Polyphenolic fraction of Algerian propolis protects rat kidney against acute oxidative stress induced by doxorubicin

Exploring the Prospective Role of Propolis in Modifying Aging Hallmarks

Aging populations worldwide are placing age-related diseases at the forefront of the research agenda. The therapeutic potential of natural substances, especially propolis and its components, has led to these products being promising agents for alleviating several cellular and molecular-level changes associated with age-related diseases. With this in mind, scientists have introduced a contextual framework to guide future aging research, called the hallmarks of aging. This framework encompasses various mechanisms including genomic instability, epigenetic changes, mitochondrial dysfunction, inflammation, impaired nutrient sensing, and altered intercellular communication. Propolis, with its rich array of bioactive compounds, functions as a potent functional food, modulating metabolism, gut microbiota, inflammation, and immune response, offering significant health benefits. Studies emphasize propolis' properties, such as antitumor, cardioprotective, and neuroprotective effects, as well as its ability to mitigate inflammation, oxidative stress, DNA damage, and pathogenic gut bacteria growth. This article underscores current scientific evidence supporting propolis' role in controlling molecular and cellular characteristics linked to aging and its hallmarks, hypothesizing its potential in geroscience research. The aim is to discover novel therapeutic strategies to improve health and quality of life in older individuals, addressing existing deficits and perspectives in this research area.

Propolis and its therapeutic effects on renal diseases: A review

Propolis is produced by bees using a mixture of bees wax and saliva. It contains several bioactive compounds that mainly induce anti-oxidant and anti-inflammatory effects. In this review, we aimed to investigate the effects of propolis on kidney diseases. We used "Kidney", "Disease", "Propolis", "Renal", "Constituent", "Mechanism", "Infection", and other related keywords as the main keywords to search for works published before July 2023 in Google scholar, Scopus, and Pubmed databases. The search terms were selected according to Medical Subject Headings (MeSH). This review showed that propolis affects renal disorders with inflammatory and oxidative etiology due to its bioactive compounds, mainly flavonoids and polyphenols. There have been few studies on the effects of propolis on kidney diseases; nevertheless, the available studies are integrated in this review. Overall, propolis appears to be effective against several renal diseases through influencing mechanisms such as apoptosis, oxidative balance, and inflammation.

GC-MS based metabolic profile and toxicological evaluation of three Algerian propolis

This study aimed to investigate the chemical composition and toxicity of methanolic extracts of three Algerian propolis collected from Oum el Bouaghi (MEPO), El Harrouch (MEPH) and Collo (MEPC) regions. The chemical profile was characterised by GC-MS. The toxicity of the extracts was tested using brine shrimp model. The GC-MS analysis revealed the presence of ferulic acid (23.8%), pinostrobin chalcone (15.8%) and α-eudesmol (11.3%) as major compounds in MEPO, pinostrobin chalcone (22.2%), 9-octadecenoic acid, methyl ester, (E)- (17.4%), and γ-gurjunenepoxide-(2) (11.7%) were the most abundant components in MEPH, whereas MEPC was dominated by 1-heptatriacotanol (17.8%), pinostrobin chalcone (14.7%), totarol (13.7%) and 9-octadecenoic acid, methyl ester, (E)- (13.0%). The brine shrimp lethality test indicated that the extracts had moderate toxicity in which MEPC exhibited the highest activity with LC50 of 201.61 ± 7.27 µg/mL. All extracts showed no toxicity at 25 µg/mL concentration and below.

Propolis in Metabolic Syndrome and Its Associated Chronic Diseases: A Narrative Review

Propolis is a resinous product collected by bees from plants to protect and maintain the homeostasis of their hives. Propolis has been used therapeutically by humans for centuries. This review article attempts to analyze the potential use of propolis in metabolic syndrome (MetS) and its associated chronic diseases. MetS and its chronic diseases were shown to be involved in at least seven out of the top 10 causes of death in 2019. Patients with MetS are also at a heightened risk of severe morbidity and mortality in the present COVID-19 pandemic. Propolis with its antioxidant and anti-inflammatory properties is potentially useful in ameliorating the symptoms of MetS and its associated chronic diseases. The aim of this article is to provide a comprehensive review on propolis and its therapeutic benefit in MetS and its chronic diseases, with an emphasis on in vitro and in vivo studies, as well as human clinical trials. Moreover, the molecular and biochemical mechanisms of action of propolis are also discussed. Propolis inhibits the development and manifestation of MetS and its chronic diseases by inhibiting of the expression and interaction of advanced glycation end products (AGEs) and their receptors (RAGEs), inhibiting pro-inflammatory signaling cascades, and promoting the cellular antioxidant systems.

