Betulinic Acid: Recent Advances in Chemical Modifications, Effective Delivery, and Molecular Mechanisms of a Promising Anticancer Therapy

Antitumor activity and transcriptome sequencing (RNA-seq) analyses of hepatocellular carcinoma cells in response to exposure triterpene-nucleoside conjugates

Fifteen betulonic/betulinic acid conjugated with nucleoside derivatives were synthesized to enhance antitumor potency and water solubility. Among these, the methylated betulonic acid-azidothymidine compound (8c) exhibited a broad-spectrum of antitumor activity against three tested tumor cell lines, including SMMC-7721 (IC50 = 5.02 μM), KYSE-150 (IC50 = 5.68 μM), and SW620 (IC50 = 4.61 μM) and along with lower toxicity (TC50 > 100 μM) estimated by zebrafish embryos assay. Compared to betulinic acid (<0.05 μg/mL), compound 8c showed approximately 40-fold higher water solubility (1.98 μg/mL). In SMMC-7721 cells, compound 8c induced autophagy and apoptosis as its concentration increased. Transcriptomic sequencing analysis was used to understand the potential impacts of the underlying mechanism of 8c on SMMC-7721 cells. Transcriptomic studies indicated that compound 8c could activate autophagy by inhibiting the PI3K/AKT pathway in SMMC-7721 cells. Furthermore, in the xenograft mice study, compound 8c significantly slowed down the tumor growth, as potent as paclitaxel treated group. In conclusion, methylated betulonic acid-azidothymidine compound (8c) not only increases water solubility, but also enhances the potency against hepatocellular carcinoma cells by inducing autophagy and apoptosis, and suppressing the PI3K/Akt/mTOR signaling pathway.

Drug Delivery Systems of Betulin and Its Derivatives: An Overview

Natural origin products are regarded as promising for the development of new therapeutic therapies with improved effectiveness, biocompatibility, reduced side effects, and low cost of production. Betulin (BE) is very promising due to its wide range of pharmacological activities, including its anticancer, antioxidant, and antimicrobial properties. However, despite advancements in the use of triterpenes for clinical purposes, there are still some obstacles that hinder their full potential, such as their hydrophobicity, low solubility, and poor bioavailability. To address these concerns, new BE derivatives have been synthesized. Moreover, drug delivery systems have emerged as a promising solution to overcome the barriers faced in the clinical application of natural products. The aim of this manuscript is to summarize the recent achievements in the field of delivery systems of BE and its derivatives. This review also presents the BE derivatives mostly considered for medical applications. The electronic databases of scientific publications were searched for the most interesting achievements in the last ten years. Thus far, it is mostly nanoparticles (NPs) that have been considered for the delivery of betulin and its derivatives, including organic NPs (e.g., micelles, conjugates, liposomes, cyclodextrins, protein NPs), inorganic NPs (carbon nanotubes, gold NPs, silver), and complex/hybrid and miscellaneous nanoparticulate systems. However, there are also examples of microparticles, gel-based systems, suspensions, emulsions, and scaffolds, which seem promising for the delivery of BE and its derivatives.

Potent drug delivery enhancement of betulinic acid and NVX-207 into equine skin in vitro - a comparison between a novel oxygen flow-assisted transdermal application device and microemulsion gels

BACKGROUND

Gray horses are predisposed to equine malignant melanoma (EMM) with advancing age. Depending on the tumor's location and size, they can cause severe problems (e.g., defaecation, urination, feeding). A feasible therapy for EMM has not yet been established and surgical excision can be difficult depending on the location of the melanoma. Thus, an effective and safe therapy is needed. Naturally occurring betulinic acid (BA), a pentacyclic triterpene and its synthetic derivate, NVX-207 (3-acetyl-betulinic acid-2-amino-3-hydroxy-2-hydroxymethyl-propanoate) are known for their cytotoxic properties against melanomas and other tumors and have already shown good safety and tolerability in vivo. In this study, BA and NVX-207 were tested for their permeation potential into equine skin in vitro in Franz-type diffusion cell (FDC) experiments after incubation of 5 min, 30 min and 24 h, aiming to use these formulations for prospective in vivo studies as a treatment for early melanoma stages. Potent permeation was defined as reaching or exceeding the half maximal inhibitory concentrations (IC50) of BA or NVX-207 for equine melanoma cells in equine skin samples. The active ingredients were either dissolved in a microemulsion (ME) or in a microemulsion gel (MEG). All of the formulations were transdermally applied but the oil-in-water microemulsion was administered with a novel oxygen flow-assisted (OFA) applicator (DERMADROP TDA).

RESULTS

All tested formulations exceeded the IC50 values for equine melanoma cells for BA and NVX-207 in equine skin samples, independently of the incubation time NVX-207 applied with the OFA applicator showed a significant time-dependent accumulation and depot-effect in the skin after 30 min and 24 h (P < 0.05).

CONCLUSIONS

All tested substances showed promising results. Additionally, OFA administration showed a significant accumulation of NVX-207 after 30 min and 24 h of incubation. Further in vivo trials with OFA application are recommended.

Anticancer Drug Discovery Based on Natural Products: From Computational Approaches to Clinical Studies

Globally, malignancies cause one out of six mortalities, which is a serious health problem. Cancer therapy has always been challenging, apart from major advances in immunotherapies, stem cell transplantation, targeted therapies, hormonal therapies, precision medicine, and palliative care, and traditional therapies such as surgery, radiation therapy, and chemotherapy. Natural products are integral to the development of innovative anticancer drugs in cancer research, offering the scientific community the possibility of exploring novel natural compounds against cancers. The role of natural products like Vincristine and Vinblastine has been thoroughly implicated in the management of leukemia and Hodgkin's disease. The computational method is the initial key approach in drug discovery, among various approaches. This review investigates the synergy between natural products and computational techniques, and highlights their significance in the drug discovery process. The transition from computational to experimental validation has been highlighted through in vitro and in vivo studies, with examples such as betulinic acid and withaferin A. The path toward therapeutic applications have been demonstrated through clinical studies of compounds such as silvestrol and artemisinin, from preclinical investigations to clinical trials. This article also addresses the challenges and limitations in the development of natural products as potential anti-cancer drugs. Moreover, the integration of deep learning and artificial intelligence with traditional computational drug discovery methods may be useful for enhancing the anticancer potential of natural products.

Innovative Approach to Enhance Bioavailability of Birch Bark Extracts: Novel Method of Oleogel Development Contrasted with Other Dispersed Systems

Birch outer bark extract (BBE), containing pentacyclic triterpenes such as betulin, lupeol, and betulinic acid, is a widely recognized natural product renowned for its diverse pharmacological effects. However, its limited water solubility restricts its bioavailability. Therefore, the main objective is to enhance the bioavailability of BBE for pharmaceutical use. In this study, we aimed to develop a dispersion system utilizing a unique oleogel-producing method through the recrystallization of BBE from an ethanol solution in the oil phase. We generated an oleogel that demonstrates a notable 42-80-fold improvement in betulin and lupeol peroral bioavailability from BBE in Wistar rats, respectively. A physical paste-like BBE hydrogel developed with antisolvent precipitation showed a 16-56-fold increase in the bioavailability of betulin and lupeol from BBE in rat blood plasma, respectively. We also observed that the repeated administration of the BBE oleogel did not exhibit any toxicity at the tested dose (38.5 mg/kg betulin, 5.2 mg/kg lupeol, 1.5 mg/kg betulinic acid daily for 7 days). Betulin and betulinic acid were not detected in rat heart, liver, kidney, or brain tissues after the peroral administration of the oleogel daily for 7 days. Lupeol was found in rat heart, liver, and kidney tissues.

Synthesis and Cytotoxicity of Monomethylated Betulinic Acid 3-O-α-l-Rhamnopyranosides

Three original derivatives of the cytotoxic betulinic acid 3-O-α-l-rhamnopyranoside featuring a monomethylated rhamnoside residue were synthesized. An improved catalytic procedure was involved to functionalize the O-3 position of the monosaccharide in a site-selective fashion. The cytotoxicity of the novel compounds was evaluated in vitro to highlight the moderate impact of carbohydrate monomethylation on the biological activity of betulinic acid 3-O-α-l-rhamnopyranoside.

