Asiatic acid induces apoptosis in SK-MEL-2 human melanoma cells

Anti-glioma activity and the mechanism of cellular uptake of asiatic acid-loaded solid lipid nanoparticles

Asiatic acid (AA), a pentacyclic triterpene found in Centella Asiatica, has shown neuroprotective and anti-cancer activity against glioma. However, owing to its poor aqueous solubility, effective delivery and absorption across biological barriers, in particular the blood brain barrier (BBB), are challenging. Solid lipid nanoparticles (SLNs) have shown a promising potential as a drug delivery system to carry lipophilic drugs across the BBB, a major obstacle in brain cancer therapy. Nevertheless, limited information is available about the cytotoxic mechanisms of nano-lipidic carriers with AA on normal and glioma cells. This study assessed the anti-cancer efficacy of AA-loaded SLNs against glioblastoma and their cellular uptake mechanism in comparison with SVG P12 (human foetal glial) cells. SLNs were systematically investigated for three different solid lipids; glyceryl monostearate (MS), glyceryl distearate (DS) and glyceryl tristearate (TS). The non-drug containing MS-SLNs (E-MS-SLNs) did not show any apparent toxicity towards normal SVG P12 cells, whilst the AA-loaded MS-SLNs (AA-MS-SLNs) displayed a more favourable drug release profile and higher cytotoxicity towards U87 MG cells. Therefore, MS-SLNs were chosen for further in vitro studies. Cytotoxicity studies of SLNs (± AA) were performed using MTT assay where AA-SLNs showed significantly higher cytotoxicity towards U87 MG cells than SVG P12 normal cells, as confirmed by flow cell cytometry. Cellular uptake of SLNs also appeared to be preferentially facilitated by energy-dependent endocytosis as evidenced by fluorescence imaging and flow cell cytometry. Using the Annexin V-PI double staining technique, it was found that these AA-MS-SLNs displayed concentration-dependent apoptotic activity on glioma cells, which further confirms the potential of exploiting these AA-loaded MS-SLNs for brain cancer therapy.

Synthesis and biological evaluation of novel asiatic acid derivatives with anticancer activity

Structural modification of asiatic acid afforded derivatives with improved anticancer activity.

Synthesis, antiproliferative and apoptosis-inducing effects of novel asiatic acid derivatives containing α-aminophosphonates

Novel asiatic acid derivatives containing α-aminophosphonates was designed and synthesized as antitumor agents. Compound 3d blocked the T24 cell cycle at G₁/S phase by the p53-dependent pathway and induced apoptosis through mitochondrial pathway.

Gotu Kola (Centella asiatica): Nutritional Properties and Plausible Health Benefits

Centella asiatica L. (Gotu Kola) is a nutritionally important plant and a valued traditional medicine in South East Asia. In this review, the chemical composition, nutritional values, and health benefits of C. asiatica have been discussed in detail to emphasize its usage as traditional food and medicine. C. asiatica is one of the most commonly used green leafy vegetables (GLVs) in some countries including Sri Lanka due to its high amounts of medicinally important triterpenoids and beneficial carotenoids. It is consumed in the form of GLVs and in the preparation of juice, drink, and other food products. It is also known to contain vitamins B and C, proteins, important minerals, and some other phytonutrients such as flavonoids, volatile oils, tannins, and polyphenol. In vitro and in vivo studies have shown important health benefits like antidiabetic, wound-healing, antimicrobial, memory-enhancing, antioxidant, and neuroprotecting activities. However, detailed scientific approaches on clinical trials regarding health benefits and nutritional values of C. asiatica are limited, hindering the perception of its benefits, mechanisms, and toxicity in order to develop new drug prototypes. In vitro studies have shown that the method of processing C. asiatica has an impact on its nutritional values and health-related beneficial compounds. The composition of its compounds is influenced by different biotic and abiotic factors which need to be studied in detail to provide information to the public in order to maximize the usage of this valuable plant.

Synthesis, anti-tumor and anti-angiogenic activity evaluations of asiatic Acid amino Acid derivatives

Fifteen semi-synthetic derivatives of asiatic acid (AA) have been synthesized and evaluated for their biological activities. The successful modification of these compounds at the C-2, C-3, C-23 and C-28 positions was confirmed using NMR, MS and IR spectra. Further, their anti-tumor effects were evaluated in vitro using different cancer cell lines (HeLa, HepG2, B16F10, SGC7901, A549, MCF7 and PC3), while their anti-angiogenic activities were evaluated in vivo using a larval zebrafish model. Among the derivatives, compounds 4–10 showed more potent cytotoxic and anti-angiogenic effects than AA, while compounds 11–17 had significantly less effects. The new derivative 10 was also included in finished formulations to evaluate its stability using HPLC due to its potential topical use. The derivative 10 had markedly better anti-tumor activities than both AA and other derivatives, with similar stability as its parent compound AA.

