Novel rotundic acid derivatives: Synthesis, structural characterization and in vitro antitumor activity

Efficacy of Rotundic Acid and Its Derivatives as Promising Natural Anticancer Triterpenoids: A Literature-Based Study

Rotundic acid (RA) is a naturally occurring pentacyclic triterpene with a multitude of pharmacological activities. The primary emphasis of this study is on summarizing the anticancer properties with the underlying mechanisms of RA and its derivatives, as well as the pharmacokinetic features. Data was collected (up to date as of November 10, 2023) from various reliable and authentic literatures by searching in different academic search engines, including PubMed, Springer Link, Scopus, Wiley Online, Web of Science, ScienceDirect, and Google Scholar. The findings imply that RA and its synthetic derivatives possess promising anti-cancer properties against breast, colorectal, liver, and cervical cancers in various preclinical pharmacological test systems. The results also indicate that RA and its derivatives demonstrated anticancer effects via a number of cellular mechanisms, including apoptotic cell death, inhibition of oxidative stress, anti-inflammatory effect, cytotoxicity, cell cycle arrest, anti-proliferative effect, anti-angiogenic effect, and inhibition of cancer cell migration and invasion. It has been proposed that RA and its derived compounds have the capability to serve as a hopeful chemotherapeutic agent, so further extensive clinical research is necessary.

Absolute bioavailability, dose proportionality, and tissue distribution of rotundic acid in rats based on validated LC-QqQ-MS/MS method

Rotundic acid (RA), an ursane-type pentacyclic triterpene acid isolated from the dried barks of Ilex rotunda Thunb. (Aquifoliaceae), possesses diverse bioactivities. To further study its pharmacokinetics, a simple and sensitive liquid chromatography with triple quadrupole mass spectrometry (LC-QqQ-MS/MS) method was developed and validated to quantify RA concentration in rat plasma and tissue using etofesalamide as an internal standard (IS). Plasma and tissue samples were subjected to one-step protein precipitation. Chromatographic separation was achieved on a ZORBAX Eclipse XDB-C₁₈ column (4.6 mm × 50 mm, 5 μm) under gradient conditions with eluents of methanol:acetonitrile (1:1, V/V) and 5 mM ammonium formate:methanol (9:1, V/V) at 0.5 mL/min. Multiple reaction monitoring transitions were performed at m/z 487.30 → 437.30 for RA and m/z 256.10 → 227.10 for IS in the negative mode. The developed LC-QqQ-MS/MS method exhibited good linearity (2–500 ng/mL) and was fully validated in accordance with U.S. Food and Drug Administration bioanalytical guidelines. Dose proportionality and bioavailability in rats were determined by comparing pharmacokinetic data after single oral (10, 20, and 40 mg/kg) and intravenous (10 mg/kg) administration of RA. Tissue distribution was studied following oral administration at 20 mg/kg. The results showed that the absolute bioavailability of RA after administration at different doses ranged from 16.1% to 19.4%. RA showed good dose proportionality over a dose range of 10–40 mg/kg. RA was rapidly absorbed in a dose-dependent manner and highly distributed in the liver. In conclusion, this study is the first to systematically elucidate the absorption and distribution characteristics of RA in rats, which can provide additional information for further development and evaluation of RA in drug metabolism and pharmacokinetic studies.

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A simple, rapid, and sensitive LC-QqQ-MS/MS method was developed and validated for RA quantification in rat plasma and tissue.

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Absolute bioavailability of RA was calculated to range from 16.1% to 19.4%.

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Dose proportionality and tissue distribution of RA were assessed for in rats.

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RA showed good dose proportionality over a dose range of 10–40 mg/kg.

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RA was rapidly and extensively distributed and exhibited the highest concentration in the liver after oral administration.

Design, synthesis and evaluation of antitumor activity of new rotundic acid acylhydrazone derivatives

In light of the important antitumor activity of acylhydrazone compounds and based on our previous study, 18 new rotundic acid (RA) acylhydrazone derivatives were synthesized. All of the compounds were characterized by their spectroscopic data. The antiproliferative activity of the compounds was evaluated in vitro via the MTT method in three tumor cell lines, including A-375 (human malignant melanoma cells), SPC-A1 (human lung adenocarcinoma) and NCI-H446 (small cell lung cancer). The results showed that the antiproliferative activity of all of the compounds on the NCI-H446 cell line did not increase compared to RA, however, most of the derivatives exhibited higher activity against the A375 and SPC-A1 cell lines as compared to RA. Importantly, the antiproliferative activities of compounds 5a and 5b were the highest among the compounds, with IC50 values <10 μM. Collectively, compounds 5a and 5b may act as potential anti-tumor agents in the future.

Anti-Diabetic Effects of Madecassic Acid and Rotundic Acid

Anti-diabetic effects of madecassic acid (MEA) and rotundic acid (RA) were examined. MEA or RA at 0.05% or 0.1% was supplied to diabetic mice for six weeks. The intake of MEA, not RA, dose-dependently lowered plasma glucose level and increased plasma insulin level. MEA, not RA, intake dose-dependently reduced plasminogen activator inhibitor-1 activity and fibrinogen level; as well as restored antithrombin-III and protein C activities in plasma of diabetic mice. MEA or RA intake decreased triglyceride and cholesterol levels in plasma and liver. Histological data agreed that MEA or RA intake lowered hepatic lipid droplets, determined by ORO stain. MEA intake dose-dependently declined reactive oxygen species (ROS) and oxidized glutathione levels, increased glutathione content and maintained the activity of glutathione reductase and catalase in the heart and kidneys of diabetic mice. MEA intake dose-dependently reduced interleukin (IL)-1β, IL-6, tumor necrosis factor-α and monocyte chemoattractant protein-1 levels in the heart and kidneys of diabetic mice. RA intake at 0.1% declined cardiac and renal levels of these inflammatory factors. These data indicated that MEA improved glycemic control and hemostatic imbalance, lowered lipid accumulation, and attenuated oxidative and inflammatory stress in diabetic mice. Thus, madecassic acid could be considered as an anti-diabetic agent.