Cytotoxic clerodane diterpenoids from the leaves ofPolyalthia longifolia

16-Hydroxy-ent-halima-5(10),13-dien-15,16-olide from Polyalthia longifolia targets adipogenesis by inhibiting mitotic clonal expansion and ameliorates dyslipidemia

Obesity-related metabolic disorders are increasing at an alarming rate worldwide. The FDA has approved many molecules for weight loss therapy; most of them act on the gut level by inhibiting lipid uptake or on the central nervous system by controlling appetite. Limitations and drawbacks have propelled the search for new pharmacophores exhibiting favourable metabolic alteration at adipocytes, and natural products have always been there to prove their worth. In our efforts, we have identified 16-hydroxy-ent-halima-5(10),13-dien-15,16-olide (PLH), a halimane diterpene isolated from Polyalthia longifolia, demonstrating anti-adipogenic and anti-dyslipidemic activity. It inhibited adipogenesis in 3T3-L1 preadipocyte and C3H10T1/2 mesenchymal stem cell lines. Furthermore, it decreased set of adipogenic markers at transcript and protein levels. Cell cycle studies indicated that PLH halts the mitotic clonal expansion. Mechanistic studies shows that PLH activate Wnt/β-catenin signaling pathway to inhibit the adipogenesis. The study suggested that PLH inhibited adipogenesis during the early phase of differentiation by targeting mitotic clonal expansion and arresting the cell cycle in the G1 phase of the cell cycle. It improved the dyslipidemic condition in HFD-fed hamsters by decreasing the body weight, fat mass, eWAT weight and improving the serum lipid profile. Overall, PLH has been found as a potential drug candidate and a pharmacophore for combating metabolic disorders including obesity and dyslipidemia.

Mechanisms of the In Vivo Antitumor Activity of Polyalthia longifolia Leaf Extract Against HeLa Cell Xenograft Tumor: A Microscopic-Based Histological and Immunohistochemical Microanalyses

The present study investigated the effects of Polyalthia longifolia leaf extract against the growth of HeLa cell xenograft tumor in nude mice and its underlying mechanism. The nude mice xenografted with HeLa cells were treated with 5% DMSO (vehicle control), 20 mg/kg/body weight of etoposide (positive control), and 500 and 1000 mg/kg/body weight of leaf extract, respectively. Antitumor activity was evaluated with apoptosis, proliferation, and angiogenesis using microscopic-based histological and immunohistochemical microanalyses. The tumor tissue histological and immunohistochemical analyses showed that the HeLa tumor cell death was associated with apoptosis and decreased (p < 0.05) expression of Ki-67 in tumor tissues. The extract also inhibits tumor angiogenesis by downregulating (p < 0.05) the expression of VEGF and CD31 in tumor tissues after treatment for 35 days. Conclusively, the P. longifolia leaf extract effectively inhibited HeLa cell xenograft growth in nude mice. The possible mechanism was related to induction of apoptosis, inhibition of tumor HeLa cell proliferation by decreasing the Ki-67 protein expression, and prevention of tumor angiogenesis by reducing VEGF and CD31 protein expression in HeLa cells.

Design, synthesis and evaluation of novel pyrrole-hydroxybutenolide hybrids as promising antiplasmodial and anti-inflammatory agents

In the pursuance of novel scaffolds with promising antiplasmodial and anti-inflammatory activity, a series of twenty-one compounds embraced with most promising penta-substituted pyrrole and biodynamic hydroxybutenolide in single skeleton was designed and synthesized. These pyrrole-hydroxybutenolide hybrids were evaluated against Plasmodium falciparum parasite. Four hybrids 5b, 5d, 5t and 5u exhibited good activity with IC₅₀ of 0.60, 0.88, 0.97 and 0.96 μM for chloroquine sensitive (Pf3D7) strain and 3.92, 4.31, 4.21 and 1.67 μM for chloroquine resistant (PfK1) strain, respectively. In vivo efficacy of 5b, 5d, 5t and 5u was studied against the P. yoelii nigeriensis N67 (a chloroquine-resistant) parasite in Swiss mice at a dose of 100 mg/kg/day for 4 days via oral route. 5u was found to show maximum 100% parasite inhibition with considerably increased mean survival time. Simultaneously, the series of compounds was screened for anti-inflammatory potential. In preliminary assays, nine compounds showed more than 85% inhibition in hu-TNFα cytokine levels in LPS stimulated THP-1 monocytes and seven compounds showed more than 40% decrease in fold induction in reporter gene activity analyzed via Luciferase assay. 5p and 5t were found to be most promising amongst the series, thus were taken up for further in vivo studies. Wherein, mice pre-treated with them showed a dose dependent inhibition in carrageenan induced paw swelling. Moreover, the results of in vitro and in vivo pharmacokinetic parameters indicated that the synthesized pyrrole-hydroxybutenolide conjugates abide by the required criteria for the development of orally active drug and thus this scaffold can be used as pharmacologically active framework that should be considered for the development of potential antiplasmodial and anti-inflammatory agents.