Biomedical Properties of Propolis on Diverse Chronic Diseases and Its Potential Applications and Health Benefits

The use of alternative medicine products has increased tremendously in recent decades and it is estimated that approximately 80% of patients globally depend on them for some part of their primary health care. Propolis is a beekeeping product widely used in alternative medicine. It is a natural resinous product that bees collect from various plants and mix with beeswax and salivary enzymes and comprises a complex mixture of compounds. Various biomedical properties of propolis have been studied and reported in infectious and non-infectious diseases. However, the pharmacological activity and chemical composition of propolis is highly variable depending on its geographical origin, so it is important to describe and study the biomedical properties of propolis from different geographic regions. A number of chronic diseases, such as diabetes, obesity, and cancer, are the leading causes of global mortality, generating significant economic losses in many countries. In this review, we focus on compiling relevant information about propolis research related to diabetes, obesity, and cancer. The study of propolis could generate both new and accessible alternatives for the treatment of various diseases and will help to effectively evaluate the safety of its use.

Plant Sources Responsible for the Chemical Composition and Main Bioactive Properties of Poplar-Type Propolis

Propolis is a resinous mixture, made by the honeybees from substances collected from tree or other plant buds, plant exudates, or resins found in the stem, branches, or leaves of different plants. The geographical origin of propolis is given by plant sources from respective areas. Different studies have classified this bee product according to the vegetal material from the same areas. Poplar-type propolis has the widest spread in the world, in the temperate zones from Europe, Asia, or North America. The name is given by the main plant source from where the bees are collecting the resins, although other vegetal sources are present in the mentioned areas. Different Pinus spp., Prunus spp., Acacia spp. and also Betula pendula, Aesculus hippocastanum, and Salix alba are important sources of resins for "poplar-type" propolis. The aim of this review is to identify the vegetal material's chemical composition and activities of plant resins and balms used by the bees to produce poplar-type propolis and to compare it with the final product from similar geographical regions. The relevance of this review is to find the similarities between the chemical composition and properties of plant sources and propolis. The latest determination methods of bioactive compounds from plants and propolis are also reviewed.

Propolis and its potential against SARS-CoV-2 infection mechanisms and COVID-19 disease: Running title: Propolis against SARS-CoV-2 infection and COVID-19

Propolis, a resinous material produced by honey bees from plant exudates, has long been used in traditional herbal medicine and is widely consumed as a health aid and immune system booster. The COVID-19 pandemic has renewed interest in propolis products worldwide; fortunately, various aspects of the SARS-CoV-2 infection mechanism are potential targets for propolis compounds. SARS-CoV-2 entry into host cells is characterized by viral spike protein interaction with cellular angiotensin-converting enzyme 2 (ACE2) and serine protease TMPRSS2. This mechanism involves PAK1 overexpression, which is a kinase that mediates coronavirus-induced lung inflammation, fibrosis, and immune system suppression. Propolis components have inhibitory effects on the ACE2, TMPRSS2 and PAK1 signaling pathways; in addition, antiviral activity has been proven in vitro and in vivo. In pre-clinical studies, propolis promoted immunoregulation of pro-inflammatory cytokines, including reduction in IL-6, IL-1 beta and TNF-α. This immunoregulation involves monocytes and macrophages, as well as Jak2/STAT3, NF-kB, and inflammasome pathways, reducing the risk of cytokine storm syndrome, a major mortality factor in advanced COVID-19 disease. Propolis has also shown promise as an aid in the treatment of various of the comorbidities that are particularly dangerous in COVID-19 patients, including respiratory diseases, hypertension, diabetes, and cancer. Standardized propolis products with consistent bioactive properties are now available. Given the current emergency caused by the COVID-19 pandemic and limited therapeutic options, propolis is presented as a promising and relevant therapeutic option that is safe, easy to administrate orally and is readily available as a natural supplement and functional food.

