Medicinal Resins of Socotra: Phytochemical Diversity, Biological Activities, Safety, and Evidence Gaps

Socotra (Yemen) is home to several resin-producing plant groups. This review evaluates the phytochemistry, biological activities, and safety of Dracaena cinnabari, Socotran Boswellia, and Commiphora resins, identifies gaps in the available evidence, and distinguishes resin-derived findings from bark-derived evidence. D. cinnabari resin contains homoisoflavans and chalcones, but quantitative data for major phenolics remain insufficient. Resin preparations showed antifungal and radical-scavenging activity in vitro; a resin extract and two chalcone derivatives reduced hepatitis B virus antigen production in culture without establishing antiviral efficacy. A methanolic resin extract was cytotoxic to six oral squamous cell carcinoma lines (half-maximal inhibitory concentration [IC50]: 5.9–19.2 µg/mL). Two rat carcinogenesis protocols reported 14.3% carcinoma incidence at 1000 mg/kg versus 85.7% in carcinogen-only controls. A single study of acute and 28-day oral toxicity provides limited, extract-specific safety data. Boswellia and Commiphora resin chemistry is documented mainly through volatile profiles. B. elongata resin yielded 21 compounds, including boswellic acids, whose presence does not establish pharmacological equivalence to B. serrata or B. sacra; four triterpenoid acids inhibited yeast α-glucosidase (IC50 9.9–56.8 µM), but antidiabetic efficacy was not tested. Most other Boswellia bioactivity data concern bark. (+)-Yangambin accounted for 3.50–9.05% (w/w) of recovered C. ornifolia ethanol extracts. No eligible bioassays of Commiphora resins or human studies were identified. The evidence does not support therapeutic claims.