Bifunctionalized Betulinic Acid Conjugates with C-3-Monodesmoside and C-28-Triphenylphosphonium Moieties with Increased Cancer Cell Targetability

A convenient synthesis is presented for a new class of bioactive bifunctionalized conjugates of lupane-type triterpenoids with triphenylphosphonium (TPP) and glycopyranosyl targeting moieties. The main synthesis steps include glycosylation of haloalkyl esters of the triterpene acid at the C-3 position by the imidate derivatives of glycopyranose followed by the product modification at the C-28 position with triphenylphosphine. The conjugates of betulinic acid (BetA) with TPP and d-glucose, l-rhamnose, or d-mannose moieties were thus synthesized as potential next-generation BetA-derived anticancer compounds. LC-MS/MS analysis in glucose-free physiological solution indicated that the glycosides showed better accumulation in PC-3 prostate cancer cells than both BetA and TPP-BetA conjugate, while the transporting effect of monosaccharide residues increased as follows: d-mannose < l-rhamnose ≈ d-glucose. At saturated concentrations, the glycosides caused a disturbing effect on mitochondria with a more drastic drop in transmembrane potential but weaker overproduction of mitochondrial reactive oxygen species (ROS) compared to TPP-BetA conjugate. Cytotoxicity of the glycosides in culture medium was comparable with or higher than that of the nonglycosylated conjugate, depending on the cancer cell line, whereas the compounds were less active toward primary fibroblasts. Glycosylation tended to increase pro-apoptotic and decrease pro-autophagic activities of the BetA derivatives. Cytotoxicity of the synthesized glycosides was considered in comparison with the summarized data on the natural and modified BetA glycosides. The results obtained are important for the development of bifunctionalized conjugates of triterpenoids with an increased cancer cell targetability.

Pentacyclic Triterpenoid Phytochemicals with Anticancer Activity: Updated Studies on Mechanisms and Targeted Delivery

Pentacyclic triterpenoids (TTs) represent a unique family of phytochemicals with interesting properties and pharmacological effects, with some representatives, such as betulinic acid (BA) and betulin (B), being mainly investigated as potential anticancer molecules. Considering the recent scientific and preclinical investigations, a review of their anticancer mechanisms, structure-related activity, and efficiency improved by their insertion in nanolipid vehicles for targeted delivery is presented. A systematic literature study about their effects on tumor cells in vitro and in vivo, as free molecules or encapsulated in liposomes or nanolipids, is discussed. A special approach is given to liposome-TTs and nanolipid-TTs complexes to be linked to microbubbles, known as contrast agents in ultrasonography. The production of such supramolecular conjugates to deliver the drugs to target cells via sonoporation represents a new scientific and applicative direction to improve TT efficiency, considering that they have limited availability as lipophilic molecules. Relevant and recent examples of in vitro and in vivo studies, as well as the challenges for the next steps towards the application of these complex delivery systems to tumor cells, are discussed, as are the challenges for the next steps towards the application of targeted delivery to tumor cells, opening new directions for innovative nanotechnological solutions.

A Novel Betulinic Acid Analogue: Synthesis, Solubility, Antitumor Activity and Pharmacokinetic Study in Rats

Betulinic acid (BA) and betulin (BE) are naturally pentacyclic triterpenes with documented biological activities, especially antitumor and anti-inflammatory activity. However, their bioavailability in vivo is not satisfactory in terms of medical applications. Thus, to improve the solubility and bioavailability so as to improve the efficacy, 28-O-succinyl betulin (SBE), a succinyl derivative of BE, was synthesized and its solubility, in vitro and in vivo anti-tumor activities, the apoptosis pathway as well as the pharmacokinetic properties were investigated. The results showed that SBE exhibited significantly higher solubility in most of the tested solvents, and showed a maximum solubility of 7.19 ± 0.66 g/L in n-butanol. In vitro and in vivo anti-tumor activity assays indicated both BA and SBE exhibited good anti-tumor activities, and SBE demonstrated better potential compared to BA. An increase in the ratio of Bad/Bcl-xL and activation of caspase 9 was found in SBE treated Hela cells, suggesting that the intrinsic mitochondrial pathway is involved in SBE induced apoptosis. Compared with BA, SBE showed much-improved absorption and bioavailability in pharmacokinetic studies.

Phytochemical Analysis of Anastatica hierochuntica and Aerva javanica Grown in Qatar: Their Biological Activities and Identification of Some Active Ingredients

Plant-derived compounds and their extracts are known to exhibit chemo preventive (antimicrobial, antioxidant and other) activities. The levels of such chemo preventive compounds vary depending on environmental factors, including the regions where they grow. Described in this study are: (i) a phytochemical analysis of the two plants grown in the desert environment of Qatar, viz., Anastatica hierochuntica and Aerva javanica; (ii) the antibacterial, antifungal and antioxidant activities of various solvent extracts of these plants; (iii) a report on the isolation of several pure compounds from these plants. The phytochemical screening indicated the presence of glycosides, tannins, flavonoids, terpenoids, saponins, phenol and anthraquinones in various extracts of each of the plants. Antibacterial and antioxidant activities were studied using agar diffusion and DPPH methods, respectively. The extracts of Anastatica hierochuntica as well as Aerva javanica inhibit the growth of both gram-positive and gram-negative bacterial species. Various extracts of the two plants also exhibited higher or similar antioxidant activities as those of the standard antioxidants, α-tocopherol and ascorbic acid. The extracts of these plants were further purified by HPLC and characterized by IR and NMR techniques. This process has led to identification of β-sitosterol, campesterol and methyl-9-(4-(3,4-dihydroxy-1'-methyl-5'-oxocyclohexyl)-2-hydroxycyclohexyl)nonanoate from Anastatica hierochuntica, and lupenone, betulinic acid, lupeol acetate and persinoside A and B from Aerva javanica. The results reported herein suggests that Anastatica hierochuntica and Aerva javanica are potent sources of phytomedicines.

Betulin and Its Derivatives Reduce Inflammation and COX-2 Activity in Macrophages

Betulin is a heavily studied natural compound for its use as an anticancer or pro-regenerative agent. The structural similarity between betulin to steroids gives rise to the idea that the substance may as well act as an anti-inflammatory drug. This study is the first to describe the anti-inflammatory properties of betulinic acid, betulin, and its derivatives with amino acids 1,4-diaminebutane (Dab), 1,3-diaminepropane (Dap), Ornithine (Orn), and lysine (Lys) on murine macrophages from lymphoma site. The compounds were compared to dexamethasone. To establish the response of the macrophages to the natural compounds, we tested the viability as well as sensitivity to the inflammatory signaling (IFNγR). IL-6 secretory properties and HSP-70 content in the cells were examined. Furthermore, we characterized the effects of compounds on the inhibition of cyclooxygenase-2 (COX-2) activity both in the enzymatic assays and molecular docking studies. Then, the changes in COX-2 expression after betulin treatment were assessed. Betulin and betulinic acid are the low-cytotoxicity compounds with the highest potential to decrease inflammation via reduced IL-6 secretion. To some extent, they induce the reorganization of IFNγR with nearly no effect on COX-2 activity. Conversely, Bet-Orn and Bet-Lys are highly cytotoxic and induce the aggregation of IFNγR. Besides, Bet-Lys reduces the activity of COX-2 to a higher degree than dexamethasone. Bet-Orn is the only one to increase the HSP-70 content in the macrophages. In case of IL-6 reduction, all compounds were more potent than dexamethasone.