Structural analysis of metabolites of asiatic acid and its analogue madecassic acid in zebrafish using LC/IT-MSn

Although zebrafish has become a significant animal model for drug discovery and screening, drug metabolism in zebrafish remains largely unknown. Asiatic acid (AA) and madecassic acid (MA), two natural pentacyclic triterpenoids mainly obtained from Centella asiatica (L.) Urban, have been found to possess many pharmacological effects. This study is to probe the metabolic capability of zebrafish via investigation of the drug metabolism of AA and MA in zebrafish, using a sensitive LC/IT-MSn method. In addition, the main fragmentation pathways of AA and MA were reported for the first time. Nineteen metabolites of AA and MA were firstly identified after zebrafish was exposed to the drug, which all were the phase I metabolites and mainly formed from hydroxylation, dehydrogenation, hydroxylation and dehydrogenation, dihydroxylation and dehydrogenation, and dehydroxylation reaction. The results indicated that zebrafish possessed strong metabolic capacity, and the metabolites of AA and MA were formed via similar metabolic pathways and well matched with the known metabolic rules in vivo and in vitro, which supports the widely use of this system in drug metabolism research. This investigation would also contribute to the novel information on the structural elucidation, in vivo metabolites and metabolic mechanism of pentacyclic triterpenoids.

Chitosan-aluminum monostearate composite sponge dressing containing asiaticoside for wound healing and angiogenesis promotion in chronic wound

There are many factors that delay healing in chronic wounds including lowering level of growth factors and increasing exudate level comprising high amount of tissue destructive enzymes. Asiaticoside possesses interesting wound healing and angiogenic activities that are employed to stimulate tissue regeneration in wound healing application. This study attempted to develop chitosan-aluminum monostearate (Alst) composite sponge containing asiaticoside for use as an absorbent medical dressing in chronic wound. N-methyl-2-pyrrolidone (NMP) was used to enhance homogeneity of asiaticoside in the polymer composite matrix. The sponge dressings were prepared by lyophilization and dehydrothermal treatment (DHT). Functional group interaction, crystallinity, and morphology of the prepared sponges were investigated using FT-IR, PXRD, and SEM, respectively. Physicochemical properties, porosity, hydrophilic/hydrophobic properties and mechanical property, were evaluated. Wound dressing properties, water vapor transmission rate (WVTR), fluid absorbency, oxygen permeation (OP), and bio-adhesive property, were investigated. In vitro asiaticoside release study was conducted using immersion method. Cytotoxicity was studied in normal human dermal fibroblast (NHDF) and normal human epidermal keratinocyte (NHEK). Angiogenic activity of asiaticoside was evaluated using chick-chorioallantoic membrane (CAM) assay. FT-IR and PXRD results revealed the amidation after DHT to enhance the crystallinity of the prepared sponges. The prepared sponges had high porosity comprising high Alst-loaded amount that exhibited more compact structure. Alst enhanced hydrophobicity therefore it reduced the fluid absorption and WVTR together with bio-adhesion of the prepared sponge dressings. Porosity of all sponges was more than 85% therefore resulting in their high OP. Enhancing hydrophobicity of the material by Alst and more homogeneity caused by NMP eventually retarded the asiaticoside release for 7 days. The sponge extractions were non-toxic to the cells moreover they promoted NHDF and NHEK cell proliferation. Asiaticoside and asiaticoside-contained dressings exhibited dose-dependent angiogenic activity in CAM model.

Asiatic acid promotes p21(WAF1/CIP1) protein stability through attenuation of NDR1/2 dependent phosphorylation of p21(WAF1/ CIP1) in HepG2 human hepatoma cells

Previous studies have suggested anti-tumor effects of asiatic acid in some human cancer cell lines. This agent is reported to increase the levels of p21WAF1/CIP1 in human breast cancer cell lines. However, the molecular mechanisms have not been established. Here we report that asiatic acid up-regulates p21WAF1/CIP1 protein expression but not the level of p21WAF1/CIP1 mRNA in HepG2 human hepatoma cells. Furthermore, we found that the asiatic acid induced increase of p21WAF1/CIP1 protein was associated with decreased phosphorylation (ser-146) of p21WAF1/CIP1. Knockdown of NDR1/2 kinase, which directly phosphorylates p21WAF1/CIP1 protein at ser-146 and enhances its proteasomal degradation, increased the levels of p21WAF1/CIP1 protein and eliminated the regulation of p21WAF1/ CIP1 stability by asiatic acid. At the same time, the expression of NDR1/2 kinase decreased during treatment with asiatic acid in HepG2 cells. Moreover, asiatic acid inhibited the proliferation of HepG2 cells, this being attenuated by knockdown of p21WAF1/CIP1. In conclusion, we propose that asiatic acid inhibits the expression NDR1/2 kinase and promotes the stability of p21WAF1/CIP1 protein through attenuating NDR1/2 dependent phosphorylation of p21WAF1/CIP1 in HepG2 cells.