Toxicological Effects of Copaiba Oil (Copaifera spp.) and Its Active Components

Vegetable oils are among the most important traditional resources of Amazonia. Oleoresins are a type of oil that have interesting characteristics and highly bioactive properties with pharmacological potential. Oleoresins produced in the trunks of Copaifera (Fabaceae) spp. trees, known as copaiba oils, are made up of terpenes from the sesquiterpene (volatile) and diterpene (resinous) classes, but in amounts that vary between species and depending on several factors, such as soil type. Despite being used for medicinal purposes, via topical and oral application, the toxic effects of copaiba oils and their constituents are little known. The current paper reviews the toxicological studies, both in vitro and in vivo, described in the literature for copaiba oils, as well as the cytotoxic characteristics (against microorganisms and tumor cells) in in silico, in vitro and in vivo models for the sesquiterpenes and diterpenes that make up these oils.

Potential anti-hepatocellular carcinoma properties and mechanisms of action of clerodane diterpenes isolated from Polyalthia longifolia seeds

Diterpenes are secondary metabolites that have attracted much attention due to their potential biological activities including anti-cancer potential. The aim of the current study is to assess the anticancer potential of the six known clerodane diterpenes (1–6) isolated from Polyalthia longifolia seeds and their underlying molecular mechanisms. These compounds were evaluated for their cytotoxicity in vitro by using MTT assays. The “two-phase model” with NDEA and PB ad libitum was used for induction of HCC and sorafenib was used as the standard drug. Prophylactic studies were carried out for compounds 4/6 at both low (5 mg/kg b.w) and high (10 mg/kg b.w) doses. Based on the MTT assay results, the two best compounds, 4 and 6, were selected for in vivo studies. The results showed that treatment with compound 4/6 significantly restored the changes in biochemical parameters and liver morphology observed in (NDEA + PB)-induced HCC rats. Additionally, the docking studies showed that compound 4/6 interacted with several key proteins such as MDM2, TNF-α, FAK, thereby inhibiting these proteins and reversing the negative impacts of NDEA. In conclusion, our results suggested that compounds 4 and 6 are potential therapeutic agents for HCC, mostly due to their ability to control typical cancer pathways.

In vitro antiaging activity of polyphenol rich Polyalthia longifolia (Annonaceae) leaf extract in Saccharomyces cerevisiae BY611 yeast cells

ETHNOPHARMACOLOGICAL RELEVANCE

Polyalthia longifolia var. angustifolia Thw. (Annonaceae) is commonly used in traditional medicine as a tonic for rejuvenation and exhibiting good antioxidant activities.

AIM OF THE STUDY

To evaluate P. longifolia methanolic leaf extract (PLME) antiaging activity at 1 mg/mL in Saccharomyces cerevisiae BY611 yeast.

MATERIALS AND METHODS

The antiaging effect of PLME was studied via replicative lifespan assay, antioxidative stress assays, reactive oxygen species (ROS) determination, reduced glutathione (GSH) determination, superoxide dismutase (SOD) and Sirtuin 1 (SIRT1) genes regulation studies and SOD and SIRT1 proteins activities.

RESULTS

The PLME treatment increased the growth and prolonged the lifespan of the yeast significantly (p < 0.05) compared to the untreated yeast group. Besides, the PLME also protected the yeast from oxidative stress induced by 4-mM-H₂O₂ via decreasing (p < 0.05) the ROS from 143.207 to 127.223. The antioxidative action of PLME was proved by spot assay. Phloxine B staining was further confirmed the PLME antioxidative action of PLME, where more whitish-pink live yeast cells were observed. In addition, the PLME also enhanced GSH content significantly (p < 0.05) in yeast treated with PLME from 16.81 to 25.31 μmol. Furthermore, PLME increased the SOD and SIRT1 genes expression significantly (p < 0.05) with ΔCt values of 1.11 and 1.15, respectively. The significantly (p < 0.05) elevated SOD and SIRT1 protein activities were recorded as 51.54 U/mg Prot and 1716 ng/mL, respectively.