Flavonoids differentially modulate liver X receptors activity-Structure-function relationship analysis

Liver X receptors (LXRs) α (NR1H3) and β (NR1H2) are nuclear receptors that have been involved in the regulation of many physiological processes, principally in the control of cholesterol homeostasis, as well as in the control of the cell death and proliferation balance. These receptors are thus promising therapeutic targets in various pathologies such as dyslipidemia, atherosclerosis, diabetes and/or cancers. These receptors are known to be activated by specific oxysterol compounds. The screening for LXR-specific ligands is a challenging process: indeed, these molecules should present a specificity towards each LXR-isoform. Because some natural products have significant effects in the regulation of the LXR-regulated homeostasis and are enriched in flavonoids, we have decided to test in cell culture the effects of 4 selected flavonoids (galangin, quercetin, apigenin and naringenin) on the modulation of LXR activity using double-hybrid experiments. In silico, molecular docking suggests specific binding pattern between agonistic and antagonistic molecules. Altogether, these results allow a better understanding of the ligand binding pocket of LXRα/β. They also improve our knowledge about flavonoid mechanism of action, allowing the selection and development of better LXR selective ligands.

Ethanolic extract of Algerian propolis decreases androgen receptor transcriptional activity in cultured LNCaP cells

Antiandrogens have a peculiar place in the treatment of metastatic prostate cancer by blocking the androgen receptor (AR). Unfortunately, aggressive tumors could rapidly develop into a castration resistant state. It is therefore essential to look for new molecules that are more effective, affecting not only the androgen signaling and with minimum undesirable effects. Natural products are an interesting source of new therapeutics, especially for cancer therapy as 70% of them have botanical origin. Based on an ethnobotany screening, we evaluated the effects of ethanolic extract of propolis (EEP) from Algeria on LNCaP cells. Results pointed out that EEP reduces the survival of LNCaP cells with an IC₅₀ of 0.04 mg/ml, induces the apoptosis and blocks the cell cycle at G0/G1 phase. Interestingly, EEP decreased the accumulation of AR suggesting some anti-androgen activity. Indeed, secreted amount of the androgen target protein PSA was decreased when LNCaP cells were incubated with EEP, starting after 4 h of treatment. This anti-androgen activity was also shown on the androgen target genes Fkbp5 and Sgk1. Finally, the capacity of EEP to block AR functioning was demonstrated in transient transfections with human AR and the reporter gene ARE-tk-Luc. Propolis antagonizes the induction of the luciferase activity induced by the natural androgen DHT (10^-8M) or the synthetic AR agonist R1881 (10^-7M). Altogether, these results highlight the potential pharmacological effects of EEP in future treatments of prostate cancer.

Chemical Diversity and Biological Activity of African Propolis

Natural remedies have for centuries played a significant role in traditional medicine and continue to be a unique reservoir of new chemical entities in drug discovery and development research. Propolis is a natural substance, collected by bees mainly from plant resins, which has a long history of use as a folk remedy to treat a variety of ailments. The highly variable phytochemical composition of propolis is attributed to differences in plant diversity within the geographic regions from which it is collected. Despite the fact that the last five decades has seen significant advancements in the understanding of the chemistry and biological activity of propolis, a search of the literature has revealed that studies on African propolis to date are rather limited. The aim of this contribution is to report on the current body of knowledge of African propolis, with a particular emphasis on its chemistry and biological activity. As Africa is a continent with a rich flora and a vast diversity of ecosystems, there is a wide range of propolis phytochemicals that may be exploited in the development of new drug scaffolds.

Hepatoprotective Effects of Algerian Crataegus oxyacantha Leaves

BACKGROUND

Hawthorn (C. oxyacantha), a common edible plant, is widely used for the preparation of a different foodstuff and is also used in traditional medicine to treat heart problems and gastrointestinal ailments. Recently, a few patents of Crataegus preparation for protective effects (prevention of cardiovascular and hepatic diseases) have been developed.

OBJECTIVE

The current study aimed to explore the antioxidant and hepatoprotective effects of nbutanol extract of Crataegus oxyacantha leaves in acute liver damage induced by Doxorubicin (DOX).

METHODS

Crataegus oxyacantha (100 mg/kg body weight) or vitamin E as a standard antioxidant (100 mg/kg body weight) were administered orally to female rats for 10 days, in the presence or absence of hepatotoxicity induced by a single intraperitoneal (i.p.) injection of DOX (15 mg/kg on the 8th day). On day 11, blood and liver samples were analyzed for biomarker levels and histopathological changes. Liver homogenates were used for determination of oxidative stress parameters that include Malondialdehyde (MDA), Glutathione (GSH) level and Glutathione Peroxidase (GPx) activity.

