Organ-Specific Chemobiology and Translational Readiness of Calotropis gigantea: A Systematic Review of Preclinical Evidence

Abstract

Background. Calotropis gigantea (Apocynaceae) has been investigated for anticancer, antioxidant, anti-inflammatory, wound-healing, antidiabetic, antimicrobial, anti-angiogenic, neuropharmacological and toxicological effects. Interpretation is complicated by differences in plant organ, extraction solvent, chemical composition, experimental model, dose expression and outcome measurement. A biologically meaningful synthesis therefore requires integration of plant organ, extraction polarity, dominant chemotype, mechanism and therapeutic activity.

Objective. To systematically evaluate preclinical pharmacological and toxicological evidence for C. gigantea and determine how plant organ and extraction strategy relate to three major chemobiological pathways: stem-bark cardenolides, leaf/flower flavonoid-rich preparations and latex cysteine proteases.

Methods. The review was conducted in accordance with PRISMA 2020. PubMed/MEDLINE, Scopus, Web of Science and Embase were searched, with supplementary searching of Google Scholar and reference lists. English-language original studies published between 1 January 2005 and 31 December 2025 were eligible. In vitro experimental and biochemical assays, disease-relevant cell systems and animal studies were considered. Animal studies were assessed using the SYRCLE risk-of-bias tool, while in vitro and in silico reports were assessed for experimental identity, concentration-response testing, replication, controls, selectivity and chemical characterization. Certainty was considered using a preclinical adaptation of GRADE. Because of substantial heterogeneity in preparations, models, dose units and outcome definitions, quantitative meta-analysis was not appropriate and synthesis followed SWiM principles. A bibliographic completeness check completed on 14 March 2026 identified one additional eligible root-bark anticancer study.

Results. The search identified 450 records. After removal of 123 duplicates, 327 records underwent title and abstract screening; 241 were excluded. Eighty-six full-text reports were assessed and 65 were excluded, leaving 21 studies for qualitative synthesis. Mid-polar stem-bark fractions provided the most chemically resolved anticancer evidence. CGDCM contained 6.2 mg calotropin per 10 g extract and produced IC50 values of 5.9 microg/mL in HCT116 cells and 44.0 microg/mL in HT-29 cells. Root-bark calotroposides provided an additional chemically resolved anticancer signal, with calotroposides 2, 4 and 5 showing micromolar cytotoxicity against MDA-MB-231 cells. Leaf and flower preparations predominantly supported antioxidant, anti-inflammatory, metabolic and wound-repair effects but were generally less chemically standardized. Latex showed a distinct protein-based profile associated with wound repair and tissue-remodelling biology. Certainty was Low for the stem-bark cytotoxicity/apoptosis cluster and Very low for the other major outcome groups.

Conclusions. C. gigantea is best interpreted as an organ-dependent chemobiological system rather than as a chemically uniform herbal preparation. Stem-bark cardenolides represent the most developed pharmacological axis, although absent pharmacokinetic characterization and inadequate mammalian cardiac-safety assessment currently limit translation. Leaf/flower flavonoids and latex proteases require substantially improved chemical and functional standardization. Future work should prioritize validated analytical markers, normalized dosing, exposure-response relationships, disease-relevant models, pharmacokinetics and safety rather than additional nonspecific screening experiments.