Betulin binds to melanocortin receptors and antagonizes alpha-melanocyte stimulating hormone induced cAMP generation in mouse melanoma cells

Betulin Attenuates TGF-β1- and PGE2-Mediated Inhibition of NK Cell Activity to Suppress Tumor Progression and Metastasis in Mice

Transforming growth factor (TGF)-β1 and prostaglandin E₂ (PGE₂) are humoral factors critically involved in the induction of immunosuppression in the microenvironment of various types of tumors, including melanoma. In this study, we identified a natural compound that attenuated TGF-β1- and PGE₂-induced immunosuppression and examined its effect on B16 melanoma growth in mice. By screening 502 natural compounds for attenuating activity against TGF-β1- or PGE₂-induced suppression of cytolysis in poly(I:C)-stimulated murine splenocytes, we found that betulin was the most potent compound. Betulin also reduced TGF-β1- and PGE₂-induced downregulation of perforin and granzyme B mRNA expression and cell surface expression of NKG2D and CD69 in natural killer (NK) cells. Cell depletion and coculture experiments showed that NK cells, dendritic cells, B cells, and T cells were necessary for the attenuating effects of betulin. Structure-activity relationship analysis revealed that two hydroxyl groups at positions C3 and C28 of betulin, their cis-configuration, and methyl group at C30 played crucial roles in its attenuating activity. In a subcutaneous implantation model of B16 melanoma in mice, intratumor administration of betulin and LY2157299, a TGF-β1 type I receptor kinase inhibitor, significantly retarded the growth of B16 melanoma. Notably, betulin increased significantly the number of CD69 positive NK cells in tumor sites at early stages of post-tumor cell injection. Our data suggest that betulin inhibits the growth of B16 melanoma by enhancing NK cell activity through attenuating the immunosuppressive tumor microenvironment.

Betulin Promotes Differentiation of Human Osteoblasts In Vitro and Exerts an Osteoinductive Effect on the hFOB 1.19 Cell Line Through Activation of JNK, ERK1/2, and mTOR Kinases

Although betulin (BET), a naturally occurring pentacyclic triterpene, has a variety of biological activities, its osteogenic potential has not been investigated so far. The aim of this study was to assess the effect of BET on differentiation of human osteoblasts (hFOB 1.19 and Saos-2 cells) in vitro in osteogenic (with ascorbic acid as an osteogenic supplement) and osteoinductive (without an additional osteogenic supplement) conditions. Osteoblast differentiation was evaluated based on the mRNA expression (RT-qPCR) of Runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP), type I collagen-α1 (COL1A1), and osteopontin (OPN). Additionally, ALP activity and production of COL1A1 (western blot analysis) and OPN (ELISA) were evaluated. The level of mineralization (calcium accumulation) was determined with Alizarin red S staining. BET upregulated the mRNA level of RUNX2 and the expression of other osteoblast differentiation markers in both cell lines (except the influence of BET on ALP expression/activity in the Saos-2 cells). Moreover, it increased mineralization in both cell lines in the osteogenic conditions. BET also increased the mRNA level of osteoblast differentiation markers in both cell lines (except for ALP in the Saos-2 cells) in the osteoinductive conditions, which was accompanied with increased matrix mineralization. The osteoinductive activity of BET in the hFOB 1.19 cells was probably mediated via activation of MAPKs (JNK and ERK1/2) and mTOR, as the specific inhibitors of these kinases abolished the BET-induced osteoblast differentiation. Our results suggest that BET has the potential to enhance osteogenesis.

Botanicals With Dermatologic Properties Derived From First Nations Healing: Part 1—Trees

Introduction:

First Nations people have a long history of working with medicinal plants used to treat skin diseases. The purpose was to assess the dermatologic therapeutic potential of western red cedar, white spruce, birch, balsam poplar, and black spruce.

Methods:

Based on expert recommendations, 5 trees were selected that were used in First Nations medicine for cutaneous healing and have potential and/or current application to dermatology today. We searched several databases up to June 12, 2014.

Results:

Western red cedar’s known active principal compound, β-thujaplicin, has been studied in atopic dermatitis. White spruce’s known active principal compound, 7-hydroxymatairesinol, has anti-inflammatory activity, while phase II clinical trials have been completed on a birch bark emulsion for the treatment of actinic keratoses, epidermolysis bullosa, and the healing of split thickness graft donor sites. Balsam poplar has been used clinically as an anti-aging remedy. Black spruce bark contains higher amounts of the anti-oxidant trans-resveratrol than red wine.

Discussion:

North American traditional medicine has identified important botanical agents that are potentially relevant to both cosmetic and medical dermatology. This study is limited by the lack of good quality evidence contributing to the review. The article is limited to 5 trees, a fraction of those used by First Nations with dermatological properties.