RESULTS

Treatment with n-butanol extract of C. oxyacantha leaves significantly improved the altered liver enzyme activities and oxidative stress markers. The histopathological observations confirm the results of biochemical parameters.

CONCLUSION

The obtained results support the traditional use of C. oxyacantha to cure gastrointestinal ailments and highlighted its possible use in the food and pharmaceutical industries as a source of natural antioxidant.

The effects of propolis extract on ovarian tissue and oxidative stress in rats with maternal separation stress

BACKGROUND

Stress in infancy has dramatic effects on different systems, including the nervous system, endocrine, immune, reproductive and etc.

OBJECTIVE

The purpose of this study was to investigate the effects of extract of Iranian propolis (EIP) on ovarian tissue and oxidative stress in rats with maternal separation stress.

MATERIALS AND METHODS

48 immature female rats were divided randomly into six groups. 1) Control group, 2) Control group+saline, 3) Stress group, includes infants that were separated from their mothers 6 hr/day, the 4th, 5th and 6th groups consisted of infants who in addition to daily stress received 50, 100 and 200 mg/kg of EIP, respectively. Then serum corticosterone, 17-beta-estradiol, malondialdehyde, total superoxide dismutase, glutathione peroxidase and ferric reducing antioxidant power levels were measured. The ovarian sections were stained by H&E, PAS, and TUNEL methods and were studied with optical microscopy.

RESULTS

Stress increased the blood serum corticosterone levels and 17-beta-estradiol reduced significantly (p<0.001) and EIP prevented from this changes (p<0.01). EIP significantly increased the number of ovarian follicles, oocytes and oocytes diameter in neonatal rat following stress (p<0.01). EIP also significantly decreased the number of atretic follicles, TUNEL+granulosa cells, malondialdehyde levels and increased ferric reducing antioxidant power, total superoxide dismutase and glutathione peroxidase serum levels in neonatal rats following stress. The dose of 200 mg/kg EIP was more effective.

CONCLUSION

This Study showed that the Iranian Propolis significantly could prevent oxidative stress and histopathological changes in the ovary of the neonatal rat the following stress.

Biological properties of propolis extracts: Something new from an ancient product

Natural products are an interesting source of new therapeutics, especially for cancer therapy as 70% of them have botany origin. Propolis, a resinous mixture that honey bees collect and transform from tree buds, sap flows, or other botanical sources, has been used by ethnobotany and traditional practitioners as early in Egypt as 3000 BCE. Enriched in flavonoids, phenol acids and terpene derivatives, propolis has been widely used for its antibacterial, antifungal and anti-inflammatory properties. Even though it is a challenge to standardize propolis composition, chemical analyses have pointed out interesting molecules that also present anti-oxidant and anti-proliferative properties that are of interest in the field of anti-cancer therapy. This review describes the various geographical origins and compositions of propolis, and analyzes how the main compounds of propolis could modulate cell signaling. A focus is made on the putative use of propolis in prostate cancer.

Effects of ethanol extract of propolis on histopathological changes and anti-oxidant defense of kidney in a rat model for type 1 diabetes mellitus

Aims/Introduction

Oxidative stress has a key role in the pathogenesis of diabetes. Propolis and its constituents have a wide range of medicinal properties against oxidative stress. In the present study, we evaluated the anti‐oxidant effects of ethanolic extracts of propolis on kidneys in diabetes mellitus rats.

Materials and Methods

A total of 40 male Wistar rats were randomly divided into the following five groups: control, diabetes mellitus, diabetes mellitus with vehicle treatment, diabetes mellitus with propolis treatment (100 mg/kg) and diabetes mellitus with propolis treatment (200 mg/kg). Diabetes mellitus in rats was induced by intraperitoneal injection of streptozotocin (60 mg/kg). Diabetic groups were treated with vehicle or ethanolic extracts of Iranian propolis for 6 weeks. Serum concentration of malondialdehyde, superoxide dismutase and glutathione peroxidase were measured.