CONCLUSIONS

PLME exhibited good antiaging activities in S. cerevisiae, by modulating oxidative stress, enhancing GSH content, and increasing SOD and SIRT1 genes expression.

Clerodane Diterpenoids Identified from Polyalthia longifolia Showing Antifungal Activity against Plant Pathogens

In the search for new natural resources showing plant disease control effects, we found that the methanol extract of Polyalthia longifolia suppressed fungal disease development in plants. To identify the bioactive substances, the methanol extract of P. longifolia was extracted by organic solvents, and consequently, four new 2-oxo-clerodane diterpenes (1-4), a new 4(3 → 2)-abeo-clerodane diterpene (5), together with ten known compounds (6-16) were isolated and identified from the extracts. Of the new compounds, compound 2 showed a broad spectrum of antifungal activity with moderated minimum inhibitory concentration (MIC) values in a range of 50-100 μg/mL against tested fungal pathogens. Considering with the known compounds, compound 6 showed the most potent antifungal activity with an MIC value in the range of 6.3-12.5 μg/mL. When compound 6 was evaluated for an in vivo antifungal activity against rice blast, tomato late blight, and pepper anthracnose, compound 6 reduced the plant disease by at least 60% compared to the untreated control at concentrations of 250 and 500 μg/mL. Together, our results suggested that the methanol extract of twigs and leaves of P. longifolia and its major compound 6 could be used as a source for the development of eco-friendly plant protection agents.

Phytochemicals from Polyalthia Species: Potential and Implication on Anti-Oxidant, Anti-Inflammatory, Anti-Cancer, and Chemoprevention Activities

Polyalthia belong to the Annonaceae family and are a type of evergreen tree distributed across many tropical and subtropical regions. Polyalthia species have been used long term as indigenous medicine to treat certain diseases, including fever, diabetes, infection, digestive disease, etc. Recent studies have demonstrated that not only crude extracts but also the isolated pure compounds exhibit various pharmacological activities, such as anti-oxidant, anti-microbial, anti-tumor, anti-cancer, etc. It is known that the initiation of cancer usually takes several years and is related to unhealthy lifestyle, as well as dietary and environmental factors, such as stress, toxins and smoking. In fact, natural or synthetic substances have been used as cancer chemoprevention to delay, impede, or even stop cancer growing. This review is an attempt to collect current available phytochemicals from Polyalthia species, which exhibit anti-cancer potentials for chemoprevention purposes, providing directions for further research on the interesting agents and possible clinical applications.

Essential Oils of Polyalthia suberosa Leaf and Twig and Their Cytotoxic and Antimicrobial Activities

Essential oils from the leaf and twig of Polyalthia suberosa (Roxb.) Thwaites were analyzed using GC/MS/FID. A total of sixty-three constituents were namely identified accounting for 96.03 and 94.12 % in the hydrodistilled oils of the leaf and twig, respectively. Monoterpenes, monoterpenoids, sesquiterpenes, and sesquiterpenoids were characteristic derivatives of P. suberosa essential oils. Sesquiterpenes bicyclogermacrene (26.26 %) and (E)-caryophyllene (7.79 %), and monoterpene β-pinene (12.71 %) were the major constituents of the leaf oil. Sesquiterpenes (E)-caryophyllene (17.17 %) and α-humulene (9.55 %), sesquiterpenoid caryophyllene oxide (9.41 %), and monoterpenes camphene (8.16 %) and tricyclene (6.35 %) were to be main components in the twig oil. The leaf oil indicated cytotoxic activity against three cancer cell lines HepG2, MCF7 and A549 with the IC₅₀ values of 60.96-69.93 μg/mL, while the twig oil inhibited MCF7 with the IC₅₀ value of 66.70 μg/mL. Additionally, the twig oil successfully suppressed the growth of the negative Gram bacterium Pseudomonas aeruginosa, fungus Aspergillus niger, and yeast Candida albicans with the same MIC value of 50 μg/mL, whereas the leaf oil had the same result on the negative Gram bacterium Escherichia coli.