Asiatic acid induces endoplasmic reticulum stress and apoptotic death in glioblastoma multiforme cells both in vitro and in vivo

Glioblastoma multiforme (GBM) is an untreatable malignancy. Existing therapeutic options are insufficient, and adversely affect functional and non-cancerous cells in the brain impairing different functions of the body. Therefore, there is an urgent need for additional preventive and therapeutic non-toxic drugs against GBM. Asiatic acid (AsA; 2,3,23-trihydroxy-12-ursen-28-oic acid, C30 H48 O5 ) is a natural small molecule widely used to treat various neurological disorders, and the present research investigates AsA's efficacy against GBM both in vitro and in vivo. Results showed that AsA treatment (10-100 µM) decreased the human GBM cell (LN18, U87MG, and U118MG) viability, with better efficacy than temozolomide at equimolar doses. Orally administered AsA (30 mg/kg/d) strongly decreased tumor volume in mice when administered immediately after ectopic U87MG xenograft implantation (54% decrease, P ≤ 0.05) or in mice with established xenografts (48% decrease, P ≤ 0.05) without any apparent toxicity. Importantly, AsA feeding (30 mg/kg/twice a day) also decreased the orthotopic U87MG xenografts growth in nude mice as measured by magnetic resonance imaging. Using LC/MS-MS methods, AsA was detected in mice plasma and brain tissue, confirming that AsA crosses blood-brain barrier. Mechanistic studies showed that AsA induces apoptotic death by modulating the protein expression of several apoptosis regulators (caspases, Bcl2 family members, and survivin) in GBM cells. Furthermore, AsA induced ER stress (increased GRP78 and Calpain, and decreased Calnexin and IRE1α expression), enhanced free intra-cellular calcium, and damaged cellular organization in GBM cells. These experimental results demonstrate that AsA is effective against GBM, and advocate further pre-clinical and clinical evaluations of AsA against GBM.

Nepalese traditional medicine and symptoms related to Parkinson's disease and other disorders: Patterns of the usage of plant resources along the Himalayan altitudinal range

ETHNOPHARMACOLOGICAL RELEVANCE

Nepal is a hotspot for cultural and biological diversities. The tremendous diversity of ecosystems and climates and the blend of medicinal practices inherited from Ayurvedic and Traditional Tibetan Medicine are well suited to a study aimed at discovering information about medicinal plants to treat Parkinson's disease (PD). In addition, this study across Nepal's altitudinal range is relevant to understanding how cultural and ecological environments influence local traditional medicines. The aim of the study is to document the uses of medicinal plants in three different eco-geographical areas of Nepal (Chitwan-Panchase-Mustang) to treat symptoms related to PD. A second goal is to analyze the impact of culture and environment on the evolution of traditional medicine.

MATERIALS AND METHODS

The study was conducted in five communities located in three different eco-geographical environments and at altitudes ranging from 300m to 3700m. We interviewed a total of 56 participants (local people, folk, Ayurvedic and Amchi healers) across the three research areas. We conducted open-ended interviews to document the uses of medicinal plants to treat PD-related symptoms. Information provided by the interviewees suggested that the medicinal plants are also used to treat symptoms related to other disorders. We determined the informant consensus factor as well as the importance of specific plant species to (i) identify plants that are the best candidates to be analyzed experimentally for their potential to treat PD and (ii) perform a cross-cultural comparison of the three areas of study.

RESULTS

This study reports the local uses of 35 different plant species along the Chitwan-Panchase-Mustang altitudinal range. We identify a total of eight plant species that were used in all three research areas, and more specifically one species used to treat PD-like symptoms. We identify a potential dual protective activity of medicinal plants used to treat PD-related symptoms as recent literature suggests that these plants also have anti-cancer properties. In addition, we document that the presence of Ayurvedic healers could influence local practices and that local practices could influence local Ayurvedic practices.

CONCLUSIONS

This study documents the uses of medicinal plants to treat symptoms related to PD and other disorders across the Chitwan-Panchase-Mustang altitudinal range. PD is a neurodegenerative disease affecting a growing number of people worldwide. No cures are available to slow the death of the neurons, and there is a critical need to work towards innovative therapeutic strategies. We identify medicinal plants based on traditional practices to help develop a cure for PD. The three areas of study were chosen for their ecological and cultural diversities, and two of these are included in conservation programs (Panchase Protected Forest and Annapurna Conservation Area). The documentation of community-natural resource relationships is another step in the preservation of traditional practices and local biodiversity and a reflection of communities' rights in the design of conservation programs.