Results

The results showed that Iranian propolis significantly inhibited bodyweight loss in diabetes mellitus rats. The propolis extracts significantly reduced serum glucose levels and kidney weight in diabetes mellitus rats (P < 0.001). Furthermore, propolis extracts significantly reduced the malondialdehyde content, and increased the activity of superoxide dismutase and glutathione peroxidase (P < 0.001) along with the total anti‐oxidant activity in the kidney tissue of diabetes mellitus rats. In the kidneys of the diabetes mellitus and vehicle group, the glomerular basement membrane thickness and glomerular area were significantly increased. Treatment of diabetes mellitus rats with the propolis extract significantly reduced the glomerular basement membrane thickness and glomerular area.

Conclusions

The present study results showed that the Iranian propolis extract could enhance the anti‐oxidant levels and histopathological changes in the kidneys of rats. The final results showed that most of the favorable effects of propolis are mediated by a reduction of blood glucose levels in diabetic animals.

Ameliorative effect of propolis against cyclophosphamide-induced toxicity in mice

CONTEXT

Cyclophosphamide (CTX) is a common anticancer agent used for the treatment of several malignancies. However, upon treatment, it induces severe toxicity due to its oxidative stress capability. Propolis, a natural product collected by honey bees, has shown several biological activities, such as free radical scavenging and antioxidant agent.

OBJECTIVE

This study elucidates the protective effects of propolis against CTX-induced changes in mice.

MATERIALS AND METHODS

Forty-eight male Swiss albino mice were divided into four groups; group 1 was intraperitoneally (i.p.) injected with 200 µL of phosphate buffer saline (PBS), group 2 was injected with 100 mg/kg/d propolis, group 3 was injected with a single dose of CTX (200 mg/kg), and group 4 was injected with a single dose of CTX (200 mg/kg) followed by propolis (100 mg/kg) for 7 consecutive days. After 12 d, mice were bled and then sacrificed to analyze the hematological, biochemical, and histological parameters.

RESULTS

The results indicated that CTX-injected mice showed an increase in the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), urea, and creatinine and a decrease in the total number of white blood cells (WBCs) and platelets. Moreover, dramatically changes in the histological architectures of the liver and kidney were observed. The mice that were injected with CTX/propolis showed an improvement in the levels of ALT, AST, urea, creatinine, WBCs, and platelets. Moreover, the histological picture of the liver and kidney was significantly improved.

CONCLUSIONS

In conclusion, propolis might be considered an effective agent in ameliorating the toxicity resulted from CTX treatment.

In vivo Studies on the Protective Effect of Propolis on Doxorubicin-Induced Toxicity in Liver of Male Rats

Objective:

Since anticancer drugs are to be administered for long durations of time and are associated with systemic toxicities, the present studies were conducted to evaluate the protective potential of honey bee propolis against a widely used anticancer drug, doxorubicin (DXR) induced toxicity and oxidative damage in liver tissues of rats.

Materials and Methods:

Sixteen male Sprague Dawley rats, weighing between 200-220 g, were used and were divided into four equal groups. Propolis was given orally to rats [250 mg/kg body weight (bw) for 14 consecutive days] and DXR [25 mg/kg bw; intraperitoneally (i.p) was administered on 12^th, 13^th and 14^th day of the experiment. All the animals were sacrificed on day 15^th day by decapitation. Blood and tissue samples were collected for measurement of toxicity and oxidative damage parameters (enzymatic assays and biochemical estimations).

Results:

Administration of DXR for 3 days at a cumulative dose of 25 mg/kg bw, induced toxicity and oxidative stress in rats as significantly decreased activity of catalase (CAT), superoxide dismutase (SOD), glutathione-S-transferase (GST), glutathione peroxidase (GSH-Px) and glutathione reductase (GR) were observed in rat liver supernatants when compared to control group. Increased activity of serum glutamic pyruvic transaminase (SGPT) and serum glutamic oxaloacetic transaminase (SGOT) was obtained in DXR administered rats. Also there are significantly increased levels of lipid peroxides (measured as malondialdehyde formation) and significantly decreased level of glutathione (GSH) in doxorubicin treated rat liver supernatants as compared to healthy controls. On the other hand, administration of animals with propolis prior to DXR treatment led to significant modulation of the oxidative damage related parameters in liver and hepatotoxicity parameters in blood, when compared to doxorubicin treated group. However results were still not comparable to control group or only propolis group indicating partial protection by propolis at the concentration used against anticancer drug toxicity.

Conclusion:

Propolis extract was found to have a protective effect against doxorubicin-induced toxicity in rat liver though it was still not normalized. It can be concluded that propolis provides partial protection from toxicity of anticancer drug.