Comparison of In Vitro Antimelanoma and Antimicrobial Activity of 2,3-Indolo-betulinic Acid and Its Glycine Conjugates

Malignant melanoma is one of the most pressing problems in the developing world. New therapeutic agents that might be effective in treating malignancies that have developed resistance to conventional medications are urgently required. Semisynthesis is an essential method for improving the biological activity and the therapeutic efficacy of natural product precursors. Semisynthetic derivatives of natural compounds are valuable sources of new drug candidates with a variety of pharmacological actions, including anticancer ones. Two novel semisynthetic derivatives of betulinic acid-N-(2,3-indolo-betulinoyl)diglycylglycine (BA1) and N-(2,3-indolo-betulinoyl)glycylglycine (BA2)-were designed and their antiproliferative, cytotoxic, and anti-migratory activity against A375 human melanoma cells was determined in comparison with known N-(2,3-indolo-betulinoyl)glycine (BA3), 2,3-indolo-betulinic acid (BA4) and naturally occurring betulinic acid (BI). A dose-dependent antiproliferative effect with IC₅₀ values that ranged from 5.7 to 19.6 µM was observed in the series of all five compounds including betulinic acid. The novel compounds BA1 (IC₅₀ = 5.7 µM) and BA2 (IC₅₀ = 10.0 µM) were three times and two times more active than the parent cyclic structure B4 and natural BI. Additionally, compounds BA2, BA3, and BA4 possess antibacterial activity against Streptococcus pyogenes ATCC 19615 and Staphylococcus aureus ATCC 25923 with MIC values in the range of 13-16 µg/mL and 26-32 µg/mL, respectively. On the other hand, antifungal activity toward Candida albicans ATCC 10231 and Candida parapsilosis ATCC 22019 was found for compound BA3 with MIC 29 µg/mL. This is the first report of antibacterial and antifungal activity of 2,3-indolo-betulinic acid derivatives and also the first extended report on their anti-melanoma activity, which among others includes data on anti-migratory activity and shows the significance of amino acid side chain on the observed activity. The obtained data justify further research on the anti-melanoma and antimicrobial activity of 2,3-indolo-betulinic acid derivatives.

Polyethyleneglycol-Betulinic Acid (PEG-BA) Polymer-Drug Conjugate Induces Apoptosis and Antioxidation in a Biological Model of Pancreatic Cancer

Pancreatic cancer (PC) is one of the most aggressive solid malignancies with poor treatment response and low survival rates. Herbal medicines such as betulinic acid (BA) have shown potential in treating various solid tumours, but with limitations that can be circumvented by polymer-drug conjugation. Polyethylene glycol-BA (PEG-BA) polymer-drug conjugate has previously shown selective anticancer activity against PC cells. Here, we elucidate the mechanism of cell death and the cell death pathway, anti-inflammatory and antioxidant activities of PEG-BA. PEG-BA induced apoptotic cell death by arresting MIA-PaCa-2 cells in the Sub-G1 phase of the cell cycle compared with BA and untreated cells (39.50 ± 5.32% > 19.63 ± 4.49% > 4.57 ± 0.82%). NFκB/p65 protein expression was moderately increased by PEG-BA (2.70 vs. 3.09 ± 0.42 ng/mL; p = 0.1521). However, significant (p < 0.05) overexpression of the proapoptotic genes TNF (23.72 ± 1.03) and CASPASE 3 (12,059.98 ± 1.74) compared with untreated cells was notable. The antioxidant potential of PEG-BA was greater (IC50 = 15.59 ± 0.64 µM) compared with ascorbic acid (25.58 ± 0.44 µM) and BA-only (>100 µM) and further confirmed with the improved reduction of hydroperoxide levels compared with BA-only (518.80 ± 25.53 µM vs. 542.43 ± 9.70 µM). In conclusion, PEG-BA activated both the intrinsic and extrinsic pathways of apoptosis and improved antioxidant activities in PC cells, suggesting enhanced anticancer activity upon conjugation.

Betulinic acid and its ionic derivatives impaired growth of prostate cancer cells without induction of GRP78 and CHOP

Prostate cancer (PCa) is the most common invasive malignancy for men in the USA. The incidence and mortality rates of PCa are significantly higher among African American men, as compared to those in Caucasian men. Betulinic acid (BA) is a penta-cyclic triterpenoid that is often found in the bark of several species of plants. It possesses a variety of biological activities, including anti-cancer activities. We examined the cytotoxic effects and endoplasmic reticulum (ER) stress induced by BA and its ionic derivatives with PCa cells derived from African Americans and Caucasian men. The viability of all PCa cells was reduced by the BA compounds, and the cytotoxicity of these BA compounds was independent of ethnicity and androgen dependency. The BA compounds induced modest effects on ER stress proteins when compared with ER stress inducers, tunicamycin and thapsigargin. The induction of glucose regulated protein 78 (GRP78) was largely correlated with the expression of C/EBP homologous protein (CHOP) and cleaved poly [ADP-ribose] polymerase (PARP)/caspase-3 in the PCa cells. In summary, our data demonstrated that BA compounds impaired the growth of PCa cells regardless of ethnicity – through GRP78- and CHOP-independent pathways.

Laticifer ontogenesis and the chemical constituents of Marsdenia zehntneri (Apocynaceae) latex in a semiarid environment

Anastomosed laticifers with intrusive growth produce latex containing methyl comate and betulin with economic and ecological value in arid environments. Climatic factors influence laticifer development in the apical meristem and vascular cambium. Latex is a complex emulsion with high medicinal as well as ecological value related to plant survival. Marsdenia zehntneri is a shrubby plant that grows on limestone outcrops in the semiarid regions of Brazil. We sought to characterize the ontogenesis of the laticifers of this species and to relate that process to climatic seasonality and phenology through anatomical, ultrastructural, and micro-morphometric evaluations of the apical meristem and vascular cambium. The histochemistry of the secretory structure was investigated and the chemical composition of the latex was analyzed. Phenological assessments were performed by monitoring phenological events for 1 year. The laticifers network of M. zehntneri permeates the entire primary and secondary body of the plant, providing a wide distribution system of defensive compounds. Its laticifers, of a distinct mixed type (anastomosed, with intrusive growth), are numerous and voluminous in the apical meristem but scarce and minute in the secondary phloem. Latex secretion involves the participation of oleoplasts, polysomes, and dictyosomes. Methyl 2,3-dihydroxy-ursan-23-oate, methyl 3-hydroxy-ursan-23-oate, and betulin are encountered in high proportions in the latex and have ecological and medicinal functions. The development of primary laticifers is related to the resumption of apical meristem activity with increasing day length at the end of the austral winter. The development of secondary laticifers is related to high summer temperatures and rainfall that favor vascular cambium activity. The wide distribution of laticifers, their seasonal pattern of secretion, and their latex composition contribute to the adaptation of M. zehntneri to its natural environment.

Comparative Study of Cytotoxic and Membranotropic Properties of Betulinic Acid-F16 Conjugate on Breast Adenocarcinoma Cells (MCF-7) and Primary Human Fibroblasts

The present study evaluates the cytotoxicity of a previously synthesized conjugate of betulinic acid (BA) with the penetrating cation F16 on breast adenocarcinoma (MCF-7) and human fibroblast (HF) cell lines, and also shows the mechanism underlying its membranotropic action. It was confirmed that the conjugate exhibits higher cytotoxicity compared to native BA at low doses also blocking the proliferation of both cell lines and causing cell cycle arrest in the G₀/G₁ phase. We show that the conjugate indeed has a high potential for accumulation in mitochondria, being visualized in these organelles, which is most pronounced in cancer cells. The effect of the conjugate was observed to be accompanied by ROS hyperproduction in both cancerous and healthy cells, despite the lower base level of ROS in the latter. Along with this, using artificial liposomes, we determined that the conjugate is able to influence the phase state of lipid membranes, make them more fluid, and induce nonspecific permeabilization contributing to the overall cytotoxicity of the tested agent. We conclude that the studied BA-F16 conjugate does not have significant selective cytotoxicity, at least against the studied breast cancer cell line MCF-7.

Synthesis and Anticancer Activity of Indole-Functionalized Derivatives of Betulin

Pentacyclic triterpenes, including betulin, are widespread natural products with various pharmacological effects. These compounds are the starting material for the synthesis of substances with promising anticancer activity. The chemical modification of the betulin scaffold that was carried out as part of the research consisted of introducing the indole moiety at the C-28 position. The synthesized new 28-indole-betulin derivatives were evaluated for anticancer activity against seven human cancer lines (A549, MDA-MB-231, MCF-7, DLD-1, HT-29, A375, and C32). It was observed that MCF-7 breast cancer cells were most sensitive to the action of the 28-indole-betulin derivatives. The study shows that the lup-20(29)-ene-3-ol-28-yl 2-(1H-indol-3-yl)acetate caused the MCF-7 cells to arrest in the G1 phase, preventing the cells from entering the S phase. The performed cytometric analysis of DNA fragmentation indicates that the mechanism of EB355A action on the MCF-7 cell line is related to the induction of apoptosis. An in silico ADMET profile analysis of EB355A and EB365 showed that both compounds are bioactive molecules characterized by good intestinal absorption. In addition, the in silico studies indicate that the 28-indole-betulin derivatives are substances of relatively low toxicity.