Asiatic acid isolated from Centella asiatica inhibits TGF-β1-induced collagen expression in human keloid fibroblasts via PPAR-γ activation

Keloids are fibroproliferative disorders characterized by exuberant extracellular matrix deposition and transforming growth factor (TGF)-β/Smad pathway plays a pivotal role in keloid pathogenesis. Centella asiatica extract has been applied in scar management for ages. As one of its major components, asiatic acid (AA) has been recently reported to inhibit liver fibrosis by blocking TGF-β/Smad pathway. However, its effect on keloid remains unknown. In order to investigate the effects of AA on cell proliferation, invasion and collagen synthesis, normal and keloid fibroblasts were exposed to TGF-β1 with or without AA. Relevant experiments including 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, 5-ethynyl-2-deoxyuridine (EdU) incorporation assay, Transwell invasion assay, enzyme-linked immunosorbent assay, Western blot, quantitative polymerase chain reaction and RNA interference assay were conducted. As a result, keloid fibroblasts showed higher responsiveness to TGF-β1 stimulation than normal fibroblasts in terms of invasion and collagen synthesis. AA could suppress TGF-β1-induced expression of collagen type I, inhibit Smad 2/3 phosphorylation and plasminogen activator inhibitor-1 (PAI-1) expression, while elevate Smad 7 protein level. Noteworthy, the effects of AA on keloid fibroblasts could be abrogated by PPAR-γ antagonist GW9662 and by silencing of PPAR-γ. The present study demonstrated that AA inhibited TGF-β1-induced collagen and PAI-1 expression in keloid fibroblasts through PPAR-γ activation, which suggested that AA was one of the active constituents of C. asiatica responsible for keloid management, and could be included in the arsenal for combating against keloid.

Asiatic acid, a triterpene, inhibits cell proliferation through regulating the expression of focal adhesion kinase in multiple myeloma cells

The aim of the present study was to investigate whether asiatic acid (AA), a pentacyclic triterpene derived from Centella asiatica, exerts anti-proliferative effects on multiple myeloma RPMI 8226 cells and to determine the molecular mechanism underlying the anticancer action of AA. The study sought to analyze the potential role of AA on the proliferation of the RPMI 8226 cells using a 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium assay. Cell cycle arrest was detected by flow cytometry, and the expression levels of focal adhesion kinase (FAK) in the myeloma cells induced by AA were analyzed using the western blotting and immunoprecipitation methods. The results indicated that AA significantly inhibited cell proliferation in a time- and dose-dependent manner and led to G₂/M phase arrest at concentrations of 35 and 40 μmol/l in the RPMI 8226 cells. The expression levels of FAK and p-FAK were distinctly decreased following AA treatment (at the concentration of 40 μmol/l) for 24 h compared with that of the control groups. Taken together, these results demonstrated that AA was able to regulate cell cycle progression in RPMI 8226 cells, thereby significantly inhibiting cell growth. Furthermore, AA decreased the expression levels of FAK, indicating that the antitumor mechanism of AA may be associated with the inhibition of signal transduction mediated by FAK.

Identification of Major Active Ingredients Responsible for Burn Wound Healing of Centella asiatica Herbs

Centella asiatica herbs have been prescribed as a traditional medicine for wound healing in China and Southeast Asia for a long time. They contain many kinds of triterpenoid compounds, mainly including glycosides (asiaticoside and madecassoside) and corresponding aglycones (asiatic acid and madecassic acid). To identify which is the major active constituent, a comprehensive and comparative study of these compounds was performed. In vitro, primary human skin fibroblasts, originating from healthy human foreskin samples, were treated with various concentrations of asiaticoside, madecassoside, asiatic acid, and madecassic acid, respectively. Cell proliferation, collagen synthesis, MMP-1/TIMP-1 balance, and TGF-β/Smad signaling pathway were investigated. In vivo, mice were orally administered with the four compounds mentioned above for two weeks after burn injury. The speed and quality of wound healing, as well as TGF-β(1) levels in skin tissues, were examined. Interestingly, in contrast to prevalent postulations, asiaticoside and madecassoside themselves, rather than their corresponding metabolites asiatic acid and madecassic acid, are recognized as the main active constituents of C. asiatica herbs responsible for burn wound healing. Furthermore, madecassoside is more effective than asiaticoside (P = 0.0446 for procollagen type III synthesis in vitro, P = 0.0057 for wound healing speed, and P = 0.0491 for wound healing pattern in vivo, correspondingly).

Two new oxidation products obtained from the biotransformation of asiatic acid by the fungus Fusarium avenaceum AS 3.4594

Asiatic acid (AA) is a natural triterpenoid possessing anti-inflammatory, anticancer, neuroprotective, and hepatoprotective activities. Structural modification of AA may provide valuable information for further structure-activity relationship analysis. Biotransformation is an efficient, specific, and environment friendly technology for structural modification of complicated natural products. In this study, the capabilities of twenty-five strains of filamentous fungi to transform AA were screened. Two new and one known oxidation products metabolized by Fusarium avenaceum AS 3.4594 were isolated. Their chemical structures were characterized as 2-oxo-3β,15α,23-trihydroxyurs-12-en-28-oic acid (1), 3-oxo-2,15α,23-trihydroxyurs-1,12-dien-28-oic acid (2), and 2-oxo-3β,23-dihydroxyurs-12-en-28-oic-acid (3) by extensive analysis of spectroscopic data.