Propolis attenuates doxorubicin-induced testicular toxicity in rats

Doxorubicin (Dox), an effective anticancer agent, can impair testicular function leading to infertility. The present study aimed to explore the protective effect of propolis extract on Dox-induced testicular injury. Rats were divided into four groups (n=10). Group I (normal control), group II received propolis extract (200 mg kg(-1); p.o.), for 3 weeks. Group III received 18 mg kg(-1) total cumulative dose of Dox i.p. Group IV received Dox and propolis extract. Serum and testicular samples were collected 48 h after the last treatment. In addition, the effects of propolis extract and Dox on the growth of solid Ehrlich carcinoma in mice were investigated. Dox reduced sperm count, markers of testicular function, steroidogenesis and gene expression of testicular 3β-hydroxysteroid dehydrogenase (3β-HSD), 17β-hydroxysteroid dehydrogenase (17β-HSD) and steroidogenic acute regulatory protein (StAR). In addition, it increased testicular oxidative stress, inflammatory and apoptotic markers. Morphometric and histopathologic studies supported the biochemical findings. Treatment with propolis extract prevented Dox-induced changes without reducing its antitumor activity. Besides, administration of propolis extract to normal rats increased serum testosterone level coupled by increased activities and gene expression of 3ß-HSD and 17ß-HSD. Propolis extract may protect the testis from Dox-induced toxicity without reducing its anticancer potential.

Tissue regeneration and stem cell distribution in adriamycin induced glomerulopathy

BACKGROUND AND OBJECTIVES

Glomerulosclerosis develops secondary to various kidney diseases. It was postulated that adriamycin (ADR) induce chronic glomerulopathy. Treatment combinations for one year did not significantly modify renal function in resistant focal segmental glomerulosclerosis (FSGS). Recurrence of FSGS after renal transplantation impacts long-term graft survival and limits access to transplantation. The present study aimed at investigating the relation between the possible therapeutic effect of human mesenchymal stem cells (HMSCs), isolated from cord blood on glomerular damage and their distribution by using ADR induced nephrotoxicity as a model in albino rat.

METHODS AND RESULTS

Thirty three male albino rats were divided into control group, ADR group where rats were given single intraperitoneal (IP) injection of 5 mg/kg adriamycin. The rats were sacrificed 10, 20 and 30 days following confirmation of glomerular injury. In stem cell therapy group, rats were injected with HMSCs following confirmation of renal injury and sacrificed 10, 20 and 30 days after HMSCs therapy. Kidney sections were exposed to histological, histochemical, immunohistochemical, morphometric and serological studies. In response to SC therapy multiple Malpighian corpuscles (MC) appeared with patent Bowman's space (Bs) 10 and 20 days following therapy. One month following therapy no remarkable shrunken glomeruli were evident. Glomerular area and serum creatinine were significantly different in ADR group in comparison to control and SC therapy groups.

CONCLUSIONS

ADR induced glomerulosclerosis regressed in response to cord blood HMSC therapy. A reciprocal relation was recorded between the extent of renal regeneration and the distribution of undifferentiated mesenchymal stem cells.

Protective effect of plaunotol against doxorubicin-induced renal cell death

In searching for a safe and effective compound to be used as a chemoprotective agent to prevent toxicity of the anthracyclin doxorubicin to renal cells, the present study demonstrated that plaunotol, a purified acyclic diterpene from Croton stellatopilosus Ohba, showed potential protection against doxorubicin-induced cell death in human proximal tubule cells. Treatment of renal cells with doxorubicin resulted in a significant decrease in viability of the cells, and we next proved that such toxicity was mainly due to apoptotic cell death. Pretreatment of the cells with plaunotol for at least 9 h prior to doxorubicin exposure improved the cells' survival. Plaunotol was shown to up-regulate the anti-apoptotic myeloid cell leukemia-1 (Mcl-1) level whereas it had no effect on the Bcl-2 level. The reduction in Mcl-1 after doxorubicin treatment was shown to be closely associated with the toxic action of the drug, and the increase in Mcl-1 induced by plaunotol pretreatment was able to prevent cell death induced by doxorubicin. Furthermore, the protective effect of plaunotol was evaluated in human lung and melanoma cells. Results indicated that plaunotol had no significantly protective effect in human lung carcinoma cells, whereas it sensitized melanoma cells to drug-induced cell death.