Targeting Effect of Betulinic Acid Liposome Modified by Hyaluronic Acid on Hepatoma Cells In Vitro

Betulinic acid (BA) is a natural pentacyclic triterpenoid with broad-spectrum anticancer activity, which has great development potential as an anti-cancer drug. In this study, a novel hyaluronic acid (HA)-modified BA liposome (BA-L) was developed for use in targeted liver cancer therapy. The size, polymer dispersity index (PDI), zeta potential, and entrapment efficiency were measured. Cell viability, cell migration and clonogenicity, cellular uptake, immunohistochemistry of CD44, and protein expression of ROCK1/IP3/RAS were also investigated. BA, BA-L, and HA-BA-L had no inhibitory effect on the activity of LO2 normal hepatocytes, but they inhibited the proliferation of HepG2 and SMMC-7721 cells in a dose- and time-dependent manner, with HA-BA-L exhibiting the most prominent inhibitory effect. Compared with the BA-L group, the expression of CD44 in HepG2 cells in the HA-BA-L group was decreased. The results of WB showed that BA, BA-L, and HA-BA-L downregulated the expression of ROCK1, IP3, and RAS in HepG2 cells, and the expression level in the HA-BA-L group was significantly decreased. The easily prepared HA-BA-L was demonstrated to be an excellent CD44-mediated intracellular delivery system capable of targeting effects. Further mechanistic research revealed that the inhibition of HA-BA-L on HepG2 cells may be mediated by blocking the ROCK1/IP3/RAS signaling pathways.

Role of collagen regulators in cancer treatment: A comprehensive review

Abstract:

Collagen is the most important structural protein and also a main component of extra-cellular matrix (ECM). It plays a role in tumor progression. Collagen can be regulated by altering it’s biosynthesis pathway through various signaling pathways, receptors and genes. Activity of cancer cells can also be regulated by other ECM components like metalloproteinases, hyaluronic acid, fibronectin and so on. Hypoxia is also one of the condition which leads to cancer progression by stimulating the expression of procollagen lysine as a collagen crosslinker, which increases the size of collagen fibres promoting cancer spread. The collagen content in cancerous cells leads to resistance in chemotherapy. So, to reduce this resistance, some of the collagen regulating therapies are introduced, which include inhibiting its biosynthesis, disturbing cancer cell signaling pathway, mediating ECM components and directly utilizing collagenase. This study is an effort to compile the strategies reported to control the collagen level and different collagen inhibitors reported so far. More research is needed in this area, growing understandings of collagen’s structural features and its role in cancer progression will aid in the advancement of newer chemotherapies.

Binding Interaction of Betulinic Acid to α-Glucosidase and Its Alleviation on Postprandial Hyperglycemia

Inhibiting the intestinal α-glucosidase can effectively control postprandial hyperglycemia for type 2 diabetes mellitus (T2DM) treatment. In the present study, we reported the binding interaction of betulinic acid (BA), a pentacyclic triterpene widely distributed in nature, on α-glucosidase and its alleviation on postprandial hyperglycemia. BA was verified to exhibit a strong inhibitory effect against α-glucosidase with an IC₅₀ value of 16.83 ± 1.16 μM. More importantly, it showed a synergistically inhibitory effect with acarbose. The underlying inhibitory mechanism was investigated by kinetics analysis, surface plasmon resonance (SPR) detection, molecular docking, molecular dynamics (MD) simulation and binding free energy calculation. BA showed a non-competitive inhibition on α-glucosidase. SPR revealed that it had a strong and fast affinity to α-glucosidase with an equilibrium dissociation constant (K_D) value of 5.529 × 10⁻⁵ M and a slow dissociation. Molecular docking and MD simulation revealed that BA bound to the active site of α-glucosidase mainly due to the van der Waals force and hydrogen bond, and then changed the micro-environment and secondary structure of α-glucosidase. Free energy decomposition indicated amino acid residues such as PHE155, PHE175, HIE277, PHE298, GLU302, TRY311 and ASP347 of α-glucosidase at the binding pocket had strong interactions with BA, while LYS153, ARG210, ARG310, ARG354 and ARG437 showed a negative contribution to binding affinity between BA and α-glucosidase. Significantly, oral administration of BA alleviated the postprandial blood glucose fluctuations in mice. This work may provide new insights into the utilization of BA as a functional food and natural medicine for the control of postprandial hyperglycemia.

A Betulinic Acid Derivative, BA5, Induces G0/G1 Cell Arrest, Apoptosis Like-Death, and Morphological Alterations in Leishmania sp

Leishmaniasis are endemic diseases caused by different species of intracellular parasites of the genus Leishmania. Due to the high toxicity and drug resistance of current antileishmanial drugs, it is necessary to identify new and more effective drugs. Previously, we investigated the immunomodulatory and anti-Trypanosoma cruzi action of BA5, a derivative of betulinic acid. In the present study, we investigated the in vitro activity of BA5 against different species of Leishmania and their action mechanism. BA5 exhibited low cytotoxicity against macrophages and inhibited the proliferation of promastigote forms of Leishmania amazonensis (IC₅₀ = 4.5 ± 1.1 μM), Leishmania major (IC₅₀ = 3.0 ± 0.8 μM), Leishmania braziliensis (IC₅₀ = 0.9 ± 1.1 μM) and Leishmania infantum (IC₅₀ = 0.15 ± 0.05 μM). Incubation with BA5 reduced the percentage of Leishmania amazonensis-infected macrophages and the number of intracellular parasites (IC₅₀ = 4.1 ± 0.7 μM). To understand the mechanism of action underlying BA5 antileishmanial activity (incubation at IC₅₀/2_, IC₅₀ or 2xIC₅₀ values of the drug), we investigated ultrastructural changes by scanning electron microscopy and evaluated cell cycle, membrane mitochondrial potential, and cell death against promastigote forms of Leishmania amazonensis by flow cytometry. Promastigotes incubated with BA5 presented membrane blebbing, flagella damage, increased size, and body deformation. Flow cytometry analysis showed that parasite death is mainly caused by apoptosis-like death, arrested cell cycle in G0/G1 phase and did not alter the membrane mitochondrial potential of Leishmania amazonensis. Surprisingly, the combination of BA5 and amphotericin B, an assay used to determine the degree of drug interaction, revealed synergistic effects (CI = 0.15 ± 0.09) on promastigotes forms of Leishmania amazonensis. In conclusion, BA5 compound is an effective and selective antileishmanial agent.

Bioactivity of betulinic acid nanoemulsions on skin carcinogenesis in transgenic mice K14E6

Alternative therapies for cancer treatment have been developed using bioactive compounds such as betulinic acid (BA). The objective of this study was to investigate the bioactivity of BA in its free form and compare it with its nano-encapsulated form under a skin carcinogenesis protocol in a genetically modified murine model. K14E6 and FVB mice were divided into four groups to be treated with free BA and with betulinic acid nanoemulsion (BANE). Lecithin enriched with medium chain fatty acids (MCFAs) was employed as an emulsifier to prepare the nanoemulsions with a mean droplet size of 40 nm. Skin tumors were induced by exposure to DMBA and TPA directly to the transgenic mice. Tumor development was completely inhibited by BANE and by 70% with free BA. This was validated by histological sections and the gene expression of the Cdk4 and Casp8 genes.

The Role of Cyclodextrins in the Design and Development of Triterpene-Based Therapeutic Agents

Triterpenic compounds stand as a widely investigated class of natural compounds due to their remarkable therapeutic potential. However, their use is currently being hampered by their low solubility and, subsequently, bioavailability. In order to overcome this drawback and increase the therapeutic use of triterpenes, cyclodextrins have been introduced as water solubility enhancers; cyclodextrins are starch derivatives that possess hydrophobic internal cavities that can incorporate lipophilic molecules and exterior surfaces that can be subjected to various derivatizations in order to improve their biological behavior. This review aims to summarize the most recent achievements in terms of triterpene:cyclodextrin inclusion complexes and bioconjugates, emphasizing their practical applications including the development of new isolation and bioproduction protocols, the elucidation of their underlying mechanism of action, the optimization of triterpenes’ therapeutic effects and the development of new topical formulations.