Terpenes isolated from Polyalthia simiarum and their cytotoxic activities

Two new C₃₁ triterpenes, polysimiaric acid A (1) and B (2) as well as one new clerodane diterpenoid, 16,16-dimethoxy-cleroda-3,13Z-dien-15-oic acid (3), together with six known compounds were isolated from Polyalthia simiarum. Their structures were determined by analysis of 1D and 2D NMR data. Three new compounds were tested for their cytotoxicity against five human tumour cell lines. Compound 3 showed cytotoxic activities against SMMC-7721 with the IC₅₀ value of 22.43 μM.

Dual COX and 5-LOX inhibition by clerodane diterpenes from seeds of Polyalthia longifolia (Sonn.) Thwaites

Natural metabolites with their specific bioactivities are being considered as a potential source of materials for pharmacological studies. In this study, we successfully isolated and identified five known clerodane diterpenes, namely 16-oxo-cleroda-3,13(14)E-dien-15-oic acid (1), 16-hydroxy-cleroda-3,13-dien-15-oic acid (2), 16-hydroxy-cleroda-4(18),13-dien-16,15-olide (3), 3α,16α-dihydroxy-cleroda-4(18),13(14)Z-dien-15,16-olide (4), and 16α-hydroxy-cleroda-3,13(14)Z-dien-15,16-olide (5) from the methanolic extract of seeds of Polyalthia longifolia. Initially, all the isolated metabolites were investigated for COX-1, COX-2, and 5-LOX inhibitory activities using the standard inhibitory kits. Of which, compounds 3, 4, and 5 exhibited to be potent COX-1, COX-2, and 5-LOX inhibitors with the IC₅₀ values similar or lower to those of the reference drugs. To understand the underlying mechanism, these compounds were subjected to molecular docking on COX-1, COX-2, and 5-LOX proteins. Interestingly, the in silico study results were in high accordance with in vitro studies where compounds 3, 4, and 5 hits assumed interactions and binding pattern comparable to that of reference drugs (indomethacin and diclofenac), as a co-crystallized ligand explaining their remarkable dual (COX/LOX) inhibitor actions. Taken together, our findings demonstrated that compounds 3, 4, and 5 functioned as dual inhibitors of COX/5-LOX and can contribute to the development of novel, more effective anti-inflammatory drugs with minimal side-effects.

Two clerodane diterpenes isolated from Polyalthia longifolia leaves: comparative structural features, anti-histaminic and anti-Helicobacter pylori activities

Phytochemical studies of methylene chloride soluble fraction from the 70% aqueous-alcoholic extract of Polyalthia longifolia (leaves) resulted in the isolation of two known clerodane diterpenes, namely: 16α-hydroxycleroda-3,13(14)-dien-16,15-olide (1) and (4→2)-abeo-16-hydroxy-cleroda-2,13(14)-dien-15,16-olide-3-al (2). The isolated compounds were evaluated for their anti-histaminic and anti-Helicobacter pylori activities. Compound 1 was more potent than 2 with IC₅₀ 29.7 μg/mL and 189.2 μg/mL in the anti-histaminic assay and MIC equals to 31.25 μg/mL and 125 μg/mL in the anti-H. pylori assay, as compared with diclofenac (IC₅₀ = 17.9 μg/mL) and clarithromycin (MIC = 1.95 μg/mL), respectively. The differences in their structures, as well as their activity results, indicated important characteristic features necessary for activity. It was suggested that the decalin moiety in 1 was important for both activities. On the other hand, the (4→2)-abeo migration in 2 reduced both activities. The potent activities of 1 suggest its potential application as an anti-histaminic and antimicrobial agent.

Polyalthia longifolia Extract Triggers ER Stress in Prostate Cancer Cells Concomitant with Induction of Apoptosis: Insights from In Vitro and In Vivo Studies

Plant-based therapies are being explored to prevent or treat several cancer types. The antioxidant properties of Polyalthia longifolia plant are well established. In our previous work, we demonstrated the presence of cytotoxic compounds in the methanol extract of Polyalthia longifolia (MEP) with potent activity against human leukemia cells. In the present study, we evaluated the efficacy of MEP against prostate cancer (PCa) and established the molecular basis of its effect in in vitro and in vivo models. We observed that MEP treatment resulted in a significant decrease in the growth and viability of PCa cells, associated with arrest in the G1/S phase of the cell cycle. Apoptosis was confirmed as the primary mode of MEP-induced cell death through activation of the intrinsic apoptotic machinery. Proteomic and biochemical studies identified BiP as an important target of MEP with the activation of the ER stress pathway, as a potential mechanism driving MEP-induced apoptosis. The extract exhibited strong efficacy in the PCa xenograft mouse model with significant inhibition of tumor growth and reduced tumor burden. Taken together, our findings indicate that MEP-induced apoptosis in PCa cells concomitant with the activation of the ER stress pathways results in the inhibition of tumor growth, in vitro and in vivo. Our studies provide initial evidence of the efficacy of MEP against PCa and advocate for in-depth studies in other preclinical models for its possible use in clinical settings.