Ursane-type pentacyclic triterpenoids as useful platforms to discover anticancer drugs

This review highlights the potential of natural and semisynthetic ursane-type triterpenoids as candidates for the design of multi-target bioactive compounds, with focus on their anticancer effects. A brief illustration of the biosynthesis, sources, and general biological effects of the main classes of naturally occurring pentacyclic triterpenoids (PTs) are provided.

Factors affecting the content of pentacyclic triterpenes in Centella asiatica raw materials

CONTEXT

Pentacyclic triterpenes, mainly, asiatic acid, madecassic acid, asiaticoside, and madecassoside are the active constituents of Centella asitica (L.) Urban. (Apiaceae). These compounds possess various pharmacological activities that have been shown to assist with wound healing and brain enrichment.

OBJECTIVE

Determination of these active pentacyclic triterpenes in extracts from the various parts of C. asiatica plants harvested at different times of the year and grown in different environments.

MATERIALS AND METHODS

The separate plant parts selected were leaves, stolons, petioles, flowers, fruits, and nodes with roots. Dried powder from each part was extracted with ethanol by microwave-assisted extraction and subjected to determination of their content of the four pentacyclic triterpenes using a HPLC method. The effects of the places of cultivation as well as harvesting periods on the content of the four pentacyclic triterpenes in the extracts were also determined.

RESULTS AND DISCUSSION

Among the various parts of C. asiatica, the leaves contained the highest amount of pentacyclic triterpenes with a total content of pentacyclic triterpenes of 19.5 mg/g dry powder. However, the contents of the pentacyclic triterpenes in C. asiatica varied according to the place of cultivation and the harvesting period. C. asiatica collected from Trang, Thailand gave the highest content of total pentacyclic triterpenes (37.2 mg/g dry powder) when harvested in March, while those collected from Songkhla, Thailand gave the highest value (37.4 mg/g dry powder) when collected in December. C. asiatica collected from Nakornsrithammarat and Ratchaburi, Thailand gave the lowest content of total pentacyclic triterpenes in all experimental harvesting periods.

Synthesis and antitumor activity evaluation of new asiatic acid derivatives

Twelve novel asiatic acid (AA) derivatives were designed and synthesized. Their structures were confirmed using NMR, MS, and IR spectra. Their in vitro cytotoxicities on various cancer cell lines (HeLa, HepG2, BGC-823, and SKOV3) were evaluated by the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. Most of the derivatives were found to have stronger cell growth inhibitory activity than AA. Among them, compounds 5-8 and 11 with substituted amide group at C-28 exhibited more potent cytotoxicity than AA, Gefitinib, and etoposide (positive control).

Asiatic acid, a pentacyclic triterpene in Centella asiatica, attenuates glutamate-induced cognitive deficits in mice and apoptosis in SH-SY5Y cells

AIM

To investigate whether asiatic acid (AA), a pentacyclic triterpene in Centella asiatica, exerted neuroprotective effects in vitro and in vivo, and to determine the underlying mechanisms.

METHODS

Human neuroblastoma SH-SY5Y cells were used for in vitro study. Cell viability was determined with the MTT assay. Hoechst 33342 staining and flow cytometry were used to examine the apoptosis. The mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) were measured using fluorescent dye. PGC-1α and Sirt1 levels were examined using Western blotting. Neonatal mice were given monosodium glutamate (2.5 mg/g) subcutaneously at the neck from postnatal day (PD) 7 to 13, and orally administered with AA on PD 14 daily for 30 d. The learning and memory of the mice were evaluated with the Morris water maze test. HE staining was used to analyze the pyramidal layer structure in the CA1 and CA3 regions.

RESULTS

Pretreatment of SH-SY5Y cells with AA (0.1-100 nmol/L) attenuated toxicity induced by 10 mmol/L glutamate in a concentration-dependent manner. AA 10 nmol/L significantly decreased apoptotic cell death and reduced reactive oxygen species (ROS), stabilized the mitochondrial membrane potential (MMP), and promoted the expression of PGC-1α and Sirt1. In the mice models, oral administration of AA (100 mg/kg) significantly attenuated cognitive deficits in the Morris water maze test, and restored lipid peroxidation and glutathione and the activity of SOD in the hippocampus and cortex to the control levels. AA (50 and 100 mg/kg) also attenuated neuronal damage of the pyramidal layer in the CA1 and CA3 regions.

CONCLUSION

AA attenuates glutamate-induced cognitive deficits of mice and protects SH-SY5Y cells against glutamate-induced apoptosis in vitro.