Mitochondria-Targeted Triphenylphosphonium Conjugated C-3 Modified Betulin: Synthesis, Antitumor Properties and Mechanism of Action

A series of mitochondria-targeted triphenylphosphonium conjugated C-3 modified betulin were synthesized and evaluated against tumor cells. As a result, a new derivative 13 i, the conjugate of 3-O-(3'-acetylphenylacetate)-betulin with triphenylphosphonium, was identified as the one with the best anti-tumor effect. Conjugate 13 i significantly inhibited HCT116 cells with IC₅₀ at 0.66 μM. While betulin, C-3 modified betulin, and the triphenylphosphonium moiety showed no inhibition of HCT116 cell proliferation at 20 μM. More importantly, 13 i exhibited a more cytotoxic effect against the tumor cell HCT116 than normal cell NCM460. Mode of action studies demonstrated that 13 i induced the G2/M phase cell cycle arrest and apoptosis in HCT116 cells through the mitochondrial pathway. Structure-activity relationship analysis revealed that integration of triphenylphosphonium moiety into the C-28 of betulin can greatly improve cytotoxicity. Appropriate modification on C-3 of the conjugate would improve the selectivity.

Effects of Topically Applied Betulinic Acid and NVX-207 on Melanocytic Tumors in 18 Horses

Simple Summary

Melanomas are skin tumors of the pigment-producing melanocytes. Equine melanomas are among the most frequently diagnosed tumors affecting grey horses. The melanocytic tumors progress to malignancy in more than two-thirds of cases. Previous laboratory experiments and studies with horses utilizing the naturally occurring betulinic acid (BA) and its derivative NVX-207 showed promising results with respect to the topical (epicutaneous) treatment of equine melanoma. Therefore, the aim of this feasibility study was to gain first insights into the effect and safety of BA and NVX-207 in eighteen horses with early-stage melanocytic tumors after a 13-week-long topical application. The topical treatment was convenient and safe. Compared to a placebo, the data suggest a positive treatment effect from topical application of BA and NVX-207 on equine melanomas toward the end of the treatment period. However, the time period studied was too short to conclusively prove this. Further advancement of the investigational medicinal products studied herein could lead to an effective, topical and marketable novel drug which helps to relieve suffering and, consequently, improve the welfare of equine skin cancer patients.

Abstract

The naturally occurring betulinic acid (BA) and its derivative NVX-207 induce apoptosis in equine melanoma cells in vitro. After topical application, high concentrations of the substances can be reached in healthy equine skin. With the aim to investigate the effect and safety of topically applied BA and NVX-207 in horses with melanocytic tumors, the longitudinal, prospective, randomized, double-blind, placebo-controlled study protocol included eighteen Lipizzaner mares with early-stage cutaneous melanoma assigned to three groups. Melanocytic lesions were topically treated either with a placebo, 1% BA or 1% NVX-207 twice a day for 91 days. Caliper measurements, clinical examinations and blood tests were performed to assess the effects and safety of the medication. The topical treatment was convenient and safe. The volumes of tumors treated with BA were significantly reduced over time as compared to tumors treated with the placebo from day 80 of the study. Although treatment with NVX-207 seemed to decrease tumor volume, these results did not reach statistical significance. The findings must be regarded as preliminary due to the limited group size and need to be replicated in a larger cohort with modified pharmaceutical test formulations. Accordingly, the treatment protocol cannot yet be recommended in its current form.

Betulinic acid and its spray dried microparticle formulation: In vitro PDT effect against ovarian carcinoma cell line and in vivo plasma and tumor disposition

The race against ovarian cancer continue to motivate the research worldwide. It is known that many antitumor drugs have limited penetration into solid tumor tissues due to its microenvironment, thus contributing to their low efficacy. Therapeutic modalities have been exploited to elicit antitumor effects based on microenvironment of tumor, including Photodynamic therapy (PDT). Prospection of natural small molecules and nanotechnology are important tools in the development of new ways of obtaining photoactive compounds that are biocompatible. The Betulinic acid (BA) has shown potential biological effect as bioactive drug, but it has low water solubility. Thus, in the present study, owing to the poor solubility of the BA, its free form (BAF) was compared to a spray dried microparticle betulinic acid/HP-β-CD formulation (BAC) aiming to assess the BAF and BAC efficacy as a photosensitizer in PDT for application in ovarian cancer. BAF and BAC were submitted to assays in the presence of LED (λ = 420 nm) under different conditions (2.75 J/cm2, 5.5 J/cm2, and 11 J/cm2) and in absence of irradiation, after 5 min or 4 h of contact with ovarian carcinoma cells (A2780) or fibroblast murine cells (3T3). Furthermore, HPLC-MS/MS and MALDI-MSI methods were developed and validated in plasma and tumor of mice proving suitable for in vivo studies. The results found a greater photoinduced cytotoxic effect for the BAC at low concentration for A2780 when irradiated with LED with similar results for fluorescence microscopy. The results motivate us to continue the studies with the BA as a potential antitumor bioactive compound.

Role of Pentacyclic Triterpenoid Acids in the Treatment of Bladder Cancer

Bladder cancer carries a poor prognosis and has proven resistance to chemotherapy. Pentacyclic Triterpenoid Acids (PTAs) are natural bioactive compounds that have a well-known impact on cancer research because of their cytotoxic and chemopreventive activities. This review focuses on bladder cancer which can no longer be successfully treated by DNA damaging drugs. Unlike most of the existing drugs against bladder cancer, PTAs are non-toxic to normal cells. Collecting findings from both in vitro and in vivo studies, it has been concluded that PTAs may serve as promising agents in future bladder cancer therapy. In this review, the roles of various PTAs in bladder cancer have been explored, and their mechanisms of action in the treatment of bladder cancer have been described. Specific PTAs have been shortlisted from each of the chief skeletons of pentacyclic triterpenoids, which could be effective against bladder cancer because of their mode of action. This review thereby throws light on the multi targets and mechanisms of PTAs, which are responsible for their selective anticancer effects and provides guidelines for further research and development of new natural antitumor compounds.

Recent progress on betulinic acid and its derivatives as antitumor agents: a mini review

Natural products are one of the important sources for the discovery of new drugs. Betulinic acid (BA), a pentacyclic triterpenoid widely distributed in the plant kingdom, exhibits powerful biological effects, including antitumor activity against various types of cancer cells. A considerable number of BA derivatives have been designed and prepared to remove their disadvantages, such as poor water solubility and low bioavailability. This review summarizes the current studies of the structural diversity of antitumor BA derivatives within the last five years, which provides prospects for further research on the structural modification of betulinic acid.

Betulinic acid exerts antigenotoxic and anticarcinogenic activities via inhibition of COX-2 and PCNA in rodents

Phytochemicals have been suggested as an effective strategy for cancer prevention. Within this context, triterpene betulinic acid (BA) exhibits several biological properties but its chemopreventive effect has not been fully demonstrated. The present study investigated the antigenotoxic potential of BA against doxorubicin (DXR)-induced genotoxicity using the mouse peripheral blood micronucleus assay, as well as its anticarcinogenic activity against 1,2dimethylhydrazine (DMH)-induced colorectal lesions in rats. Micronuclei (MN) assay and aberrant crypt foci assay were used to assess the antigenotoxic and the anticarcinogenic potential, respectively. The molecular mechanisms underlying the anticarcinogenic activity of BA were evaluated by assessing anti-inflammatory (COX-2) and antiproliferative (PCNA) pathways. The results demonstrated that BA at the dose of 0.5 mg/kg bodyweight exerted antigenotoxic effects against DXR, with a reduction of 70.2% in the frequencies of chromosomal damage. Animals treated with BA showed a 64% reduction in the number of preneoplastic lesions when compared to those treated with the carcinogen alone. The levels of COX-2 and PCNA expression in the colon were significantly lower in animals treated with BA and DMH compared to those treated with the carcinogen alone. The chemopreventive effect of BA is related, at least in part, to its antiproliferative and anti-inflammatory activity, indicating a promising potential of this triterpene in anticancer therapies, especially for colorectal cancer.

