Effects of Panax notoginseng Water Extract on Immune Responses and Digestive Enzymes in White Shrimp Litopenaeus vannamei

**Background:** Litopenaeus vannamei is a commercially important aquaculture species, but disease outbreaks from intensive farming pose sustainability challenges. Chinese herbal medicines offer potential alternatives to antibiotics for disease management. Panax notoginseng is a traditional Chinese herbal medicine with over 200 active substances including saponins, but its effects on shrimp immune responses and digestive enzymes had not been studied.

**Methods:** Shrimp (mean weight 3.8 ± 0.5 g) were acclimated for 7 days and divided into four groups: control (saline) and three PNWE doses (50, 100, 200 μg/g body weight) injected intramuscularly. Immune parameters (THC, DHC, PO activity, RB activity, PR, PI) were measured at 12, 24, 48, 72, 168, and 240 h post-injection. Intestinal digestive enzyme activities (trypsin, chymotrypsin, amylase, lipase) and Vibrio numbers were assessed at the same time points. Hepatopancreas and intestine histopathology was examined at 240 h. Statistical analysis used ANOVA with Duncan's multiple range test (p < 0.05).

**Key Results:** No mortality occurred in any group. From 24–72 h, THC was significantly higher in 100 and 200 μg/g groups vs control (p < 0.05); from 168–240 h, all PNWE doses significantly increased THC (p < 0.05). GC and SGC percentages were significantly higher in all PNWE groups from 24–240 h (p < 0.05), while HC was significantly lower (p < 0.05). RB activity was significantly higher in all PNWE groups from 12–240 h (p < 0.05), with 200 μg/g showing the most significant increase from 72–240 h. PR and PI were significantly higher in all PNWE groups from 12–240 h (p < 0.05). PO activity was significantly higher in all PNWE groups from 12–240 h (p < 0.05). Trypsin activity was significantly higher from 12–72 h in all PNWE groups (p < 0.05), with 50 and 100 μg/g most significant at 12–48 h. Chymotrypsin activity was significantly higher at 12–24 h in all PNWE groups (p < 0.05), with 50 μg/g most significant; from 48–240 h, 100 and 200 μg/g showed the most significant increases. Amylase activity was significantly higher from 12–240 h in all PNWE groups (p < 0.05). Lipase activity was significantly higher only in the 50 μg/g group at 12–24 h (p < 0.05). At 48 h, Vibrio numbers were significantly lower in 100 and 200 μg/g groups (p < 0.05); from 72–240 h, all PNWE doses significantly reduced Vibrio numbers (p < 0.05). No histopathological differences were observed in hepatopancreas or intestine tissues between groups at 240 h.

**Clinical Implications:** PNWE enhances shrimp immunity by increasing haemocyte counts, PO activity, and phagocytosis while improving digestive enzyme activity and reducing intestinal Vibrio without tissue damage. The effective dose for enhancing both immune response and digestive enzyme expression was >100 μg (g shrimp)^−1. PNWE shows potential as an immunomodulator for sustainable shrimp aquaculture, offering an alternative to antibiotics. The active components are likely Panax notoginseng saponins, with the PNWE containing 13.98 ± 2.60 mg/g notoginsenoside R1 and 34.67 ± 5.51 mg/g ginsenoside Rg1.