Targeted inhibition of tumor proliferation, survival, and metastasis by pentacyclic triterpenoids: potential role in prevention and therapy of cancer

Over the last two decades, extensive research on plant-based medicinal compounds has revealed exciting and important pharmacological properties and activities of triterpenoids. Fruits, vegetables, cereals, pulses, herbs and medicinal plants are all considered to be biological sources of these triterpenoids, which have attracted great attention especially for their potent anti-inflammatory and anti-cancer activities. Published reports in the past have described the molecular mechanism(s) underlying the various biological activities of triterpenoids which range from inhibition of acute and chronic inflammation, inhibition of tumor cell proliferation, induction of apoptosis, suppression of angiogenesis and metastasis. However systematic analysis of various pharmacological properties of these important classes of compounds has not been done. In this review, we describe in detail the pre-clinical chemopreventive and therapeutic properties of selected triterpenoids that inhibit multiple intracellular signaling molecules and transcription factors involved in the initiation, progression and promotion of various cancers. Molecular targets modulated by these triterpenoids comprise, cytokines, chemokines, reactive oxygen intermediates, oncogenes, inflammatory enzymes such as COX-2, 5-LOX and MMPs, anti-apoptotic proteins, transcription factors such as NF-κB, STAT3, AP-1, CREB, and Nrf2 (nuclear factor erythroid 2-related factor) that regulate tumor cell proliferation, transformation, survival, invasion, angiogenesis, metastasis, chemoresistance and radioresistance. Finally, this review also analyzes the potential role of novel synthetic triterpenoids identified recently which mimic natural triterpenoids in physical and chemical properties and are moving rapidly from bench to bedside research.

Asiatic acid inhibits liver fibrosis by blocking TGF-beta/Smad signaling in vivo and in vitro

Liver fibrosis is a major cause of liver failure, but treatment remains ineffective. In the present study, we investigated the mechanisms and anti-hepatofibrotic activities of asiatic acid (AA) in a rat model of liver fibrosis induced by carbon tetrachloride (CCl₄) and in vitro in TGF-beta1-stimulated rat hepatic stellate cell line (HSC-T6). Treatment with AA significantly attenuated CCl₄-induced liver fibrosis and functional impairment in a dosage-dependent manner, including blockade of the activation of HSC as determined by inhibiting de novo alpha smooth muscle actin (a-SMA) and collagen matrix expression, and an increase in ALT and AST (all p<0.01). The hepatoprotective effects of AA on fibrosis were associated with upregulation of hepatic Smad7, an inhibitor of TGF-beta signaling, thereby blocking upregulation of TGF-beta1 and CTGF and the activation of TGF-beta/Smad signaling. The anti-fibrosis activity and mechanisms of AA were further detected in vitro in HSC-T6. Addition of AA significantly induced Smad7 expression by HSC-T6 cells, thereby inhibiting TGF-beta1-induced Smad2/3 activation, myofibroblast transformation, and collagen matrix expression in a dosage-dependent manner. In contrast, knockdown of Smad7 in HSC-T6 cells prevented AA-induced inhibition of HSC-T6 cell activation and fibrosis in response to TGF-beta1, revealing an essential role for Smad7 in AA-induced anti-fibrotic activities during liver fibrosis in vivo and in vitro. In conclusion, AA may be a novel therapeutic agent for liver fibrosis. Induction of Smad7-dependent inhibition of TGF-beta/Smad-mediated fibrogenesis may be a central mechanism by which AA protects liver from injury.

Genotoxicity of polar and apolar extracts obtained from Qualea multiflora and Qualea grandiflora

ETHNOPHARMACOLOGICAL RELEVANCE

The species Qualea grandiflora and Qualea multiflora, which belong to the Vochysiaceae family, are common in the Brazilian savannah (Cerrado biome), and the local inhabitants use these species to treat external ulcers and gastric diseases and as an anti-inflammatory agent. Studies have demonstrated that these plants contain compounds that exhibit pharmacological activities; however, the risks associated with their consumption are not known.

MATERIAL AND METHODS

In the present study, the mutagenicity of polar and apolar extracts from Qualea grandiflora and Qualea multiflora were assessed by employing the Ames assay with and without metabolic activation. Additionally, phytochemical analyses (HPLC-ESI-IT-MS, HPLC-UV-PDA and GC-IT-MS) were performed to identify the chemical constituents present in these species, including the evaluation of physico-chemical properties, such as polarity or apolarity of the organic compounds, which are related to each fraction obtained. These studies provide important information regarding the biochemical behaviour of these compounds.

RESULTS

All extracts exhibited mutagenicity, inducing frameshift mutations and base substitutions in DNA. Phytochemical analysis identified terpenes, ellagic acid derivatives and phytosteroids.

CONCLUSIONS

The mutagenicity observed might be due to the presence of pentacyclic triterpenes and polyphenols, which are able to generate reactive oxygen species (ROS) and result in the potential to cause DNA damage. The genetic risk identified in this present work shows that special attention should be considered for the use of compounds obtained from these plant species in medicinal treatments. Further studies must be conducted to identify safe therapeutic doses.

