Determination of pKa and forced degradation of the indoloquinoline antimalarial compound cryptolepine hydrochloride

Recent Advances in the Chemistry and Pharmacology of Cryptolepine

Cryptolepine, the principal constituent of the West African climbing shrub Cryptolepis sanguinolenta, continues to be of interest as a lead to new therapeutic agents, especially for the treatment of protozoal infections and cancer. This contribution reviews the research published in the last decade, highlighting new synthesis routes to cryptolepine and to analogs of this alkaloid, as well as their pharmacology. Studies relating to the use of C. sanguinolenta as an herbal medicine for the treatment of malaria are discussed, as well as the development of analogs of cryptolepine as leads to new agents for the treatment of malaria, trypanosomiasis, and cancer with an emphasis on the pharmacological mechanisms involved. Other potential therapeutic applications include antimicrobial, antidiabetic, and anti-inflammatory activities; the pharmacokinetics and toxicity of cryptolepine are also reviewed.

Environmental Remediation of Antineoplastic Drugs: Present Status, Challenges, and Future Directions

The global burden of cancer is on the rise, and as a result, the number of therapeutics administered for chemotherapy is increasing. The occupational exposure, recalcitrant nature and ecotoxicological toxicity of these therapeutics, referred to as antineoplastic (ANP) drugs, have raised concerns about their safe remediation. This review provides an overview of the environmental source of ANPs agents, with emphasis on the currently used remediation approaches. Outpatient excreta, hospital effluents, and waste from pharmaceutical industries are the primary source of ANP waste. The current review describes various biotic and abiotic methods used in the remediation of ANP drugs in the environment. Abiotic methods often generate transformation products (TPs) of unknown toxicity. In this light, obtaining data on the environmental toxicity of ANPs and its TPs is crucial to determine their toxic effect on the ecosystem. We also discuss the biodegradation of ANP drugs using monoculture of fungal and bacterial species, and microbial consortia in sewage treatment plants. The current review effort further explores a safe and sustainable approach for ANP waste treatment to replace existing chemical and oxidation intensive treatment approaches. To conclude, we assess the possibility of integrating biotic and abiotic methods of ANP drug degradation.

Cryptolepine and quindoline: understanding their photophysics

Quindoline (QUIND, indolo[3,2-b]quinoline) and cryptolepine (CRYPT, 5-methyl-10H-indolo[3,2-b]quinoline) together with their corresponding derivatives have been studied for decades due to their important biological activity against diseases like malaria. The biological activity of drugs is routinely investigated using fluorescence based methods. However, recent reports show that the photophysics of CRYPT and its analogues is not yet understood. Herein, the photophysics of CRYPT and QUIND is studied in aqueous solutions at different pH values and in both protic and aprotic solvents of different polarities. CRYPT and QUIND are shown to exist in different prototropic forms depending on pH and solvent polarity. CRYPT is found to be more sensitive to the solvent nature. Both compounds are shown to have two-photon stimulated emission. Their two-photon absorption (TPA) cross-sections were measured in the 710-960 nm range. The TPA cross-section is relatively low but allows for the observation of both compounds in HEK 293 T cells, where CRYPT is found mostly in the nucleus and QUIND accumulates in the cytoplasm.

Ultraviolet-visible study on acid-base equilibria of aporphine alkaloids with antiplasmodial and antioxidant activities from Alseodaphne corneri and Dehaasia longipedicellata

The UV-vis spectra of isocorydine 1, norisocorydine 2 and boldine 3 were studied in 2% v/v acetonitrile, at constant ionic strength (0.1 M NaCl, 35 degree Celsius). The pK_a values of isocorydine 1 and norisocorydine 2 were 11.75 and 12.07, respectively. Boldine 3 gave a pK_a value of 9.16 and 10.44. All of the alkaloids 1–3 were stable at physiological pH; thereby all of them will not ionize, thus permitting the basic nitrogen to be protonated and accumulated within the acidic food vacuole of Plasmodium via pH trapping. Subsequently, acidic food vacuoles that have been neutralized by alkaloids would result in enhancement of the antiplasmodial activity. The alkaloids showed antiplasmodial activity against Plasmodium falciparum and antioxidant activities; DPPH radical scavenging, metal chelating and ferric reducing power. The antioxidant properties of the alkaloids under investigation revealed that in addition to the antiplasmodial activity, the alkaloids can also prevent oxidative damage. It can be prevented by binding free heme and neutralizing the electrons produced during the Plasmodium falciparum mediated haemoglobin destruction in the host. Slightly basic properties of the aforementioned alkaloids, along with their antioxidant activities, are advantageous in improving the suppression of malaria infection that cause less damage to the host.