Flavonoids from Polyalthia longifolia prevents advanced glycation end products formation and protein oxidation aligned with fructose-induced protein glycation

Advanced glycation end products (AGEs) are reactive chemical entities formed by non-enzymatic reaction between reducing sugars and amino group of proteins. Enhanced accumulation of AGEs and associated protein oxidation contribute to pathogenesis of diabetes-associated complications. Here, we evaluated the inhibitory activity of flavonoid compounds isolated from the leaves of Polyalthia longifolia on formation of AGEs and protein oxidation. Antiglycation activity was determined by measuring the formation of AGE fluorescence intensity, Nε-(carboxymethyl) lysine, and level of fructosamine. Protein oxidation was examined using levels of protein carbonyls and thiol group. Compounds significantly (p < 0.001) restricted the formation of fluorescent AGEs in fructose- BSA and methylglyoxal-BSA systems. Furthermore, there was a decrease in levels of fructosamine and protein carbonyls, and elevation in level of thiol group in fructose-BSA in presence of flavonoids. In summary, flavonoids from Polyalthia longifolia inhibit fructose-mediated protein glycation and oxidation, and can be potential agent for preventing AGE-mediated diabetic complications.

The medicinal uses, toxicities and anti-inflammatory activity of Polyalthia species (Annonaceae)

ETHNOPHARMACOLOGICAL RELEVANCE

Polyalthia is one of the largest and notable genera in Annonaceae family. Polyalthia species have been widely used in folklore medicine for the treatment of rheumatic fever, gastrointestinal ulcer and generalized body pain. Numerous in vitro and in vivo studies on Polyalthia Species have also corroborated the significant anti-inflammatory potential of its extracts and secondary metabolites.

AIM OF THE STUDY

This review is an attempt to assess the anti-inflammatory activity of Polyalthia species by giving critical appraisal and establishing evidences of their traditional uses. Moreover this review will highlight the lead compounds for future drug development that can serve as a potential anti-inflammatory drug with comparative efficacy and minimum side effects.

MATERIALS AND METHODS

An extensive literature review, focusing the anti-inflammatory potential of Polyalthia species was conducted using the following databases:PubMed, ScienceDirect, SpringerLink, Ovid, Scopus and ProQuest, as well as the locally available books, journals and relevant documents. The reference lists of retrieved papers were also searched for additional studies.

RESULTS

The Polyalthia species have shown significant anti-inflammatory activity through various mechanism of action. The most significant anti-inflammatory mechanism includes the inhibition of nuclear factor kappa B (NF-κB), prostaglandins (PGs), pro-inflammatory cytokines, inducible nitric oxide synthase (iNOS) and reactive oxygen species (ROS). The data suggests that hydroxycleroda-3,13-dien-15,16-olide and 16-oxocleroda-3,13-dien-15-oic acid, quercetin, rutin, spinasterol, α-spinasterol, goniothalamin and (-)-5-hydroxygoniothalamin are the most potent anti-inflammatory compounds from Polyalthia species with comparable IC₅₀ with positive controls.

CONCLUSIONS

Numerous pharmacological studies have supported the use of Polyalthia species against pain, rheumatic fever, haemorrhages and inflammation in traditional medicine. Flavonoids, diterpenoids, sterols and styrylpyrones from genus Polyalthia are the most significant class of compounds with potent anti-inflammatory activity. Secondary metabolites from these classes should be brought into further research to fill the gaps of knowledge in pharmacokinetics, pharmacodynamics, bioavailability, and toxicity in order to convert the pre-clinical results into clinical data for further investigation.

