Comparative Analysis of Lespedeza Species: Traditional Uses and Biological Activity of the Fabaceae Family

With around 40 species spread throughout temperate and subtropical environments, mostly in East Asia and North America, the genus Lespedeza (Fabaceae) includes a variety of species that have been used in traditional folk medicine for centuries. Particularly in antioxidant, anti-inflammatory, anticancer, and antidiabetic applications, Lespedeza species show notable pharmacological promise, due in large part to their high polyphenolic content. With a 2,2-diphenyl-1-picrylhydrazyl (DPPH) IC50 of 20–25 µg/mL and a ferric ion reducing antioxidant power (FRAP) value of 819.5 µmol Fe2+/g, L. cuneata demonstrated the highest antioxidant activity among the three Lespedeza species. The rich polyphenolic profile includes quercetin, catechin, rutin, and special substances like lespeflorin B/C and lespecunioside A/B, which explain its efficacy. Its broad-spectrum action across DPPH, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and nitric oxide (NO) tests points to its importance for neuroprotective and anti-aging uses. Anti-inflammatory studies support its capacity to downregulate tumor necrosis factor (TNF-α) and interleukin 6 (IL-6) via nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) suppression. L. bicolor has shown excellent promise, owing to its high total flavonoid content (109.2 mg QE/g) and presence of bioactives including kaempferol-3-O-rutinoside and xanthoangelol, albeit displaying somewhat lower antioxidant capacity (FRAP: 912.3 µmol Fe2+/g). In macrophage models it showed clear anti-inflammatory action. Its capacity to prevent advanced glycation end products’ (AGEs) generation ties it to possible antidiabetic and antiaging effects. Although it showed the worst antioxidant profile (IC50: 40–60 µg/mL; FRAP: 743.2 µmol Fe2+/g), L. capitata nonetheless had useful components like quercetin, chlorogenic acid, and lespedecapitoside (syn. isoorientin). Though little researched, they have modest antioxidant, nephroprotective, and anti-inflammatory action.