Novel berberine derivatives: Design, synthesis, antimicrobial effects, and molecular docking studies

Alkaloids of Dicranostigma franchetianum (Papaveraceae) and Berberine Derivatives as a New Class of Antimycobacterial Agents

Tuberculosis (TB) is a widespread infectious disease caused by Mycobacterium tuberculosis. The increasing incidence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains has created a need for new antiTB agents with new chemical scaffolds to combat the disease. Thus, the key question is: how to search for new antiTB and where to look for them? One of the possibilities is to search among natural products (NPs). In order to search for new antiTB drugs, the detailed phytochemical study of the whole Dicranostigma franchetianum plant was performed isolating wide spectrum of isoquinoline alkaloids (IAs). The chemical structures of the isolated alkaloids were determined by a combination of MS, HRMS, 1D, and 2D NMR techniques, and by comparison with literature data. Alkaloids were screened against Mycobacterium tuberculosis H37Ra and four other mycobacterial strains (M. aurum, M. avium, M. kansasii, and M. smegmatis). Alkaloids 3 and 5 showed moderate antimycobacterial activity against all tested strains (MICs 15.625–31.25 µg/mL). Furthermore, ten semisynthetic berberine (16a–16k) derivatives were developed and tested for antimycobacterial activity. In general, the derivatization of berberine was connected with a significant increase in antimycobacterial activity against all tested strains (MICs 0.39–7.81 μg/mL). Two derivatives (16e, 16k) were identified as compounds with micromolar MICs against M. tuberculosis H37Ra (MIC 2.96 and 2.78 µM). All compounds were also evaluated for their in vitro hepatotoxicity on a hepatocellular carcinoma cell line (HepG2), exerting lower cytotoxicity profile than their MIC values, thereby potentially reaching an effective concentration without revealing toxic side effects.

Molecular Simplification of Natural Products: Synthesis, Antibacterial Activity, and Molecular Docking Studies of Berberine Open Models

Berberine, the main bioactive component of many medicinal plants belonging to various genera such as Berberis, Coptis, and Hydrastis is a multifunctional compound. Among the numerous interesting biological properties of berberine is broad antimicrobial activity including a range of Gram-positive and Gram-negative bacteria. With the aim of identifying berberine analogues possibly endowed with higher lead-likeness and easier synthetic access, the molecular simplification approach was applied to the secondary metabolite and a series of analogues were prepared and screened for their antimicrobial activity against Gram-positive and Gram-negative bacterial test species. Rewardingly, the berberine simplified analogues displayed 2-20-fold higher potency with respect to berberine. Since our berberine simplified analogues may be easily synthesized and are characterized by lower molecular weight than the parent compound, they are further functionalizable and should be more suitable for oral administration. Molecular docking simulations suggested FtsZ, a well-known protein involved in bacterial cell division, as a possible target.

An insight into the medicinal attributes of berberine derivatives: A review

In the last few decades, traditional natural products have been the center of attention for the scientific community and exploration of their therapeutic abilities is proceeding perpetually. Berberine, with remarkable therapeutic diversity, is a plant derived isoquinoline alkaloid which is widely used as a traditional medicine in China. Berberine has been tackled as a fascinating pharmacophore to make great contributions to the discovery and development of new therapeutic agents against variegated diseases. Despite its tremendous therapeutic potential, clinical utility of this alkaloid was significantly compromised due to undesirable pharmacokinetic properties. To overcome this limitation, several structural modifications were performed on this scaffold to improve its therapeutic efficacy. The collective efforts of the community have achieved the tremendous advancements, bringing berberine to clinical use and discovering new therapeutic opportunities by structural modifications on the berberine scaffold. In this review, recent advancements in the medicinal chemistry of berberine and its derivatives in the last few years (2016-2020) have been compiled to represent inclusive data associated with various biological activities of this alkaloid. The comprehensive structure-activity relationship studies along with molecular modelling and mechanistic studies have also been summarized. This article would be highly helpful for the scientific community to get better insight into medicinal research of berberine and become a compelling guide for the rational design of berberine based compounds.

Discovery of Novel Sultone Fused Berberine Derivatives as Promising Tdp1 Inhibitors

A new type of berberine derivatives was obtained by the reaction of berberrubine with aliphatic sulfonyl chlorides. The new polycyclic compounds have a sultone ring condensed to C and D rings of a protoberberine core. The reaction conditions were developed to facilitate the formation of sultones with high yields without by-product formation. Thus, it was shown that the order of addition of reagents affects the composition of the reaction products: when sulfochlorides are added to berberrubine, their corresponding 9-O-sulfonates are predominantly formed; when berberrubine is added to pre-generated sulfenes, sultones are the only products. The reaction was shown to proceed stereo-selectively and the cycle configuration was confirmed by 2D NMR spectroscopy. The inhibitory activity of the synthesized sultones and their 12-brominated analogs against the DNA-repair enzyme tyrosyl-DNA phosphodiesterase 1 (Tdp1), an important target for a potential antitumor therapy, was studied. All derivatives were active in the micromolar and submicromolar range, in contrast to the acyclic analogs and 9-O-sulfonates, which were inactive. The significance of the sultone cycle and bromine substituent in binding with the enzyme was confirmed using molecular modeling. The active inhibitors are mostly non-toxic to the HeLa cancer cell line, and several ligands show synergy with topotecan, a topoisomerase 1 poison in clinical use. Thus, novel berberine derivatives can be considered as candidates for adjuvant therapy against cancer.

Data on molecular docking of naturally occurring flavonoids with biologically important targets

Flavonoids in nature are known to possess various activities such as anti-inflammatory, antimicrobial, anticancer, antioxidant, neuroprotective, anti-HIV activities etc., The molecular docking was performed by 26 naturally occurring flavonoids with selected targets COX-2, hydroxyacyl-ACP dehydratase, tyrosinase from Agaricus bisporus, isomaltase from Saccharomyces cerevisiae, Human IkB kinase beta, Human ABC transporter, topoisomerase II, topoisomerase IV, N-myristoyltransferase from Candida albicans, Peptide deformylase from Pseudomonas aeruginosa, polypeptide deformylase from Streptococcus pneumoniae. The analysis was based on docking score, glide energy, interactions type (bond type and distance) and interaction with amino acids. The top 5 flavonoids with best docking score was reported. The in-silico results provided for 26 naturally occurring flavonoid shows that they reduce the risk of inflammation, cancer and infectious disease if people have taken in diet continuously. The provided docking data of flavonoids may be useful to synthesis novel drug candidate for the mentioned targets.