Comparative Antileukemic Activity of a Tetranorditerpene Isolated from Polyalthia longifolia Leaves and the Derivative against Human Leukemia HL-60 Cells

The discovery of potent cytotoxic isolates from botanicals provides an opportunity to explore this viable tool for cancer chemoprevention. The antileukemic potential of clerodane diterpene from Polyalthia longifolia leaves has already been established. However, in this present study, utilizing chromatographic techniques we report for the first time, the isolation of a rare tetranorditerpene (compound 1) from P. longifolia. The structure of compound 1 was elucidated and confirmed by spectrophotometric data. UPLC-MS analysis was conducted on the methanolic extract, ethyl acetate fraction, and isolated tetranorditerpene showed that the tetranorditerpene is one of the major constituents of the plant with a retention time of 30.78 min. In addition, a methyl ester derivative (compound 2) of the isolated tetranorditerpene was synthesized. Using the CCK-8 assay, we compared the cytotoxic potential of isolated tetranorditerpene (1) and methyl ester derivative (2) with the previously isolated clerodane diterpenes. Our results showed that the methyl ester derivative (2) displayed the highest inhibitory activity against human leukemia HL-60 cells. The isolated tetranorditerpene (1) did not exhibit significant inhibitory effect against HL-60 cells. Morphological examination indicated chromatin condensation and nuclear fragmentation suggesting induction of apoptosis in compound 2 treated HL-60 cells. The methyl esterification of the isolated tetranorditerpene (1) conferred on it a significant level of antileukemic activity suggesting the possibility of a synergistic relationship between pure compound isolation and synthetic reaction in the discovery of new chemopreventive agents.

Clerodane diterpenes: sources, structures, and biological activities

Covering: 1990 to 2015The clerodane diterpenoids are a widespread class of secondary metabolites and have been found in several hundreds of plant species from various families and in organisms from other taxonomic groups. These substances have attracted interest in recent years due to their notable biological activities, particularly insect antifeedant properties. In addition, the major active clerodanes of Salvia divinorum can be used as novel opioid receptor probes, allowing greater insight into opioid receptor-mediated phenomena, as well as opening additional areas for chemical investigation. This article provides extensive coverage of naturally occurring clerodane diterpenes discovered from 1990 until 2015, and follows up on the 1992 review by Merritt and Ley in this same journal. The distribution, chemotaxonomic significance, chemical structures, and biological activities of clerodane diterpenes are summarized. In the cases where sufficient information is available, structure activity relationship (SAR) correlations and mode of action of active clerodanes have been presented.

A new sesquiterpenoid from Polyalthia petelotii

A new sesquiterpenoid (‒)-ethyl dihydrophaseate (1) was isolated from the stems and leaves of Polyalthia petelotii, together with two clerodane diterpenoids, 16α-hydroxycleroda-3,13(14)Z-dien-15,16-olide (2), 15-hydroxy-cis-ent-cleroda-3,13(E)-diene (3), a eudesmane sesquiterpenoid, eudesm-4(15)-ene-7α,11-diol (4), an aromatic aldehyde, vanillin (5), a bisisoquinolines alkaloid, spinosine (6) and an aporphine alkaloid, (‒)-oliveroline-β-N-oxide (7). Their structures were established by extensive spectroscopic analysis, including 2D-NMR techniques. Compounds 3, 4 and 6 were isolated from the genus Polyalthia for the first time and the others obtained originally from P. petelotii. The isolates were assessed for their cytotoxicity against five human tumour lines (HL-60, SMMC-7721, A-549, MCF-7 and SW-480), and the result showed that only 2 displayed weak inhibitory activity.

Clerodane diterpenes from Polyalthia longifolia (Sonn) Thw. var. pendula: Potential antimalarial agents for drug resistant Plasmodium falciparum infection

BACKGROUND

Plasmodium falciparum drug resistance is a major public health challenge in sub-Sahara Africa. Many people are now resorting to the use of herbs in managing malaria due to the increasing treatment failures with the conventional drugs. In this study the ethanolic extract of Polyalthia longifolia (Sonn) Thw. var. pendula, a variety fondly used in folklore medicine in Ghana was investigated for potential antimalarial drug development.

METHOD

The ethanolic extract of P. longifolia (Sonn) Thw. var. pendula stem bark was screened against the multidrug resistant, K1 strain of P. falciparum by the parasite lactate dehydrogenase (pLDH) assay and a good antiplasmodial activity (IC50 22.04± 4.23µg/ml) was observed which led to further chromatographic analysis in search for actives.

