Abstract Exposure to solar ultraviolet (UV) radiation is a major contributing factor to the increasing number of skin cancer cases. Interest has grown to use plant extracts as natural ingredients in cosmetic formulations due to their photoprotective effect, antioxidant and anti-inflammatory activity, as well as other biological activities. The aim of this study was to evaluate the biological activity of two South African plant extracts, Helichrysum odoratissimum (L.) Sweet. and Buddleja saligna Willd., and to successfully incorporate these extracts into sunscreen formulations (o/w emulsions) due to their reported biological activity. Ethanolic extracts were prepared from the leaves and stems of H. odoratissimum and B. saligna and evaluated for their antioxidant activity, mutagenic potential and antiproliferative activity against human dermal fibroblasts (MRHF). The extracts were further characterized using gas chromatography-mass spectrometry (GC-MS). Thereafter, the extracts were incorporated into separate sunscreen formulations to evaluate the in vivo dermal irritancy potential, in vivo sun protection factor, in vitro UVA protection, photostability and long term stability of the formulation, to confirm that by incorporating the extracts, the stability or photoprotective effect of the sunscreen formulation was not reduced and that these formulation were considered safe for topical application. Three separate sunscreen formulations were prepared; the base sunscreen formulation (formulation A), the base sunscreen formulation containing B. saligna (formulation B) and H. odoratissimum (formulation C) respectively. Both extracts showed significant radical scavenging activity using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay with a fifty percent inhibitory concentration (IC50) of 5.13 ± 0.07 and 8.16 ± 0.34 µg/mL for H. odoratissimum and B. saligna respectively. No mutagenic activity was observed when the extracts were tested in the Ames assay using Salmonella typhimurium (TA98 and TA100). The PrestoBlue® cell viability assay was used to determine the antiproliferative activity of the extracts against MRHF cells, both extracts showed an IC50 value >90 µg/mL. Photoprotective activity was measured using in vivo sun protection factor (SPF) test method according to South African (SANS 1557) and International (ISO 24444) standards as well as the in vitro UVA SPF testing procedure (ISO 24443). The SPF results showed that the formulations had broad-spectrum UV protection with SPF values of 15.8±0.41, 16.1±0.66 and 16.0±0.49 and UVAPF values of 6.47±0.06, 6.45±0.06 and 6.47±0.07 for formulation A, B and C respectively. Furthermore, the formulations remained stable under normal and extreme conditions and the plant extracts did not affect the photoprotective effect of the sunscreen formulations and contributed towards the formulations stability. Additionally, each of the formulations were photostable, whereas the formulations with the addition of the extracts showed an incremental increase in photostability when compared to the base formulation. Both these extracts have been previously reported to display antiproliferative activity against skin cancer cell lines (previously published data), with an IC50 value of 31.80 ± 0.35 µg/mL (human malignant melanoma, UCT-MEL-1) for B. saligna and IC50 values of 15.50 ± 0.20 (human epidermoid carcinoma, A431) and 55.50 ± 6.60 µg/mL (human malignant melanoma, A375) for H. odoratissimum, contributing towards the medicinal benefit of using these extracts as ingredients into sunscreen formulations. Therefore, Helichrysum odoratissimum and Buddleja saligna could be considered as useful and viable additives to sunscreen formulations due to their reported biological activity.

中文翻译：

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南非植物 Buddleja saligna Willd 的乙醇提取物。和 Helichrysum odoratissimum (L.) Sweet，作为防晒配方中的多功能成分

摘要 暴露于太阳紫外线 (UV) 辐射是导致皮肤癌病例增加的主要因素。由于植物提取物的光保护作用、抗氧化和抗炎活性以及其他生物活性，人们越来越关注在化妆品配方中使用植物提取物作为天然成分。本研究的目的是评估两种南非植物提取物 Helichrysum odoratissimum (L.) Sweet 的生物活性。和 Buddleja saligna Willd.，并由于它们报道的生物活性而成功地将这些提取物加入防晒配方（o/w 乳液）中。从 H. odoratissimum 和 B. saligna 的叶和茎中制备乙醇提取物，并评估它们的抗氧化活性，对人真皮成纤维细胞 (MRHF) 的诱变潜力和抗增殖活性。使用气相色谱-质谱法 (GC-MS) 进一步表征提取物。此后，将提取物掺入单独的防晒制剂中，以评估制剂的体内皮肤刺激潜力、体内防晒系数、体外 UVA 保护、光稳定性和长期稳定性，以确认通过掺入提取物，稳定性或防晒配方的光保护效果没有降低，并且这些配方被认为可以安全地用于局部应用。制备了三种单独的防晒配方；基础防晒制剂(制剂A)、分别含有B. saligna (制剂B)和H. odoratissimum (制剂C)的基础防晒制剂。两种提取物均使用 2,2-二苯基-1-苦基肼 (DPPH) 测定显示出显着的自由基清除活性，对 H. odoratissimum 和 B. saligna 的 50% 抑制浓度 (IC50) 分别为 5.13 ± 0.07 和 8.16 ± 0.34 µg/mL分别。当使用鼠伤寒沙门氏菌（TA98 和 TA100）在 Ames 测定中测试提取物时，未观察到诱变活性。PrestoBlue® 细胞活力测定用于确定提取物对 MRHF 细胞的抗增殖活性，两种提取物的 IC50 值均 >90 µg/mL。根据南非 (SANS 1557) 和国际 (ISO 24444) 标准以及体外 UVA SPF 测试程序 (ISO 24443)，使用体内防晒因子 (SPF) 测试方法测量光保护活性。SPF结果表明，配方具有广谱紫外线防护，配方A、B和C的SPF值为15.8±0.41、16.1±0.66和16.0±0.49，UVAPF值为6.47±0.06、6.45±0.06和6.47±0.07分别。此外，配方在正常和极端条件下保持稳定，植物提取物不影响防晒配方的光保护效果，有助于配方稳定性。此外，每种配方都是光稳定的，而添加提取物的配方与基础配方相比，光稳定性增加。先前已报道这两种提取物对皮肤癌细胞系具有抗增殖活性（先前公布的数据），IC50 值为 31.80 ± 0。35 µg/mL（人恶性黑色素瘤，UCT-MEL-1）用于 saligna，IC50 值为 15.50 ± 0.20（人表皮样癌，A431）和 55.50 ± 6.60 µg/mL（人恶性黑色素瘤，A375）。 odoratissimum，有助于将这些提取物用作防晒配方成分的药用价值。因此，由于报道的生物活性，蜡菊和佛手柑可以被认为是防晒配方的有用和可行的添加剂。