Betulin Sulfonamides as Carbonic Anhydrase Inhibitors and Anticancer Agents in Breast Cancer Cells

Hypoxia-regulated protein carbonic anhydrase IX (CA IX) is up-regulated in different tumor entities and correlated with poor prognosis in breast cancer patients. Due to the radio- and chemotherapy resistance of solid hypoxic tumors, derivatives of betulinic acid (BA), a natural compound with anticancer properties, seem to be promising to benefit these cancer patients. We synthesized new betulin sulfonamides and determined their cytotoxicity in different breast cancer cell lines. Additionally, we investigated their effects on clonogenic survival, cell death, extracellular pH, HIF-1α, CA IX and CA XII protein levels and radiosensitivity. Our study revealed that cytotoxicity increased after treatment with the betulin sulfonamides compared to BA or their precursors, especially in triple-negative breast cancer (TNBC) cells. CA IX activity as well as CA IX and CA XII protein levels were reduced by the betulin sulfonamides. We observed elevated inhibitory efficiency against protumorigenic processes such as proliferation and clonogenic survival and the promotion of cell death and radiosensitivity compared to the precursor derivatives. In particular, TNBC cells showed benefit from the addition of sulfonamides onto BA and revealed that betulin sulfonamides are promising compounds to treat more aggressive breast cancers, or are at the same level against less aggressive breast cancer cells.

Betulinic acid in the treatment of tumour diseases: Application and research progress

Betulinic acid (BA) is a pentacyclic triterpene compound that can be obtained by separation, chemical synthesis and biotransformation from birch. BA has antitumour activity, and its mechanisms of action mainly include the induction of mitochondrial oxidative stress; the regulation of specificity protein transcription factors, and the inhibition of signal transducer and activator of transcription 3 and nuclear factor-κB signalling pathways. In addition, BA can increase the sensitivity of cancer cells to other chemotherapy drugs. Recent studies have shown that BA plays an anticancer role in several kinds of tumour diseases. In this article, the anticancer mechanism of BA and its application in the treatment of tumour diseases are reviewed.

Phytochemical library screening reveals betulinic acid as a novel Skp2-SCF E3 ligase inhibitor in non-small cell lung cancer

Skp2 is overexpressed in multiple cancers and plays a critical role in tumor development through ubiquitin/proteasome-dependent degradation of its substrate proteins. Drugs targeting Skp2 have exhibited promising anticancer activity. Here, we identified a plant-derived Skp2 inhibitor, betulinic acid (BA), via high-throughput structure-based virtual screening of a phytochemical library. BA significantly inhibited the proliferation and migration of non-small cell lung cancer (NSCLC) through targeting Skp2-SCF E3 ligase both in vitro and in vivo. Mechanistically, BA binding to Skp2, especially forming H-bonds with residue Lys145, decreases its stability by disrupting Skp1-Skp2 interactions, thereby inhibiting the Skp2-SCF E3 ligase and promoting the accumulation of its substrates; that is, E-cadherin and p27. In both subcutaneous and orthotopic xenografts, BA significantly inhibited the proliferation and metastasis of NSCLC through targeting Skp2-SCF E3 ligase and upregulating p27 and E-cadherin protein levels. Taken together, BA can be considered a valuable therapeutic candidate to inhibit metastasis of NSCLC.

MSBA-S - A pentacyclic sulfamate as a new option for radiotherapy of human breast cancer cells

Many pentacyclic triterpenoids show anti-cancer and anti-inflammatory properties. Recently, we detected a pronounced cytotoxicity and radiosensitivity of two betulinyl sulfamates in human breast cancer cells. Besides betulinic acid scaffold (BSBA-S), we synthesized several new sulfamate-coupled scaffolds from oleanolic acid (OSBA-S), ursolic acid (USBA-S), platanic acid (PSBA-S) and maslinic acid (MSBA-S). Highest cytotoxicity was monitored in breast cancer cell lines after MSBA-S treatment showing in SRB assays IC₅₀ values between 3.7 μM and 5.8 μM. Other sulfamate/triterpene conjugates, however, were less cytotoxic holding IC₅₀ values between 6.6 μM and >50 µM, respectively. MSBA-S-treated breast cancer cells displayed significantly reduced clonogenic survival and an increased rate of apoptosis as compared to the other conjugates. In addition, MSBA-S in combination with irradiation resulted in effects on radiosensitivity in MDA-MB-231 cells (DMF₁₀ = 1.14). In particular, ROS formation was strongly assessed in MSBA-S-treated breast cancer cells. Our findings suggest that the sulfamate derivative of maslinic acid MSBA-S might be a new option for the radiation therapy in breast cancer cells.

Acankoreagenin and acankoreosides, a family of lupane triterpenoids with anti-inflammatory properties: an overview

Acankoreagenin (ACK, also known as acankoreanogenin and HLEDA) and impressic acid are two lupane-type triterpenes that can be isolated from various Acanthopanax and Schefflera species. They efficiently block activation of the NF-κB signaling pathway and the release of proinflammatory cytokines and/or the action of inflammation mediators (HMGB1, iNOS, and NO). These effects are the basis for the antiviral and anticancer activities reported with these pentacyclic compounds or their various glycoside derivatives. More than 15 acankoreosides (Ack-A to -O, and -R) and a few other mono- and bidesmosidic saponins (acantrifoside A and acangraciliside S) derive from the ACK aglycone. Compounds like Ack-A and -B are remarkable anti-inflammatory agents, inhibiting cytokine release from activated macrophages. Despite their effectiveness, ACK and impressic acid are far much less known and studied than the structurally related compounds betulinic acid and 23-hydroxybetulinic acid (anemosapogenin). The structural differences (notably the R/S stereoisomerism of the 3-hydroxyl group) and functional similarities of these compounds are discussed. The complete series of acankoreosides is presented for the first time. These natural products deserve further attention as anti-inflammatory agents, and ACK is recommended as a template for the design of new anticancer and antiviral drugs.

Conjugation of Natural Triterpenic Acids with Delocalized Lipophilic Cations: Selective Targeting Cancer Cell Mitochondria

Currently, a new line of research on mitochondria-targeted anticancer drugs is actively developing in the field of biomedicine and medicinal chemistry. The distinguishing features of this universal target for anticancer agents include presence of mitochondria in the overwhelming majority, if not all types of transformed cells, crucial importance of these cytoplasmic organelles in energy production, regulation of cell death pathways, as well as generation of reactive oxygen species and maintenance of calcium homeostasis. Hence, mitochondriotropic anticancer mitocan agents, acting through mitochondrial destabilization, have good prospects in cancer therapy. Available natural pentacyclic triterpenoids are considered promising scaffolds for development of new mitochondria-targeted anticancer agents. These secondary metabolites affect the mitochondria of tumor cells and initiate formation of reactive oxygen species. The present paper focuses on the latest research outcomes of synthesis and study of cytotoxic activity of conjugates of pentacyclic triterpenoids with some mitochondria-targeted cationic lipophilic molecules and highlights the advantages of applying them as novel mitocan agents compared to their prototype natural triterpenic acids.

Modified Gold Nanoparticles for Efficient Delivery of Betulinic Acid to Cancer Cell Mitochondria

Advances in nanomedicine have seen the adaptation of nanoparticles (NPs) for subcellular delivery for enhanced therapeutic impact and reduced side effects. The pivotal role of the mitochondria in apoptosis and their potential as a target in cancers enables selective induction of cancer cell death. In this study, we examined the mitochondrial targeted delivery of betulinic acid (BA) by the mitochondriotropic TPP⁺-functionalized epigallocatechin gallate (EGCG)-capped gold NPs (AuNPs), comparing the impact of polyethylene glycol (PEG) and poly-L-lysine-graft-polyethylene glycol (PLL-g-PEG) copolymer on delivery efficacy. This included the assessment of their cellular uptake, mitochondrial localization and efficacy as therapeutic delivery platforms for BA in the human Caco-2, HeLa and MCF-7 cancer cell lines. These mitochondrial-targeted nanocomplexes demonstrated significant inhibition of cancer cell growth, with targeted nanocomplexes recording IC₅₀ values in the range of 3.12–13.2 µM compared to that of the free BA (9.74–36.31 µM) in vitro, demonstrating the merit of mitochondrial targeting. Their mechanisms of action implicated high amplitude mitochondrial depolarization, caspases 3/7 activation, with an associated arrest at the G0/G1 phase of the cell cycle. This nano-delivery system is a potentially viable platform for mitochondrial-targeted delivery of BA and highlights mitochondrial targeting as an option in cancer therapy.

