Di Gu Pi (Lycium chinense bark)

Di Gu Pi (Lycium chinense Miller root bark) is not consumed as a macronutrient source and has negligible caloric, protein, fat, and carbohydrate value at typical medicinal doses (6–15 g dried bark per decoction). Its therapeutic relevance derives from its bioactive compound profile: **Alkaloids:** Kukoamine A and Kukoamine B (spermine alkaloids, approximately 0.02–0.08% w/w of dried bark), which contribute to antihypertensive and antioxidant activity. Betaine (trimethylglycine, ~0.1–0.5% w/w) supports hepatoprotective and osmoregulatory functions. **Steroids/Terpenoids:** Melianodiols and related limonoids have been identified; cyclic peptides including lyciumins (trace amounts) exhibit ACE-inhibitory activity. **Phenolic compounds:** Contains phenolic acids including chlorogenic acid (~0.05–0.2% w/w), caffeic acid, and p-coumaric acid, contributing to antioxidant capacity. Flavonoids including linarin and acacetin glycosides are present in small concentrations (~0.01–0.05% w/w). **Organic acids:** Cinnamic acid derivatives and ferulic acid contribute to anti-inflammatory effects. **Minerals (trace):** Contains small amounts of zinc (Zn), iron (Fe), calcium (Ca), and potassium (K), though quantities are modest at medicinal doses (e.g., Ca ~200–400 mg/100g dry weight, K ~500–900 mg/100g dry weight, Fe ~5–15 mg/100g dry weight — values vary with soil and cultivation conditions). **Polysaccharides:** Water-soluble polysaccharides (LBPs-related root bark polysaccharides, ~2–5% w/w) with potential immunomodulatory activity. **Vitamins:** Trace amounts of B-vitamins; not a significant source at standard doses. **Bioavailability notes:** Kukoamines are water-soluble and moderately bioavailable via oral decoction; however, they are susceptible to enzymatic degradation in the GI tract. Betaine is highly bioavailable orally. Polysaccharides are poorly absorbed intact but exert prebiotic and immunomodulatory effects via gut-associated lymphoid tissue (GALT). Phenolic acids have moderate oral bioavailability (~10–30%) improved by co-administration in decoction form. Traditional preparation as a water decoction (煎剂) enhances extraction of polar compounds (alkaloids, betaine, polysaccharides) while limiting non-polar terpenoid recovery.