RESULTS

Bioassay guided fractionation of the extract yielded; three clerodane diterpenes [16-hydroxycleroda-3,13-dien-16,15-olide (1), 16-oxocleroda-3,13E-dien-15-oic acid (2) and 3,16-dihydroxycleroda-4(18),13(14)Z-dien-15,16-olide (3)], a steroid [beta-stigmasterol (4)] and two alkaloids [darienine (5) and stepholidine (6)]. While compounds 4, 5 and 6 exhibited weak antiplasmodial activity (IC50 22-105µg/ml), the clerodane diterpenes exhibited significantly potent (p<0.005) blood schizonticidal activity (IC50: 3-6µg/ml). This is the first report of the antiplasmodial activity of compounds 2 and 3. In combination assay with chloroquine, compounds 1, 2, 3 and 5 antagonized the antiplasmodial activity of chloroquine while 4 and 6 demonstrated a synergistic action.

CONCLUSION

The potent antiplasmodial activity of the extract of P. longifolia (Sonn) Thw. var. pendula and compounds therein strongly suggests its usefulness as an antimalarial agent and supports its inclusion or exploitation in formulations of herbal remedies for malaria in Ghana.

Biological activities and cytotoxicity of diterpenes from Copaifera spp. Oleoresins

Copaifera spp. are Amazonian species widely studied and whose oleoresins are used by local people for various medicinal purposes. However, a detailed study of the activity of the main phytochemical components of these oleoresins remains to be done. Here, we studied the cytotoxicity and in vitro anti-inflammatory effects of six diterpene acids: copalic, 3-hydroxy-copalic, 3-acetoxy-copalic, hardwickiic, kolavic-15-metyl ester, and kaurenoic, isolated from the oleoresins of Copaifera spp. The diterpenes did not show cytotoxicity in normal cell lines, nor did they show significant changes in viability of tumoral line cells. The 3-hydroxy-copalic was able to inhibit the enzyme tyrosinase (64% ± 1.5%) at 250 µM. The kolavic-15-metyl ester at 200 µM showed high inhibitory effect on lipoxygenase (89.5% ± 1.2%). Among the diterpenes tested, only kaurenoic and copalic acids showed significant hemolytic activities with 61.7% and 38.4% at 100 µM, respectively. In addition, it was observed that only the copalic acid (98.5% ± 1.3%) and hardwickiic acid (92.7% ± 4.9%) at 100 mM inhibited nitric oxide production in macrophages activated by lipopolysaccharide. In this assay, the diterpenes did not inhibit tumor necrosis factor-α production. The acids inhibited the production of IL-6, 3-acetoxy-copalic (23.8% ± 8.2%), kaurenoic (11.2% ± 5.7%), kolavic-15-methyl ester (17.3% ± 4.2%), and copalic (4.2% ± 1.8%), respectively, at 25 µM. The kaurenoic, 3-acetoxy-copalic and copalic acids increased IL-10 production. This study may provide a basis for future studies on the therapeutic role of diterpenic acids in treating acute injuries such as inflammation or skin disorders.

Anticancer effect of the extracts from Polyalthia evecta against human hepatoma cell line (HepG2)

OBJECTIVE

To investigate the anticancer activity of Polyalthia evecta (P. evecta) (Pierre) Finet & Gagnep against human hepatoma cell line (HepG2).

METHODS

The anticancer activity was based on (a) the cytotoxicity against human hepatoma cells (HepG2) assessed using a neutral red assay and (b) apoptosis induction determined by evaluation of nuclei morphological changes after DAPI staining. Preliminary phytochemical analysis of the crude extract was assessed by HPLC analysis.

RESULTS

The 50% ethanol-water crude leaf extract of P. evecta (EW-L) showed greater potential anticancer activity with high cytotoxicity [IC50 = (62.8 ± 7.3)µg/mL] and higher selectivity in HepG2 cells than normal Vero cells [selective index (SI) = 7.9]. The SI of EW-L was higher than the positive control, melphalan (SI = 1.6) and the apoptotic cells (46.4 ± 2.6) % induced by EW-L was higher than the melphalan (41.6 ± 2.1)% (P<0.05). The HPLC chromatogram of the EW-L revealed the presence of various kinds of polyphenolics and flavonoids in it.

CONCLUSIONS

P. evecta is a potential plant with anticancer activity. The isolation of pure compounds and determination of the bioactivity of individual compounds will be further performed.

Synergistic anticancer effect of the extracts from Polyalthia evecta caused apoptosis in human hepatoma (HepG2) cells

OBJECTIVE

To evaluate the anticancer activity of the extract fraction of Polyalthia evecta (P. evecta) (Pierre) Finet & Gagnep and the synergistic anticancer effect of the extracts from P. evecta by using the ATR/FT-IR spectroscopy.