In vitro anti-bacterial activity and network pharmacology analysis of Sanguisorba officinalis L. against Helicobacter pylori infection

Background

Helicobacter pylori (H. pylori) infection has become an international public health problem, and antibiotic-based triple or quadruple therapy is currently the mainstay of treatment. However, the effectiveness of these therapies decreases due to resistance to multiple commonly used antibiotics. Sanguisorba officinalis L. (S. officinalis), a traditional Chinese medicine clinically used for hemostasis and treatment of diarrhea, has various pharmacological activities. In this study, in vitro antimicrobial activity was used for the preliminary evaluation of S. officinalis against H. pylori. And a pharmacology analysis approach was also utilized to elucidate its underlying mechanisms against H. pylori infection.

Methods

Micro-broth dilution method, agar dilution method, checkerboard assay, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were used for the assessment of anti-bacterial activity. Active ingredients screening, GO analysis, KEGG analysis, construction of PPI network, molecular docking, and RT-qPCR were used to elucidate the underlying pharmacological mechanisms of S. officinalis against H. pylori infection.

Results

The minimum inhibitory concentration (MIC) values of S. officinalis against multiple H. pylori strains including clinically isolated multi-drug resistant (MDR) strains were ranging from 160 to 320 µg/ml. These results showed that S. officinalis had additive interaction with four commonly used antibiotics and could exert antibacterial effect by changing the morphology of bacteria without developing drug resistance. Through network pharmacology analysis, 8 active ingredients in S. officinalis were screened out for subsequent studies. Among 222 putative targets of S. officinalis, 49 targets were identified as potential targets for treatment of H. pylori infection. And these 49 targets were significantly enriched in GO processes such as protein kinase B signaling, protein kinase activity, protein kinase binding, and KEGG pathways such as Pathways in cancer, MicroRNAs in cancer, and TNF signaling pathway. Protein-protein interaction analysis yielded 5 core targets (AKT1, VEGFA, EGFR, SRC, CCND1), which were validated by molecular docking and RT-qPCR.

Conclusions

Overall, this study confirmed the in vitro inhibitory activity of S. officinalis against H. pylori and explored the possible pharmacological mechanisms, laying the foundation for further research and clinical application.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-021-00442-1.

Anticancer Potential of Betulonic Acid Derivatives

Clinical trials have evidenced that several natural compounds, belonging to the phytochemical classes of alkaloids, terpenes, phenols and flavonoids, are effective for the management of various types of cancer. Latest research has proven that natural products and their semisynthetic variants may serve as a starting point for new drug candidates with a diversity of biological and pharmacological activities, designed to improve bioavailability, overcome cellular resistance, and enhance therapeutic efficacy. This review was designed to bring an update regarding the anticancer potential of betulonic acid and its semisynthetic derivatives. Chemical derivative structures of betulonic acid including amide, thiol, and piperidine groups, exert an amplification of the in vitro anticancer potential of betulonic acid. With the need for more mechanistic and in vivo data, some derivatives of betulonic acids may represent promising anticancer agents.

Stimulatory Effects of Oleci Acid and Fungal Elicitor on Betulinic Acid Production by Submerged Cultivation of Medicinal Mushroom Inonotus obliquus

To evaluate the novel strategy of oleic acid and fungal elicitor (made from Aspergillus niger) to elicit betulinic acid biosynthesis in medicinal mushroom Inonotus obliquus, we conduct the stimulatory effects investigation for synthesizing betulinic acid from betulin. HPLC results indicated oleic acid and fungal elicitor were effective stimulators. The supplementation of 1.0 g/L oleic acid led to the highest increase of betulinic acid either in dry mycelia or fermentation broth by 2-fold of the control. Fungal elicitor at 45 mg/L markedly increases mycelia growth by 146.0% and enhance intracellular betulinic acid accumulation by 429.5% as compared to the controls. Quantification of transcription levels determined that oleic acid, fungal elicitor and their combinations could induce the expressions of key genes involved in betulinic acid biosynthesis, such as HMG-CoA reductase and squalene synthase. These findings indicated that oleic acid and fungal elicitor could enhance betulinic acid metabolism by up-regulating key genes expression.

Application of TLC to Evaluate the Lipophilicity of Newly Synthesized Betulin Derivatives

Designing a new drug has recently become a very important topic that many researches are concerned with. This work relates to a newly synthesized betulin and betulone derivatives which have anticancer activity. Thin-layer chromatography was applied to evaluate the lipophilicity of these triterpenes in order to find the correlation between theoretically and experimentally calculated values of lipophilicity and the structure of compounds investigated. Moreover, the relationships between lipophilicity and pharmacokinetic parameters or anticancer activity were carried out. The similarity analysis was also done for the purpose to divide the compounds investigated into groups pointing which of these can meet the criteria for medicine substances. The cluster analysis showed the differences in the compounds grouping in relation which the values of lipophilicity are considered, i.e., calculated by computer software or obtained experimentally by use of TLC. Analysis clearly shows that those theoretically calculated values of lipophilicity are strongly connected to the structure of the compounds.

Synthesis, Anticancer, and Antibacterial Activity of Betulinic and Betulonic Acid C-28-Triphenylphosphonium Conjugates with Variable Alkyl Linker Length

BACKGROUND

Conjugation of triterpenoids such as betulinic acid 1 with the Triphenylphosphonium (TPP) group is a powerful approach to generating medicinal compounds. Their development proposes structure optimization in respect of availability and activity towards target cells and organelles. Selection of 1 or its precursor betulonic acid 2 and the optimal linker is of particular importance for drug candidate identification among the TPP-triterpenoid conjugates.

OBJECTIVE

In this study, new C-28-TPP conjugated derivatives of 1 and 2 with the alkyl/alkoxyalkyl linkers of variable length were synthesized and compared regarding their anticancer, antibacterial, and mitochondriatargeted effects.

METHODS

The TPP conjugates of 1 and 2 [6a-f, 7a-f] were synthesized by the reaction of halogenalkyl esters [3a-f, 4a-f, 5] with triphenylphosphine in acetonitrile upon heating. Cytotoxicity (MTT assay), antibacterial activity (microdilution assay), and mitochondrial effects (flow cytofluorometry) were studied.

RESULTS

Conjugation with the TPP group greatly increased the cytotoxicity of the triterpenoids up to 30 times. The conjugates were up to 10-17 times more active against MCF-7 (IC50 = 0.17μM, 72h, 6c) and PC-3 (IC50 = 0.14μM, 72h, 6a) cancer cells than for human skin fibroblasts. The enhanced antibacterial (bactericidal) activity of the TPP-triterpenoid conjugates with MIC for Gram-positive bacteria as low as 2μM (6a, 7a) was for the first time revealed. The conjugates were found to effectively inhibit fluorescence of 2′,7′-dichlorofluorescin probe in the cytosol upon oxidation, decrease transmembrane potential, and increase superoxide radical level in mitochondria.

CONCLUSION

Relationships between the effects and structure of the TPP-triterpenoid conjugates were evaluated and discussed. Based on the results, 6a can be selected for further preclinical investigation as a potential anticancer compound.

Biotransformation of betulinic acid by Circinella muscae and Cunninghamella echinulata to discover anti-inflammatory derivatives

Biotransformation of betulinic acid was carried out with Circinella muscae CGMCC 3.2695 and Cunninghamella echinulata CGMCC 3.970, yielded six previously undescribed hydroxylated metabolites and four known compounds. C. muscae could catalyze the regioselecitve hydroxylation and carbonylation at C-3, C-7, C-15 and C-21 to yield seven products. C. echinulata could catalyze the C-1, C-7 and C-26 regioselecitve hydroxylation and acetylation to yield five metabolites. The structures of the metabolites were established based on extensive NMR and HR-ESI-MS data analyses. Furthermore, most of the metabolites exhibited pronounced inhibitory activities on lipopolysaccharides-induced NO production in RAW264.7 cells.