Pharmacological research on natural substances in Latvia: Focus on lunasin, betulin, polyprenol and phlorizin

In this concise review the current research in plant bioactive compound studies in Latvia is described. The paper summarizes recent studies on substances from edible plants (e.g., cereals and apples) or their synthetic analogues, such as peptide lunasin, as well as substances isolated from inedible plants (e.g., birch and conifer), such as pentacyclic triterpenes (e.g., betulin, betulinic acid, and lupeol) and polyprenols. Latvian researchers have been first to demonstrate the presence of lunasin in triticale and oats. Additionally, the impact of genotype on the levels of lunasin in cereals was shown. Pharmacological studies have revealed effects of lunasin and synthetic triterpenes on the central nervous system in rodents. We were first to show that synthetic lunasin causes a marked neuroleptic/cataleptic effect and that betulin antagonizes bicuculline-induced seizures (a GABA A receptor antagonist). Studies on the mechanisms of action showed that lunasin binds to dopamine D1 receptors and betulin binds to melanocortin and gamma-aminobutyric acid A receptors therefore we suggest that these receptors play an essential role in lunasin's and betulin's central effects. Recent studies on conifer polyprenols demonstrated the ability of polyprenols to prevent statin-induced muscle weakness in a rat model. Another study on plant compounds has demonstrated the anti-hyperglycemic activity of phlorizin-containing unripe apple pomace in healthy volunteers. In summary, research into plant-derived compounds in Latvia has been focused on fractionating, isolating and characterizing of lunasin, triterpenes, polyprenols and phlorizin using in vitro, and in vivo assays, and human observational studies.

Comprehensive review on betulin as a potent anticancer agent

Numerous plant-derived substances, and their derivatives, are effective antitumour and chemopreventive agents. Yet, there are also a plethora of tumour types that do not respond, or become resistant, to these natural substances. This requires the discovery of new active compounds. Betulin (BE) is a pentacyclic triterpene and secondary metabolite of plants abundantly found in the outer bark of the birch tree Betulaceae sp. BE displays a broad spectrum of biological and pharmacological properties, among which the anticancer and chemopreventive activity attract most of the attention. In this vein, BE and its natural and synthetic derivatives act specifically on cancer cells with low cytotoxicity towards normal cells. Although the antineoplastic mechanism of action of BE is not well understood yet, several interesting aspects of BE's interactions are coming to light. This review will summarize the anticancer and chemopreventive potential of BE in vitro and in vivo by carefully dissecting and comparing the doses and tumour lines used in previous studies, as well as focusing on mechanisms underlying its activity at cellular and molecular level, and discuss future prospects.

Betulin complex in γ-cyclodextrin derivatives: properties and antineoplasic activities in in vitro and in vivo tumor models

Given the present high incidence of melanoma and skin cancer, interest in potential drugs of plant origin has increased significantly. Pentacyclic lupane-type triterpenes are widely distributed in plants, offering numerous pharmacological benefits. Betulin is an important compound in the bark of Betula pendula Roth and has important therapeutic properties, including antitumor activities. Its biological effect is limited by its poor water solubility, which can be improved by cyclodextrin complexation. The best results have been obtained by using a novel cyclodextrin derivative, octakis-[6-deoxy-6-(2-sulfanyl ethanesulfonate)]-γ-CD. The complexes between betulin and the previously mentioned cyclodextrin were analyzed by scanning electron microscopy (SEM)and differential scanning calorimetry (DSC) and pharmacologically evaluated in vitro (MTT and immunocytochemistry tests) and in vivo in C57BL/6J mice. The solubility of betulin is improved by cyclodextrin complexation, which creates a stable complex that improves the in vitro and in vivo properties of the active compound.

Identification of drug candidates which increase cytochrome c oxidase activity in deficient patient fibroblasts

Cytochrome c oxidase (COX) activity reflects the expressed level of respiratory chain complexes, mtDNA levels, titer and mass of mitochondria. Activity is also indicative of the overall fitness of mt-transcription factors and the import, transcription and translation of mt-proteins. We have developed a high-throughput assay to measure COX activity using live cells to screen chemical libraries for compounds capable of increasing COX activity. These libraries have revealed four examples which elevated the activities of COX in NIH-3T3 fibroblasts and in fibroblasts from patients with COX defects independent of the peroxisome proliferator activated receptor family.

Betulin elicits anti-cancer effects in tumour primary cultures and cell lines in vitro

Betulin is a pentacyclic triterpene found in many plant species, among others, in white birch bark. The aim of the study was in vitro characterization of the anticancer activity of betulin in a range of human tumour cell lines (neuroblastoma, rhabdomyosarcoma-medulloblastoma, glioma, thyroid, breast, lung and colon carcinoma, leukaemia and multiple myeloma), and in primary tumour cultures isolated from patients (ovarian carcinoma, cervical carcinoma and glioblastoma multiforme). In this study, we demonstrated a remarkable anti-proliferative effect of betulin in all tested tumour cell cultures. Neuroblastoma (SK-N-AS) and colon carcinoma (HT-29) were the most sensitive to the anti-proliferative effect of betulin. Furthermore, betulin altered tumour cells morphology, decreased their motility and induced apoptotic cell death. These findings demonstrate the anti-cancer potential of betulin and suggest that they may be applied as an adjunctive measure in cancer treatment.