Background: Growing consumer and regulatory concern over synthetic azo and coal-tar dyes in lip cosmetics has renewed interest in botanical colorants with intrinsic bioactivity. Clitoria ternatea (butterfly pea) flowers accumulate an unusually pH-stable family of polyacylated delphinidin glycosides, ternatins, that combine vivid colour with documented antioxidant activity, yet their deliberate use as a primary colourant in lipstick has received little systematic investigation.

Methods: Three fusion-cast lipstick formulations (F1–F3) containing 5%, 10%, and 15% w/w C. ternatea flower extract in a conventional wax–oil base were developed, with 0.5% w/w citric acid incorporated to lower the microenvironmental pH and shift the ternatin pigments from their native blue-violet hue toward a lipstick-appropriate pink-rose through stabilisation of the flavylium cation. Formulations were characterised for colour behaviour, pH, hardness, melting range, spreadability, DPPH radical-scavenging activity, and 90-day accelerated stability (40 °C ± 2 °C / 75% RH ± 5%) of the optimised batch.

Results: All formulations displayed pharmacopoeially acceptable hardness (280–395 g), melting behaviour (58–68 °C), and spreadability, with citric acid reproducibly shifting pH from 5.8–6.3 to 3.8–4.2 and colour from blue-violet to pink-rose without loss of structural integrity. One-way ANOVA confirmed that extract concentration had a statistically significant effect on every physicochemical and antioxidant parameter examined (p < 0.01 in all cases), and Tukey’s HSD post-hoc test showed that the majority of pairwise formulation differences were individually significant. F2 (10% extract) offered the best overall balance of texture, hardness, and spreadability, and exhibited concentration-dependent DPPH scavenging (IC50 = 48.7 µg/mL). Accelerated stability testing of F2 showed less than 9% anthocyanin loss and only minor pH and hardness drift over 90 days.

Conclusion: C. ternatea anthocyanins, deployed with a citric-acid pH-shifting strategy, constitute a viable and statistically validated natural colorant for lip cosmetics that additionally confers antioxidant benefit, supporting their development as a clean-label alternative to synthetic lip pigments, pending confirmatory chromatographic standardisation and dedicated dermal safety evaluation as outlined in Sections 4 and 6.

KEYWORDS: Clitoria Ternatea, Butterfly Pea Flower, Ternatin Anthocyanins, Natural Cosmetic Colorant, Herbal Lipstick, DPPH Antioxidant Activity, One-way ANOVA.