Fu Rong Ye

Working explicitly on Fu Rong Ye, the leaf of Hibiscus mutabilis, and the major herbal component of Fupo Ganmao Granules, the authors used bioassay-guided isolation to obtain tiliroside. It inhibited four influenza A virus strains in MDCK cells with EC50 values of 3.87 to 27.61 micromolar by suppressing viral ribonucleoprotein activity, downregulated cytokine and chemokine expression in A549 cells, and at 800 mg/kg per day protected 50 percent of PR8-infected BALB/c mice from death and improved lung oedema. This is the first identification of the anti-influenza principle of this leaf.

Network pharmacology identified 22 active constituents of the dried leaf extract, with enrichment in inflammatory signalling. In HaCaT keratinocytes the extract reduced UV-induced inflammatory mediators and improved survival. In UV-exposed mice treated transdermally for seven days it reduced dermatitis severity, epidermal and dermal thickening and inflammatory infiltration, lowered MMP-9, TNF-alpha, IL-6, IL-17 and EGFR, and inhibited over-activation of AKT-STAT3. This supports the traditional topical use for burns, mastitis and inflamed skin.

The methanolic leaf extract was partitioned between water, n-butanol and ethyl acetate and fractionated on alpha-glucosidase inhibition. Ferulic acid and caffeic acid were identified as the active constituents and were concentrated in the ethyl acetate fraction, and a validated RP-HPLC-DAD method was developed for quantifying them as standardisation markers. The work is entirely enzymatic; no glycaemic effect was measured in an animal or a person.

The methanol extract of the petals of the cultivar Hibiscus mutabilis 'versicolor' showed allergy-preventive activity in mice sensitised with hen egg-white lysozyme, assayed by the fall in tail-vein blood flow. Bioassay-directed fractionation yielded a new flavonol triglycoside, mutabiloside, with four known flavonols; mutabiloside and quercetin 3-O-[beta-D-xylopyranosyl(1-2)]-beta-D-galactopyranoside had significant activity. The material was petal from a named cultivar, not the leaf that constitutes Fu Rong Ye.

One new and nine known flavonoids were isolated from the FLOWERS, not the leaves, of Hibiscus mutabilis. The new compound at 6.25 micromolar significantly inhibited LPS-induced nitric oxide and TNF-alpha production in RAW264.7 macrophages, outperforming dexamethasone as positive control. Fu Rong Hua (the flower) and Fu Rong Ye (the leaf) are distinct drugs, so this activity should not be attributed to the leaf without further work.