarcinoma.

Biosynthesis of 4-methylproline in cyanobacteria: cloning of nosE and nosF genes and biochemical characterization of the encoded dehydrogenase and reductase activities

The biosynthesis of the unusual amino acid 4-methylproline in the Nostoc genus of cyanobacteria was investigated on the genetic and enzymatic level. Two genes involved in the biosynthesis were cloned and the corresponding enzymes, a zinc-dependent long-chain dehydrogenase and a Delta(1)-pyrroline-5-carboxylic acid (P5C) reductase homologue, were overexpressed in Escherichia coli and biochemically characterized. Putative substrates were synthesized to test enzyme substrate specificities, and deuterium labeling studies were carried out to reveal the stereospecificities of the enzymatic reactions with respect to the substrates as well as to the coenzymes.

Isolation and structure determination of nostocyclopeptides A1 and A2 from the terrestrial cyanobacterium Nostoc sp. ATCC53789

The isolation and total structure determination of nostocyclopeptides A1 (1) and A2 (2) are described. These cyclic heptapeptides, which possess a unique imino linkage in the macrocyclic ring, are characteristic constituents of the cryptophycin-producing cyanobacterium Nostoc sp. ATCC53789. 1D TOCSY experiments proved to be very useful in identifying the seven amino acid residues in each compound, and HMBC and NOESY correlations made it possible to sequence the seven units into a total gross structure. The absolute stereochemistry was determined by directly comparing the amino acids in the acid hydrolyzate of each natural product and its peroxide oxidation and borohydride reduction products with authentic standards. Studies were carried out on the biosynthesis and initiated on the biological activity of these cyclic peptides.

Discovery of cryptophycin-1 and BCN-183577: examples of strategies and problems in the detection of antitumor activity in mice

Historically, many new anticancer agents were first detected in a prescreen; usually consisting of a molecular/biochemical target or a cellular cytotoxicity assay. The agent then progressed to in vivo evaluation against transplanted human or mouse tumors. If the investigator had a large drug supply and ample resources, multiple tests were possible, with variations in tumor models, tumor and drug routes, dose-decrements, dose-schedules, number of groups, etc. However, in most large programs involving several hundred in vivo tests yearly, resource limitations and drug supply limitations have usually dictated a single trial. Under such restrictive conditions, we have implemented a flexible in vivo testing protocol. With this strategy, the tumor model is dictated by in vitro cellular sensitivity; drug route by water solubility (with water soluble agents injected intravenously); dosage decrement by drug supply, dose-schedule by toxicities encountered, etc. In this flexible design, many treatment parameters can be changed during the course of treatment (e.g., dose and schedule). The discovery of two active agents are presented (Cryptophycin-1, and Thioxanthone BCN 183577). Both were discovered by the intravenous route of administration. Both would have been missed if they were tested intraperitoneally, the usual drug route used in discovery protocols. It is also likely that they would have been missed with an easy to execute fixed protocol design, even if injected i.v.

Three new cryptophycins from Nostoc sp. GSV 224

Cryptophycin 46 (2), -175 (3), and -176(4) have been identified as three new trace constituents of Nostoc sp. GSV 224. Cryptophycin-46 is an epimer of cryptophycin-3 (5) and to date is the only naturally occurring analogue having the S configuration at C-10 (C-2 in Unit B). Cryptophycins-175 and -176 also differ in unit B where 3 is the O-methyl analogue of cryptophycin-45 (6) and 4 is the O-desmethyl analogue of cryptophycin-21 (8). The relative and absolute stereochemistries of the three new analogues have been related to known cryptophycins by synthesis.

Treatment of human prostate tumors PC-3 and TSU-PR1 with standard and investigational agents in SCID mice

Both the PC-3 and the TSU-PR1 prostate tumor models were found to be satisfactory for chemotherapeutic investigations in ICR-SCID mice. The 30 to 60 mg fragments implanted took in all mice (as judged by 100% takes in the controls of all experiments as well as the passage mice). The tumor volume doubling time was 4.0 days for PC-3 and 2.5 days for TSU-PR1. Nine agents were evaluated IV against early stage subcutaneous PC-3 tumors, with Nano-piposulfan being the only agent highly active (4.9 log kill). Three other agents were moderately active: Taxol (1.5 log kill), Cryptophycin-8 (1.6 log kill), Vinblastine (1.0 log kill). Five agents were inactive: VP-16, Adriamycin, CisDDPt, 5-FUra, and Cyclophosphamide. Ten agents were evaluated IV against early stage subcutaneous TSU-PR1 tumors. Three agents were highly active, producing > 6 log kill and cures: Taxol (5/5 cures), Cryptophycin-8 (5/5 cures), Vinblastine (2/4 cures). Two other agents were moderately active: Nano-piposulfan (1.2 log kill), and Cyclophosphamide (1.1 log kill). Five agents were inactive: VP-16, Adriamycin, CisDDPt, 5-FUra, and BCNU. In part, activity was determined by the ability of the SCID mice to tolerate meaningful dosages of the agents. Agents producing granulocyte toxicity (e.g., Adriamycin) were poorly tolerated and appeared less active than expected. Vinblastine, producing little or no granulocyte toxicity was very well tolerated and appeared to be more active than expected.

Preclinical anticancer activity of cryptophycin-8

Cryptophycin-8 was prepared by the conversion of the epoxide group on cryptophycin-1 to a chlorohydrin. In the studies reported here, cryptophycin-8 was evaluated for preclinical activity against subcutaneous tumors of both mouse and human origin. At the highest non-toxic single course treatment, the following results were obtained (Table A). Cryptophycin-8 was less potent than cryptophycin-1 by approximately 4-fold; however, it was both more water soluble and had greater therapeutic efficacy, as demonstrated by % T/C, tumor cell log kill values, range of dose effectiveness and host cures.