Methyl ester and aromatic ether modification of mitragynine for generation of mitragynine-specific polyclonal antibodies.

Mitragynine is an alkaloid from Mitragyna speciosa Korth. (kratom), a native tropical plant in Southeast Asia. It could render psychotropic effects and is often misused in substitution for commercial drugs. In recent years, the consumption of kratom has grown rapidly and has led some countries to ban its use. The misuse of kratom can be detected and monitored through the determination of mitragynine from biological samples of the users. Therefore, the development of a rapid and effective detection method is needed. In this study, polyclonal antibodies were produced using mitragynine coupled to a carrier protein (cationic bovine serum albumin, cBSA) as an immunogen, which was prepared with coupling agents (i.e., N, N- dicyclohexylcarbodiimide, DCC and N-hydroxysuccinimide, NHS). It was conjugated to different mitragynine structure, 16-COOCH3 (methyl ester) and 9-OCH3 (aromatic ether). 2,4,6-Trinitrobenzenesulfonic acid (TNBS) method showed that 45 and 46 amino groups were bound to C22-MG-cBSA and C9-MG-cBSA, respectively. Fourier-transform infrared spectroscopy (FTIR) spectral changes at C22- and C9-hydroxymitragynine indicated reduction and demethylation process. In UV-Vis spectra, conjugated mitragynine to cBSA and OVA were displayed at a spectral region at 240-300 nm. For the antibody titre, the C22-MG-cBSA anti-serum showed a significantly higher titre than the C9-MG-cBSA at 1/128000 and 1/32000 dilutions, respectively. The detection range of the developed competitive indirect ELISA (CI-ELISA) was 0.01 to 10.00 µg/mL (R2 = 0.9964). The assay exhibited a limit of detection (LOD) and limit of quantification (LOQ) at 0.041 and 0.124 µg/mL, respectively. The antibody produced is a high-value biorecognition molecule that can be further used in developing immuno-based detection methods such as immunosensors and immunochromatographic lateral flow assays. This will benefit the task force or forensic agencies for toxicological screening with high speed and efficiency.

Preparation, Characterization, and Radiolabeling of [68Ga]Ga-NODAGA-Pamidronic Acid: A Potential PET Bone Imaging Agent.

Early diagnosis of bone metastases is crucial to prevent skeletal-related events, and for that, the non-invasive techniques to diagnose bone metastases that make use of image-guided radiopharmaceuticals are being employed as an alternative to traditional biopsies. Hence, in the present work, we tested the efficacy of a gallium-68 (68Ga)-based compound as a radiopharmaceutical agent towards the bone imaging in positron emitting tomography (PET). For that, we prepared, thoroughly characterized, and radiolabeled [68Ga]Ga-NODAGA-pamidronic acid radiopharmaceutical, a 68Ga precursor for PET bone cancer imaging applications. The preparation of NODAGA-pamidronic acid was performed via the N-Hydroxysuccinimide (NHS) ester strategy and was characterized using liquid chromatography-mass spectrometry (LC-MS) and tandem mass spectrometry (MSn). The unreacted NODAGA chelator was separated using the ion-suppression reverse phase-high performance liquid chromatography (RP-HPLC) method, and the freeze-dried NODAGA-pamidronic acid was radiolabeled with 68Ga. The radiolabeling condition was found to be most optimum at a pH ranging from 4 to 4.5 and a temperature of above 60 °C. From previous work, we found that the pamidronic acid itself has a good bone binding affinity. Moreover, from the analysis of the results, the ionic structure of radiolabeled [68Ga]Ga-NODAGA-pamidronic acid has the ability to improve the blood clearance and may exert good renal excretion, enhance the bone-to-background ratio, and consequently the final image quality. This was reflected by both the in vitro bone binding assay and in vivo animal biodistribution presented in this research.

Acetyl- and O-alkyl- derivatives of ß-mangostin from Garcinia mangostana and their anti-inflammatory activities.

Pure ß-mangostin (1) was isolated from the stem bark of Garcinia mangostana L. One monoacetate (2) and five O-alkylated ß-mangostin derivatives (3-7) were synthesised from ß-mangostin. The structures of these compounds were elucidated and determined using spectroscopic techniques such as 1D NMR and MS. The cytotoxicities and anti-inflammatory activities of these five compounds against RAW cell 264.7 were tested. The structural-activity relationship studies indicated that ß-mangostin showed a significant activity against the LPS-induced RAW cell 264.7, while the acetyl- as well as the O-alkyl- ß-mangostin derivatives did not give good activity. Naturally occurring ß-mangostin demonstrated comparatively better anti-inflammatory activity than its synthetic counterparts.

Isolation and structural modifications of ananixanthone from Calophyllum teysmannii and their cytotoxic activities.

Two naturally occurring xanthones, ananixanthone (1) and ß-mangostin (2), were isolated using column chromatographic method from the n-hexane and methanol extracts of Calophyllum teysmannii, respectively. The major constituent, ananixanthone (1), was subjected to structural modifications via acetylation, methylation and benzylation yielding four new xanthone derivatives, ananixanthone monoacetate (3), ananixanthone diacetate (4), 5-methoxyananixanthone (5) and 5-O-benzylananixanthone (6). Compound 1 together with its four new derivatives were subjected to MTT assay against three cancer cell lines; SNU-1, K562 and LS174T. The results indicated that the parent compound has greater cytotoxicity capabilities against SNU-1 and K562 cell lines with IC50 values of 8.97 ± 0.11 and 2.96 ± 0.06 µg/mL, respectively. Compound 5 on the other hand exhibited better cytotoxicity against LS174T cell line with an IC50 value of 5.76 ± 1.07 µg/mL.