Antimicrobial preservatives are substances that are added into formulation or product to prevent microbial spoilage and thus, prolong the product shelf-life. Our preliminary study indicated ethanolic extract of Syzygium malaccense leaf (SmL) exhibited antimicrobial activity via the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) test. SmL was then incorporated into a formulated topical application product before being subjected to a preservative efficacy test. Microbial preservative efficacy of SmL at 0.25% (w/v) and 0.5% (w/v) were evaluated against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans for the duration of 28 days. Euxyl-K300 (0.5%, w/v)), a synthetic chemical preservative was used as positive control in the study. The preservative efficacy study showed that both the 0.25% (w/v) and 0.5 % (w/v) of SmL exhibited inhibitory activity against S. aureus on the 7 day and against C. albicans on the 21 day. The SmL has the potential to be developed as antimicrobial preservative agent in the topical application products.

Backhousia citriodora commonly known as lemon myrtle belongs to Myrtaceae family. This species is an evergreen tree which can grow up to 30 meters. Lemon myrtle is highly aromatic, having an exquisite flavour and aroma of a blend of lemongrass, lime and lemon. The leaf and flowers are used in tea blends and beverages, dairy, biscuits, breads, confectionery, pasta, syrups, liqueurs, flavoured oils, dipping and simmer sauces. In our study, the chemical composition and antioxidant properties of the lemon myrtle volatile oil obtained via hydro distillation were investigated. Examination by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) analysis showed that the volatile oil obtained from the leaves was made up predominantly neral (39.57%) and geranial (52.43%). Linalool (0.37%), citronellal (0.15%), E-isocitral (2.47%), geraniol (0.66%), ethyl geranate (0.13%), caryophyllene (0.08%) and spathulenol (0.09%) were the other component present in significant amounts. For the stem part, similarly the major components also are neral (36.76%) and geranial (56.30%). Other minor components found in stem oil were 6-methyl-5-hepten-2-one (0.13%), linolool (0.24%), citronellal (0.09%), trans-paramentha-2,8-dien-1-ol (0.39%), E-isocitral (0.92%), (3Z)-hexenyl-(3Z)-hexenoate (0.22%), 8-hydroxy-neo-menthol (1.17%), (E)-α-Damascene 0.70%), spathulenol (0.17%) and globulol (0.14%). The obtained volatile oils were screen for the antioxidant properties by using DPPH (1,2-diphenyl-2-picryl-hydrazyl) radical scavenging assay and xanthine/xanthine oxidase superoxide scavenging assay. Our study indicated both the lemon myrtle leaf and stem volatile oil showed high antioxidant properties. DPPH scavenging activity for both the leaf and stem parts are 83.72% and 84.46% respectively. As for the xanthine/ xanthine oxidase superoxide scavenging assay, both the lemon myrtle leaf and stem volatile oil showed high superoxide scavenging activity, which are 83.72% and 84.46% respectively.

Preservatives are substances added into product to prevent their premature spoilage. Preservative helps to prolong the product’s shelf life by protecting the product from microbial growth and oxidation process. In this study, the potential of a Piper sp. as preservative for cosmetic products is being investigated. The exploration begins with the screening of major phytochemical groups; flavonoid, steroid, alkaloid, saponin and triterpene. Evaluation of biological activities exhibited the plant possessed antimicrobial property towards two strains of Staphylococcus aureus and free radical scavenging capacity. The minimum inhibitory concentration values (MIC) for both S. aureus ATCC 25923 and S. aureus ATCC 6538 is 2500 mg/mL and 312.5 mg/mL respectively. Free radical scavenging capacity of the plant was determined via Superoxide scavenging assay and DPPH radical scavenging assay and the capacity values are 76.4+0.35% and 59.7+0.75% respectively. Cytotoxicity study was also carried out to determine the safety of Piper sp. where median inhibitory concentration (IC50) value for normal kidney cell lines (Vero) is 62.96 mg/mL and normal liver cell lines (WRL-68) is 69.91mg/mL. The extract of Piper sp. was formulated as cosmetic preservative ingredient especially for topical product. The specification of ingredient’s characteristic and performance were described based on colour, odour, pH value as well the solubility in product formulation and stability at 4°C, room temperature and 40°C.

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