Phytochemical Analysis, Quantification of Flavonoids and Phenols, and Assessment of Anti-Tubercular Activity of Citrus jambhiri Fruit Peel Extract

Introduction:
Tuberculosis remains a global health challenge, and natural products are being explored as alternative sources for novel therapeutics. Citrus fruit peels, often discarded as waste, are rich in bioactive compounds with potential antimicrobial effects.

Methods:
Preliminary phytochemical screening of the peel extract was performed using standard qualitative tests. Total phenolic content was quantified by the Folin–Ciocalteu method, while total flavonoid content was estimated using the aluminium chloride colorimetric assay. Anti-tubercular activity was evaluated against Mycobacterium tuberculosis H37Rv strain using Microplate Alamar Blue Assay (MABA)], with results expressed as minimum inhibitory concentration (MIC).

Results:
The extract revealed the presence of alkaloids, flavonoids, tannins, phenols, terpenoids, and saponins. Quantitative analysis revealed that the ethyl acetate extract had the highest levels of total phenolic content (7.66 mg gallic acid equivalents per gram) and total flavonoid content (10.76 mg rutin equivalents per gram), suggesting strong antioxidant potential. For anti-tubercular testing, the Microplate Alamar Blue Assay (MABA) was employed—a reliable, colorimetric method for evaluating inhibition of M. tuberculosis. Both extracts exhibited promising activity, with a minimum inhibitory concentration (MIC) of 25 μg/ml, indicating potential anti-TB action.

Conclusion:
Citrus jambhiri fruit peel extract is rich in polyphenols and flavonoids and displays promising anti-tubercular activity. These findings highlight its potential as a natural source of lead molecules for anti-tubercular drug discovery. Further isolation and mechanistic studies are recommended.