Functionalization of Betulinic Acid with Polyphenolic Fragments for the Development of New Amphiphilic Antioxidants

The present work aimed at the valorization of biomass derived compounds by their transformation into new added-value compounds with enhanced antioxidant properties. In this context, betulinic acid (BA) was decorated with polyphenolic fragments, and polyhydroxylated (E)-2-benzylidene-19,28-epoxyoleanane-3,28-diones 4a–d were obtained. For that, the synthetic strategy relied on base-promoted aldol condensation reactions of methyl betulonate, which was previously prepared from natural BA, with appropriate benzaldehydes, followed by cleavage of the methyl protecting groups with BBr₃. It is noteworthy that the HBr release during the work-up of the cleavage reactions led to the rearrangement of the lupane-type skeleton of the expected betulonic acid derivatives into oleanane-type compounds 4a–d. The synthesized compounds 4a–d were designed to have specific substitution patterns at C-2 of the triterpene scaffold, allowing the establishment of a structure-activity relationship. The radical scavenging ability of 4a–d was evaluated using the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH^•) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid radical cation (ABTS^•+) scavenging assays. In particular, derivative 4c, bearing a catechol unit, revealed to be the most efficient scavenger against both free radicals DPPH^• and ABTS^•+. Subsequently, we designed two analogues of the hit derivative 4c in order to achieve more potent antioxidant agents: (i) the first analogue carries an additional unsaturation in its lateral chain at C-2 (analogue 5) and (ii) in the second analogue, E-ring was kept in its open form (analogue 6). It was observed that the presence of an extended π-conjugated system at C-2 contributed to an increased scavenging effect, since analogue 5 was more active than 6, α-tocopherol, and 4c in the ABTS^•+ assay.

Novel pentacyclic triterpenes exhibiting strong neuroprotective activity in SH-SY5Y cells in salsolinol- and glutamate-induced neurodegeneration models

Novel triterpene derivatives were prepared and evaluated in salsolinol (SAL)- and glutamate (Glu)-induced models of neurodegeneration in neuron-like SH-SY5Y cells. Among the tested compounds, betulin triazole 4 bearing a tetraacetyl-β-d-glucose substituent showed a highly potent neuroprotective effect. Further studies revealed that removal of tetraacetyl-β-d-glucose part (free triazole derivative 10) resulted in strong neuroprotection in the SAL model at 1 μM, but this derivative suffered from cytotoxicity at higher concentrations. Both compounds modulated oxidative stress and caspase-3,7 activity, but 10 showed a superior effect comparable to the Ac-DEVD-CHO inhibitor. Interestingly, while both 4 and 10 outperformed the positive controls in blocking mitochondrial permeability transition pore opening, only 4 demonstrated potent restoration of the mitochondrial membrane potential (MMP) in the model. Derivatives 4 and 10 also showed neuroprotection in the Glu model, with 10 exhibiting the strongest oxidative stress reducing effect among the tested compounds, while the neuroprotective activity of 4 was probably due recovery of the MMP.

Combined 3-O-acetylbetulin treatment and carbonic anhydrase IX inhibition results in additive effects on human breast cancer cells

Hypoxia plays a key role in tumor progression and resistance to radiotherapy. Expression of the transmembrane-tethered enzyme carbonic anhydrase IX (CA IX) is strongly induced by hypoxia. High CA IX expression levels correlate with poor prognosis in cancer patients. Previously, we showed that the downregulation of CA IX expression by siRNA interference and the inhibition of CA IX activity results in increased cytotoxicity, inhibition of migration and radiosensitization of hypoxic cancer cells. Betulinic acid (BA) is a natural compound derived from birch bark. It has shown promising anti-tumor effects due to its cancer cell specific cytotoxic properties. We have shown that BA inhibits the HIF-1α pathway, resulting in apoptosis, inhibition of migration and enhanced cytotoxicity of breast cancer cells. In this study, we investigate the effects of the novel betulin derivative 3-O-acetylbetulin (3-AC) and carbonic anhydrase inhibitors (CAI) octyl disulfamate (OCT) or 4-(3-[4-fluorophenyl]ureido)benzenesulfonamide (SLC-0111), on cellular and radiobiological parameters in MDA-MB-231 and MCF-7 cells. Treatment with 3-AC or OCT alone only caused moderate cytotoxicity, reduction in cell migration, ROS production and DNA damage. However, the combined treatment with 3-AC and CAI strongly enhanced radiosensitivity, increased cytotoxicity, inhibited cell motility and enhanced DNA damage. Our findings suggest that the combination of two bioactive drugs 3-AC and a CAI, such as OCT or SLC-0111, could be a promising therapeutic approach for targeting hypoxic tumor cells.

Allobetulone rearrangement to l8αH,19βH-ursane triterpenoids with antiviral activity

Allobetulone E-ring rearrangement under treating with HClO₄ in Ac₂O under reflux afforded new triterpenoids: 3,28-diacetoxy-21-acetyl-2(3),20(21)-18α,19βH-ursandiene 3 and 3,28-diacetoxy-2(3),18(19)-oleandiene 4. 18α,19βH-Ursanes were transformed at A- and E-rings into indolo- and bis-furfurylidene 7 derivatives. Structure elucidation was performed using COSY, NOESY, HSQC and HMBC experiments, and X-Ray analysis for 3. The potential of newly obtained 18α,19βH-ursanes was evaluated against HCMV and HPV-11, the NCI-60 cancer cell panel and inhibition of α-glucosidase. All of the compounds have shown viral inhibition towards HCMV compared to standard drug Acyclovir. 3β-Acetoxy-21β-acetyl-20β,28-epoxy-18α,19βН-ursane 1 showed moderate activity (EC₅₀ 4.87 μM) towards the HCMV-resistant isolate (GDGr K17) compared to standard drug Cidofovir and was four times more potent than Ganciclovir. Compound 7 inhibited the cell growth of the three melanoma and one colon cancer cell. 3-Oxo-21β-acetyl-20β,28-epoxy-18α,19βН-ursane 5 and compound 7 inhibited α-glucosidase with IC₅₀ 28.0 µM and 4.0 µM being from 6 to 44 times more active than acarbose.

In vitro assessment of triterpenoids NVX-207 and betulinyl-bis-sulfamate as a topical treatment for equine skin cancer

Equine sarcoid (ES) is the most prevalent skin tumor in equids worldwide. Additionally, aging grey horses frequently suffer from equine malignant melanoma (EMM). Current local therapies targeting these skin tumors remain challenging. Therefore, more feasible topical treatment options should be considered. In order to develop a topical therapy against ES and EMM, betulinyl-bis-sulfamate and NVX-207, derivatives of the naturally occurring betulin and betulinic acid, respectively, were evaluated for their antiproliferative (crystal violet staining assay), cytotoxic (MTS assay) and apoptotic (AnnexinV staining, cell cycle investigations) effects on primary ES cells, EMM cells and equine dermal fibroblasts in vitro. The more potent derivative was assessed for its in vitro penetration and permeation on isolated equine skin within 30 min and 24 h using Franz-type diffusion cells and HPLC analysis. Betulinyl-bis-sulfamate and NVX-207 inhibited the proliferation and metabolism in ES cells, EMM cells and fibroblasts significantly (p < 0.001) in a time- and dose-dependent manner. NVX-207 had superior anticancer effects compared to betulinyl-bis-sulfamate. Both compounds led to the externalization of phosphatidylserines on the cell membrane and DNA fragmentation, demonstrating that the effective mode of action was apoptosis. After 48 h of treatment with NVX-207, the number of necrotic cells was less than 2% in all cell types. Detected amounts of NVX-207 in the different skin layers exceeded the half-maximal inhibitory concentrations calculated by far. Even though data obtained in vitro are auspicious, the results are not unconditionally applicable to the clinical situation. Consequently, in vivo studies are required to address the antitumoral effects of topically applied NVX-207 in ES and EMM patients.