Asiatic acid inhibits pro-angiogenic effects of VEGF and human gliomas in endothelial cell culture models

Malignant gliomas are one of the most devastating and incurable tumors. Sustained excessive angiogenesis by glioma cells is the major reason for their uncontrolled growth and resistance toward conventional therapies resulting in high mortality. Therefore, targeting angiogenesis should be a logical strategy to prevent or control glioma cell growth. Earlier studies have shown that Asiatic Acid (AsA), a pentacyclic triterpenoid, is effective against glioma and other cancer cells; however, its efficacy against angiogenesis remains unknown. In the present study, we examined the anti-angiogenic efficacy of AsA using human umbilical vein endothelial cells (HUVEC) and human brain microvascular endothelial cells (HBMEC). Our results showed that AsA (5–20 µM) inhibits HUVEC growth and induces apoptotic cell death by activating caspases (3 and 9) and modulating the expression of apoptosis regulators Bad, survivin and pAkt-ser473. Further, AsA showed a dose-dependent inhibition of HUVEC migration, invasion and capillary tube formation, and disintegrated preformed capillary network. AsA also inhibited the VEGF-stimulated growth and capillary tube formation by HUVEC and HBMEC. Next, we analyzed the angiogenic potential of conditioned media collected from human glioma LN18 and U87-MG cells treated with either DMSO (control conditioned media, CCM) or AsA 20 µM (AsA20 conditioned media, AsA20CM). CCM from glioma cells significantly enhanced the capillary tube formation in both HUVEC and HBMEC, while capillary tube formation in both endothelial cell lines was greatly compromised in the presence of AsA20CM. Consistent with these results, VEGF expression was lesser in AsA20CM compared to CCM, and indeed AsA strongly inhibited VEGF level (both cellular and secreted) in glioma cells. AsA also showed dose-dependent anti-angiogenic efficacy in Matrigel plug assay, and inhibited the glioma cells potential to attract HUVEC/HBMEC. Overall, the present study clearly showed the strong anti-angiogenic potential of AsA and suggests its usefulness against malignant gliomas.

Electrochemical sensing for caspase 3 activity and inhibition using quantum dot functionalized carbon nanotube labels

A novel electrochemical sensing platform for sensitive determination of caspase 3 activity and inhibition was developed by combining the site-specific recognition and cleavage of the DEVD-peptide with quantum dots as signal amplification.

Targeting inflammatory pathways by triterpenoids for prevention and treatment of cancer

Traditional medicine and diet has served mankind through the ages for prevention and treatment of most chronic diseases. Mounting evidence suggests that chronic inflammation mediates most chronic diseases, including cancer. More than other transcription factors, nuclear factor-kappaB (NF-κB) and STAT3 have emerged as major regulators of inflammation, cellular transformation, and tumor cell survival, proliferation, invasion, angiogenesis, and metastasis. Thus, agents that can inhibit NF-κB and STAT3 activation pathways have the potential to both prevent and treat cancer. In this review, we examine the potential of one group of compounds called triterpenes, derived from traditional medicine and diet for their ability to suppress inflammatory pathways linked to tumorigenesis. These triterpenes include avicins, betulinic acid, boswellic acid, celastrol, diosgenin, madecassic acid, maslinic acid, momordin, saikosaponins, platycodon, pristimerin, ursolic acid, and withanolide. This review thus supports the famous adage of Hippocrates, “Let food be thy medicine and medicine be thy food”.

Microbial transformation of asiatic acid by Alternaria longipes

Asiatic acid is a major pentacyclic triterpene isolated from Centella asiatica. It shows a variety of bioactivities. In order to obtain its derivatives, potentially useful for detailed pharmacological studies, the substrate was subjected to incubations with selected micro-organisms. In this work, asiatic acid was converted into three new compounds: 2α,3β,23,30-tetrahydroxyurs-12-ene-28-oic acid (1), 2α,3β,22β,23-tetrahydroxyurs-12-ene-28-oic acid (2), and 2α,3β,22β,23,30-pentahydroxyurs-12-ene-28-oic acid (3) by the fungus Alternaria longipes AS 3.2875. The structures of the three metabolites were determined by 1D and 2D NMR spectral data.

Asiatic acid induces colon cancer cell growth inhibition and apoptosis through mitochondrial death cascade

Cancer is one of the leading causes of death in the world. The triterpenoid compound asiatic acid derived from the tropical medicinal plant Centella asiatica displays cytotoxic activity on fibroblast cells and several other kinds of cells. The present work studies asiatic acid-mediated growth inhibition of cancer cells and the underlying mechanism. Asiatic acid markedly inhibited cancer cell proliferation. Apoptosis of SW480 human colon cancer cells was induced by asiatic acid as shown by flow cytometry, DNA fragmentation and nuclear chromatin condensation experiments. Through increasing mitochondrial membrane permeability and cytochrome c release from mitochondria into cytosol, asiatic acid induced caspase-9 activity, which further activated caspase-3 and poly(ADP-ribose) polymerase cleavage resulting in irreversible apoptotic death in the tumor cells. Taken together, these results suggest that mitochondrial death apoptosis cascade plays very important roles in asiatic acid-induced cancer apoptosis.