METHODS

The 50% ethanol-water crude leaf extract of P. evecta (EW-L) was prepared and was further fractionated to isolate various fractions. The anticancer activity was investigated from cytotoxicity against HepG2 using a neutral red assay and apoptosis induction by evaluation of nuclei morphological changes after DAPI staining. Synergistic anticancer effects of the extracts from P. evecta were performed using the ATR/FT-IR spectroscopy.

RESULTS

The result showed that the EW-L showed higher cytotoxicity and apoptosis induction in HepG2 cells than its fractionated extracts. The hexane extract exhibited higher cytotoxicity and apoptosis induction than the water extracts, but less than the EW-L. The combined water and hexane extracts apparently increased cytotoxicity and apoptosis induction. The %apoptotic cells induced by the extract mixture were increased about 2-fold compared to the single hexane extract.

CONCLUSIONS

The polar extract fraction is necessary for the anticancer activity of the non-polar extract fraction. The ATR/FT-IR spectra illustrates the physical interaction among the constituents in the extract mixture and reveals the presence of polyphenolic constituents in the EW-L, which might play a role for the synergistic anticancer effect.

Antioxidant and antityrosinase proanthocyanidins from Polyalthia longifolia leaves

In the present study the structure of proanthocyanidins from Polyalthia longifolia leaves was characterized with (13)C nuclear magnetic resonance, high performance liquid chromatography electrospray ionization mass spectrometry, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analyses. The results showed that the proanthocyanidins were mixture of homopolymers of B-type procyanidins with degree of polymerization up to 14-mer. Furthermore, the antioxidant activity of the proanthocyanidins was studied through 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) free-radical scavenging activities, and ferric reducing/antioxidant power assays. In addition, antityrosinase activity of the proanthocyanidins was investigated. The IC50 for 2,2-diphenyl-1-picrylhydrazyl and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) free-radical scavenging activity of the proanthocyanidins were 89.32 ± 12.07 and 76.79 ± 5.88 μg/mL, respectively; the ferric reducing/antioxidant power value was 710.54 ± 142.82 mg ascorbic acid equivalent/g dry weight. The IC50 for antityrosinase activity was 773.09 ± 1.47 μg/mL. In conclusion, the proanthocyanidins from P. longifolia leaves exhibited potent antioxidant and antityrosinase activities. This research would provide scientific evidence for the use of proanthocyanidins from P. longifolia leaves as antioxidant and antityrosinase agents.

Chemical composition of essential oils from the leaves and stem barks of Vietnamese species of Polyalthia harmandii, Polyalthia jucunda and Polyalthia thorelii

This article reports the chemical components identified in the essential oil from the leaf and stem barks of Polyalthia harmandii (Pierre) Fin. and Gagnep., Polyalthia jucunda (Pierre) Fin. and Gagnep. and Polyalthia thorelii (Pierre) Fin. and Gagnep. The compounds identified in all the samples were α-pinene (0.2-3.2%), myrcene (0.3-4.1%), (E)-β-ocimene (0.2-9.6%), bicycloelemene (0.2-18.0%), β-elemene (0.3-4.9%), β-caryophyllene (0.1-17.8%), germacrene D (4.4-20.1%), bicyclogermacrene (4.2-27.9%) and δ-cadinene (0.2-4.5%). Besides, benzyl benzoate (9.7%) and ishwarane (8.0%), respectively, were the other prominent compounds in the leaf and stem of P. harmandii. In addition, δ-3-carene (8.2%), α-amorphene (6.5%), β-phellandrene (5.5%) and β-pinene (5.1%) were identified in P. jucunda leaf, while sabinene (30.9%) and β-phellandrene (10.2%) occurred largely in the stem. Moreover, γ-elemene (22.3% and 12.3%), germacrene D (10.5% and 6.9%) and spathulenol (9.1% and 11.8%) were identified in the leaf and stem of P. thorelii, while α-terpinene (7.8%) and β-gurjunene (5.2%) were identified only in the leaf oil.

Clerodane diterpenes from Polyalthia longifolia var. pendula protect SK-N-MC human neuroblastoma cells from β-amyloid insult

The n-hexane layer of Polyalthia longifolia methanolic extract showed neuroprotective activity, resulting in the isolation of three new clerodane diterpenes.