**Background:** Boesenbergia rotunda (fingerroot) is a plant used in Southeast Asia for culinary and traditional medicinal purposes. Its rhizome extract contains bioactive compounds panduratin A and pinostrobin, which have demonstrated anti-inflammatory, antioxidant, and antiviral activities, including against SARS-CoV-2. However, the extract has limited water solubility, which may mask its toxicity. To address this, a formulation with β-cyclodextrin was developed to improve solubility. This study aimed to evaluate the sub-chronic oral toxicity of this fingerroot extract formulation in Wistar rats over 90 days, following OECD GLP 408 guidelines, to support its development as a phytopharmaceutical for chronic inflammation, particularly long COVID.
**Methods:** The fingerroot extract formulation contained 20 mg of fingerroot extract (with panduratin A 29% w/w and pinostrobin 32% w/w), 40 mg of cyclodextrin, and 40 mg of other diluents per 100 mg. One hundred Wistar rats (50 males, 50 females) were randomly assigned to six groups: vehicle control (distilled water), low dose (25 mg/kg/day), medium dose (50 mg/kg/day), high dose (100 mg/kg/day), control-recovery, and high dose-recovery (each recovery group with 5 males and 5 females observed for 14 additional days). The formulation was administered orally once daily for 90 days. Clinical observations, body weight, feed and water consumption, neurological and motor assessments (including grip strength), and ophthalmological examinations were performed. At the end of the study, blood samples were collected for hematology (RBC, HGB, HCT, MCV, MCH, MCHC, PLT, WBC, and differential) and clinical biochemistry (glucose, BUN, creatinine, uric acid, cholesterol, triglycerides, HDL, LDL, AST, ALT, ALP, total protein, albumin, globulin, electrolytes, T3, T4, TSH). Organs were weighed and examined histopathologically. Statistical analyses used ANOVA with Dunnett's test or Mann-Whitney U test; p < 0.05 was considered significant.
**Key Results:** No mortality or clinical signs of toxicity were observed in any group. Body weight gain was consistent across all groups. Some statistically significant differences in feed and water consumption were noted (e.g., decreased feed consumption in low-dose males and females, increased water consumption in high-dose males and females), but these were transient and not dose-dependent. Neurological assessments showed no consistent abnormalities; occasional reductions in motor activity and hind-limb grip strength in males were not dose-related. Ophthalmological examinations were normal. Clinical biochemistry parameters showed some statistically significant differences (e.g., decreased creatinine in medium- and high-dose males, decreased AST in female treatment groups, increased HDL in all male treatment groups), but all values remained within normal ranges for healthy rats. Hematology revealed a statistically significant increase in white blood cell count in medium- and high-dose groups of both sexes, but again within normal limits. Organ weights were generally comparable across groups; a lower left adrenal weight in high-dose males and an increase in left thyroid/parathyroid weight in high-dose recovery males were considered coincidental. Histopathological findings (e.g., thymus hemorrhage, uterine fluid retention, minimal renal hyaline casts) occurred sporadically across groups, including controls, and were not dose-dependent. The No Observed Adverse Effect Level (NOAEL) was determined to be 100 mg/kg/day.
**Clinical Implications:** This study demonstrates that the fingerroot extract formulation is well-tolerated in rats at doses up to 100 mg/kg/day for 90 days, with no serious adverse effects. The observed changes in white blood cell count and HDL may reflect immunomodulatory and lipid-modulating properties of fingerroot extract, warranting further investigation. The established NOAEL supports the safe use of this formulation in future clinical trials for chronic inflammatory conditions, such as long COVID, where long-term anti-inflammatory therapy is needed. The improved water solubility of the formulation enhances its oral bioavailability and practical administration. These findings contribute to the development of fingerroot extract as a potential phytopharmaceutical with a favorable safety profile.