Antioxidant and cytotoxic activities of Centella asiatica (L) Urb

In the present study, the phenolic (Folin-Dennis) and flavonoid (colorimetric assay) constituents, antioxidant [2,2-diphenyl-2-picrylhydrazyl hydrate (DPPH) assay] and cytotoxic activities of an aqueous extract (AE) of Centella asiatica leaves were investigated. The aqueous extract (50 g/L) was obtained by infusion followed by cold maceration for 24 h. The levels of phenolic and flavonoid compounds were 2.86 g/100 g and 0.361 g/100 g, respectively. The AE showed elevated DPPH scavenging activity, with an IC₅₀ value of 31.25 μg/mL. The AE had a promising activity against mouse melanoma (B₁₆F₁), human breast cancer (MDA MB-231) and rat glioma (C₆) cell lines, with IC₅₀ values of 698.0, 648.0 and 1000.0 μg/mL, respectively. A positive correlation was established between the level of flavonoids, antioxidant and antitumor activities.

Apoptosis induction of Centella asiatica on human breast cancer cells

The present study evaluated the ability of methanolic extract of Centella asiatica (Linn) Urban (Umbelliferae) to induce apoptosis in different cancer cell lines. MCF-7 cells emerged as the most sensitive cell line for in vitro growth inhibitory activity. C. asiatica extract induced apoptosis in MCF-7 cells as indicated by nuclear condensation, increased annexin staining, loss of mitochondrial membrane potential and induction of DNA breaks identified by TUNEL reactivity. It is possible that the use of C. asiatica extract as a component in herbal medicines could be justifiable.

Antigenotoxic role of Centella asiatica L. extract against cyproterone acetate induced genotoxic damage in cultured human lymphocytes

The majority of the Indian population use traditional natural preparations derived from plant material for the treatment of various diseases, and for that reason it becomes necessary to assess the mutagenic potential or modulating action of plants extract when associated with other substances. The genotoxicity testing provides human a risk assessment. Earlier in vitro and in vivo studies reveal that the plant extracts from various parts of the plant play a modulating role in xenobiotic effects. Identification and characterization of some active principles may lead to the development of the strategies to reduce the risk for developing cancer in humans. Cyproterone acetate (CPA), a synthetic progestin is not only a genotoxic agent but also a tumor initiating agent. It is used in oral contraceptives formulations and also in the treatment of various sexual and metabolic disorders. In this context, the antigenotoxic effect of Centella asiatica L. extract was studied against the genotoxic effect induced by CPA on human lymphocytes using chromosomal aberrations and sister chromatid exchanges as parameters. The treatment of the two doses of CPA, i.e. 20 and 30 microM was given along with the C. asiatica extract at the dosages of 1.075 x 10(-4), 2.125 x 10(-4), 3.15 x 10(-4) and 4.17 x 0(-4)g/ml of culture medium. A clear dose dependent decrease in the genotoxic damage of CPA was observed, suggesting a protective role of C. asiatica extract during CPA therapy. The results of the present study suggest that the plant extract per se do not have genotoxic potential, but can modulate the genotoxicity of CPA on human lymphocytes in vitro.

Beneficial effects of Centella asiatica aqueous extract against arsenic-induced oxidative stress and essential metal status in rats

The efficacy of an aqueous extract of Centella asiatica (100, 200 and 500 mg/kg for 5 consecutive days) was studied in the depletion of arsenic and in the recovery of a few altered biochemical variables in arsenic pre-exposed rats (20 ppm in drinking water for 5 weeks). Exposure to arsenic significantly depleted delta-aminolevulinic acid dehydratase (ALAD) activity, reduced glutathione (GSH) level, superoxide dismutase (SOD) and increased thiobarbituric acid reactive substance (TBARS) activity in red blood cells. Significant depletion of ALAD activity, GSH level, glutathione peroxidase (GPx), SOD and catalase (CAT) activities and an increase in TBARS levels in liver tissues was also noted. There was a significant depletion of SOD, CAT and GPx activities in kidneys and an increased TBARS levels in kidney and brain accompanied by increased arsenic concentration in blood and soft tissues. Treatment with aqueous extract of Centella asiatica provided significant protection against ALAD, GSH and TBARS levels, particularly at doses of 200 and 500 mg. Centella asiatica also provided significant recovery in the inhibited liver ALAD and G6PD activities. Arsenic concentration in blood and soft tissues remained uninfluenced after Centella asiatica administration. The present study thus suggests a beneficial effect of Centella asiatica against arsenic-induced oxidative stress but possesses no chelating property.